This paper introduced an extended cohesive damage model (ECDM) for simulating multicrack propagation in fibre composites. The proposed ECDM is developed by introducing a cohesive damage model (CDM) into the eXtended Finite Element Method (XFEM) and eliminating the enriched degree of freedoms (DoFs) to effectively predict multicrack propagation in fibre composites without knowing beforehand the crack paths. A shifted Heaviside function is introduced to approximate existing cracks and crack propagations. A new strain field related cohesive damage law is introduced to describe the behaviour at the crack tip. The proposed ECDM is verified by three fracture test benchmarks and an example of predicting delamination migration together with matrix cracking. This investigation proved that the developed ECDM works very well when compared to analytical and experimental work. This developed ECDM supplies a novel numerical modelling approach for investigating multicrack failure mechanism in fibre composites.

  • Effects of Characteristic Material Lengths on Ductile Crack PropagationE
  • Damage propagation analysis for CFRP laminate by quasi-3D
  • Therefore, the XFEM is used to solve rock displacements in the hydraulic fracturing problem
  • Full text of "Tom Proulx - Experimental and Applied
  • Modeling Environment-Assisted Fatigue Crack PropagationJ

Strain-based models are widely used in the design of structural members made from other construction materials than timber. For reinforced concrete (RC) columns, a strain-based model is suggested in . Up to now, these models have not been common for timber columns since the failure mechanism in timber is influenced by the distinct nonlinear stress-strain relationship, which leads to a more complex calculation procedure. As a consequence, only a few applications for timber structures are reported in literature [18, 19]. Figure 2 shows the calculation procedure when applying the strain-based model. On the left hand side, the calculation of the internal force Ni and the bending moment Mi is illustrated. The calculation starts by selecting values for the strain 0 at the mass centre of the cross-section and for the curvature m. These two parameters define the strain distribution within the whole cross-section, when assuming that plane sections remain plane. Based on the strain distribution, the stress distribution is calculated using the relationship given by the stress-strain curve. Any shape of stress-strain curve can be applied in the calculation. Finally, the internal force Ni and moment Mi are estimated by integrating the stresses over the whole cross-section.


Sample records for nonhermetic encapsulation materials

We relax the assumption of homogeneous media and investigate dynamic shear fracture in heterogeneous media using two-dimensional finite-element simulations and a linear slip-weakening cohesive law. We consider bulk inclusions with contrasting stiffness while preserving constant interface properties. These inclusions have shown to affect the dynamic crack propagation (official site) and, under certain circumstances, to promote supershear transition (Albertini and Kammer 2021).

Table 1: Summary of the available data. Data Bending Tension Total KOA data available 5773 7064 12837 Additional SKA data available 3054 4587 7641 Before we further subdivide the data a short description of the source of the data and the testing procedure is given: Only sawfalling material was used. All data for which single knot values (SKA) are available were tested at Holzforschung Mnchen between 1995 and 2021. The major part of the remaining data was recorded during the Gradewood project finished in 2021. All destructive tests were performed according to EN 408:2021. The factors given in EN 384:2021 (kh-factor, kl-factor) were applied. A symmetrical two point loading was used for the determination of bending strength, usually over a span of 18 times the depth. The orientation of the board in edgewise bending tests was chosen randomly. For tension tests usually a span of 9 times the depth was used. Whenever possible the weakest section along the beam axis was tested.


We encourage you to apply the basic principles of rock mechanics and rock engineering to all potentially complex analyses, as most of the trends in rock behaviour can be predicted from basic principles. The type of approach illustrated by the list of questions following in Section 20/2 is a good way to begin. It is only when the overall rock behaviour is not clear, or when large numbers of numerical values are required, that more sophisticated analyses should be implemented. Accordingly, we concentrate in this chapter on the application of the basic principles and techniques to a variety of rock engineering circumstances.

Fracture Materials and Structures

The majority of these fatigue cohesive laws employ Paris laws to guide the cohesive crack propagation rate [39, 13, 23, 20]. Beyond this volume, it is sold on a subscription basis, starting at 20, 000 Euros a year. In fact, this failure mode is typical. The discontinuity created by the crack can make re meshing difficult, and extended finite element modeling (XFEM) allows for a crack to propagate without having to re-mesh at each step (Areias and Belytschko. The second topic concerns crack propagation and more especially its physical nature. Quantification of plantar tissue behavior of the heel pad is essential in developing computational models for predictive analysis of preventive treatment options such as footwear for patients with diabetes. The software is free for less than 100, 000 data lines. Morfeo/Crack for Abaqus enhances Abaqus and is capable of performing crack propagation simulations in complex geometries. Furthermore, the remaining limitations and challenges for mesolevel analysis of composite failure are discussed. The following topics are discussed. The VCCT associates the nodal force with displacements around the crack tip. A review of the BRC goals and work scope along with relevant previous research of both flaws and progressive damage models is offered in Chapter 2. In addition, the objectives and research plan are summarized. AND STRUCTURES Fracture of Nano and Engineering Materials and Structures Proceedings of the 16th European Conference of Fracture, Alexandroupolis, Greece, July 3-7, 2020. The model used the extended finite element method (XFEM) combined with a cohesive zone model (CZM) in a two-dimensional.


Keeping MOM: Reaction of biphenyl-3,4',5-tricarboxylate and Cd(NO 3) 2 in the presence of meso-tetra(N-methyl-4-pyridyl)porphine tetratosylate afforded [email protected], a microporous metal–organic material (MOM) that encapsulates cationic porphyrins and solvent in alternating open channels. [email protected] has cation and anion binding sites that facilitate cooperative addition of inorganic salts (such as M +Cl -) in a stoichiometric fashion.

The highly insulating, adhesive and bonding properties of thermosetting epoxies, their ability to be injection moulded in an uncured state, as well as their presence in a wide number of composites, has resulted in their widespread use in both electrical and aerospace applications. There is thus a need to understand the compressive response of epoxies over the range of temperatures likely to be experienced within their working environment. The effects of varying strain rates and temperatures on an epoxy resin (Scotchcast 8) and an epoxy-based syntactic foam (Stycast 1090) were investigated. The samples were studied from -20 °C to +80 °C over a range of strain rates (10-4 - 10+3 s-1). Stress-strain data was obtained, with further analysis from high-speed images. Dynamic Mechanical Analysis (DMA) was also performed on the two materials. Data obtained from these experiments demonstrated key differences in the behaviour of the two materials, forming a basis for comparison with numerical simulations.


The composite material was used as a catalyst for the ethylene hydrogenation reaction and showed catalytic activity at higher temperatures. TEM studies confirmed the changed environment of the nanoparticles at these temperatures.

Efforts were made to use fully bonded and debonded threadbars for dynamic rock support . Differently from the other rockbolts described above, threadbars absorb energies by partially or fully mobilizing the strength and deformation capacities of the bolt steel.


Slovenia: Timber from Slovenia shows extraordinary good strength values and consequently good grading results with low reject rates. Graded using the threshold values based on DIN, the reject rate is as low as 3%. Grading output for tension is presented without precise listing of the results and only for those groups for which no SKA data is available. PINE: Pine tension data with missing SKA data is available from FI, FR, RU and SE. Table 2 shows that there are already big differences in strength properties for the ungraded timber. These differences are reflected in the grading results. For timber from FI and SE the required values are reached. While the yields are close together, Finnish timber shows tensile strength values far above the requirements (26/8 MPa for C30, n=54/ 17/9 MPa for C24-DIN, n=123). Timber from FR and RU shows clearly lower values for the ungraded samples. The grading leads to low yields for timber from RU and to high yields for FR. This results in an almost safe output for RU, while timber from FR fails the strength requirements by far. Grading into C24-BS leads to a characteristic strength of 8/9 MPa (n=105), where 14 MPa is required. SPRUCE: For spruce tested in tension the differences for the ungraded material are small for different sources.

Use of thermoplastic materials as encapsulants in photovoltaic (PV) modules presents a potential concern in terms of high temperature creep, which should be evaluated before thermoplastics are qualified for use in the field. Historically, the issue of creep has been avoided by using thermosetting polymers as encapsulants, such as crosslinked ethylene-co-vinyl acetate (EVA). Because they lack crosslinked networks, however, thermoplastics may be subject to phase transitions and visco-elastic flow at the temperatures and mechanical stresses encountered by modules in the field, creating the potential for a number of reliability and safety issues. Thermoplastic materials investigated in this study include PV-grademore » uncured-EVA (without curing agents and therefore not crosslinked); polyvinyl butyral (PVB); thermoplastic polyurethane (TPU); and three polyolefins (PO), which have been proposed for use as PV encapsulation.


Furthermore, the dynamic process of crack propagation has been analyzed by means of the XFEM. The electrochemical performance of the tin-based composite synthesized by electrostatic spray deposition as an anode material for Li-ion batteries were evaluated by charge-discharge experiments. Fibre reinforced polymers (FRP) are one of the fastest growing materials in advanced structural applications. Even if fracture mechanics was successfully applied to rubber-like materials, some special phenomena are not well-understood. The word extended is added because the method enhances (or extends) crack-propagation simulation capability of the conventional finite elements. Meanwhile, XFEM predictions for crack onset and propagation rely on the stress field which tends to converge at a slower rate than that of displacements, making it challenging to capture critical. INTERNATIONAL COUNCIL FOR RESEARCH AND INNOVATION IN BUILDING AND CONSTRUCTION WORKING COMMISSION W18 - TIMBER STRUCTURES MEETING FORTY-FIVE VXJ. The XFEM results showed the good agreement between crack location and areas of highest principal strain and were able to capture crack propagation and the effect this has on the stress state under punching failure. Both two- and three-dimensional models are studied. When material elements are pulled apart, separation will take place across a cohesive zone, and the pulling effect will be resisted by cohesive tractions. The methodology simulates microcrack initiation and propagation using the extended finite element method (XFEM) and delamination using a mixed-mode cohesive zone model. An alternate method, based on using an experimental defect. Fluid ALE mesh motion propagation from boundary to volume often creates significant and some time critical mesh distortion in presence of large structural deformation. Accelerated corrosion will take place Corrosion begins to affect rebars buried further within.

An encapsulant material includes a layer of metallocene polyethylene disposed between two layers of ionomer. More specifically, the layer of metallocene polyethylene is disposed adjacent a rear surface of the first ionomer layer, and a second layer of ionomer is disposed adjacent a rear surface of the layer of metallocene polyethylene. The encapsulant material can be used in solar cell module and laminated glass applications.


It provides state of the art techniques and algorithms for fracture analysis of structures including numeric examples at the end of each chapter as well as an accompanying website which will include MATLAB resources, executables, data files, and simulation. The analytical technique develops the regularized extended finite element method for the simulation of matrix crack initiation and propagation. NOTES Block Shear - H J Larsen Single Shearing Properties on Various Types of Screwed Joints Tested According to ISO16670 - K Kobayashi, M Yasumura Failure Criteria for Post-tensioned Timber Beams - W van Beerschoten, A Palermo, D Carradine, A Buchanan Some comments on CIB-W18 paper 45-102-1 by J. Khler, R. Steiger, G. Fink and R. Jockwer - T Poutanen The withdrawal strength of 8 threaded. Fries and M. Baydoun May, Abstract A method for two and three dimensional crack propagation is presented which. Crack propagation criteria in three dimensions using the XFEM and an explicit{implicit crack description M. Baydoun1, T. P. Fries2 1 Aachen Institute of Computational Engineering Sciences, RWTH Aachen, Germany. The model consists of elastic phase inclusions in elastic-plastic metal matrix as shown in. In the original x-FEM formulation, degrees of. Journal Article: Initiation and propagation of delamination in a centrally notched composite laminate. The x-FEM-based techniques have seen rapid development in the past decade and have recently been applied to strength prediction in composite laminates. Full Cord Bluegrass Podcasts. In this article, a method to. XFEM is an extension of the conventional finite element method, with the difference being that it allows the presence of discontinuities in an element by enriching degrees of freedom with special displacement. Examples of these could be: curved sections, drop-offs, free edges, among others.

This volume contains two-page abstracts of the 698 papers presented at the “16th European Conference of Fracture,” (ECF16) held in Alexandroupolis, Greece, July 3-7, 2006. The accompanying CD attached at the back cover of the book contains the full length papers. The abstracts of the fifteen plenary lectures are included in the beginning of the book. The remaining 683 abstracts are arranged in 25 tracks and 35 special symposia/sessions with 303 and 380 abstracts, respectively. The papers of the tracks have been contributed from open call, while the papers of the symposia/sessions have been solicited by the respective organizers. Both tracks and symposia/sessions fall into two categories, namely, fracture of nanomaterials and structures and engineering materials and structures with 88 and 595 papers, respectively. Started in 1976, the European Conference of Fracture (ECF) takes place every two years in a European country. Its scope is to promote world-wide cooperation among scientists and engineers concerned with fracture and fatigue of solids. ECF16 was under the auspices of the European Structural Integrity Society (ESIS) and was sponsored by the American Society of Testing and Materials, the British Society for Stain Measurement, the Society of Experimental Mechanics, the Italian Society for Experimental Mechanics, and the Japanese Society of Mechanical Engineers. ECF16 focused in all aspects of structural integrity with the objective of improving the safety and performance of engineering structures, components, systems and their associated materials.


The effects of laminate lay-up, joint geometry, hole size and bolt clamp-up torque were considered

Through an Air Force Research Laboratory sponsored STM program, reliable, low-cost, low-weight, non-hermetic coatings for multi-chip-module(MCK applications were developed. Using the combination of Sandia Laboratory ATC-01 test chips, AvanTeco's moisture sensor chips(MSC's), and silicon slices, we have shown that organic and organic/inorganic overcoatings are reliable and practical non-hermetic moisture and oxidation barriers. The use of the MSC and unpassivated ATC-01 test chips provided rapid test results and comparison of moisture barrier quality of the overcoatings. The organic coatings studied were Parylene and Cyclotene. The inorganic coatings were Al2O3 and SiO2. The choice of coating(s) is dependent on the environment that the device(s) will be exposed to. We have defined four(4) classes of environments: Class I(moderate temperature/moderate humidity). Class H(high temperature/moderate humidity). Class III(moderate temperature/high humidity). Class IV(high temperature/high humidity). By subjecting the components to adhesion, FTIR, temperature-humidity(TH), pressure cooker(PCT), and electrical tests, we have determined that it is possible to reduce failures 50-70% for organic/inorganic coated components compared to organic coated components.

The potentially useful encapsulating materials for Task 3 of the Low-Cost Silicon Solar Array project were studied to identify, evaluate, and recommend encapsulant materials and processes for the production of cost-effective, long-life solar cell modules. Materials for study were chosen on the basis of existing knowledge of generic chemical types having high resistance to environmental weathering. The materials varied from rubbers to thermoplastics and presented a broad range of mechanical properties and processing requirements. Basic physical and optical properties were measured on the polymers and were redetermined after exposure to indoor artificial accelerated aging conditions covering four time periods. Strengths and weaknesses of the various materials were revealed and data was accumulated for the development of predictive methodologies. To date, silicone rubbers, fluorocarbons, and acrylic polymers appear to have the most promising combination of characteristics. The fluorocarbons may be used only as films, however, because of their high cost.


Riberholt H (2008): European spruce - Picea abies - graded by Chinese visual rules. Technical University of Denmark, Department of Civil Engineering. BYG Rapport (ISBN: 978-8-77877-25-72).

Baker's yeast (BY) encapsulated in silica materials was synthesized using a yeast cell suspension and its cell-free extract during a sol-gel reaction of tetramethoxysilane with nitric acid as a catalyst. The synthesized samples were fully characterized using various methods, such as scanning electron microscopy, nitrogen adsorption-desorption, Fourier transform infrared spectroscopy, thermogravimetry, and differential thermal analysis. The BY cells were easily encapsulated inside silica-gel networks, and the ratio of the cells in the silica gel was approximately 75 wt%, which indicated that a large volume of BY was trapped with a small amount of silica. The enzyme activity (asymmetric reduction of prochiral ketones) of BY and its cell-free extract encapsulated in silica gel was investigated in detail. The activities and enantioselectivities of free and encapsulated BY were similar to those of acetophenone and its fluorine derivatives, which indicated that the conformation structure of BY enzymes inside silica-gel networks did not change. In addition, the encapsulated BY exhibited considerably better solvent (methanol) stability and recyclability compared to free BY solution. We expect that the development of BY encapsulated in sol-gel silica materials will significantly impact the industrial-scale advancement of high-efficiency and low-cost biocatalysts for the synthesis of valuable chiral alcohols.


Influence of stacking sequence on leakage characteristics through CFRP composite laminates

These profiles are tailored on spruce data, knowing that other softwood species may have other relationships. The name is a combination out of "C" for conferious and combined with a "T" for tension. The proposal links the tensile strength classes to the bending strength classes in EN 338 based on E. For the same E, the tensile strength of the proposal is slightly higher than given in the C classes. This finding is supported by EN 338 itself: The relationship of characteristic tensile strength to characteristic bending strength is fixed with 0/6 on the safe side. Therefore, this equation is only valid if tensile strength is calculated out of given bending strength values, and not vice versa. In reality, this relationship is assumed to be higher. In the proposal the relationship developed with the data is approximately 0/64. The relationship between mean E in tension and characteristic density is not too different from EN 338. For the high strength classes, the proposal slightly reduces the density values. This is based on the test data especially from Northern and Eastern Europe.

Terrafore successfully demonstrated and optimized the manufacturing of capsules containing phase-changing inorganic salts. The phase change was used to store thermal energy collected from a concentrating solar-power plant as latent heat. This latent heat, in addition to sensible heat increased the energy density (energy stored per unit weight of salt) by over 50%, thus requiring 40% less salt and over 60% less capsule container. Therefore, the cost to store high-temperature thermal energy collected in a concentrating solar power plant will be reduced by almost 40% or more, as compared to conventional two-tank, sensible-only storage systems. The cost for thermal energymore » storage (TES) system is expected to achieve the Sun Shot goal of $15 per kWh(t). Costs associated with poor heat-transfer in phase change materials (PCM) were also eliminated. Although thermal energy storage that relies on the latent heat of fusion of PCM improves energy density by as much as 50%, upon energy discharge the salt freezes and builds on the heat transfer surfaces. Since these salts have low thermal conductivity, large heat-transfer areas, or larger conventional heat-exchangers are needed, which increases costs. By encapsulating PCM in small capsules we have increased the heat transfer area per unit volume of salt and brought the heat transfer fluid in direct contact with the capsules. These two improvements have increased the heat transfer coefficient and boosted heat transfer.


Key Words: XFEM, 3D crack propagation, bone fracture, hydraulic fracturing. In this paper, nonlinear vibration techniques are applied to investigate stages of progressive damage in RC beams induced by static loading tests. SIMULIA Community Conference 0.1 1 10 1 10 100 1000 10000 100000 1000000. The XFEM methodology for a 2D delamination crack was demonstrated in Phase I. In order to investigate interfacial mechanics of SiC-based multi-layer low. The changes in resonant frequency with increasing loads are examined along with the nonlinear vibration characteristics. Motamedi and Mohammadi 33 did the dynamic analysis to laminates with XFEM. Morfeo/Crack for Abaqus is built upon the implementation of XFEM available in Abaqus since version The functionality of Abaqus for SIF computation is however limited to the calculation of stationary cracks. Reinforced concrete (RC) structures are subject to microcrack initiation and propagation at load levels far below the actual failure load. In this type of Paris-law based fatigue CZM formulations, the CZMs are. Recently, an exciting new paradigm of CMCs based on the use of three-dimension fiber reinforcement that enables functionality in heat exchange, transpiration, detailed shape, and thermal strain management that significantly exceeds the prior art. This approach is predicated on the random distribution of laminate strength within the finite element model of the laminate. I know i should use Direct Cyclic. At extreme occasions, the mechanical stress even counterbalances the chemical driving force and causes staganation of the reaction front, as shown in the right panel of the figure.

Classes above C20 can definitely not be reached for Sitka spruce from the UK. NF: Using absolute knot values as grading criteria is unique within the analysed standards. This is also one reason why the yields in C30 are low compared to the other standards. The effectiveness of this method can certainly not be shown by the resulting characteristic values. The resulting bending strength for C24 is 20/5 MPa, while 21/1 MPa is reached for C18. Hence this standard does not seem applicable for grading Central European timber. SIA: Knots in the SIA are measured at right angles to the length of the pieces, which is comparable to other grading standards. Extreme threshold values lead to extremely high reject rates. A ratio of 1/3 for the single knot is the value which leads to a rejection of the piece. Single knots of that size are still allowed according to the INSTA where, as edge knots they are graded into C30. The practical use of a standard with reject rates between 65 % and 83 % does not seem logical.

Xfem crack propagation abaqus
1 Xfem crack growth abaqus 100%
2 Stationary xfem crack abaqus 86%
3 Xfem fatigue crack growth mechanism 27%
4 Crack only motogp 08 33%
5 Madden 08 pc cracked 43%
6 Nba live 08 cracked 8%
7 Crack game motogp 08 11%
8 Full crack motogp 08 36%
9 Crack propagation analysis abaqus 1%
10 Fatigue crack propagation abaqus 52%

The species comprised only Norway spruce (Picea abies), European Silver fir (Abies alba) and Scots pine (Pinus sylvestris). Other softwoods have not been considered. Norway spruce and European Silver fir are analysed together in the following as European Silver fir only comprises a small amount of pieces.


This strip, then, is discretized using a FD scheme in space and time while the virtual boundaries of the strip are handled using the SBI formulation that represents the two elastic half spaces outside the strip. Modeling the elastodynamic response in these two halfspaces is carried out by an Independent Spectral Formulation before joining them to the strip with the appropriate boundary conditions. Dirichlet and Neumann boundary conditions are imposed on the strip and the two half-spaces, respectively, at each time step to propagate the solution forward. We illustrate that this implementation provides an exact truncation of the wave field in the near field and provides an exact absorbing boundary condition for the discretized bulk. We further demonstrate the accuracy and efficiency of the method using several examples and demonstrate the coupling using both explicit and implicit schemes.

Lithium-rich materials represented by xLi2MnO3·(1 - x)LiMO2 (M = Mn, Co, Ni) are attractive cathode materials for lithium-ion battery due to their high specific energy and low cost. However, some drawbacks of these materials such as poor cycle and rate capability remain to be addressed before applications. In this study, a thin polyimide (PI) layer is coated on the surface of Li1/2Ni0/13Mn0/54Co0/13O2 (LNMCO) by a polyamic acid (PAA) precursor with subsequently thermal imidization process. X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HR-TEM) results confirm the successful formation of a PI layer (∼3 nm) on the surface of LNMCO without destruction of its main structure. X-ray photoelectron spectroscopy (XPS) spectra show a slight shift of the Mn valence state from Mn(IV) to Mn(III) in the PI-LNMCO treated at 450 °C, elucidating that charge transfer takes place between the PI layer and LNMCO surface. Electrochemical performances of LNMCO including cyclic stability and rate capability are evidently improved by coating a PI nanolayer, which effectively separates the cathode material from the electrolyte and stabilizes their interface at high voltage.


All these issues are addressed in this presentation with new concepts and new methods. Specifically, accuracy verification with the classical continuum solutions is developed after handling two types of data with one being continuous and the other is point-wise. The basic issue for improving the existing multiscale scheme is addressed by an extension of the GP method in which the model inner region consists of core atomistic region surrounded by several succeeding higher scales of particles. Since FE nodes are connected only with the outmost particles where the deformation gradient is smooth the extended GP can avoid artificial effects on the most interesting atomic regions. This is quite different from the quasicontinuum (QC) and other direct coupling methods which directly connect FE nodes with atoms. This new method are confirmed with analytical solutions of an edge-crack in a two dimensional plate.

Low temperature synthesis of monolithic transparent Ta2O5 gels from hydrolysis of metal alkoxide. NOTES Block Shear - H J Larsen Single Shearing Properties on Various Types of Screwed Joints Tested According to ISO16670 - K Kobayashi, M Yasumura Failure Criteria for Post-tensioned Timber Beams - W van Beerschoten, A Palermo, D Carradine, A Buchanan Some comments on CIB-W18 paper 45-102-1 by J. Khler, R. Steiger, G. Fink and R. Jockwer - T. About twenty clients have already been won over. There will also be a short hands-on demonstration using Abaqus. The beam model is studied under different dynamic excitations, including sine sweep and single excitation frequency, for various damage levels. The progression of damage in composite laminates is influenced by the interactions of several failure/damage mechanisms including matrix cracking, fibre breakage, splitting and delamination. A two-dimensional discontinuity representation by two implicit functions f(x) and g(x, t)decomposition of the function into its continuous and. For wave propagation described in terms of the magnetic field in the widely used class of non-magnetic materials, the divergence-free condition is imposed on the magnetic field. The structural model is based on the first-order shear deformable laminated beam theory and moving mesh strategy developed in the framework of Arbitrary Lagrangian–Eulerian (ALE) formulation. Finite Element Method or XFEM is a revolutionary technique in the field of fracture mechanics since it lets one model a propagating crack without use of a focused mesh and without any previous knowledge of crack location. When wave propagation is described using the electric field, the divergence-free condition must be imposed. BEGIN: VCALENDAR VERSION: 2.0 PRODID -//CERN//INDICO//EN BEGIN: VEVENT SUMMARY: Trapped field property of iron-pnictide bulk magnet DTSTART; VALUE=DATE-TIME. The UBC Composite Damage Model (CODAM) is a sub-laminate based model that is designed to simulate the. The Weibull distribution is adjusted to account for specimen volume, allowing mesh independent crack density predictions.


Modelling of permeation and damage in graphite/epoxy laminates for cryogenic fuel storage

A single-step synthesis route is described for the preparation of a metal-polymer composite in which palladium acetate and meta-amino benzoic acid were used as the precursors for palladium nanoparticles and poly(meta-amino benzoic acid) (PABA). The palladium nanoparticles were found to be uniformly dispersed and highly stabilized throughout the macromolecule matrix.

This is related to the knots, usually not reaching values of above 0/5 (DEK and tKAR) as can be seen in Figure 3. Downgrading of boards into C24 is not accurate enough. However, strength values for C24-BS are high compared to the smaller cross-sections, as the larger cross-sections lead to a homogenization of the material. Trying to assign higher classes than C24 according to BS rules would also cause problems. Considering absolute knot sizes like in EN 1310 could help to obtain higher strength values for larger timber dimensions. Actually, the NF which uses EN 1310, reaches the required values for larger thicknesses. Unfortunately in this case the yields are very poor. For strength classes above C24 there should be limitations on the size of the specimens. Disregarding the cross-section for the allocation of national grades to C-Classes is not justified according to these results. SKA BS: The assignments based on the BS standard are safe. The main reason for this is that C 24 is the highest possible grade.


For any piece of hardware that degrades when subject to environmental and application stresses, the route or sequence that describes the degradation process may be summarized in terms of six key words: LOADS, RESPONSE, CHANGE, DAMAGE, FAILURE, and PENALTY. Applied to photovoltaic modules, these six factors form the core outline of an expanded failure analysis matrix for unifying and integrating relevant material degradation data and analyses. An important feature of this approach is the deliberate differentiation between factors such as CHANGE, DAMAGE, and FAILURE. The application of this outline to materials degradation research facilitates the distinction between quantifying material property changes and quantifying module damage or power loss with their economic consequences. The approach recommended for relating material stability data to photovoltaic module life is to use the degree of DAMAGE to (1) optical coupling, (2) encapsulant package integrity, (3) PV circuit integrity or (4) electrical isolation as the quantitative criterion for assessing module potential service life rather than simply using module power loss.

To use timber as best as possible, the relationship of characteristic tensile strength, mean E in tension and characteristic density should follow reality as good as possible. If inadequate relationships are used for the derivation of strength classes, the grading is mainly based on the most critical property, whereas the other two can be easily fulfilled.


The permeability of modelled laminates is also compared to previously measured leak rates from test specimens

Encapsulant materials and processes for the production of cost effective, long life solar cell modules are identified, and evaluated. Ethylene vinyl acetate lamination pottant studies are conducted with respect to the time/temperature cure requirements for successful use of this compound. The time needed to produce successful gel contents are redetermined at a variety of temperatures and are related to the peroxide half life temperature curve. Formulation of the butyl acrylate syrup casting pottant is complete. The formulation contains an ultraviolet stabilizer system and is cured with an initiator that presents no shipping or handling hazards. The catalyzed syrup is stable at room temperature and has a pot life of at least an eight hour period of time. The syrup cures to a transparent rubber in 18 minutes at a temperature of 60 C.

An XFEM-based methodology for fatigue delamination and

In the above, we have discussed the possible mechanism of oil recovery by seismic stimulation. However, another important issue is how to transfer the vibration energy from the source to the oil-rich zone efficiently. As it is common that the amplitude of the vibration will attenuate rapidly before it propagates to the oil zone, which will lead to failure to IOR. Some of the researchers suggested the generation of resonance in the oil zone to deliver the vibration energy effectively [13,80,81]. A small amplitude vibration can generate a large amplitude rock displacement in the formation. A simple example can be used to have a qualitative look for the possibility of resonance.


Neglecting the influence of the cross-section (which has an influence) the grading results for pieces tested in edgewise bending are not generally bad. For C30 from spruce a characteristic strength of 28/2 MPa is reached, for C18 20/0 MPa. However with 20/7 MPa the strength for C24 is too low. Allocating spruce and pine tested in tension to the given classes seems reasonable. However, this is not true for Douglas fir and larch. Characteristic strength values in these cases are not reached, except for a small sample of larch graded into C30. The suggested strength classes for Sitka spruce are simply too high. Lower classes similar to those used in BS can easily be reached. DIN-K: The discussion about Douglas fir, larch and Sitka spruce is close to the discussion for DIN-B grading. Looking more closely at the grading of Sitka spruce, this seems possible if the strength classes used in the BS are adopted.

Chapter 9: Performance in Fire 13-100-3a Comments on CIB Structural Timber Design Code 13-100-3b Comments on CIB Structural Timber Design Code - W R A Meyer 13-100-3c Comments on CIB Structural Timber Design Code - British Standards Institution 13-100-4 CIB Structural Timber Design Code. Proposal for Section 6/1.5 Nail Plates - N I Bovim 14-103-2 Comments on the CIB Structural Timber Design Code - R H Leicester 15-103-1 Resolutions of TC 165-meeting in Athens 1981-10-12/13 21-100-1 CIB Structural Timber Design Code.


Ceramic fuel pellets used in nuclear light water reactors experience significant fracture due to the high thermal gradients experienced under normal operating conditions. This has important effects on the performance of the fuel system. Because of this, a realistic, physically based fracture modeling capability is essential to predict fuel behavior in a wide variety of normal and off-normal conditions. The extended finite element method (X-FEM) is a powerful method to represent arbitrary propagating discrete cracks in finite element models, and has many characteristics that make it attractive for nuclear fuel performance analysis. This paper describes the implementation of X-FEM in a multiphysics fuel performance code and presents applications of that capability. These applications include several thermal mechanics fracture benchmark problems, which demonstrate the accuracy of this approach. It also includes application of this capability to study nuclear fuel fracture, both on stationary and propagating cracks. The study on stationary cracks shows the effects of interactions between cracks, and aids in understanding the process of crack propagation during a power ramp. The propagating crack case demonstrates random initiation and subsequent propagation (you can find out more) of interacting thermally induced cracks during an initial ramp to full power with fresh fuel.

A detailed summary of the diverse encapsulation materials and techniques that evolved to meet the cost goals of the Flat-plate Solar Array (FSA) Project is presented. A typical solar cell now consists of low iron glass, two layers of ethylene vinyl acetate (EVA) polymers, a porous space, primers/adhesives, a back cover of Tedlar, and a gasket/seal for a volume cost of $1/30/sq ft. This compares well with the project goal of $1/40/sq ft.


Proceedings - CIB-W18 [PDF] - Free Online Publishing

Thermal energy storage is a major contributor to bridge the gap between energy demand (consumption) and energy production (supply) by concentrating solar power. The utilization of high latent heat storage capability of phase change materials is one of the keys to an efficient way to store thermal energy. However, some of the limitations of the existing technology are the high volumetric expansion and low thermal conductivity of phase change materials (PCMs), low energy density, low operation temperatures and high cost. The present work deals with encapsulated PCM system, which operates at temperatures above 500°C and takes advantage of the heat transfer modes at such high temperatures to overcome the aforementioned limitations of PCMs. Encapsulation with sodium silicate coating on preformed PCM pellets were investigated. A low cost, high temperature metal, carbon steel has been used as a capsule for PCMs with a melting point above 500° C. Sodium silicate and high temperature paints were used for oxidation protection of steel at high temperatures. The emissivity of the coatings to enhance heat transfer was investigated.

Explicit three-dimensional finite-element: Topics by

For the BS the difference is smaller, as the main grading parameter is the KAR value, which is used in the BS anyway. Yet a difference exists, as margin KAR values are a second important grading parameter based on knot measurements close to the edges of the pieces. Differences between the assignments according to BS and to the new assignment for the KOA grading can be estimated by looking at Figure 4. The exact values which would lead to approximately the same yield are given in Table 6. The threshold values between the different test modes or species are small. For C24 the total KAR value to be used is always 0/29 except for DIN grading where this value is slightly higher 0/30. The differences reach a maximum for grading into C30 according to DIN yields. Values vary between 0/13 and 0/16 in this case. As these values are close together, the following grading procedure is only based on the total KAR values for spruce tested in bending.


A numerical study of fracture spacing and through-going fracture formation in layered rocks

N is the set of all nodes in the discretized model. Ncr is the set of nodes of all elements containing cracks but not crack (https://zhilservis-rzn.ru/free/?key=2156) tips. Ntip is the set of nodes of all elements containing the crack tip. NI is the finite-element shape function. H(φ(x)) is the Heaviside step function, and φ(x) is the signed distance function.

It is assumed that the average deflection resulting from the tension load on the bottom block cross section can be theoretically considered as equal to /10. Thus, the additional average tensile stiffness for the bottom block cross section, Ktb, can be estimated as Ktb EAtb (10L) where Atb is the effective tensile area of the bottom block given as Atb=SqXb(NR-1). Summing the two components (tension and shear), the average bottom shear plane stiffness can be defined by Kb K sb Ktb (7) Foschi and Longworth observed that when the bottom distance dz becomes less than Xb, the bottom shear stress decreases and the load thus released is transferred almost in its entirety to the tensile plane. To take this effect into account, a factor H is proposed .


For sources for which SKA data was available they are usually met or nearly met. Having only two grades in a standard (such as BS) makes it easier to reach the required values for all possible combinations of species and type of loading. All three standards could be used for Central European timber. Reject rates are lowest for INSTA as only here a grade for C 14 exists. This trend is not transferable to high grades. Yields for C24 and higher vary from 62% for grading according to DIN to 45% for grading according to INSTA (spruce, bending). For all three standards characteristic values are close to the required values with a maximum below of around 10%, considering European spruce. Absolute reject rates for visual grading vary depending on several factors, such as cross-section, grading standard or knot definitions. In practice these rates even will be higher as here the central section has been graded while in practice the full board length will be graded. The results for NF show low yields for C30.

Book of Abstracts ICM12

The curve is characterized by an upper linear segment and a lower nonlinear segment. The rockmass elastically relaxes until the support pressure drops below a certain level, thus resulting in the upper linear segment of the curve. With further dropping in the support pressure, the rockmass starts to fail in the immediate zone surrounding the tunnel, which leads to a nonlinear radial displacement with the reduction in the support pressure. In competent rockmasses, the tunnel walls may be still stable after a certain amount of displacement after the support pressure drops to zero, as shown by the thin GRC in the figure. In poor rockmasses, the failure zone surrounding the tunnel may be so severely fractured that broken rock blocks fall under gravity. In this case, the GRC turns upward after a certain displacement when the fractured zone becomes disintegrated. The thick GRC in the figure describes such a situation.


Structural timber - Determination of characteristic values of mechanical properties and density". European Committee for Standardization, Brussels, 2021. EN 408 Timber structures - Structural timber and glued laminated timber - Determination of some physical and mechanical properties. European Committee for Standardization, Brussels, 2021. FprEN 14080 Timber structures Glued laminated timber and glued solid timber. Working document of CEN TC 124 / WG 3. 12-2021.

Thermal energy storage systems using phase change materials (PCMs) as latent heat storage are one of the main challenges at European level in improving the performances and efficiency of concentrated solar power energy generation due to their high energy density. PCM with high working temperatures in the temperature range 300-500 °C are required for these purposes. However their use is still limited due to the problems raised by the corrosion of the majority of high temperature PCMs and lower thermal transfer properties. Micro-encapsulation was proposed as one method to overcome these problems. Different micro-encapsulation methods proposed in the literature are presented and discussed.


Similar effects were found for MoE and density. The results were not analysed separately for the different origins. Small scale comparisons for a limited number of specimens were carried out by Almazn et al (2008) for German pine graded by DIN 4074 and UNE 56544 or by Riberholt (2008) for European spruce graded according to Chinese visual rules. Visual grading is addressed in several available CIB-articles (Uzielli (1986), Fewell (1984), Barrett et al (1992), Stapel et al (2021)). None of these focused on the comparison of different grading rules and the assignment according to EN 1912. About 12000 pieces of softwood were graded and tested in tension or bending. We used the following grading standards for the classification of the pieces: DIN 4074-1:2021-06, BS 4978:2007+A1:2021, DS/INSTA 142:2009 (E), NF B 52-001-1:2021 and SIA 265/1:2009. Timber was available from Central, Northern and Eastern Europe. Spruce, pine, larch, Douglas fir and Sitka spruce were tested in edgewise bending or tension. We analyse three main factors influencing the grading.

Slovenia: Table 2 already shows very high mean values for the timber properties in the ungraded dataset. This general trend is also reflected in the grading results with high yields and extremely good characteristic values. If the ungraded spruce material shows values which are moving in the upper range of possible strength, MoE and density distributions, the choice of the grading standard should be done focussing on the yield only, as the grading results will always be safe. However, the question may be raised if the sample is representative for the timber growing in the country. Comparing bending and tension, it seems more likely that required characteristic values for pieces tested in tension are met. Many deviations from the required strength values are small or can be explained. For instance, the timber from Switzerland was tested over a longer span than 9x the height, leading to lower strength values (length effect). When comparing results for French and Russian pine, the following observations can be made: Raw data is almost equal for both countries (see Table 2). However, the yields for French timber are much higher, but the characteristic tension strength values are much lower than those required (8/9 MPa instead of 14 MPa for C24). As also the mean knot values of the ungraded material are close together for both sources, we checked the correlation between total KAR and tension strength. For the whole dataset of pine loaded in tension a value of R=0/47 is found.


A new category of rockbolts have recently been developed and gradually accepted by many ground control engineers with the aim of combating high-stress induced instability problems such as rockburst and rock squeezing conditions. This category includes the cone bolts, Durabar, modified cone bolts, Garford solid bolts, Roofex, Yield-Lok bolts, D-bolts, He bolts and Kinloc bolts, which are here collectively called energy-absorbing or yielding bolts. An energy-absorbing rockbolt can carry a high load and also accommodate significant rock displacement, and thus its energy-absorbing capacity is high. The test results show that the energy absorption of these bolts is much larger than that of all conventional bolts.

He also commented on the over strength factor. F Brhl agreed that the over strength factor was a driving factor. K Malo asked and received clarification on the characteristic strength of the connection. T Poutanen asked about the benefit in terms of numerical value. F Brhl stated that they did not have a number. P Quenneville questioned whether this connection was the most effective as plates with inclined wood screw underneath was also an option. W van Beerschoten questioned about damage after a big earthquake as large deformation might lead to non-repairable problems. F Brhl stated that in case of Europe this should be okay. I Smith commented and discussed the analog of links in a chain versus link in a double chain and practical achievement of ductility was difficult. K Malo discussed alternative of using the steel bracket.


Recently, the incorporation of biomolecules in Metal-organic frameworks (MOFs) attracts many attentions because of controlling the functions, properties and stability of trapped molecules. Although there are few reports on protein/MOFs composites and their applications, none of DNA/MOFs composite is reported, as far as we know. Here, we report a new composite material which is self-assembled from 3D DNA (guest) and pre-synthesized MOFs (host) by electrostatic interactions and hydrophilic interactions in a well-dispersed fashion. Its biophysical characterization is well analyzed by fluorescence spectroscopy, quartz crystal microbalance (QCM) and transmission electron microscopy (TEM). This new composite material keeps 3D DNA nanostructure more stable than only 3D DNA nanostructure in DI water at room temperature, and stores amounts of genetic information. It will make DNA as a guest for MOFs and MOFs become a new platform for the development of DNA nanotechnology.

The disclosure provides methods and materials suitable for use as encapsulation barriers in electronic devices. In one embodiment, for example, there is provided an electroluminescent device or other electronic device encapsulated by alternating layers of a silicon-containing bonding material and a ceramic material. The encapsulation methods provide, for example, electronic devices with increased stability and shelf-life. The invention is useful, for example, in the field of microelectronic devices.


A small amplitude vibration can generate a large amplitude rock displacement in the formation

Johnsson and Stehn , using a load distribution model based on a spring system, showed that the maximum variation from the linear assumption was approximately 12%. The head tensile plane stiffness can then be derived by considering the tensile deformation of the loaded block, which is given by N c 1 L Phi PL h EAth ( N C 1) i 1 N C 2 EAth (4) where E is the modulus of elasticity, L is the length subjected to the tensile stress and Ath the area subjected to the tensile stress at the head of the block.

The XFEM has been widely used for discontinuous problems

A summary version of Volume 1, presenting the basic encapsulation systems, their purposes and requirements, and the characteristics of the most promising candidate systems and materials, as identified and evaluated by the Flat-Plate Solar Array Project is presented. In this summary version considerable detail and much supporting and experimental information has necessarily been omitted. A reader interested in references and literature citations, and in more detailed information on specific topics, should consult Reference 1, JPL Document No. 5101-177, JPL Publication 81-102, DOE/JPL-1012-60 (JPL), June 1, 1982.


Damage characterisation of cryogenically cycled carbon fibre/PEEK laminates

An atmospheric corrosion model was developed and verified by five months of corrosion rate and climatology data acquired at the Mead, Nebraska LSA test site. Atmospheric corrosion rate monitors (ACM) show that moisture condensation probability and ionic conduction at the corroding surface or interface are controlling factors in corrosion rate. Protection of the corroding surface by encapsulant was shown by the ACM recordings to be maintained, independent of climatology, over the five months outdoor exposure period. The macroscopic corrosion processes which occur at Mead are shown to be reproduced in the climatology simulator. Controlled experiments with identical moisture and temperature aging cycles show that UV radiation causes corrosion while UV shielding inhibits LSA corrosion.

Procedure of peer review Submission of manuscripts: all members of the CIB-W18 group attending the meeting receive the manuscripts of the papers at least four weeks before the meeting. Everyone is invited to read and review the manuscripts especially in their respective fields of competence and interest. Presentation of the paper during the meeting by the author Comments and recommendations of the experts, discussion of the paper Comments, discussion and recommendations of the experts are documented in the minutes of the meeting and are printed on the front page of each paper. Final acceptance of the paper for the proceedings with no changes minor changes major changes or reject Revised papers are to be sent to the editor of the proceedings and the chairman of the CIB- W18 group Editor and chairman check, whether the requested changes have been carried out.


Crack propagation analysis ansys

The distinction between C24 and C18 is not really sharp. This leads to equal yields and similar characteristic values for these two grades. Hence characteristic values for C18 are met while for C24 they are not, considering CE spruce. The SIA 265/1:2009 standard leads to extreme reject rates. A practical use is not possible. Visual grading results are influenced by the source of the timber. Especially grading into C30 seems to be problematic in a number of cases. Depending on species, source and grading rules declared growth areas need clarification for a number of standards and growth areas cannot be extended without additional testing. Allocations in EN 1912 for softwoods are not correct in a number of cases, and a review seems necessary. New limits for source areas and cross-sections are required.


Thus, NaNO3 has been microencapsulated by sol-gel technology using SiO2 as shell material. Feasibility of the microparticles synthetized has been demonstrated by different experimental techniques in terms of TES capacity and thermal stability as well as durability through thermal cycles. The effectiveness of microencapsulated NaNO3 as TES material depends on the core:shell ratio used for the synthesis and on the maximum temperature supported by NaNO3 during use.

This study presents novel, recently patented technology for encapsulating hydrophilic species in lipid nano-emulsions. The method is based on the phase-inversion temperature method (the so-called PIT method), which follows a low-energy and solvent-free process. The nano-emulsions formed are stable for months, and exhibit droplet sizes ranging from 10 to 200 nm. Hydrophilic model molecules of fluorescein sodium salt are encapsulated in the oily core of these nano-emulsion droplets through their solubilisation in the reverse micellar system. As a result, original, multi-scaled nano-objects are generated with a 'hydrophilic molecule in a reverse-micelles-in-oil-in-water' structure. Once fluorescein has been encapsulated it remains stable, for thermodynamic reasons, and the encapsulation yields can reach 90%. The reason why such complex objects can be formed is due to the soft method used (PIT method) which allows the conservation of the structure of the reverse micelles throughout the formulation process, up to their entrapment in the nano-emulsion droplets. In this study, we focus the investigation on the process itself, revealing its potential and limits. Since the formulation of nanocarriers for the encapsulation of hydrophilic substances still remains a challenge, this study may constitute a significant advance in this field.


About Northeastern University’s Research

The two monitoring points at 170 and 130 m elevation of the slope section No. 1 show displacement to the goaf hollow, respectively, and monitoring points above 98 m on sections No. 2 and No. 3 show displacement to the hollow area of the slope. The displacements to the hollow area of the other points on the three monitoring sections are smaller. Though there is larger displacement to the hollow area near the top of the slope, it is helpful to the slope stability. So, the deformation situation is stable to the slope in general.

M Frese stated that 1000 replicates were considered in the simulation and one could smooth the results with regression. He clarified also that E1 and E2 ratio was the ratio of the E of the outer and intermediate zone. Higher ratios imply more loads and stresses are attached to the higher grade lumber. S Aicher commented that as the results were based on 600 mm deep beam, would the same results apply to 2 m deep beams. M Frese responded that yes they had to take into account of the percentage of the different grades. G Stapf asked what assumptions were made for the laminates. M. Frese would look into the details and discuss with G Stapf. G Stapf asked why only considered MOE in compression and not the MOE in tension for moisture content adjustment. M Frese stated that there was no moisture adjustment method for MOE in tension and engineers in general did not consider this. T Poutanen stated that one option was to consider proof loading of the bottom chord.


In case of brittle failures, the maximum connection deformation was 2 to 3 mm and the wood rupture occurred suddenly. Beyond the connection deformation of 0/5 mm, it can be observed that the load-slip curves for brittle failures show some inelastic behaviour. This can be explained by the plastic response of the wood embedment behaviour next to the rivet head during the elastic deformation of the rivets . For mixed mode failures in which wood failed before final yielding of the rivets, more deflection can be seen compared to brittle failures due to some rivet deformation. Results for the LVL and glulam groups tested are listed in Tables 1 and 2 respectively. After observing the test results, the groups were matched and identified based on the modes of failure.

The Xilinx Virtex 4QV and 5QV (V4 and V5) are next-generation field-programmable gate arrays (FPGAs) for space applications. However, there have been concerns within the space community regarding the non-hermeticity of V4/V5 packages; polymeric materials such as the underfill and lid adhesive will be directly exposed to the space environment. In this study, reliability concerns associated with the non-hermeticity of V4/V5 packages were investigated by studying properties and behavior of the underfill and the lid adhesvie materials used in V4/V5 packages.


Cracking scc resistance: Topics by Science.gov

Biochar constitutes a promising support material for the formulation of controlled-release fertilizers (CRFs). In this study we evaluated the effect of different polymeric materials as encapsulating agents to control nitrogen (N) leaching from biochar based CRFs. Nitrogen impregnation onto biochar was performed in a batch reactor using urea as N source. The resulting product was encapsulated by using sodium alginate (SA), cellulose acetate (CA) and ethyl cellulose (EC). Leaching potential was studied in planted and unplanted soil columns, monitoring nitrate, nitrite, ammonium and urea concentrations. After 90 days, plants were removed from the soil columns and plant yield was evaluated. It was observed that the ammonium concentration in leachates presented a maximum concentration for all treatments at day 22. The highest concentration of N in the leachates was the nitrate form. The crop yield was negatively affected by all developed CRFs using biochar compared with the traditional fertilization.

Mech, 155, 2021) brings more attention to its central issue: simulation accuracy verification of crack-tip behavior. This is fundamentally important in determining whether the analysis is significant or nonsense. Unfortunately, this kind of accuracy verification including the model size effect has been researched the least. This is mainly due to a lack of effective method to verify the accuracy of atomisticlly-based multiscale crack (try these out) analysis, shortcomings of existing multiscale methods in developing large model with high accuracy and a lack of basic understanding and effective scheme to investigate and control the model size effects.


This property is characterised by a high variability and cannot directly be determined from regression equations but rather has to be assessed based on some assumptions. In addition, only 23 experiments in pure bending were performed, whereas the test series with pure compression and combined compression and bending contained a larger database with 44 and 81 tests respectively. Table 1: Mean value and coefficient of correlation of the ratio between the predicted and the experimentally determined load-bearing capacity.

Notably, displacement is a quantity which should be restrained by the support system rather than to which the support system should adapt. To absorb a given amount of energy, the smaller the displacement of the bolt is, the better the support effect is. Thus, the energy absorption per unit displacement is an appropriate parameter to evaluate the performance of a rockbolt.


ECS Transactions, Volume 85, Number 13, April 2020, 2020

Naturally fractured reservoirs are an important source of hydrocarbons. Computational models capable of generating fracture geometries according to geomechanical principles offer a means to create a numerical representation of a more realistic rock mass structure. In this work, the combined finite-discrete element method is applied to investigate fracture patterns in layered rocks. First, a three-layer model undergoing layer normal compression is simulated with the aim of examining the controls on fracture spacing in layered rocks. Second, a seven-layer model with low competence contrast is modelled under direct tension parallel to the layering and bending conditions with the focus on investigating through-going fracture formation across layer interfaces. The numerical results give an insight into the understanding of various mechanisms that contribute to fracture pattern development in layered rocks.

Fracture of Nano and Engineering Materials and Structures

He stated that satisfying equilibrium condition only was not enough as kinematic conditions needed to be considered also. Also the diagonal shear test configuration could have compression failure; therefore, there could be an interaction effect. Diagonal shear test configuration which puts the panel in tension needs to be used. R Tomasi agreed that the model only considered equilibrium and these were their assumptions. He also agreed that the diagonal test configuration did not yield a pure shear case. The TU Graz diagonal shear device is the only tension shear apparatus that gives stiffness measurement. I Sustersic asked if there was any observed difference in results between panels produced with hydraulic and vacuum presses. R Tomasi stated that conclusion could not be drawn on this issue. F Lam asked for clarification on how many specimens were studied.


The capability of the model in providing adequate values of load-bearing capacity of solid timber columns supported in simply beam configuration was assessed by benchmarking calculated values to experimental results from a study performed at ETH in 1995. In addition, the mechanical model was combined with a stochastic model for the material properties and according Monte Carlo simulations were performed. The results of these simulations were compared to the design rules given in Eurocode 5. While the simplified calculation model (Effective Length Method) coincides with the results from the simulations, the 2nd order structural analysis may lead to an overestimation of the load-bearing capacity. This result indicates that the design rules given in Eurocode 5 should be reconsidered. In particular, modifications are suggested for the design value of the MOE which is the basis of the 2nd order structural analysis.

We examine a proposed test standard that can be used to evaluate the maximum representative change in linear dimensions of sheet encapsulation products for photovoltaic modules (resulting from their thermal processing). The proposed protocol is part of a series of material-level tests being developed within Working Group 2 of the Technical Committee 82 of the International Electrotechnical Commission. The characterization tests are being developed to aid module design (by identifying the essential characteristics that should be communicated on a datasheet), quality control (via internal material acceptance and process control), and failure analysis. Discovery and interlaboratory experiments were used to select particular parameters for the size-change test. The choice of a sand substrate and aluminum carrier is explored relative to other options. The temperature uniformity of +/-5°C for the substrate was confirmed using thermography. Considerations related to the heating device (hot-plate or oven) are explored. The time duration of 5 minutes was identified from the time-series photographic characterization of material specimens (EVA, ionomer, PVB, TPO, and TPU). The test procedure was revised to account for observed effects of size and edges. The interlaboratory study identified typical size-change characteristics, and also verified the absolute reproducibility of +/-5% between laboratories.


Time: Authors: Talk Title: 10: 15am: D. S. Kammer*: Invited: Simulation of Dynamic Shear Crack Propagation along weak Interfaces with Various Stress Distributions Abstract: The propagation of shear cracks along weak interfaces is a long-standing problem of great importance to earthquake source mechanics and engineering (composite materials). The second topic concerns crack propagation and more especially its. A stress field is associated with the sharp interface, and the stress field influences the thermodynamic driving force for the propagation of the reaction front. In a previous blog I showed how to model a stationary crack and calculate the J-integral to determine whether the crack propagates. At different levels of damage, a modal analysis is carried out, assuming the structure to behave linearly. The present paper addresses the issue of direct simulation of complex local failure patterns in laminated composites. Figure 9 shows the established 3D model based on the standard notched beam shear test method. Keywords: FRP composites, Delamination, Mixed mode fracture, Non-linear XFEM. Generally, it was observed and predicted that higher shear stresses lead to faster cracks. The interfacial properties and fracture toughness can be obtained by inputting critical stress/energy as criteria for nucleation and propagation of. Dec 18, Delamination Buckling and Crack Propagation Simulations in Fiber-Metal Laminates Using xFEM and Cohesive Elements. By this method, the strain energy release rate can be easily obtained. Due to the complexity and existence of multiple and interactive modes of failure, there is a lack of comprehensive theory that describes the damage behaviour of these materials. Today, Value Management (VM) is an approach that has been widely used by various industries in managing their projects or programs to get the best value.

Concrete damaged plasticity: Topics by Science.gov

These opportunities, however, present us with both process and materials design questions. For example, what is the target CO 2 absorption strength (enthalpy of chemical absorption) for the tunable AHA IL? What is the target for micro-capsule diameter in order to obtain a high mass transfer rate and good fluidization performance? What are the appropriate temperatures and pressures for the absorber and stripper? In order to address these and other questions, we have developed a rate-based model of a post-combustion CO 2 capture process using micro-encapsulated ILs.


And from the bottom to 100 m, the local displacement of the slope in the pit side presents large on the bottom and small at the 100 m top. On the condition of rain filtering, the deformation of the edge slope after mining No. 4 coal seam show the subsidence mainly. The maximum subsidence is about 116 mm.

Kuilen JW, Rais A (2021): Influence of Origin and Grading Principles on the Engineering Properties of European Timber. CIB W 18 paper 43-5-2, Nelson, New Zealand. SIA 265/1:2009 Holzbau Ergnzende Festlegungen.


(PDF) Numerical analysis of impact failure of automotive

We have developed a method based on melt coaxial electrospinning for fabricating phase change nanofibers consisting of long-chain hydrocarbon cores and composite sheaths. This method combines melt electrospinning with a coaxial spinneret and allows for nonpolar solids such as paraffins to be electrospun and encapsulated in one step. Shape-stabilized, phase change nanofibers have many potential applications as they are able to absorb, hold, and release large amounts of thermal energy over a certain temperature range by taking advantage of the large heat of fusion of long-chain hydrocarbons. We have focused on compounds with melting points near room temperature (octadecane) and body temperature (eicosane) as these temperature ranges are most valuable in practice. We have produced thermally stable, phase change materials up to 45 wt % octadecane, as measured by differential scanning calorimetry. In addition, the resultant fibers display novel segmented morphologies for the cores due to the rapid solidification of the hydrocarbons driven by evaporative cooling of the carrier solution. Aside from the fabrication of phase change nanofibers, the melt coaxial method is promising for applications related to microencapsulation and controlled release of drugs.

The severe capacity decay of LiFePO4 at low temperatures (≤0 °C) limits its wide applications as cathode materials for energy storage batteries. Creating comprehensive carbon network between particles with improved electronic conductivity is a well known solution to this problem. Here, a novel structured LiFePO4/C composite was prepared by a facile solid state route, in which nanosized LiFePO4 spheres were encapsulated by in-situ graphitized carbon cages. With the enhancement in electronic conductivity (2/15e-1 S cm-1), the composite presented excellent rate performance at room temperature and remarkable capacity retention at -40 °C, with charge transfer resistance much lower than commercial LiFePO4.


Our first step is to utilize Dimensional Analysis to connect the scratch force to the probe geometry and material characteristic. In order to apply the energetic size effect law, we define the nominal strength and nominal size at both the macroscopic and microscopic levels. The type II size effect law is then articulated to model the ductile-to-brittle transition during scratch tests. The theoretical developments are later implemented into an experimental procedure to assess the solid fracture toughness and characteristic length directly from scratch tests measurements. The theoretical framework is validated at first on homogeneous materials such as paraffin wax, polycarbonate, polyacetal, and aluminum. An excellent agreement is found between the theoretical predictions and measurements from conventional fracture testing methods such as three-point bending tests on single-edge notched specimens. The theoretico-experimental framework is then extended to an extensive characterization campaign including conventional Portland cement paste, natural shale and organic-rich shale.

To carry out essential life processes, nature has had to evolve heme enzymes capable of synthesizing and manipulating complex molecules. These proteins perform a plethora of chemical reactions utilizing a single iron porphyrin active site embedded within an evolutionarily designed protein pocket. We herein report the first class of metal–organic materials (MOMs) that mimic heme enzymes in terms of both structure and reactivity. The MOMzyme-1 class is based upon a prototypal MOM, HKUST-1, into which catalytically active metalloporphyrins are selectively encapsulated in a “ship-in-a-bottle” fashion within one of the three nanoscale cages that exist in HKUST-1. MOMs offer unparalleled levelsmore » of permanent porosity and their modular nature affords enormous diversity of structures and properties.


Eight urethane compounds were evaluated as possible replacement for the existing encapsulating compoounds for electrical cables for the Launch Support System at Kennedy Space Center (KSC). The existing encapsulating compound, PR-1535, contains the curative MOCA 4-4'-Methylene-BIS (2-chloroaniline), which is a suspect carcinogen and hence may be the subject of further restrictions of its use by the Occupational Safety and Health Administration (OSHA). The samples made in the configuration of cable joints and in the form of disks were evaluated for flammability and hypergolic compatibility. These also underwent accelerated weatherability tests that measured the residual hardness of the exposed samples. Three candidates and the existing compound passed the hardness test. Of these, only one candidate and the existing compound passed the flammability test. The thermal and hydrolytic stability (weatherability) of these samples was studied using thermogravimetric analysis (DSC) techniques. The TMA and DSC data correlated with the residual hardness data; whereas, the TGA data showed no correlation. A hypergolic compatibility test will be conducted on the compound V-356-HE80, which passed both the flammability and accelerated weatherability tests.

During this quarter, flat-plate solar collector systems were considered and six basic construction elements were identified: outer coatings, superstrates, pottants, substrates, undercoats, and adhesives. Materials surveys were then initiated to discover either generic classes or/and specific products to function as each construction element. Cost data included in the surveys permit ready evaluation of each material. Silicones, fluorocarbons, glass, and acrylic polymers have the highest inherent weatherability of materials studied to date. Only acrylics, however, combine low costs, environmental resistance, and potential processability. This class will receive particular emphasis.


Rock overlying a mineral deposit is in a state of natural equilibrium. Unsupported mine voids created during underground mining cause a disequilibrium in rocks, leading to their displacement and deformation. Rock displacement that occurs in the vicinity of an underground mine working extends upward to the upper layers of the overburden. Once the underground working reaches a sufficiently large size, the displacement of rock strata will extend to the ground surface, which will in turn undergo deformation. As early as the mid-19th century, subsidence began to cause severe damage to buildings, facilities, transportation links, and agricultural land in a number of European coalfields. This led coal mine surveyors to install monitoring stations and conduct systematic monitoring of subsurface rock deformation and subsidence. Based on the summary of the results of this monitoring and theoretical understanding, a new subfield was formed within mining science—rock deformation.

A photothermal test matrix and a low cost testing apparatus for encapsulant materials of photovoltaic modules were defined. Photothermal studies were conducted to screen and rank existing as well as future encapsulant candidate materials and/or material formulations in terms of their long term physiochemical stability under accelerated photothermal aging conditions. Photothermal characterization of six candidate pottant materials and six candidate outer cover materials were carried out. Principal products of photothermal degradation are identified. Certain critical properties are also monitored as a function of photothermal aging.


Hydrophobic silicon-based material having magnetic properties was fairly synthesized by a classical sol-gel approach. Pepsin enzyme was encapsulated in the sol-gel material and the enzyme activity was evaluated in consequence of the digestion of some common proteins such as α- and β-casein, cytochrome c, myoglobin, and bovine serum albumin (BSA) both in a single protein batch and in the protein mixture. The optimum digestion time of the studied proteins using pepsin-encapsulated magnetic sol-gel material was found to be 20min. To produce the magnetic sol-gel material for convenient and easy proteomics applications, Fe3O4 was doped inside sol-gel material during the gelation step. It was observed that the activity of encapsulated pepsin was not affected by the amount of Fe3O4. Poly(ethylene glycol) was also inserted in sol-gel bulk to obtain suitable roughness and increase the hydrophilicity of the material surface to let protein molecules reach to the sol-gel material easily. The digestion of the protein mixture and non-fat bovine milk was performed with the pepsin-encapsulated magnetic sol-gel material and the digested solutions were analyzed using SDS-PAGE, MALDI-TOF-MS and LC-MS/MS for the protein identification. Reusability of the pepsin-encapsulated sol-gel material was examined and it was determined that they could be used at least 20 times. Finally, IgG digestions with a fast incubation time period were carried out using pepsin-encapsulated sol-gel material for generation of (Fab)2 product to evaluate the kinetic performance of the material.

Knots smaller than 5 millimeters were not recorded. For bending tests knots were only recorded in the section between or close to the loading points, for tension tests between the grips. Visual grading for KOA data needs to be based on the total KAR value only, as no other data is available. The available data is restricted to the maximum knot area ratio. The tKAR is defined as the knot area within 150 mm projected on the end grain divided by the area of the cross section. Overlapping areas are only counted once.


M Popovski responded that the hold-downs took vertical uplift forces while shear connectors took shear forces. In CLT hold-downs contribute to shear response. B Dujic commented about openings in the assembly and asked how the step joints affected the results. M Popovski stated that the building was designed with step joints in openings and there was no special consideration of the influence of openings. B Dujic commented that in performance based design you did not need the R or Q factor. M Popovski stated that they did performance based design to show that it worked for CLT and R factors were chosen based on drift limits. I smith asked what was the status of discussion on performance based design in US. M Popovski stated that the performance objectives in FEMA were used and they were considered to be conservative. I Smith commented that he wondered whether steel and concrete people were in agreement with performance based design principles. T Skaggs commented that the results show CLT without hold-down had higher R factors than cases with hold-down. M Popovski responded that hold-downs were desirable but there were trade-offs.

Linear eigenvalue buckling analysis for cracked (https://zhilservis-rzn.ru/free/?key=1657) uni-layer composite plates is performed in the framework of the extended finite element method (XFEM (my company)). The geometry of the problem is discretized using the 8-noded degenerated shell element, which includes transverse shear deformation effects. The effects of several parameters such as crack lengths and angles, fiber directions and boundary conditions on the buckling behavior of cracked (https://zhilservis-rzn.ru/free/?key=8095) composite plates are comprehensively investigated for different loading conditions including compressive, tensile and shear loadings. Also, the accuracy and efficiency of the proposed method are discussed and compared with the available results.


Orthopaedic devices using unidirectional carbon fibre reinforced poly-ether-ether-ketone (PEEK) laminates potentially offer several benefits over metallic implants including: anisotropic material properties; radiolucency and strength to weight ratio. However, despite FDA clearance of PEEK-OPTIMA™ Ultra-Reinforced, no investigation of the mechanical properties or failure mechanisms of a medical grade unidirectional laminate material has been published to date, thus hindering the development of first-generation laminated orthopaedic devices. This study presents the first investigation of the mechanical behaviour and failure mechanisms of PEEK-OPTIMA™ Ultra-Reinforced. The following multi-axial suite of experimental tests are presented: 0° and 90° tension and compression, in-plane shear, mode I and mode II fracture toughness, compression of ±45° laminates and flexure of 0°, 90° and ±45° laminates. Three damage mechanisms are uncovered: (1) inter-laminar delamination (read this article), (2) intra-laminar cracking and (3) anisotropic plasticity. A computational damage and failure model that incorporates all three damage mechanisms is developed. The model accurately predicts the complex multi-mode failure mechanisms observed experimentally. The ability of a model to predict diverse damage mechanisms under multiple loading directions conditions is critical for the safe design of fibre reinforced laminated orthopaedic devices subjected to complex physiological loading conditions.

Therefore, the application of an adequate material model (stress-strain relation) is essential when modelling the behaviour of timber members subjected to compression. In the present study the model proposed by Glos is used, since it appears to be more suitable than other material models because it is based on extensive experimental investigations on solid timber boards. In addition Glos developed the model for timber members subjected to compression and bending while other models are mainly focused on timber members subjected to pure bending. Glos model accounts for the reduction of stiffness before reaching the ultimate compression strength as well as for the subsequent softening. Figure 3 qualitatively shows the stress-strain relationship proposed by Glos. The description of the full curve in a mathematical form asks for six parameters (Figure 3 right). The MOE in tension Et,0 and the tension strength describe the linear-elastic behaviour subjected to tension. When modelling bending, not the tension strength ft,0 of a timber member but rather the ultimate tension strength at extreme fibres position ft,m,0 is of interest. This strength is remarkably higher than the tension strength ft,0. The four parameters Ec,0, fc,m,0, fc,m,u,0 and c,0 define the material behaviour subjected to compression.

  • Wrinkling and failure behavior of single-layer MoS2 sheets
  • Lubricant Effects on Propagation of Surface-Breaking Cracks Under Rolling Contact LoadingJ
  • Mesolevel Modeling of Failure in Composite Laminates
  • Fatigue Crack Propagation of Super-Duplex Stainless Steel at Different TemperaturesG
  • Dynamic Delamination of Fire Insulation Applied on Steel
  • Numerical Investigation of Crack Propagation in Sandwich StructuresE
  • Computational modeling of progressive damage and rupture

Gdoutos, E. E - Experimental Analysis of Nano and Engineering Materials and Structures, ebook

Nobakhti* | S. ShefelbineMultiscale Characteristics of Bone Toughness Abstract: Bone achieves toughness through structural hierarchy and various toughening mechanisms acting at different length scales. At the nanoscale, bone is a composite of collagen molecules and hydroxyapatite mineral crystals. Alterations in quantity/quality of the collagen and mineral at the nanoscale influence other properties such as porosity, tissue mineral density and the matrix elasticity at the micro-scale and consequently, the strength and toughness at the whole bone level. Previous studies on bovine and human bone have proposed that bone’s toughness derives from its mechanical heterogeneity. It is generally believed that the elastic modulus is positively correlated to the amount of mineral in bone and therefore, toughness should be primarily affected by the bone mineral content and distribution. Genetically altered mouse models of bone pathology allow us to examine how molecular defects alter the bone mineral and drive whole bone toughness across length-scales.


To sustain the bioactivity of proanthocyanidins-rich plant-derived extracts via encapsulation within biodegradable polymer microcapsules. Polylactide microcapsules containing grape seed extract (GSE) were manufactured using a combination of double emulsion and solvent evaporation techniques. Microcapsule morphology, size distribution, and cross-section were examined via scanning electron microscopy. UV-vis measurements were carried out to evaluate the core loading and encapsulation efficiency of microcapsules. The bioactivity of extracts was evaluated after extraction from capsules via solvent partitioning one week or one year post-encapsulation process. Fifteen human molars were cut into 7mm×1/7mm×0/5mm thick mid-coronal dentin beams, demineralized, and treated with either encapsulated GSE, pristine GSE, or left untreated. The elastic modulus of dentin specimens was measured based on three-point bending experiments as an indirect assessment of the bioactivity of grape seed extracts. The effects of the encapsulation process and storage time on the bioactivity of extracts were analyzed. Polynuclear microcapsules with average diameter of 1/38μm and core loading of up to 38wt% were successfully manufactured. There were no statistically significant differences in the mean fold increase of elastic modulus values among the samples treated with encapsulated or pristine GSE (p=0/333), or the storage time (one week versus one year storage at room temperature, p=0/967).

A combined XFEM and cohesive zone model for composite laminate microcracking and permeability

This goes together with a considerable reduction in yield compared to Central Europe. However, the resulting density values are well below the requirements. The requirement for C30 is 380 kg/m, only 336 kg/m are reached. France: The dataset from France is too small to get reliable answers. Poland (pine): Strength values are far below the requirements for all grades.


A high-performance anode material for lithium storage was successfully synthesized by glucose as carbon source and cobalt nitrate as Co3O4 precursor with the assistance of sodium chloride surface as a template to reduce the carbon sheet thickness. Ultrafine Co3O4 nanoparticles were homogeneously embedded in ultrathin porous graphitic carbon in this material. The carbon sheets, which have large specific surface area, high electronic conductivity, and outstanding mechanical flexibility, are very effective to keep the stability of Co3O4 nanoparticales which has a large capacity.

A model compound was encapsulated in pectin and then extruded with thermoplastic starch to form a composite. The intended product was a food-contact tray made of biobased polymers infused with an anti-microbial agent; however, caffeine was used as the model compound in the preliminary work.


Springborn Laboratories is engaged in a study of evaluating potentially useful encapsulating materials for Task 3 of the Low-Cost Silicon Solar Array project (LSA) funded by DOE. The goal of this program is to identify, evaluate, and recommend encapsulant materials and processes for the production of cost-effective, long-life solar cell modules. This report presents the results of a cost analysis of candidate potting compounds for long life solar module encapsulation. Additionally, the two major encapsulation processes, sheet lamination and liquid casting, are costed on the basis of a large scale production facility.