This paper reports on an…. Modeled test configurations will regulatkons limited to the special case of where temperature gradients are oriented perpendicular to the composite material ply angle. Since the powder deformation and consolidation is governed by specific pressure-dependent constitutive equations, several solution algorithms were developed for the ABAQUS user material жмите сюда, UMAT.❿
 
 

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Spectrally formulated user -defined element in conventional finite element environment for wave motion analysis in 2-D composite structures. Wave propagation analysis in 2-D composite structures is performed efficiently and accurately through the formulation of a User -Defined Element UEL based on the wavelet spectral finite element WSFE method.

The WSFE method is based on the first-order shear deformation theory which yields accurate results for wave motion at high frequencies. The 2-D WSFE model is highly efficient computationally and provides a direct relationship between system input and output in the frequency domain. The UEL is formulated and implemented in Abaqus commercial finite element software for wave propagation analysis in 2-D composite structures with complexities.

Five numerical examples are presented in this article, namely undamaged plate, impacted plate, plate with ply drop, folded plate and plate with stiffener. Wave motions predicted by the developed UEL correlate very well with Abaqus simulations. Critical assessment of this model identified The model also takes into account the plastic expansion or contraction of voids and therefore the stresses are appropriately modified to account for. The scope of this white paper is Documentation of the 1-D user element subroutine is This is followed Characteristics of shear damage for 60SnPb solder material.

This paper presents an investigation of the development of a continuum damage model capable of accurately analyzing shear damage in 60SnPb solder material. Based on the theory of damage mechanics, an internal state variable known as the damage variable is introduced to characterize material degradation caused by the change of material microstructures under load.

A damage surface in stress space is proposed to quantify damage initiation and its successive expanding surfaces to represent damage hardening. With the aid of irreversible thermodynamics, the damage-coupled constitutive equations and the damage evolution equations are established.

A failure criterion is proposed based on themore » accumulation of overall damage in the material. The program is applied to predict shear deformation in a notched specimen. The predicted failure mode and maximum load agree well with those measured experimentally. The effect of finite element meshing on the numerical results is also examined and discussed. The development of a pressure-dependent constitutive model with combined multilinear kinematic and isotropic hardening is presented.

First the pressure-dependent plasticity model is derived. Following this, the combined bilinear and combined multilinear hardening equations are developed for von Mises plasticity theory. The hardening rule equations are then modified to include pressure dependency.

User applications driven by the community contribution framework MPContribs in the Materials Project. The MP is a searchable database of electronic structure properties of over 65, bulk solid materials , which is accessible through a web-based science-gateway.

We describe the motivation for enabling user contributions to the materials data and present the framework’s features and challenges in the context of two real applications. These use cases illustrate how scientific collaborations can build applications with their own ‘ user -contributed’ data using MPContribs.

The Nanoporous Materials Explorer application provides a unique searchmore » interface to a novel dataset of hundreds of thousands of materials , each with tables of user -contributed values related to material adsorption and density at varying temperature and pressure. The Unified Theoretical and Experimental X-ray Spectroscopy application discusses a full workflow for the association, dissemination, and combined analyses of experimental data from the Advanced Light Source with MP’s theoretical core data, using MPContribs tools for data formatting, management, and exploration.

The capabilities being developed for these collaborations are serving as the model for how new materials data can be incorporated into the MP website with minimal staff overhead while giving powerful tools for data search and display to the user community.

The translation of these results is accomplished using a newly developed Python script. Full details of Our primary objective here is to report on these recent works conducted over the past decade, in the context of their incorporation into ABAQUS through the various user subroutines. Representative results will be shown to demonstrate the features of the developed schemes. A numerical multi-scale model to predict macroscopic material anisotropy of multi-phase steels from crystal plasticity material definitions.

A numerical multi-scale model is being developed to predict the anisotropic macroscopic material response of multi-phase steel. The embedded microstructure is given by a meso-scale Representative Volume Element RVE , which holds the most relevant features like phase distribution, grain orientation, morphology etc.

For the elasto-plastic response of the individual grains, single crystal plasticity based plastic potential functions are proposed as Abaqus material definitions. The plastic potential functions are derived using the Facet method for individual phases in the microstructure at the level of single grains.

The proposed method is a new modeling framework and the results presented in terms of macroscopic flow curves are based on the building blocks of the approach, while the model would eventually facilitate the construction of an anisotropic yield locus of the underlying multi-phase microstructure derived from a crystal plasticity based framework.

Implicit and explicit solutions methods are used as appropriate. User subroutines Work is not Coupled material responses, such as electrical- thermal for capacitor materials or electrical. Waste minimization for commercial radioactive materials users generating low-level radioactive waste. The objective of this document is to provide a resource for all states and compact regions interested in promoting the minimization of low-level radioactive waste LLW.

This project was initiated by the Commonwealth of Massachusetts, and Massachusetts waste streams have been used as examples; however, the methods of analysis presented here are applicable to similar waste streams generated elsewhere. Massachusetts waste stream characterization data from key radioactive materials users in each category are used to illustrate the applicability of various minimization techniques.

The utility group is not included because extensive information specific to this category of LLW generators is available in the literature. Stochastic-based, discrete-event progressive damage simulations of ceramic-matrix composite and polymer matrix composite material structures have been enabled through the development of a unique multiscale modeling tool. Abaqus is used at the global scale to model the overall composite structure. A comprehensive example problem, simulating the progressive damage of laminated ceramic matrix composites under various off-axis loading conditions and including a double notched tensile specimen geometry, is described in a separate report.

This paper presents a viscoplasticity model taking into account the effects of change in grain or phase size and damage on the characterization of creep damage in 60SnPb solder. Based on the theory of damage mechanics, a two-scalar damage model is developed for isotropic materials by introducing the free energy equivalence principle. The damage evolution equations are derived in terms of the damage energy release rates.

In addition, a failure criterion is developed based on the postulation that a material element is said to have ruptured when the total damage accumulated in the element reaches a critical value. To illustrate the application of the model, several example cases are introduced to analyze, both numerically and experimentally, the tensile creep behaviors of the material at three stress levels.

The model is then applied to predict the deformation of a notched specimen under monotonic tension at room temperature 22 C. The results demonstrate that the proposed model can successfully predict the viscoplastic behavior of the solder material.

To ensure desirable outcome of hydraulic fracturing based on ultra-short radius radial systems, it is required to investigate the stress distribution regularity and stability of the cement sheath.

On the basis of the theoretical model of the cement sheath stress distribution, a reservoir mechanical model was built using the finite element software, ABAQUS , according to the physical property of a certain oil reservoir of the Shengli oilfield. The stress distribution of the casing-cement-sheath-formation system under the practical condition was simulated, based on which analyses were conducted from multiple points of view.

Results show that the stress on the internal interface of the cement sheath exceeds that on the external interface, and fluctuates with higher amplitudes, which means that the internal interface is the most failure-prone. The unevenness of the cement sheath stress distribution grows with the increasing horizontal principal stress ratio, and so does the variation magnitude.

This indicates that higher horizontal principal stress ratios are unfavourable for the structural stability of the cement sheath. Both the wellbore quantity of the URRS and the physical property of the material can affect the cement sheath distribution. At last, the impact level of the above factor was analysed, with the help of the grey correlation analysis.

An engineering approach to predict the fatigue life and progressive failure of multilayered composite and textile laminates is presented. Analytical models which account for matrix cracking, statistical fiber failures and nonlinear stress-strain behavior have been developed for both composites and textiles. The analysis method is based on a combined micromechanics, fracture mechanics and failure statistics analysis. Experimentally derived empirical coefficients are used to account for the interface of fiber and matrix, fiber strength, and fiber-matrix stiffness reductions.

Similar approaches were applied to textiles using Repeating Unit Cells. In composite fatigue analysis, Walker’s equation is applied for matrix fatigue cracking and Heywood’s formulation is used for fiber strength fatigue degradation. The analysis has been compared with experiment with good agreement. For textile materials , comparisons were made with triaxial braided and plain weave materials under biaxial or uniaxial tension.

Computer codes were developed to perform the analysis. User Test Planning Guide. Revision 1. This report describes User Education Resources USER , an Australian database containing both print and audiovisual materials related to library instruction. Intended to make a wide range of ideas readily available to librarians interested in educating library patrons, USER collects catalog guides, classification guides, evaluation forms, floor….

Identifies and describes sublevels of novices using a database management package, clustering those whose interaction is effective, partially effective, and totally ineffective. Among assistance documentation, functional tree diagrams FTDs were more beneficial to partially effective users than traditional reference material. The results have…. Long-term injection and storage of CO2 in deep underground reservoirs may significantly modify the geomechanical behavior of rocks since CO2 can react with the constituent phases of reservoir rocks and modify their composition.

This can lead to modifications of their geomechanical properties i. This paper attempts to elucidate the geochemical effects of CO2 on geomechanical properties of typical reservoir rocks by means of numerical analyses using the STOMP- ABAQUS sequentially coupled simulator that includes the capability to handle geomechanics and the reactive transport of CO2 together with a module EMTA to compute the homogenized rock poroelastic properties as a function of composition changes.

The ABAQUS models then read STOMP output data for cell center coordinates, gas pressures, aqueous pressures, temperatures, saturations, constituent volume fractions, as well as permeability and porosity that are affected by chemical reactions.

Explicit and implicit springback simulation in sheet metal forming using fully coupled ductile damage and distortional hardening model. The springback is an important phenomenon which accompanies the forming of metallic sheets especially for high strength materials. A quantitative prediction of springback becomes very important for newly developed material with high mechanical characteristics.

In this work, a numerical methodology is developed to quantify this undesirable phenomenon. The most important ingredient of this methodology consists on the use of highly predictive mechanical model. A thermodynamically-consistent, non-associative and fully anisotropic elastoplastic constitutive model strongly coupled with isotropic ductile damage and accounting for distortional hardening is then used.

An algorithm for local integration of the complete set of the constitutive equations is developed. This algorithm considers the rotated frame formulation RFF to ensure the incremental objectivity of the model in the framework of finite strains. Finally, the purpose of this work is to evaluate the reliability of different methods predict efficiently springback in sheet metal forming.

The model is implemented using Abaqus user element subroutine and verified against the experimental ABAQUS and other commercially available finite element codes do not have the capability to solve general electromigration problem directly. Hazardous Materials Control Module. Author s 8. Performing Organization After presenting.

Formability of steel and aluminium alloys in hot stamping and cold die quenching processes is studied in this research. Viscoplastic-damage constitutive equations are developed and determined from experimental data for the prediction of viscoplastic flow and ductility of the materials. An FE process simulation model and numerical procedures are established for the modeling of hot stamping processes for a spherical part with a central hole.

Different failure modes failure takes place either near the central hole or in the mid span of the part are obtained. To validate the simulation results, a test programme is developed, a test die set has been designed and manufactured, and tests have been carried out for the materials with different forming rates.

It has been found that very close agreements between experimental and numerical process simulation results are obtained for the ranges of temperatures and forming rates carried out. Federal Register , , , , For Applied Materials China , Inc Acceptable noise level ANL with Danish and non-semantic speech materials in adult hearing-aid users.

The acceptable noise level ANL test is used for quantification of the amount of background noise subjects accept when listening to speech. ANL was measured in three conditions in both ears at two test sessions. ANLs were similar to results with American English speech material.

The coefficient of repeatability CR was 6. The magnitude of the CR indicates that ANL with Danish and non-semantic speech materials is not suitable for prediction of individual patterns of future hearing-aid use or evaluation of individual benefit from hearing-aid features.

The SME provides an integrated set of management tools that can be used by software development managers in their day-to-day management and planning activities.

This document provides an overview of the SME, a description of all functions, and detailed instructions concerning the software’s installation and use. A multi- user real time inventorying system for radioactive materials : a networking approach. A computerized system for radioisotope management and real time inventory coordinated across a large organization is reported.

It handles hundreds of individual users and their separate inventory records. Use of highly efficient computer network and database technologies makes it possible to accept, maintain, and furnish all records related to receipt, usage, and disposal of the radioactive materials for the users separately and collectively.

Radioisotope decay is automatically calculated by the program, so that it can make the up-to-date radioisotope inventory data of an entire institution available immediately. The system is specifically designed to allow use by large numbers of users about and accommodates high volumes of data input and retrieval without compromising simplicity and accuracy. Overall, it is an example of a true multi- user , on-line, relational database information system that makes the functioning of a radiation safety department efficient.

SPECabq v. The SPEC model was published in the open literature in The subroutine is used to analyze the thermomechanical behavior of isotropic polymers predicting things like how a polymer may undergo stress or volume relaxation under different temperature and loading environments. This subroutine enables the ABAQUSmore » finite element code to be used for analyzing the thermo-mechanical behavior of samples and parts that are made from glassy polymers.

The entire model 22 including the boundary. The new model was used to simulate the thermally reversible flow behaviour for C-S type two-step deformation, and the results are A tangent modulus method [48] was used for the time This approach was motivated by modern understanding of dislocation mechanisms for Ni3Al.

Owing to the attendant large strains and This finding is consistent with the In accordance with the previously observed larger thermal – expansion effects in Al, Figure 5 b shows that the. Zhang, K. Simulation of microplasticity -induced deformation in uniaxially strained ceramics by 3-D Voronoi. Thermal analysis of friction riveting of dissimilar materials. Friction riveting is a new technique which finds its applications in a variety of domains, where there is a need to join dissimilar materials for the sake of achieving weight reduction of the components produced especially in the fields of aerospace and automobile.

In this present work, a numerical simulation on the heat transfer analysis has been done to predict the variation of temperature on the surface of the components being joined. Owing to the applications, Aluminum rivet is chosen for friction riveting on Poly Methyl Metha Acrylate base material.

Abaqus explicit version 6. Heat flux at the joint interface has been computed and thermal distribution at the work material is predicted. Nemeth, Noel N. A finite element FE model is developed for the progressive failure analysis of fiber reinforced polymer laminates. The gradual degradation of the material properties is controlled by the individual fracture energies of fiber and matrix. The failure and damage in composite laminates containing a central hole subjected to uniaxial tension are simulated.

The numerical results show that the damage model can be used to accurately predicte the progressive failure behaviour both qualitatively and quantitatively. Users ‘ input has been utilized to help: 1 design the…. Material modeling of biofilm mechanical properties. A biofilm material model and a procedure for numerical integration are developed in this article.

They enable calculation of a composite Young’s modulus that varies in the biofilm and evolves with deformation. Compressive, tensile, and shear loads are imposed, and the way the biofilm mechanical properties evolve is assessed. Results show that the local values of Young’s modulus increase under compressive loading, since compression results in the voids “closing,” thus making the material stiffer.

For the opposite reason, biofilm stiffness decreases when tensile loads are imposed. Furthermore, the biofilm is more compliant in shear than in compression or tension due to the how the elastic shear modulus relates to Young’s modulus. M50 steel V-Ring raceways, and extended the bearing life prediction methods of Ioannides and Harris 10 to predict the remaining useful life of Second Edition, , Cambridge University Finite Element Model Geometry Figure 6.

Tracings of spall edges from M50 and Pyrowear bearing steels. Author s S. Performing Organization Rapt. Dress ESA WANG 1I. While many surveys aim primarily at measuring general user satisfaction, this survey is dedicated to understanding music users ‘ needs, usage patterns, and preferences towards various collections. Findings showed dissimilar use behavior and perceived importance of materials between academic- and performance-oriented music users.

Needs for different…. After a The majority of creep tests are uniaxial compressive tests Kennedy, and Perry Volume 1: Main Text. The heat transfer capability of ABAQUS uses the finite element method to numerically solve the governing differential The different concrete mixture.

Proceedings of the U. Circumferential, or cross-barrel The code will perform static, dynamic, and thermal anal- ysis on a broad range of structures In this investigation, a thermo-mechanical model of pebble beds is adopted and developed based on experiments by Dr. The framework of the present material model is composed of a non-linear elastic law, the Drucker-Prager-Cap theory, and a modified creep law. Furthermore, the volumetric inelastic strain dependent thermal conductivity of beryllium pebble beds is taken into account and full thermo-mechanical coupling is considered.

Investigation showed that the Drucker-Prager-Cap model implemented in ABAQUS can not fulfill the requirements of both the prediction of large creep strains and the hardening behaviour caused by creep, which are of importancemore » with respect to the application of pebble beds in fusion blankets.

An elastic predictor radial return mapping algorithm is used to solve the non-associated plasticity iteratively, and a proper tangent stiffness matrix is obtained for cost-efficiency in the calculation. An explicit creep mechanism is adopted for the prediction of time-dependent behaviour in order to represent large creep strains in high temperature.

The oedometric compression tests and creep tests of pebble beds at different temperatures are simulated with the help of the present UMAT and UMATHT routines, and the comparison between the simulation and the experiments is made. It is challenging for primary care physicians PCPs to review and apply the growing amount of clinical evidence available.

Printed educational materials PEMs , which synthesize evidence, are often ineffective at improving knowledge, possibly due to poor design and limited uptake.

In this study, we collected PCP preferences for the design and content of physician-oriented PEMs and determined key attributes that may increase their usability and uptake.

Focus groups included discussion about whether and how participants use PEMs, feedback on three examples of PEMs, and a discussion on general format and design preferences in PEMs.

We analyzed focus group transcripts using a thematic analysis and summarized results in a list of user preferences. Four focus groups were held with 13 PCPs. We found that participants only read PEMs relevant to their patients and prefer short, concise documents, with links to sources that can provide more detailed information. Simplicity of materials was important, with many participants preferring PEMs without lengthy backgrounds or scientific explanations.

Most participants wanted to see key messages highlighted to easily assess the relevance of the materials to their practice. Some participants shared physician-oriented PEMs with patients. This study shows that PCPs may prefer shorter, simpler, and more concise documents that have less scientific detail but provide references to further information sources.

It is important to understand end user preferences for the design and content of these materials to enhance their uptake. Splitting, ultimate failure load and the damage path in center notched composite specimens subjected to in-plane tension loading are predicted using progressive failure analysis methodology. A 2-D Hashin-Rotem failure criterion is used in determining intra-laminar fiber and matrix failures. A 2-D finite element model is used for predicting the intra-laminar damages.

The importance of modeling delamination in progressive failure analysis methodology is recognized for future studies. The use of an explicit integration dynamics code for simple specimen geometry and static loading establishes a foundation for future analyses where complex loading and nonlinear dynamic interactions of damage and structure will necessitate it.

As a result, a Langragian treatment of the structure is preferred. Therefore, a finite element solver with the capability of This is followed by a remapping The hydrostatic behavior of. Shape memory alloy hybrid composites with adaptive-stiffening or morphing functions are simulated using finite element analysis. The composite structure is a laminated fiber-polymer composite beam with embedded SMA ribbons at various positions with respect to the neutral axis of the beam.

Adaptive stiffening or morphing is activated via selective resistance heating of the SMA ribbons or uniform thermal loads on the beam. The examples demonstrate the usefulness of the methods for the design and simulation of SMA hybrid composites.

Keywords: shape memory alloys, Nitinol, ABAQUS , finite element analysis, post-buckling control, shape control, deflection control, adaptive stiffening, morphing, constitutive modeling, user element. Numerical analysis of strain localization for transversely isotropic model with non-coaxial flow rule. To analyse the strain localization behavior of geomaterials, the forward Euler schemes and the tangent modulus matrix are formulated based on the transversely isotropic yield criterion with non-coaxial flow rule developed by Lade, the program code is implemented based on the user subroutine UMAT of ABAQUS.

The influence of the material principal direction on the strain localization and the bearing capacity of the structure are investigated and analyzed. Numerical results show the validity and performance of the proposed model in simulating the strain localization behavior of geostructures. A hybrid modeling system designed to support decision making in the optimization of extrusion of inhomogeneous materials. Mathematical models and a hybrid modeling system are developed for the implementation of the experimental-calculation method for the engineering analysis and optimization of the plastic deformation of inhomogeneous materials with the purpose of improving metal-forming processes and machines.

Practical application of the software solution is exemplified by modeling the process of extrusion of a bimetallic billet. The results of the engineering analysis and optimization of the extrusion process are shown, the material damage being monitored. Mechatronic Materials and Systems. One side of the structure is fully clamped, while the other is free to displace. As in prior assessments [ To simulate the complete system, the core and the Kagome face members are modeled using linear To simulate the complete actuation system, the core and Kagome members are modeled using linear Timoshenko-type beams, while the solid.

Wheelchair propulsion exposes the user to a high risk of shoulder injury and to whole-body vibration that exceeds recommendations of ISO Reducing the mechanical work required to travel a given distance WN-WPM, weight-normalized work-per-meter can help reduce the risk of shoulder injury, while reducing the vibration transmissibility VT of the wheelchair frame can reduce whole-body vibration.

New materials such as titanium and carbon are used in today’s wheelchairs and are advertised to improve both parameters, but current knowledge on this matter is limited. In this study, WN-WPM and VT were measured simultaneously and compared between six folding wheelchairs 1 titanium, 1 carbon, and 4 aluminium.

Ten able-bodied users propelled the six wheelchairs on three ground surfaces. The subjects discussed include the following: 1 statics and buckling, 2 vibrations and dynamics, 3 substructing, 4 new capability, 5 user ‘s experience, and 6 system experience. A simple continuum damage mechanics CDM based 3D progressive damage analysis PDA tool for laminated composites was developed and implemented as a user defined material subroutine to link with a commercially available explicit finite element code.

This PDA tool uses linear lamina properties from standard tests, predicts damage initiation with an easy-to-implement Hashin-Rotem failure criteria, and in the damage evolution phase, evaluates the degradation of material properties based on the crack band theory and traction-separation cohesive laws. It follows Matzenmiller et al. Since nonlinear shear and matrix stress-strain relations are not implemented, correction factors are used for slowing the reduction of the damaged shear stiffness terms to reflect the effect of these nonlinearities on the laminate strength predictions.

Strength predictions obtained, using this VUMAT, are correlated with test data for a set of notched specimens under tension and compression loads. Cyclic softening based on dislocation annihilation at sub-cell boundary for SA Grade-6 C-Mn steel. In this work, the response of SA Grade-6 C-Mn steel subjected to uniaxial and in-phase biaxial tension-torsion cyclic loading is experimented and an attempt is made to model the material behaviour.

The relevant material parameters are extracted from the appropriate experimental results and metallurgical investigations. The material model is plugged as user material subroutine into ABAQUS FE platform to simulate pre-saturation low cycle fatigue loops with cyclic softening and other cyclic plastic behaviour under prescribed loading. The stress-strain hysteresis loops and peak stress with cycles were compared with the experimental results and good agreements between experimental and simulated results validated the material model.

Turon s methodology for determining optimal analysis parameters for the simulation of progressive delamination is reviewed. The Abaqus cohesive element, COH3D8, and a user -defined cohesive element are used to develop finite element models of the double cantilever beam specimen, the end-notched flexure specimen, and the mixed-mode bending specimen to simulate progressive delamination growth in Mode I, Mode II, and mixed-mode fracture, respectively.

The predicted responses are compared with their analytical solutions. The results show that for single-mode fracture, the predicted responses obtained with the Abaqus cohesive element correlate well with the analytical solutions. For mixed-mode fracture, it was found that the response predicted using COH3D8 elements depends on the damage evolution criterion that is used.

The energy-based criterion overpredicts the peak loads and load-deflection response. The results predicted using a tabulated form of the BK criterion correlate well with the analytical solution and with the results predicted with the user -written element.

A 3D moisture-stress FEM analysis for time dependent problems in timber structures. This paper presents a 3D moisture-stress numerical analysis for timber structures under variable humidity and load conditions. An orthotropic viscoelastic-mechanosorptive material model is specialized on the basis of previous models.

Both the constitutive model and the equations needed to describe the moisture flow across the structure are implemented into user subroutines of the Abaqus finite element code and a coupled moisture-stress analysis is performed for several types of mechanical loads and moisture changes.

The presented computational approach is validated by analyzing some wood tests described in the literature and comparing the computational results with the reported experimental data. Fracture simulation of restored teeth using a continuum damage mechanics failure model.

The aim of this paper is to validate the use of a finite-element FE based continuum damage mechanics CDM failure model to simulate the debonding and fracture of restored teeth. Fracture testing of plastic model teeth, with or without a standard Class-II MOD mesial-occusal-distal restoration, was carried out to investigate their fracture behavior. The material parameters needed for the CDM model to simulate fracture are obtained through separate mechanical tests.

The predicted results are then compared with the experimental data of the fracture tests to validate the failure model. The failure processes of the intact and restored model teeth are successfully reproduced by the simulation.

However, the fracture parameters obtained from testing small specimens need to be adjusted to account for the size effect. The results indicate that the CDM model is a viable model for the prediction of debonding and fracture in dental restorations.

This document describes the current state of the MAMA Morphological Analysis of Materials software user identified bugs, issues, and requests for improvements. It also lists Current users and current training methods. Objective stress rates are often used in commercial finite element FE programs.

However, deriving a consistent tangent modulus tensor also known as elasticity tensor or material Jacobian associated with the objective stress rates is challenging when complex material models are utilized. In this paper, an approximation method for the tangent modulus tensor associated with the Green-Naghdi rate of the Kirchhoff stress is employed to simplify the evaluation process. The effectiveness of the approach is demonstrated through the implementation of two user -defined fiber-reinforced hyperelastic material models.

Comparisons between the approximation method and the closed-form analytical method demonstrate that the former can simplify the material Jacobian evaluation with satisfactory accuracy while retaining its computational efficiency.

PAVECHECK is a software package used to integrate nondestructive test data from various testing systems to provide the pavement engineer with a comprehensive evaluation of both surface and subsurface conditions. This User ‘s Manual is intended to demo A thermodynamically consistent damage model for the simulation of progressive delamination under variable mode ratio is presented.

The model is formulated in the context of the Damage Mechanics DM. The constitutive equations that result from the variation of the free energy with damage are used to model the initiation and propagation of delamination. A new delamination initiation criterion is developed to assure that the formulation can account for changes in the loading mode in a thermodynamically consistent way.

Interfacial penetration of two adjacent layers after complete decohesion is prevented by the formulation of the free energy. The model is implemented into the commercial finite element code ABAQUS by means of a user -written decohesion element. Finally, the numerical predictions given by the model are compared with experimental results.

A 1-dimensional material model was developed for simulating the transverse thickness-direction loading and unloading response of aluminum honeycomb structure. The UMAT has been applied to analyses for simulating quasi-static indentation tests on aluminum honeycomb-based sandwich plates. Comparison of analysis results with data from these experiments shows overall good agreement. Specifically, analyses of quasi-static indentation tests yielded accurate global specimen responses.

Predicted residual indentation was also in reasonable agreement with measured values. Overall, this simple model does not involve a significant computational burden, which makes it more tractable to simulate other damage mechanisms in the same analysis. Modeling delamination of FRP laminates under low velocity impact.

Fiber reinforced plastic laminates FRP have been increasingly used in various engineering such as aeronautics, astronautics, transportation, naval architecture and their impact response and failure are a major concern in academic community.

A new numerical model is suggested for fiber reinforced plastic composites. The model considers that FRP laminates has been constituted by unidirectional laminated plates with adhesive layers.

It transpires that the present model predicted delamination is in good agreement with the experimental results for low velocity impact. Weight optimal design of lateral wing upper covers made of composite materials. The present investigation is devoted to the development of a new optimal design of lateral wing upper covers made of advanced composite materials , with special emphasis on closer conformity of the developed finite element analysis and operational requirements for aircraft wing panels.

In the first stage, 24 weight optimization problems based on linear buckling analysis were solved for the laminated composite panels with three types of stiffener, two stiffener pitches and four load levels, taking into account manufacturing, reparability and damage tolerance requirements.

Owing to the large dimension of numerical problems to be solved, an optimization methodology was developed employing the method of experimental design and response surface technique.

Tooth fracture risk analysis based on a new finite element dental structure models using micro-CT data. The finite element FE analysis is an effective method to study the strength and predict the fracture risk of endodontically-treated teeth.

With this method, the inhomogeneity of material properties of teeth was included into the model without dividing the tooth model into different regions. The material properties of the tooth were assumed to be related to the mineral density. The fracture risk at different tooth portions was assessed for root canal treatments. The micro-CT images of a tooth were processed by a Matlab software programme and the CT numbers were retrieved. The tooth contours were obtained with thresholding segmentation using Amira.

The inner and outer surfaces of the tooth were imported into Solidworks and a three-dimensional 3D tooth model was constructed. Three root canal geometries original and two enlargements were investigated. The proposed method in this study can generate detailed 3D finite element models of a tooth with different root canal enlargements and filling materials , and would be very useful for the assessment of the fracture risk at different tooth portions after root canal treatments. FRED user ‘s manual.

FRED, the friendly editor, is a screen-based structured editor. This manual is intended to serve the needs of a wide range of users of the FRED text editor.

Most users will find it sufficient to read the introductory material in section 2, supplemented with the full command set description in section 3. Advanced users may wish to change the keystroke sequences which invoke editor commands. Section 4 describes how to change key bindings and how to define command macros.

Some users may need to modify a language description or create an entirely new language description for use with FRED. Sectionmore » 5 describes the format of the language descriptions used by the editor, and describes how to construct a language grammar.

Section 6 describes known portability problems of the FRED editor and should concern only system installation personnel. The editor points out syntax errors in the file being edited and does automatic pretty printing. Phase 2 STS new user development program. Volume 1: Executive summary. The approach to user development, reflected in the implementation plan, and attendant informational material to be used were evaluated by conducting a series of test cases with selected user organizations.

These test case organizations were, in effect, used as consultants to evaluate the effectiveness, the needs, the completeness, and the adequacy of the user development approach and informational material.

The selection of the test cases provided a variety of potential STS users covering industry, other government agencies, and the educational sector. The test cases covered various use areas and provided a mix of user organization types.

A summary of the actual test cases conducted is given. The conduct of the test cases verified the general approach of the implementation plan, the validity of the user development strategy prepared for each test case organization and the effectiveness of the STS basic and user customized informational material.

One of the objectives of the LDEF Special Investigation Group SIG was to develop a LDEF data base that identifies the experiment objectives and hardware flown, summarizes results and conclusions, and provides a system analysis overview, including spacecraft design guidelines and space environmental effects. Compiling the information into an easily accessible data base format, and making it available to the space community was a major task accomplished by the System and Materials SIG effort beginning in Accompanying this document are the mini-data bases on disk.

AF-Shell 1. This document serves as a user guide for the AF-Shell 1. This guide contains minimal technical material and is meant solely as a guide for a new user to apply AF-Shell 1.

The mechanical and constitutive response of materials like cement, and bio materials like fish scale and abalone shell is very complex due to heterogeneities that are inherently present in the nano and microstructures. The intrinsic constitutive behaviors are driven by the chemical composition and the molecular, micro, and meso structures.

Therefore, it becomes important to identify the material genome as the building block for the material. For instance, in cementitious materials , the genome of C-S-H phase the glue or the paste that holds the various clinkers, such as the dicalcium silicate, tricalcium silicate, calcium ferroaluminates, and others is extremely complex. Often mechanical behaviors of C-S-H type materials are influenced by the chemistry and the structures at all nano to micro length scales.

By explicitly modeling the molecular structures using appropriate potentials, it is then possible to compute the elastic tensor from molecular dynamics simulations using all atom method. This paper presents a three-dimensional, energy based, anisotropic, stiffness reduction, progressive damage model for composite materials and composite material constituents.

The model has been implemented as a user -defined constitutive model within the Abaqus finite element software package and applied to simulate the nonlinear behavior of a damaging epoxy matrix within a unidirectional composite material. Three different composite microstructures were considered as finite element repeating unit cells, with appropriate periodicity conditions applied at the boundaries.

Results representing predicted transverse tensile, longitudinal shear, and transverse shear stress-strain curves are presented, along with plots of the local fields indicating the damage progression within the microstructure. It is demonstrated that the damage model functions appropriately at the matrix scale, enabling localization of the damage to simulate failure of the composite material. The influence of the repeating unit cell geometry and the effect of the directionality of the applied loading are investigated and discussed.

Modelling multiple cycles of static and dynamic recrystallisation using a fully implicit isotropic material model based on dislocation density. This paper presents the development and numerical implementation of a state variable based thermomechanical material model, intended for use within a fully implicit finite element formulation. Plastic hardening, thermal recovery and multiple cycles of recrystallisation can be tracked for single peak as well as multiple peak recrystallisation response.

The numerical implementation of the state variable model extends on a J2 isotropic hypo-elastoplastic modelling framework. Implementation is discussed with detailed explanation of the derivation and use of various sensitivities, internal state variable management and multiple recrystallisation cycle contributions. A flow chart explaining the proposed numerical implementation is provided as well as verification on the convergence of the material subroutine.

The material model is characterised using two high temperature data sets for cobalt and copper. The results of finite element analyses using the material parameter values characterised on the copper data set are also presented.

The paper concerns the rheological bending problem of wooden beams reinforced with embedded composite bars. A theoretical model of the behaviour of a multi-layered beam is presented. The component materials of this beam are described with equations for the linear viscoelastic five-parameter rheological model. Two numerical analysis methods for the long-term response of wood structures are presented. Laboratory investigations were conducted on sample beams of natural dimensions in order to validate the proposed theoretical model and verify numerical simulations.

Good agreement between experimental measurements and numerical results is observed. Ergonomic material -handling device. A hand-held ergonomic material -handling device capable of moving heavy objects, such as large waste containers and other large objects requiring mechanical assistance.

The ergonomic material -handling device can be used with neutral postures of the back, shoulders, wrists and knees, thereby reducing potential injury to the user. The device involves two key features: 1 gives the user the ability to adjust the height of the handles of the device to ergonomically fit the needs of the user ‘s back, wrists and shoulders; and 2 has a rounded handlebar shape, as well as the size and configuration of the handles which keep the user ‘s wrists in a neutral posture during manipulation of the device.

Parameter estimation of a nonlinear Burger’s model using nanoindentation and finite element-based inverse analysis. Nanoindentation involves probing a hard diamond tip into a material , where the load and the displacement experienced by the tip is recorded continuously.

This load-displacement data is a direct function of material ‘s innate stress-strain behavior. Thus, theoretically it is possible to extract mechanical properties of a material through nanoindentation. However, due to various nonlinearities associated with nanoindentation the process of interpreting load-displacement data into material properties is difficult. Although, simple elastic behavior can be characterized easily, a method to characterize complicated material behavior such as nonlinear viscoelasticity is still lacking.

In this study, a nanoindentation-based material characterization technique is developed to characterize soft materials exhibiting nonlinear viscoelasticity. The model parameters were calibrated using a process called inverse analysis. In this study, a surrogate model-based approach was used for the inverse analysis.

The different factors affecting the surrogate model performance are analyzed in order to optimize the performance with respect to the computational cost. LDEF materials data bases. The Long Duration Exposure Facility LDEF and the accompanying experiments were composed of and contained a wide variety of materials representing the largest collection of materials flown in low Earth orbit LEO and retrieved for ground based analysis to date.

The results and implications of the mechanical, thermal, optical, and electrical data from these materials are the foundation on which future LEO space missions will be built. The LDEF Materials Special Investigation Group MSIG has been charged with establishing and developing data bases to document these materials and their performance to assure not only that the data are archived for future generations but also that the data are available to the spacecraft user community in an easily accessed, user -friendly form.

This paper discusses the format and content of the three data bases developed or being developed to accomplish this task. The hardware and software requirements for each of these three data bases are discussed along with current availability of the data bases. The Nuclear Science User Facilities has been in the process of establishing an innovative Irradiated Materials Library concept for maximizing the value of previous and on-going materials and nuclear fuels irradiation test campaigns, including utilization of real-world components retrieved from current and decommissioned reactors.

Remember me on this computer. Enter the email address you signed up with and we’ll email you a reset link. Need an account? Click here to sign up. Download Free PDF. Loss Prevention in the Process Industries Volume 1. Related Papers. Process Safety Progress Models for domino effect analysis in chemical process industries.

Journal of Loss Prevention in The Process Industries Design of mitigation systems for indoor and outdoor ammonia releases. An integrated quantitative hazard analysis method for natural gas jet release from underground gas storage caverns in salt rock. I: Models and validation.

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