Creation Of Finite Element Models Research Articles

Predictive modeling of 3D textile composites using realistic micromechanical representations

An innovative and efficient progressive damage model, informed by coupon tests, and using minimal, readily available material parameters, is proposed in this paper to comprehensively predict the tensile, compressive and shear stress–strain response and strengths of a 3D woven angle interlock composite within 5% of test data. Realistic, high-fidelity microgeometries, with process-induced defects, and devoid of geometric assumptions, are constructed using the digital element approach. Excellent correlations with test micrographs are observed for yarn cross-section areas, aspect ratios and crimp ratios, that are on average within 5.5%, 1.9% and 1% of the micrograph measurements respectively. The mesoscale predictions capture the detailed failure mechanisms under each loading condition. Analytical stiffness expressions are derived in terms of the constituent material elastic properties and architecture geometry, which also predict the stiffnesses within 10% error margin. A robust workflow is established that combines the high-fidelity microgeometry generation, automated conformal finite element model creation and comprehensive property prediction capabilities to provide a holistic solution.

Развитие CAE системы численного моделирования НДС SIGMA GT

The paper presents the directions and results of developing the Sigma GT software suite designed for numerical modeling of the stress-and-strain state of a rock mass using the finite element method. It describes the process of computational module optimization to ensure the possibility of refined simulation in subareas of the original model. The process of storing coarse grid matrices is upgraded, which optimizes the use of computational resources when calculating the stress-and-strain state of large-scale models. The trial-and-error procedure has been improved up to the system of hierarchical interrelation of different scale models, which allows to actualize the boundary conditions of individual block models when modifying the field model configuration. An extensible library of local models is presented, which makes it possible to quickly generate models of mining system elements with adequate boundary conditions. The expandable functionality of the software product is demonstrated, which allows to accelerate the process of finite element model creation. This tool allows the software user to generate local models of various configurations, minimizing time consumption and possible errors in preparation of the finite element mesh. Application and functionality of tools for post-processing of modeling results, both in 2D and 3D form, are described. Export of stress isolines allows saving the calculation data in the format used at the mining enterprise and combining them with the maps of mine working. 3D visualization of the calculated data contributes to a comprehensive assessment of the stress-and-strain state vector field and identification of the areas with critical stress and strain concentrations under a certain mining development option.

Shells in the form of algebraic ruled surfaces on a rhombic base

One of the promising objects for application in architectural and construction practice are analytically determined structural shapes in the form of thin elastic shells with a median surface in the form of algebraic ruled surfaces on a rhombic plan on the basis of various curves. In particular, this study considers three surfaces with identical framework forming lines of superellipses using framework curves that have the appearance of waterline, midships section, and main buttock lines - lines that have been initially generated and used in shipbuilding. The shapes of structures on a rhombic base were considered. The study contains geometric modeling of such structures, creation of finite element models and their computation. A comparison of the values characterizing the stress-strain state for three different shapes with the same span and lifting arm (variant designing with optimized choice) has been carried out. From the theoretical point of view, the possibility of generating three different surfaces on the same frame seems to be an interesting result. From the viewpoint of strength analysis, one of the three obtained shells was chosen as it has the most uniform stress distribution, which is the most economical in terms of material cost.

Surrogate model development using simulation data to predict weld residual stress: A case study based on the NeT-TG1 benchmark

Surrogate models have been used as a substitute for traditional engineering simulation to get target simulation results faster. These surrogate models usually need sufficient data to fulfill their optimum performance. However, the acquisition of high quality datasets for cases like welding residual stress is both difficult and costly. This work developed a workflow that can rapidly develop machine learning based surrogate models to predict post-weld residual stresses using finite element (FE) simulation data. The workflow comprises five steps: (i) baseline FE model creation, (ii) FE model processing (iii) scripting (iv) data generation and (v) surrogate model development. The workflow presented in the paper automates all the steps involved in generating, calculating, and extracting results from FE simulations, with the aim of reducing the time and cost required for data acquisition. In addition, to minimize the possibility of FE analyses not completing successfully during the automated data generation process and to ensure that the training data can be obtained without any manual intervention, the FE model was simplified without significant loss of accuracy. A single weld bead-on-plate structure, taken from the NeT project Task Group 1, was used as a case study to validate the developed workflow. The overall aim of this work was to validate the feasibility of developing a surrogate model for specific welding conditions with no experimental dataset and with the aid of simulations, and to investigate the predictive performance of an Artificial Neural Network based surrogate model. Four welding parameters, arc advance speed, net energy input rate, arc travel length and position, were considered as the input for the surrogate model to predict the longitudinal stress along the line running across the sample thickness in the mid-length of the specimen. The relative root mean square error of the predictive surrogate model for the test dataset was 0.0024. Residual stress prediction based on the NeT-TG1 benchmark welding case met the R6 validation criteria and the developed model generates predictions that are in line with other methods used by contributors to the NeT-TG1 round robin.

Finite element analysis of the stress state of the hip joint endoprothesis while walking

The study of the stress-strain state of the biomechanical system "pelvis - customized implant" by the finite element method is widely used in the treatment of pelvic injuries in orthopedics. However, the effect of the complex loading conditions that a person encounters on a daily basis on the behavior of the hip joint is not well understood. This work is devoted to the study of the stress-strain state of the biomechanical system formed by an endoprosthesis of the hip joint and the bones of the pelvic region of a person while walking. As part of solving the problem, the features of the creation of finite element models of the pelvic bones and an individual endoprosthesis were considered on the basis of the initial geometric models obtained from the Federal State Budgetary Institution "National Medical Research Center of Traumatology and Orthopedics named after R.R. Vreden" (St. Petersburg) and performed a series of strength calculations for the walking pattern. The implant model replaced the primary installed prosthesis, which was lost due to the development of instability of the acetabular component. Analysis showed that the screws and the endoprosthesis have a sufficient margin of safety, while in the bone tissue one can expect local micro-destruction in the zone of its contacts with the screws. During the operation, it is worth focusing on the bonding of the implant to the bone tissue in order to avoid unwanted destruction of the cortical layer around the holes. Based on the analysis results, a recommendation can be made to exclude screws numbered eight and nine, since neither the screws nor the holes for them are subjected to heavy loads.

Evaluation of vertebral bone strength with a finite element method using low dose computed tomography imaging

BackgroundFocusing on compression fractures of bone by finite elements, we evaluated bone strength based on the computed tomography-based finite element method. However, the exposure dose is an issue. We aimed to investigate the quantity of reduction of the radiation dose with respect to the reference dose by comparing the calculation results of compression fractures of the vertebral body using experimental data obtained from the spine of a pig. MethodsComputed tomography images of a self-made phantom that enclosed the lower lumbar vertebra of edible wild pigs were obtained under baseline-dose conditions using various lower tube currents. Images obtained under reference-dose conditions were reconstructed using the filtered back-projection method, whereas images obtained under low-dose conditions were reconstructed using both the filtered back-projection method and the iterative reconstruction method. Computer simulations involving the creation of finite element models using all images were implemented for the compression load calculation for vertebral body parts. Based on the calculated results, images of the low-dose and reference-dose conditions were compared. ResultsUsing pigs’ lower lumbar vertebrae, finite element model analysis of low-dose X-ray computed tomography images showed that equivalent results can be obtained with a dose of approximately 40% of the standard radiographic reference doses. As for the compression stress intensity, the same results as those under reference-dose conditions were obtained using the iterative reconstruction method in combination with computed tomography-based finite element method. ConclusionsThe combination of the iterative reconstruction method with the computed tomography-based finite element method is an effective image reconstruction method for achieving dose reduction.

Interlaminar Strength Analysis of Bonded Carbon Fiber Rods

Interlaminar failure of bonded composite structures is quite often. Nowadays there is a lot of lightweight high reliability carbon or glass fiber (CFRP or GFRP) reinforced polymer composite constructions with bonded carbon or glass fiber rods. In order to better understand the delamination processes of the rods, analytical equations were analyzed. Later, mode I interlaminar failure experiments with CFRP rods 3x3 mm were performed and fracture toughness GIC = 135 J/m2 was found. According to the analytic equations, experiment and values, given literature, finite element model (FEM) of the bonded carbon fiber rods was created in software LS-Dyna. Most of the differences between experimental and simulated force-displacement curves are not higher than 6 % what validates the FEM of the bonded CFRP rods. Also, additional methods, such as peridynamics of the bond area of the rods were analyzed. Offered finite element approach of the bonded CFRP rods is very useful for FEM creation to design and evaluate high reliability CFRP or GFRP constructions.

Influence of Process and Billet Parameters on the Dimensional Accuracy of Hexagonal Pipes During Mandrel Drawing

The object of the article is hexagonal profile tubes with a round inner hole. Tubes of such configuration have wide enough application, however the way of their obtaining by drawing in profile tool is insufficiently investigated. The paper is devoted to description of creation of finite element model of plastic deformation process of pipes, the basic computational capabilities of the model are given, a number of conclusions made on the basis of modelling results are given.

A parametric modelling strategy for the numerical simulation of 3D concrete printing with complex geometries

Abstract Three-dimensional concrete printing (3DCP) is a fast-evolving manufacturing technique in the construction industry with numerous advantages over traditional construction methods. Nevertheless, many unknowns about 3DCP in the manufacturing stage still remain, such as the maximum number of printed layers before failure or the maximum speed at which a certain design can be properly printed. In this paper, a numerical model for the simulation of the structural behaviour of 3D printed fresh concrete is proposed and discussed. In order to obtain complete control over the additive process, material properties and layer interactions, the finite element mesh needs to be created from the ground up in a layer-wise manner. Therefore, a parametric tool was developed, which allows for the creation of finite element models without requiring extensive manual modelling. The main advantage of the developed tool is the possibility to automate the pre-processing step for the numerical analysis and simulate the structural behaviour of a randomly shaped object during printing. Additionally, it allows for finding the appropriate material properties for a certain print object at a desired print speed and vice versa. As such, the printing process can first be virtually simulated and improved upon without physical experimentation and the corresponding material waste. Ultimately, the developed tool can assist in an entire 3DCP workflow with regard to efficiency and material usage. Models created with the presented tool were evaluated and validated based on experimental and numerical results from literature. Finally, the case study of a geometrically complex print object is presented, demonstrating the tool’s potential.

Features of information modeling of cultural heritage objects

This paper focuses on features of heritage objects information modeling and its integration with structural analysis under various types of impacts. We discuss different results of structural analysis based on finite element model (FEM) of the New Hermitage portico. Thanks to laser scanning technology it was possible to collect all the geometric features of this object and generate an adequate mathematical model based on the obtained data. The methodology of finite element model creation based on laser scanning and BIM technologies is proposed. Some interesting results of laser scanning survey and numerical modelling have been discussed. Deviations of the portico’s structural elements have been identified based on the use of laser scanning, BIM and FEA. It has been found out that the displacement of the upper parts of the columns relative to the lower ones in the direction of the facade wall is 4 cm. An intermediate HBIM of the portico (LOD 100) has been created inside Revit. Finite element model with default element size of 300 mm has been created using ANSYS. Directions for further research have been also determined.

ВИКОРИСТАННЯ ІНСТРУМЕНТІВ MESHING TOOLBOX ДЛЯ ПІДГОТОВКИ І СТВОРЕННЯ СКІНЧЕННО-ЕЛЕМЕНТНИХ МОДЕЛЕЙ

Geometry preparation and construction of high-quality finite element mesh is one of the key steps of analysis using computer aided engineering tools. Therefore, rational application of tools used for creation of finite element models is useful skill that determines the efficiency and productivity of numerical analysis and also effects the accuracy and time required for getting the result.The capabilities of the Meshing Toolbox of FEMAP v. 10.2 finite element software, which are used for preparation and creation of finite element models of the objects with complex geometry, are described in the paper. The goal of the work is to build high-quality, mapped meshes for objects with complex geometry and reduce the dimension of the finite element model. Methods for improving the quality of the mesh in the local areas of a model with complex geometry and reducing the dimension of a model are considered using several practical examples. A useful and practical feature of the tools is that automatic remeshing is provided in case of changing the basic geometry. The effective application of tools for preparation and creation of finite element models allows you to build mapped hexahedral meshes and thereby significantly reduce the dimension of finite element models, increasing their computational efficiency. Depending on the degree of complexity of the model, the number of elements in the model decreased by several times, and the number of nodes — on average, by 20%. The issue of applying the described approach and tools is especially concern for large models and in case of limited computational resources.

Automated Segmentation of Swine Skulls for Finite Element Model Creation Using High Resolution μ-CT Images

Finite element (FE) analysis has been widely used to investigate bone responses to mechanical loading. Research in long bones has been straight forward because modeling of these bones requires only two material properties. Such an FE model may provide an adequate approximation of the anatomy for many cases. However, a more detailed model of skull bones is needed to accurately capture its complex structure of multiple bone pieces and the various mineral densities distributed throughout these bone pieces. Unfortunately, FE model development incorporating both complex geometries and anatomically accurate material properties is both computationally and labor intensive. In this study, a method is proposed to automatically segment micro-computed tomography ([Formula: see text]-CT) scan images of bone pieces to build an FE model of a full swine hemi-skull. Using the Digital Imaging and Communications in Medicine (DICOM) files from scanned bones, the complete geometry of each bone piece is recreated through seven customized processing algorithms. After assembling the bone pieces to form the skull, experimentally derived Young’s modulus values are correlated to grayscale values to produce a detailed FE model for accurate simulation. This detailed skull model can be used to predict strain/stress patterns in response to various loading regimes to facilitate research questions in fracture healing and growth, as well as bone tissue engineering and bone mineral density loss (e.g., osteoporosis).

Interactive graph-cut segmentation for fast creation of finite element models from clinical ct data for hip fracture prediction

In this study, we propose interactive graph cut image segmentation for fast creation of femur finite element (FE) models from clinical computed tomography scans for hip fracture prediction. Using a sample of N = 48 bone scans representing normal, osteopenic and osteoporotic subjects, the proximal femur was segmented using manual (gold standard) and graph cut segmentation. Segmentations were subsequently used to generate FE models to calculate overall stiffness and peak force in a sideways fall simulations. Results show that, comparable FE results can be obtained with the graph cut method, with a reduction from 20 to 2–5 min interaction time. Average differences between segmentation methods of 0.22 mm were not significantly correlated with differences in FE derived stiffness (R2 = 0.08, p = 0.05) and weakly correlated to differences in FE derived peak force (R2 = 0.16, p = 0.01). We further found that changes in automatically assigned boundary conditions as a consequence of small segmentation differences were significantly correlated with FE derived results. The proposed interactive graph cut segmentation software MITK-GEM is freely available online at https://simtk.org/home/mitk-gem.

Forecast of Mechanical Properties of Porous Nonuniform Medium

There was discoursed procedure of carrying out of virtual experimental works on assessment of the main material functions, that defining plastic current of porous materials: function of density of ellipsoidal surface of loading and dependence of yield stress on deformation. The procedure is based on creation of finite element model of representative volume (a material point) of porous body with casually distributed empty finite elements that imitated properties of porous, and was approved by means of carrying out of physical and virtual experiments. Obtained data of comparison of experimental findings give ground to recommend the new procedure instead of experimental studies of mechanical properties of porous materials.

Computer-Aided Study of Materials’ Microstructure Influence on Cracks' Propagation Pattern in Brittle Anisotropic Bodies

The purpose of the presented study is a solution of a boundary-value problem, a visualization and a study of crack propagation pattern of a plane specimen of an anisotropic brittle material by computer modeling method. As main software for the research, MSC Nastran finite-element analysis package is used. As a result of the presented study, a methodology for a creation of finite-element models of various structural constituents and specimens with consideration of material’s microstructure is developed. Developed methodology is tested during the creation of finite-element model of the specimen assigned for a fracture with stress concentrators of varying forms and with a consideration of hypothetical structure, consisting of three types of crystallite with different mechanical properties. The methodology is proposed for an evaluation of kinetics and visualization of the crack growth in models of isotropic and anisotropic brittle materials. As the result of step-by-step visualization of the crack growth, animation files in AVI-format are created, which allow us to analyze the process of the material fracture. A theoretical equation is proposed for determination of the crack growth trajectory, which defines a relationship between a work needed for the crack growth and stresses in the specimen and its geometric parameters. An influence of the material on the trajectory of the crack growth is determined. Results of the presented study can serve as a tool for development of new materials with a high crack resistance due to their optimal microstructure. Developed methodologies allow you to determine desired location, size, shape of grains and their mechanical properties in microstructure of created material, without fabrication of many expensive full-size specimens.

Solving the problem of creation of finite element models for car seats with active head restraints designed to meet the requirements of passive safety

Solving the problem of creation of finite element models for car seats with active head restraints designed to meet the requirements of passive safety

Posterior urethral injuries associated with pelvic injuries in young adults: computerized finite element model creation and application to improve knowledge and prevention of these lesions

Young adult males involved in motorcycle accidents are particularly at risk for posterior urethral injury whenever pelvic injury occurs. Posterior urethral injuries remain problematic because their diagnosis may be missed, and during the initial treatment response the urethral injury can be aggravated by urethral catheterization. Few anatomical and clinical tools exist that establish a correlation between injuries and fractures of the pelvic ring and the risk of posterior urethral injury. Based on experience with traffic accident modeling, a computerized finite element model was conceived integrating the specific anatomic structures concerned. This model was extrapolated from a CAT scan of a young adult. The anatomic structures concerned in urethral and pelvic ring trauma (PRT) were isolated, placed in 3D and given biomechanical properties. The model was verified according to available experiments on PRT. To apply the model, we recreated a lateral impact mechanism on the pelvic ring. Stretching between the prostatic and membranous portions of the urethra (before and after visualization of a pelvic fracture) as well as timing of injury was studied. The model's application permitted us to analyze precisely the link between lateral impact trauma of the pelvic ring and lesions of the posterior urethra and to identify an urethra stretching prior to visualization of a pelvic fracture. Utilization of the model with other mechanisms of injury should allow for better comprehension of this associated trauma, improved prevention, iatrogenic aggravation of, and care for, these serious injuries.

DIRECT MODIFICATION OF SEMANTICALLY-ENRICHED FINITE ELEMENT MESHES

Behaviour analysis loop is largely performed on virtual product model before its physical manufacturing. The last avoids high expenses in terms of money and time spent on intermediate manufacturing. It is gainful from the reality to the virtuality but the process could be further optimized especially during the product behaviour optimization phase. This process involves repetition of four main processing steps: CAD design and modification, mesh creation, Finite Element (FE) model generation with the association of physical and geometric data, FE Analysis. The product behaviour analysis loop is performed on the first design solution as well as on the numerous successive product optimization loops. Each design solution evaluation necessitates the same time as required for the first product design that is particularly crucial in the context of maintenance. In this paper we propose a new framework for CAD-less product optimisation through FE analysis which reduces the model preparation activities traditionally required for FE model creation. More concretely, the idea is to directly operate on the firstly created FE mesh, enriched with physical/geometric semantics, to perform the product modifications required to achieve its optimised version. In order to accomplish the proposed CAD-less FE analysis framework, modification operators acting on both the mesh geometry and the associated semantics need to be devised. In this paper we discuss the underlying concepts and present possible components for the development of such operators. A high-level operator specification is proposed according to a modular structure that allows an easy realisation of different mesh modification operators. Here, two instances of this high-level operator are described: the planar cracking and the drilling. The realised prototypes validated on industrial FE models show clearly the feasibility of this approach.

Finite element model creation and stability considerations of complex biological articulation: The human wrist joint

The finite element method has been used with considerable success to simulate the behaviour of various joints such as the hip, knee and shoulder. It has had less impact on more complicated joints such as the wrist and the ankle. Previously published finite element studies on these multi-bone joints have needed to introduce un-physiological boundary conditions in order to establish numerical convergence of the model simulation. That is necessary since the stabilizing soft tissue mechanism of these joints is usually too elaborate in order to be fully included both anatomically and with regard to material properties. This paper looks at the methodology of creating a finite element model of such a joint focussing on the wrist and the effects additional constraining has on the solution of the model. The study shows that by investigating the effects each of the constraints, a better understanding on the nature of the stabilizing mechanisms of these joints can be achieved.

Finite element-based probabilistic analysis tool for orthopaedic applications

Orthopaedic implants, as well as other physical systems, contain inherent variability in geometry, material properties, component alignment, and loading conditions. While complex, deterministic finite element (FE) models do not account for the potential impact of variability on performance, probabilistic studies have typically predicted behavior from simplified FE models to achieve practical solution times. The objective of this research was to develop an efficient and versatile probabilistic FE tool to quantify the effect of uncertainty in the design variables on the performance of orthopaedic components under relevant conditions. Key aspects of the computational tool developed include parametric and automated FE model creation for changes in dimensional variables, efficient solution using the advanced mean-value (AMV) reliability method, and identification of the most significant design variables. Two orthopaedic applications are presented to demonstrate the ability of the computational tool to efficiently and accurately represent component performance.