Finite Element Limitations for Orthotropic, Laminated Beam Analysis

1987 ◽  
Vol 109 (1) ◽  
pp. 34-38 ◽  
Author(s):  
A. R. Zak
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Cross Sections ◽  
Element Model ◽  
Finite Element Models ◽  
Laminated Beam ◽  
New Model ◽  
Beam Analysis ◽  
Laminate Beam ◽  
Orthotropic Properties

This paper discusses the limitations of the existing finite element beam models for the analysis of orthotropic laminate beam analysis. These limitations are illustrated by comparing the existing models with a finite element model which has recently been developed by the author. This new model overcomes some of the existing limitations and is applicable to thin, laminated beam cross sections which are either open or closed. A simple numerical example is given and discussed comparing the existing theories with the results from the new model. The main limitations of the existing finite element models fall into two categories. The first of these is the problem of accurately modeling stresses in laminated configurations, especially if the orthotropic properties vary from layer to layer. The second difficulty is to model accurately the interaction between various deformations such as, for example, shear and normal strains.

Adaptive Finite Element Methods: A Review

1997 ◽  
Vol 50 (10) ◽  
pp. 581-591 ◽  
Author(s):  
Long-yuan Li ◽  
Peter Bettess
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Adaptive Finite Element Method ◽  
Finite Element Models ◽  
Adaptive Finite Element ◽  
Element Discretization ◽  
New Model ◽  
Discretization Errors ◽  
The Finite Element Model

The adaptive finite element method (FEM) was developed in the early 1980s. The basic concept of adaptivity developed in the FEM is that, when a physical problem is analyzed using finite elements, there exist some discretization errors caused owing to the use of the finite element model. These errors are calculated in order to assess the accuracy of the solution obtained. If the errors are large, then the finite element model is refined through reducing the size of elements or increasing the order of interpolation functions. The new model is re-analyzed and the errors in the new model are recalculated. This procedure is continued until the calculated errors fall below the specified permissible values. The key features in the adaptive FEM are the estimation of discretization errors and the refinement of finite element models. This paper presents a brief review of the methods for error estimates and adaptive refinement processes applied to finite element calculations. The basic theories and principles of estimating finite element discretization errors and refining finite element models are presented. This review article contains 131 references.

Behavior of Structures Using Simple Plastic Hinge Theory

1994 ◽  
Author(s):  
Ramakrishnan Maruthayappan ◽  
Hamid M. Lankarani
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Cantilever Beam ◽  
Reliable Method ◽  
Plastic Hinge ◽  
Element Model ◽  
Finite Element Models ◽  
Computational Program ◽  
Hinge Model ◽  
The Impact

Abstract The behavior of structures under the impact or crash situations demands an efficient modeling of the system for its behavior to be predicted close to practical situations. The various formulations that are possible to model such systems are spring mass models, finite element models and plastic hinge models. Of these three techniques, the plastic hinge theory offers a more accurate model compared to the spring mass formulation and is much simpler than the finite element models. Therefore, it is desired to model the structure using plastic hinges and to use a computational program to predict the behavior of structures. In this paper, the behavior of some simple structures, ranging from an elementary cantilever beam to a torque box are predicted. It is also shown that the plastic hinge theory is a reliable method by comparing the results obtained from a plastic hinge model of an aviation seat structure with that obtained from a finite element model.

scholarly journals Biaxial estimation of biomechanical constitutive parameters of passive porcine sclera soft tissue

2021 ◽  
Author(s):  
Zwelihle Ndlovu ◽  
Dawood Desai ◽  
Thanyani Pandelani ◽  
Harry Ngwangwa ◽  
Fulufhelo Nemavhola
Keyword(s):  
Finite Element ◽  
Soft Tissue ◽  
Finite Element Model ◽  
Test Data ◽  
Element Model ◽  
Finite Element Models ◽  
Anisotropic Model ◽  
Material Models ◽  
Material Parameters ◽  
Constitutive Parameters

This study assesses the modelling capabilities of four constitutive hyperplastic material models to fit the experimental data of the porcine sclera soft tissue. It further estimates the material parameters and discusses their applicability to a finite element model by examining the statistical dispersion measured through the standard deviation. Fifteen sclera tissues were harvested from porcine’ slaughtered at an abattoir and were subjected to equi-biaxial testing. The results show that all the four material models yielded very good correlations at correlations above 96 %. The polynomial (anisotropic) model gave the best correlation of 98 %. However, the estimated material parameters varied widely from one test to another such that there would be needed to normalise the test data to avoid long optimisation processes after applying the average material parameters to finite element models. However, for application of the estimated material parameters to finite element models, there would be needed to consider normalising the test data to reduce the search region for the optimisation algorithms. Although the polynomial (anisotropic) model yielded the best correlation, it was found that the Choi-Vito had the least variation in the estimated material parameters thereby making it an easier option for application of its material parameters to a finite element model and also requiring minimum effort in the optimisation procedure. For the porcine sclera tissue, it was found that the anisotropy more influenced by the fiber-related properties than the background material matrix related properties.

scholarly journals Reconstruction finite element model of cars

2021 ◽  
Vol 4 (1) ◽  
pp. first
Author(s):  
Lý Hùng Anh ◽  
Nguyễn Phụ Thượng Lưu ◽  
Nguyễn Thiên Phú ◽  
Trần Đình Nhật
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Finite Element Models ◽  
Crash Analysis ◽  
Inertia Moment ◽  
Frontal Crash ◽  
Analysis Center ◽  
Simulation Results ◽  
And Behavior

The experimental method used in a frontal crash of cars costs much time and expense. Therefore, numerical simulation in crashworthiness is widely applied in the world. The completed car models contain a lot of parts which provided complicated structure, especially the rear of car models do not contribute to behavior of frontal crash which usually evaluates injuries of pedestrian or motorcyclist. In order to save time and resources, a simplification of the car models for research simulations is essential with the goal of reducing approximately 50% of car model elements and nodes. This study aims to construct the finite element models of front structures of vehicle based on the original finite element models. Those new car models must be maintained important values such as mass and center of gravity position. By using condition boundaries, inertia moment is kept unchanged on new model. The original car models, which are provided by the National Crash Analysis Center (NCAC), validated by using results from experimental crash tests. The modified (simplistic) vehicle FE models are validated by comparing simulation results with experimental data and simulation results of the original vehicle finite element models. LS-Dyna software provides convenient tools and very strong to modify finite element model. There are six car models reconstructed in this research, including 1 Pick-up, 2 SUV and 3 Sedan. Because car models were not the main object to evaluate in a crash, energy and behavior of frontal part have the most important role. As a result, six simplified car models gave reasonable outcomes and reduced significantly the number of nodes and elements. Therefore, the simulation time is also reduced a lot. Simplified car models can be applied to the upcoming frontal simulations.

Application of a FRF Based Model Updating Technique for the Validation of Finite Element Models of Components of the Automotive Industry

1995 ◽  
Author(s):  
Stefan Lammens ◽  
Marc Brughmans ◽  
Jan Leuridan ◽  
Ward Heylen ◽  
Paul Sas
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Automotive Industry ◽  
Stiffness Matrix ◽  
Model Updating ◽  
Dynamic Stiffness ◽  
Element Model ◽  
Model Parameters ◽  
Finite Element Models ◽  
Analytical Dynamic

Abstract This paper presents two applications of the RADSER model updating technique (Lammens et al. (1995) and Larsson (1992)). The RADSER technique updates finite element model parameters by solution of a linearised set of equations that optimise the Reduced Analytical Dynamic Stiffness matrix based on Experimental Receptances. The first application deals with the identification of the dynamic characteristics of rubber mounts. The second application validates a coarse finite element model of a subframe of a Volvo 480.

Support-Condition Analyses of Rotating Beams Under Distributed Imbalance Loading

2011 ◽  
Author(s):  
Kai Jokinen ◽  
Erno Keskinen ◽  
Marko Jorkama ◽  
Wolfgang Seemann
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Cross Section ◽  
Cross Sections ◽  
Natural Frequencies ◽  
Element Model ◽  
Mode Shapes ◽  
Constant Cross Section ◽  
Support Condition ◽  
Beam Elements

In roll balancing the behaviour of the roll can be studied either experimentally with trial weights or, if the roll dimensions are known, analytically by forming a model of the roll to solve response to imbalance. Essential focus in roll balancing is to find the correct amount and placing for the balancing mass or masses. If this selection is done analytically the roll model used in calculations has significant effect to the balancing result. In this paper three different analytic methods are compared. In first method the mode shapes of the roll are defined piece wisely. The roll is divided in to five parts having different cross sections, two shafts, two roll ends and a shell tube of the roll. Two boundary conditions are found for both supports of the roll and four combining equations are written to the interfaces of different roll parts. Totally 20 equations are established to solve the natural frequencies and to form the mode shapes of the non-uniform roll. In second model the flexibility of shafts and the stiffness of the roll ends are added to the support stiffness as serial springs and the roll is modelled as a one flexibly supported beam having constant cross section. Finally the responses to imbalance of previous models are compared to finite element model using beam elements. Benefits and limitations of each three model are then discussed.

Forming limit diagrams by including the M–K model in finite element simulation considering the effect of bending

2016 ◽  
Vol 232 (8) ◽  
pp. 625-636 ◽  
Author(s):  
Mostafa Habibi ◽  
Ramin Hashemi ◽  
Ahmad Ghazanfari ◽  
Reza Naghdabadi ◽  
Ahmad Assempour
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Metal Forming ◽  
Forming Limit Diagram ◽  
Element Model ◽  
Forming Limit ◽  
Finite Element Models ◽  
Element Simulation ◽  
Simple Tension ◽  
Out Of Plane

Forming limit diagram is often used as a criterion to predict necking initiation in sheet metal forming processes. In this study, the forming limit diagram was obtained through the inclusion of the Marciniak–Kaczynski model in the Nakazima out-of-plane test finite element model and also a flat model. The effect of bending on the forming limit diagram was investigated numerically and experimentally. Data required for this simulation were determined through a simple tension test in three directions. After comparing the results of the flat and Nakazima finite element models with the experimental results, the forming limit diagram computed by the Nakazima finite element model was more convenient with less than 10% at the lower level of the experimental forming limit diagram.

Simulation of Fall Loading Using a Probabilistic Shape-Based Finite Element Model of Human Femurs

2007 ◽  
Author(s):  
Todd L. Bredbenner ◽  
Daniel P. Nicolella
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Finite Element Models ◽  
Construction Process ◽  
Single Patient ◽  
Complex Morphology ◽  
Biological Structures ◽  
Efficient Construction

The efficient construction of finite element models that accurately represent the complex morphology of biological structures is a major challenge. Typically, the model constructed is a representation of a single patient and, in order to investigate a different individual, the majority of the mesh construction process must be repeated.

scholarly journals Application of Optimization Based Finite Element Model Updating Method On 3d Printed Model Structures

2019 ◽  
Author(s):  
Mohammed Kashama Guzunza ◽  
Ozgur Ozcelik ◽  
Umut Yucel ◽  
Ozgur Girgin
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Model Updating ◽  
Complex Structure ◽  
Element Model ◽  
Initial Structure ◽  
Finite Element Models ◽  
3D Printed ◽  
Building System ◽  
Shear Building

Nowadays it becomes trend in studying of dynamic behavior on complex structure. Model updating is one of the tools developed for verifying accuracy of finite element models. In this paper, method for computing model updating on finite element model and effective the experimental modal analysis of structural systems is developed. The identification method developed in this study is based on time-domain system identification numerical techniques. The case study considered in this work is a 3D printed structure that be modeled as a two-story shear building system with irregular torsion. A preliminary numerical model of the two-story shear building system is developed by using SAP2000 and the experimental modal parameters data are collected in the laboratory buy some test then are modeled by Artemis modal pro. After obtaining the results from numerical modal and experimental modal, it was brought to FEMtools software to improve the match between the dynamic properties of an initial structure and the experimentally estimated modal data for updating. After updating, it’s shown that optimization was done, that some unknown material parameters (such as mass density and young modulus) of materials and/or boundary conditions were optimized by FEMtools Optimization that provides the possibility to perform design optimization on updated finite element models.

The Influence of the Curved Transition on the Coach Roof Cross Beams in Rollover Crashworthiness

2011 ◽  
Vol 474-476 ◽  
pp. 1920-1925
Author(s):  
Fu Lin Shen ◽  
Jun Liang Jiu ◽  
Zhao Kai Li ◽  
Xu Liang Xie ◽  
Ying Hui Mao
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Energy Absorption ◽  
Collision Energy ◽  
Element Model ◽  
Finite Element Models ◽  
Complete Vehicle ◽  
Simulation Results ◽  
Survival Space ◽  
Peak Value

In order to improve the rollover crashworthiness of coach, three roof beam structures commonly used in coach were established with finite element models for the rollover simulation, then the energy absorption, acceleration and body pillar deformation were analyzed. The simulation results show that circle-curved transition and non-curved transition on the roof have better collision performance. Especially, the latter not only reduces the acceleration peak value, but also transfers more collision energy to the offside lateral. The whole coach body will be involved in deformation, thus, the intrusion of survival space would be reduced. Finally, the complete vehicle skeleton finite element model of a 6127-type high-bed coach was built, and the influences of circle-curved transition and non-curved transition on the roof in rollover test were analyzed.

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