Internal Variable and Cellular Automata-Finite Element Models of Heat Treatment

2010 ◽  
Vol 8 (3) ◽  
pp. 267-285 ◽  
Author(s):  
Piotr Maciol ◽  
Jerzy Gawad ◽  
Roman Kuziak ◽  
Maciej Pietrzyk
Keyword(s):  
Heat Treatment ◽  
Finite Element ◽  
Cellular Automata ◽  
Internal Variable ◽  
Finite Element Models

Extending the Local Approach to Fracture: Methods for Direct Incorporation of Microstructural Effects Into Finite Element Models of Fracture

2002 ◽  
Author(s):  
J. H. Beynon ◽  
S. Das ◽  
I. C. Howard ◽  
A. Chterenlikht
Keyword(s):  
Finite Element ◽  
Finite Elements ◽  
Cellular Automata ◽  
Finite Element Models ◽  
Low Alloy Steels ◽  
Structural Level ◽  
Local Approach ◽  
Gauss Point ◽  
Physical Scale ◽  
Macro Scale

The Local Approach to fracture phenomena has been very successful in helping to transfer information derived from testing one geometry on a material (laboratory specimens) to the prediction of the crack growth performance of another (the structure). At least in its most pervasive manifestations, it depends upon constructing finite element models with a ruling element size that is appropriate for the physical scale of the dominant failure mechanism. Since these are primarily of the order of the material microstructure, there is a consequential very strong mesh gradient towards the region of Local Approach interest. When applied to structures of engineering interest, which can be large, the resultant finite element models become very big, sufficiently so that they cannot be run on many computers, if at all. When there is more than one material scale involved, the situation becomes impossible to resolve with conventional finite elements, except through the use of compromise local finite element sizes that blend the requirements from each micro-scale into a smeared cell at the finite element level. Such models have shown considerable success in predicting the performance of a range of components and structures by a number of research groups. Even so, the method is constrained by the excessive computational costs associated with modeling realistic structures, and by other concerns derived from its smearing of possibly incompatible underlying physical effects. CAFE modeling, the coupling of Cellular Automata at the microstructural scale(s) with finite elements that are scaled only for the strain gradients expected at the macro-scale in the structure, offers a way out of these potential problems. The structural level field quantities, held at the element Gauss points, are modified according to information coming from the Cellular Automata with which each Gauss point is associated. Suitable code representing fracture initiation and propagation at the micro-level generates changes incrementally to the Gauss point field variables, which are then brought to equilibrium by the FE modeler (whenever it is an implicit FE system). The method allows a natural representation of the multiple scale interactions typical of the fracture of low alloy steels in the transition region.

A Finite Element Analysis of the General Rolling Contact Problem for a Viscoelastic Rubber Cylinder

1988 ◽  
Vol 16 (1) ◽  
pp. 18-43 ◽  
Author(s):  
J. T. Oden ◽  
T. L. Lin ◽  
J. M. Bass
Keyword(s):  
Finite Element ◽  
Variational Principles ◽  
Standing Waves ◽  
Rolling Contact ◽  
Finite Element Models ◽  
Viscoelastic Cylinder ◽  
Element Analysis ◽  
Elastic Rubber ◽  
Frictional Effects ◽  
Rough Foundation

Abstract Mathematical models of finite deformation of a rolling viscoelastic cylinder in contact with a rough foundation are developed in preparation for a general model for rolling tires. Variational principles and finite element models are derived. Numerical results are obtained for a variety of cases, including that of a pure elastic rubber cylinder, a viscoelastic cylinder, the development of standing waves, and frictional effects.

Affordable structural optimization for large-size dynamic finite element models

1997 ◽  
Author(s):  
Francois Hemez ◽  
Emmanuel Pagnacco ◽  
Francois Hemez ◽  
Emmanuel Pagnacco
Keyword(s):  
Finite Element ◽  
Structural Optimization ◽  
Finite Element Models ◽  
Dynamic Finite Element ◽  
Large Size

The prediction of vehicle vibration transmitted to the occupant using a modular transfer matrix

2021 ◽  
pp. 107754632199759
Author(s):  
Jianchun Yao ◽  
Mohammad Fard ◽  
John L Davy ◽  
Kazuhito Kato
Keyword(s):  
Finite Element ◽  
Transfer Matrix ◽  
Dynamic Performance ◽  
Complex Structure ◽  
Vehicle Body ◽  
Computational Time ◽  
Accurate Estimation ◽  
Finite Element Models ◽  
Transfer Matrices ◽  
Body Vibration

Industry is moving towards more data-oriented design and analyses to solve complex analytical problems. Solving complex and large finite element models is still challenging and requires high computational time and resources. Here, a modular method is presented to predict the transmission of vehicle body vibration to the occupants’ body by combining the numerical transfer matrices of the subsystems. The transfer matrices of the subsystems are presented in the form of data which is sourced from either physical tests or finite element models. The structural dynamics of the vehicle body is represented using a transfer matrix at each of the seat mounting points in three triaxial (X–Y–Z) orientations. The proposed method provides an accurate estimation of the transmission of the vehicle body vibration to the seat frame and the seated occupant. This method allows the combination of conventional finite element analytical model data and the experimental data of subsystems to accurately predict the dynamic performance of the complex structure. The numerical transfer matrices can also be the subject of machine learning for various applications such as for the prediction of the vibration discomfort of the occupant with different seat and foam designs and with different physical characteristics of the occupant body.

scholarly journals The biomechanical effect on the adjacent L4/L5 segment of S1 superior facet arthroplasty: a finite element analysis for the male spine

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Zewen Shi ◽  
Lin Shi ◽  
Xianjun Chen ◽  
Jiangtao Liu ◽  
Haihao Wu ◽  
...  
Keyword(s):  
Finite Element ◽  
Range Of Motion ◽  
Facet Joint ◽  
Adjacent Segment ◽  
Finite Element Models ◽  
Level Of Evidence ◽  
Element Analysis ◽  
Flexion Extension ◽  
Biomechanical Effect ◽  
Lumbar Range Of Motion

Abstract Background The superior facet arthroplasty is important for intervertebral foramen microscopy. To our knowledge, there is no study about the postoperative biomechanics of adjacent L4/L5 segments after different methods of S1 superior facet arthroplasty. To evaluate the effect of S1 superior facet arthroplasty on lumbar range of motion and disc stress of adjacent segment (L4/L5) under the intervertebral foraminoplasty. Methods Eight finite element models (FEMs) of lumbosacral vertebrae (L4/S) had been established and validated. The S1 superior facet arthroplasty was simulated with different methods. Then, the models were imported into Nastran software after optimization; 500 N preload was imposed on the L4 superior endplate, and 10 N⋅m was given to simulate flexion, extension, lateral flexion and rotation. The range of motion (ROM) and intervertebral disc stress of the L4-L5 spine were recorded. Results The ROM and disc stress of L4/L5 increased with the increasing of the proportions of S1 superior facet arthroplasty. Compared with the normal model, the ROM of L4/L5 significantly increased in most directions of motion when S1 superior facet formed greater than 3/5 from the ventral to the dorsal or 2/5 from the apex to the base. The disc stress of L4/L5 significantly increased in most directions of motion when S1 superior facet formed greater than 3/5 from the ventral to the dorsal or 1/5 from the apex to the base. Conclusion In this study, the ROM and disc stress of L4/L5 were affected by the unilateral S1 superior facet arthroplasty. It is suggested that the forming range from the ventral to the dorsal should be less than 3/5 of the S1 upper facet joint. It is not recommended to form from apex to base. Level of evidence Level IV

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