A Study on Fundamental Mechanisms of Warp and Recoil in Hemming

2000 ◽  
Author(s):  
Ellen Zhang ◽  
Xin Wu ◽  
S. Jack Hu
Keyword(s):  
Finite Element ◽  
Process Parameters ◽  
Flat Surface ◽  
General Purpose ◽  
Straight Edge ◽  
Finite Element Code ◽  
Localized Buckling

Abstract In this paper, the occurrence of recoil and surface warp during flat surface-straight edge hemming process is investigated. A general-purpose finite element code ABAQUS/Standard is used to simulate the hemming operations. Reverse bending, localized buckling and springback are the fundamental mechanisms that cause surface warp and recoil. Recoil and warp are not independent. One parameter called final equivalent residual warp is obtained to represent both. Feasible pre-hem ending zone is proposed based on final equivalent residual warp. The influence of the geometrical and process parameters on recoil and warp are also investigated.

A Study on Fundamental Mechanisms of Warp and Recoil in Hemming

2000 ◽  
Vol 123 (4) ◽  
pp. 436-441 ◽  
Author(s):  
Guohua Zhang ◽  
Xin Wu ◽  
S. Jack Hu
Keyword(s):  
Finite Element ◽  
Process Parameters ◽  
Flat Surface ◽  
General Purpose ◽  
Straight Edge ◽  
Finite Element Code

In this paper, the occurrence of recoil and surface warp during the flat surface-straight edge hemming process is investigated. A general-purpose finite element code ABAQUS/Standard is used to simulate the hemming operations. Reverse bending and springback are the fundamental mechanisms that cause surface warp and recoil. Recoil and warp are not independent. One parameter, final equivalent warp, is used to represent both. Pre-hemming target ending position is proposed based on the minimization of the final equivalent warp. The influence of the geometrical and process parameters on recoil and warp are also discussed.

Finite Element Simulations of Joints Used in the Automotive Industry

Manufacturing ◽  
2002 ◽  
Author(s):  
Rishikesh Bhalerao ◽  
Brad Heers ◽  
Mark Bohm ◽  
Marc Schrank
Keyword(s):  
Finite Element ◽  
Best Practices ◽  
Automotive Industry ◽  
Functional Performance ◽  
Effective Means ◽  
General Purpose ◽  
Vehicle Body ◽  
Finite Element Code ◽  
Automotive Applications ◽  
Modeling Techniques

Finite element-based simulations of vehicle body systems are an effective means of optimizing a design. However, body systems often consist of components from a variety of sources. Hence, accurate modeling requires a robust set of analysis functionality for joining such components. Joints—such as welds, bolts, rivets, clinches, and adhesives—present unique challenges to the analyst. Despite the critical influence joints have on functional performance, there is little information on best practices for modeling such connections. This paper presents a survey of some of the approaches available in ABAQUS, a general-purpose commercial finite element code, and discusses various applications of these techniques through a series of case studies. While the modeling techniques discussed in this paper have been motivated largely by automotive applications, they are also applicable to other areas such as aerospace structures.

Postbuckling Analysis of Variable Stiffness Composite Panels Using a Finite Element Based Perturbation Method

2009 ◽  
Author(s):  
T. Rahman ◽  
S. T. IJsselmuiden ◽  
M. M. Abdalla ◽  
E. L. Jansen
Keyword(s):  
Finite Element ◽  
Perturbation Method ◽  
Variable Stiffness ◽  
General Purpose ◽  
Reduced Order Model ◽  
Finite Element Code ◽  
Order Model ◽  
Reduced Order ◽  
Quick Estimate ◽  
Optimization Loop

In earlier research the authors optimized variable stiffness panels for maximum buckling load, using lamination parameters. The aim of the present research is to analyze those optimized panels in the postbuckling regime so that further improvement can be achieved in the future with respect to its postbuckling performance. Because the incremental-iterative nonlinear analysis in the postbuckling regime is not feasible within an optimization loop a finite element based perturbation method (Koiter type) is used to compute postbuckling coefficients, which are in turn used to make a quick estimate of the postbuckling stiffness of the panel and to establish a reduced order model. The proposed perturbation method has been implemented in a general purpose finite element code. In the present work the postbuckling analysis of variable stiffness panels carried out using the reduced order model is presented and the potential of the approach for incorporation within the optimization process is demonstrated.

Progress in Collapse Analyses

1987 ◽  
Vol 109 (1) ◽  
pp. 33-41 ◽  
Author(s):  
E. Riks
Keyword(s):  
Finite Element ◽  
Structural Analysis ◽  
Limit Point ◽  
Nonlinear Deformation ◽  
General Purpose ◽  
Finite Element Code ◽  
Governing Equations ◽  
Collapse Analysis ◽  
Element Technique ◽  
Intractable Problem

In the field of finite element structural analysis, the computation of collapse states of structures prone to unstable behavior has long been considered a difficult if not intractable problem. Only recently have procedures that deal effectively with this difficulty found their way in general-purpose finite element codes. Although the explanation for the cause of the so-called limit point obstacle is actually simple—an inappropriate parameterization of the governing equations in the neighborhood of the limit point—this cause does not seem to have been widely understood in the period of development of the finite element technique. In this paper, some of the remedies that have been proposed to overcome the problems are reviewed, including the principle of adaptive parameterization which is now the basis of a new procedure for collapse analysis in the finite element code STAGS. The discussion also includes the treatment of simple bifurcation points because unstable bifurcation can be considered a special form of collapse. It can be concluded that collapse problems, in the sense discussed in this paper, no longer present difficulties that exceed those normally encountered during the solution of nonlinear deformation paths. Further developments, in particular those with respect to improved efficiency, are in progress. Some of the promising ventures in this direction are indicated.

Coupling EPIC to LS-DYNA for Simulation of Blast-Structure-Fragmentation Interaction

2010 ◽  
Author(s):  
David L. Littlefield ◽  
Kenneth C. Walls ◽  
Kent T. Danielson
Keyword(s):  
Finite Element ◽  
Large Scale ◽  
General Purpose ◽  
Structural Deformation ◽  
High Fidelity ◽  
High Fidelity Simulation ◽  
Finite Element Code ◽  
Simulation Framework

In this work we have coupled the EPIC code to the LS-DYNA code to provide a high-fidelity simulation framework for simulation of blast-structure-fragmentation interaction. The coupled code exploits the strengths of the two original codes: EPIC, which has special algorithms and models for weapons effects analysis, and LS-DYNA, which is a general purpose finite element code for modeling large-scale structural deformation. Example problems are shown which illustrate the advantages of this approach.

Methods for Minimization of Solution Costs for Transient Dynamic Analysis of Nonlinear Periodic Structures

1982 ◽  
Vol 104 (3) ◽  
pp. 159-160 ◽  
Author(s):  
J. S. Van Kirk ◽  
W. T. Bogard ◽  
L. R. Wood
Keyword(s):  
Finite Element ◽  
Dynamic Analysis ◽  
Numerical Integration ◽  
Periodic Structures ◽  
General Purpose ◽  
Finite Element Code ◽  
Transient Dynamic Analysis ◽  
Transient Dynamic

Techniques are described for the transient dynamic analysis of nonlinear periodic structures. These techniques consider the special characteristics of periodic structures in conjunction with the pseudo-force approach using numerical integration to reduce computerized solution costs. Comparisons with a general purpose finite element code demonstrate the savings in solution costs.

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