Identifying Variable Effects on the Dimensional Quality of Compliant Assembly, Using Computer Experiments

2002 ◽  
Author(s):  
Stefan Dahlstro¨m ◽  
S. Jack Hu ◽  
Rikard So¨derberg
Keyword(s):  
Sheet Metal ◽  
Computer Experiments ◽  
Tolerance Analysis ◽  
Response Model ◽  
Element Analysis ◽  
Design Of Computer Experiments ◽  
Compliant Assembly ◽  
Aesthetic Form ◽  
Input Variables

Compliant sheet metal assemblies are often used as support structures in automobiles, airplanes and appliances. These structures not only provide a metrology frame for other modules to be assembled, but also give the product its aesthetic form. For this reason, the dimension quality of the assemblies is a very important factor to control, in order to make sure that the product will function as planned and continuously keep the product cost low. The assembly is influenced by variations in the component parts and the assembly processes. Tolerance analysis, as conducted in most industries today, is normally based on the assumption of rigid parts and is thus not always valid for sheet metal assemblies, due to their compliance. This paper will present a method, based on finite element analysis (FEA) and design of computer experiments, of identifying the influence of input variables on the final geometry variation of the assembly. The influence and the interactions among the input variables are analyzed with a response model that has been constructed, using the simulation results. This response model could be used to identify the important variables that need to be controlled in assembly. An example application is included, in order to demonstrate the simulation model and response model construction. Analysis of the results from the simulations can facilitate the design of the assembly process, in order to control the dimensional quality of the product.

scholarly journals Analysis of Forming Limits in Sheet Metal Forming with Pattern Recognition Methods. Part 2: Unsupervised Methodology and Application

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1892 ◽  
Author(s):  
Christian Jaremenko ◽  
Emanuela Affronti ◽  
Andreas Maier ◽  
Marion Merklein
Keyword(s):  
Pattern Recognition ◽  
Sheet Metal ◽  
Optical Measurement ◽  
Unsupervised Classification ◽  
Evaluation Methods ◽  
Time Dependent ◽  
Measuring System ◽  
Forming Limit ◽  
Element Analysis

The forming limit curve (FLC) is used in finite element analysis (FEA) for the modeling of onset of sheet metal instability during forming. The FLC is usually evaluated by achieving forming measurements with optical measurement system during Nakajima tests. Current evaluation methods such as the standard method according to DIN EN ISO 12004-2 and time-dependent methods limit the evaluation range to a fraction of the available information and show weaknesses in the context of brittle materials that do not have a pronounced constriction phase. In order to meet these challenges, a supervised pattern recognition method was proposed, whose results depend on the quality of the expert annotations. In order to alleviate this dependence on experts, this study proposes an unsupervised classification approach that does not require expert annotations and allows a probabilistic evaluation of the onset of localized necking. For this purpose, the results of the Nakajima tests are examined with an optical measuring system and evaluated using an unsupervised classification method. In order to assess the quality of the results, a comparison is made with the time-dependent method proposed by Volk and Hora, as well as expert annotations, while validated with metallographic investigations. Two evaluation methods are presented, the deterministic FLC, which provides a lower and upper limit for the onset of necking, and a probabilistic FLC, which allows definition of failure quantiles. Both methods provide a necking range that shows good correlation with the expert opinion as well as the results of the time-dependent method and metallographic examinations.

Research on the Forming Path for Fabricating the Sheet-Metal Part with Non-Horizontal End Face Using CNC Incremental Forming

2014 ◽  
Vol 599-601 ◽  
pp. 413-416 ◽  
Author(s):  
Hu Zhu ◽  
Jin Ju ◽  
Yi Bo Liu
Keyword(s):  
Sheet Metal ◽  
Incremental Forming ◽  
Analysis Method ◽  
Metal Part ◽  
Element Analysis ◽  
Sheet Metal Parts ◽  
Cnc Incremental Forming ◽  
Forming Technology ◽  
The Finite Element Analysis

For the purpose of the fabrication of the sheet-metal parts with non-horizontal end face using the sheet metal CNC incremental forming technology, two kinds of path generating methods, namely the level path perpendicular to Z axis method and the equidistant path parallel to sheet metal are proposed in this paper. Both of the paths are generated by Visual C++ and OpenGL graphics library, the effect of the two kinds of forming paths to the forming quality of the sheet part with non-horizontal end face is researched using the finite element analysis method in this paper.

Fixture Design Methodology for Sheet Metal Assembly Using Computer Simulations

Manufacturing ◽  
2003 ◽  
Author(s):  
Stefan Dahlstro¨m ◽  
Jaime A. Camelio
Keyword(s):  
Sheet Metal ◽  
Design Methodology ◽  
Computer Experiments ◽  
Design Guidelines ◽  
Fixture Design ◽  
Machining Processes ◽  
Element Analysis ◽  
Response Models ◽  
Early Evaluation ◽  
Sheet Metal Assembly

Sheet metal assembly is a common manufacturing process for several products such as automobiles and airplanes. Since all manufacturing processes are affected by variation, the key characteristics or critical dimensions may not be nominal. This paper presents a new fixture design methodology for early evaluation of sheet metal assemblies. Fixture design has been extensively studied for machining processes. Unfortunately, little investigation has been done for sheet metal assembly processes considering the effect of fixture layout on the assembly dimensional variation. The new fixture design methodology is based on classifying the assemblies into three categories depending on the stiffness of the assembly components: rigid-rigid, compliant-rigid and compliant-compliant assembly. Finite Element Analysis (FEA) and design of computer experiments have been used to derive response models for sheet metal assembly applications. The response models are used to analyze the final assembly sensitivity to fixture, part and tooling variation for different assembly configurations. Based on these results several design guidelines are proposed for fixture design on sheet metal assembly.

Customizing Procedure of Finite Element Analysis for Sheet Metal Forming

2014 ◽  
Vol 933 ◽  
pp. 212-215
Author(s):  
Xu Dong Xu ◽  
Guang Jun Li ◽  
Zhan Chong Wei ◽  
Fang Xue Li
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Model Building ◽  
Element Analysis ◽  
Standardization Procedure ◽  
Set Up

Based on Pam-Stamp software platform, standardization procedure of finite element analysis for sheet metal forming was customized by set up module such as model building, meshing, setting of boundary conditions, calculation submitting, viewing of results and report generating. Standardization procedure has been successfully applied in the development of new products, which shortens the preparation cycle of procedure, improves the forming quality of the parts and enhances the capability for rapidly researching and developing.

Tolerance Analysis for Sheet Metal Assemblies

1996 ◽  
Vol 118 (1) ◽  
pp. 62-67 ◽  
Author(s):  
S. C. Liu ◽  
S. J. Hu ◽  
T. C. Woo
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Numerical Methods ◽  
Sheet Metal ◽  
Tolerance Analysis ◽  
Element Analysis ◽  
Worst Case ◽  
Case Methods ◽  
Assembly Sequences ◽  
In Series

Traditional tolerance analyses such as the worst case methods and the statistical methods are applicable to rigid body assemblies. However, for flexible sheet metal assemblies, the traditional methods are not adequate: the components can deform, changing the dimensions during assembly. This paper evaluates the effects of deformation on component tolerances using linear mechanics. Two basic configurations, assembly in series and assembly in parallel, are investigated using analytical methods. Assembly sequences and multiple joints beyond the basic configurations are further examined using numerical methods (with finite element analysis). These findings constitute a new methodology for the tolerancing of deformable parts.

Efficient Consideration of Contact in Compliant Assembly Variation Analysis

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Georg Ungemach ◽  
Frank Mantwill
Keyword(s):  
Dimensional Accuracy ◽  
Tolerance Analysis ◽  
Nonlinear Effects ◽  
Variation Analysis ◽  
Compliant Assembly ◽  
Wide Range ◽  
Geometric Deviations ◽  
Statistical Tolerance ◽  
The Individual

The geometric deviations of real parts pose a major challenge, particularly in the extensively automated mass production of complex assemblies. To meet this challenge, an attempt is made, with the aid of statistical tolerance analysis, to predict dimensional accuracy for various assembly concepts as precisely as possible depending on the individual part tolerances. Most recent developments enable consideration to be given to the deformability of the parts during joining in order to improve the prognostic quality of simulation. The methods that are employed reveal deficits if nonlinear effects such as contact, extensive deformations, or material inelasticities occur. In this work, contact between or with adjacent parts during joining will be investigated, and an efficient and reliable method, which can be unproblematically integrated into existing compliant assembly variation analysis programs, will be developed. To achieve this, the methods of springback calculation according to Liu et al. (1995, “Variation Simulation for Deformable Sheet Metal Assemblies Using Mechanistic Models,” Trans. NAMRI/SME, 23, pp. 235–241) have been extended and coupled with numerical contact mechanics methods in order to realistically portray the problem, which usually involves intensive computing, with a minimum of additional effort. The method that has been developed will be validated on the basis of two examples with the aid of nonlinear finite element analyses, the results of which can be regarded as state-of-the-art in mechanical problems involving contact. The quality of the results reveals that this method improves the quality of prognosis for a wide range of applications and, consequently, that production problems can be combated during an early development phase.

scholarly journals Impact of Fixture Design Sheet Metal Assembly Variation

2002 ◽  
Author(s):  
Jaime A. Camelio ◽  
S. Jack Hu ◽  
Dariusz J. Ceglarek
Keyword(s):  
Sheet Metal ◽  
Design Methodology ◽  
Design Procedure ◽  
Fixture Design ◽  
Element Analysis ◽  
Sheet Metal Parts ◽  
Nonlinear Programming Methods ◽  
The Impact ◽  
Sheet Metal Assembly

This paper presents a new fixture design methodology for sheet metal assembly processes. The proposed approach focuses on the impact of fixture position on the dimensional quality of sheet metal parts after assembly, considering part and tooling variation and assembly springback. The optimization algorithm combines finite element analysis and nonlinear programming methods to find the optimal fixture position such that the assembly variation is minimized. The optimal fixture design methodology enables to significantly reduce the assembly variation in the presence of part and tooling variation. A case study is presented to demonstrate the design procedure.

Towards Predicting Relative Belt Edge Endurance With the Finite Element Method

1990 ◽  
Vol 18 (4) ◽  
pp. 216-235 ◽  
Author(s):  
J. De Eskinazi ◽  
K. Ishihara ◽  
H. Volk ◽  
T. C. Warholic
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Three Dimensional ◽  
The Finite Element Method ◽  
Shear Deformations ◽  
Element Analysis ◽  
Vertical Loading ◽  
Predicted Values ◽  
Element Method

Abstract The paper describes the intention of the authors to determine whether it is possible to predict relative belt edge endurance for radial passenger car tires using the finite element method. Three groups of tires with different belt edge configurations were tested on a fleet test in an attempt to validate predictions from the finite element results. A two-dimensional, axisymmetric finite element analysis was first used to determine if the results from such an analysis, with emphasis on the shear deformations between the belts, could be used to predict a relative ranking for belt edge endurance. It is shown that such an analysis can lead to erroneous conclusions. A three-dimensional analysis in which tires are modeled under free rotation and static vertical loading was performed next. This approach resulted in an improvement in the quality of the correlations. The differences in the predicted values of various stress analysis parameters for the three belt edge configurations are studied and their implication on predicting belt edge endurance is discussed.

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