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TECHNICAL PAPERS

# Digital Panel Assembly Methodologies and Applications for Compliant Sheet Components

[+] Author and Article Information
Wayne W. Cai, Ching-Chieh Hsieh, Yufeng Long, Samuel P. Marin, Kong P. Oh

General Motors Corporation, Warren, MI 48090-9055

The CI formula for variances (or $3σ$), as in Eq. 9, is strictly meaningful only when the outputs follow normal distributions. For engineering applications, one can still use it, provided that the outputs are near normal. The CIs for means in Eq. 10 always hold so long as the means are finite due to the central limit theorem.

J. Manuf. Sci. Eng 128(1), 270-279 (May 04, 2005) (10 pages) doi:10.1115/1.2112967 History: Received January 20, 2004; Revised May 04, 2005

## Abstract

This paper presents digital panel assembly (DPA) methodologies and applications for sheet component assembly in automotive body manufacturing processes. Core to DPA is the customized finite element analysis formulas we have developed, which simulates assembly processes and predicts assembly dimensions by taking into consideration the panel compliances. Two key analysis types of the DPA are presented, the deterministic analysis and variation analysis. We present a methodology to utilize the quadratic form of Taylor series expansion to approximate the assembly dimensions efficiently in variation simulation, and discuss its pros and cons versus the traditional Monte Carlo method under different modeling conditions. For either the deterministic or variation analysis, linear models (without contact, efficient but less accurate), and nonlinear models (with contact, less efficient but accurate) can be established. It is shown that the linear models are only valid when panels do not penetrate, and that the nonlinear models should generally be used for accurate assembly dimension prediction. Based on the DPA methodologies, a software tool called Elastic Assembly Variation Simulation (EAVS) is presented, followed by application case studies. The confidence intervals for variation analysis are also discussed.

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## Figures

Figure 1

Schematic of digital panel assembly

Figure 2

Schematic of a joining operation

Figure 3

Meshes with KPCs for FenIn (with zoomed in view)

Figure 4

Meshes with KPCs for Longi

Figure 5

Output comparisons for FenIn (top) and Longi (bottom)

Figure 6

Geometry and finite element model for one of the two L-shaped plates

Figure 7

Convergence behavior of MCS output and TSE result

Figure 8

Convergence of MCS mean output versus TSE

Figure 9

Accuracy for TSE deteriorates as contact pairs increase

Figure 10

“True” mean output is a function of contact pairs

Figure 11

Front fender assembly

Figure 12

Relative errors for 3σ output for a fender assembly

Figure 13

Motor compartment assembly

Figure 14

Relative errors for output for a motor compartment assembly

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