Simulating Assembly Geometric and Stress Variation Considering Machining-Induced Residual Stress

Abstract

Nowadays, large monolithic machined parts are increasingly used in aerospace industry. Machining-induced residual stress usually dominates thin part’s distortion. The resultant part input with mutual corresponding distortion pattern and inner residual stress has an impact on subsequent assembly geometric and stress variation of thin-walled structure. Final pre-stressed assembly state further affects product functionality. This paper illustrates a simulated methodology combining automatic scripting technique with a FEA tool to reveal the assembly variation’s distribution and pattern caused by the fluctuation of machining-induced residual stress. A typical assembly unit case in aircraft is investigated by applying the proposed methodology, more specifically, considering the uncertainty of the dominant shear stress via simulating the normal distributed weights of basis functions. Moreover, the quantitative effect of introducing residual stress is explored to examine the applicability of traditional Method of Influence Coefficients, which constructs a sensitivity matrix of the linear relation between incoming part variation and output assembly variation using FEA. This study enhances the understanding of the effect of introducing residual stress into assembly and helps the statistical inference about both geometric and stress aspects.