應用有限元素分析改善盲孔法之銲接殘留應力量測

Improvement of Welding Residual Stress Measurement Based on the Blind-Hole Method Using Finite Element Analysis

本文主要是利用三維熱彈塑有限元素模型，來模擬304不銹鋼板之銲接過程以及冷卻後平板內部之殘留應力，並提出銲接後之鑽孔流程，配合盲孔法理論計算殘留主應力。利用本文所提鑽孔有限元素模型所得之殘留應力，並與ASTM規範盲孔法理論計算所得之殘留應力比較，來驗證本文所提有限元素模型之準確性。此外，也探討鑽孔深度與鑽孔直徑對殘留應力的影響。本文也提出一經驗公式來修正盲孔法之無因次係數。結果指出，本文提出的方法可有效改善利用盲孔法量測殘留應力的精度。

In this study, a dynamic three-dimensional thermal elastic-plastic finiteelement model is proposed to simulate the welding process of two 304stainless steel plates and to estimate the residual stress in welding platesafter cooling. To match the blind-hole method, the drilling process afterwelding is also simulated. The residual stress obtained from the proposedfinite element method is then compared with the results obtained from theblind-hole method according to ASTM specification to verify the proposedFEM model. The effects of drilling depth and drill diameter on the residualstress are also discussed. An empirical equation is proposed to modifythe dimensionless parameters of the blind-hole method. The results indicatethat the proposed method may be used to improve accuracy of residualstress measurement based on the blind-hole method.