搅拌摩擦焊接中搅拌头的受力分析

MECHANICAL ANALYSIS OF PIN IN FRICTION STIR WELDING PROCESS

采用基于固体力学的有限元方法研究搅拌摩擦焊接过程中,不同过程参数情况下搅拌头的受力情况。研究发现,搅拌摩擦焊接过程中搅拌头上应力的最大值发生在搅拌头前进方向上搅拌头与焊缝中心线接触点的附近,且vonMises应力的最大值随搅拌头平移速度的增加而增加,随搅拌头转速的增加而较小。搅拌头前方的接触压力较大,后方接触压力较小,后退侧的接触压力较前进侧大。搅拌头的不停旋转决定了搅拌头受到交变载荷作用,导致疲劳成为搅拌头破坏的原因之一。焊缝中心线附近的等效塑性应变和结构纹理呈现洋葱状结构。

Finite element method based on solid mechanics is used to study the stress distributions on the pin during the friction stir welding process. Results indicate that the maximum stress on the pin occurs at the contact point in the advancing direction of the pin. The maximum yon Mises stress is increased with the increase of the translational velocity of the pin and is decreased with the increase of the angular velocity of the pin. The contact pressure at the contact point in the advancing direction is higher and the one at the opposite contact point is lower. The contact pressure on the retreating side is larger than that on the advancing side. A cyclic loading occurs with the rotation of the pin, so the fatigue may become a reason for the pin＇ s fracture. Onion tings are formed in the microstructural texture and in the equiv.,dent plastic distributions.