叶志伟，路明

江淮汽车股份有限公司技术中心

摘要：由于排气歧管螺栓受到高低温的循环载荷，螺栓预紧力发生衰减，导致在排气歧管与法兰之间发生漏气的现象。而排气歧管螺栓在高温下的预紧力衰减情况用经典公式很难计算，本文使用有限元的方法，基于非线性弹塑性材料参数，计算在全速全负荷、倒拖以及怠速工况循环作用下的排气歧管螺栓的衰减情况，结果表明此方法可以有效的预测螺栓预紧力的衰减情况，判断排气歧管法兰是否存在漏气现象。

关键词：螺栓预紧力衰减；有限元方法；排气歧管

Abstract：Because of the exhaust manifold bolts continue suffering high and low temperature load,  bolt pre-tightening force reduces causing the air leakage between the exhaust manifold and the flanges. It is difficult to calculate the bolt force release under high temperature condition by classic formula. In this paper, the finite element method is used to calculate the bolt force release under the full load, motored and low idle thermal loads on the basis of the nonlinear elastic-plastic material parameters. The results show that this method can effectively predict the bolt pre-tightening force release, and judge whether there is air leakage between the exhaust manifold and the flanges.

Keywords：Bolt Force Release；Finite Element Method；Exhaust  Manifold