膜片弹簧疲劳断裂的试验分析

通过对几种典型的汽车离合器膜片弹簧的疲劳试验及分析，从力学方面分析了以下三个问题：（1）膜片弹簧疲劳断裂时，裂纹沿碟形部分窗孔径向发展的原因；（2）为什么导致膜片弹簧疲劳断裂的根源是Ⅱ点附近的疲劳源；（3）膜片弹簧上表面为什么也会出现多个裂纹源，且裂纹扩展到一定深度后停止发展。并用试验证明了离合器在正常运行的情况下，膜片弹簧子午截面上Ⅲ点附近不可能产生疲劳断裂的裂纹源。从而提出，在膜片弹簧设计时应以Ⅱ点应力来建立疲劳强度条件。

Mechanics Analysis on Fatigue Crack of Diaphragm Springs

In this paper, through fatigue test and analysis of several typical diaphragm springs used in automotive clutches, three questions are answered based on mechanics methods: (1) Why fatigue crack extends along radial direction of the slots in disk area of the diaphragm spring. (2) Why the fatigue originates in the vicinity of point II . (3) Why there exist many fatigue crack origins at the upper surface of diaphragm springs and they cease to extend at a definite depth. It is proved with test that under normal working condition, crack origin cannot originate from the location near point III of meridian cross section, it is proposed that fatigue strength criterion should be established upon the stress at point II in designing diaphragm spring.