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(一)概述众所周知,轮齿的折断是齿轮损坏的主要形式之一。当被传递的扭矩作用在轮齿上时,其根部将产生相当大的弯曲应力。若轮齿单侧工作,弯曲应力是按脉动循环变化的;若轮齿双侧工作(正反转),则弯曲应力按对称循环变化。由于齿根产生弯曲应力,并且在齿根的过渡圆角处具有较大的应力集中,因此在载荷的多次作用下,若应力的峰值超过疲劳极限,就会出现疲劳裂纹。根据对齿轮的疲劳试验,观察到轮齿在受载的压缩侧发生晶格滑移带和裂纹都比拉伸侧早,但压缩侧的裂纹扩展速度都比拉伸侧小得多,因此疲劳破坏是受拉伸侧上的裂纹所支配的。随着裂纹逐渐不断扩展,终于招致轮齿的折断,这就是齿的疲劳折断。
(A) Overview As we all know, broken gear is one of the main forms of gear damage. When the transmitted torque acts on the gear, its root will produce considerable bending stress. If the teeth work on one side, the bending stress changes according to the pulsation cycle; if the teeth on both sides work (positive and negative), the bending stress changes in a symmetrical cycle. Fatigue cracks occur when the stress peaks exceed the fatigue limit due to bending stress at the tooth root and greater stress concentration at the transition fillet of the root, under multiple loadings. According to the fatigue test of gears, it is observed that the gear tooth slip occurs on the compressive side of the load earlier than the tensile side, but the crack propagation velocity on the compressive side is much smaller than the tensile side, Damage is dominated by cracks on the extension side. With the gradual expansion of the crack, and finally lead to broken gear, which is broken teeth fatigue.