Abstract
Geared powertrains are one of the most common forms of mechanical power transmission found in aerospace, automotive and industrial sectors. Gear failure is costly in downtime, direct financial cost, and even safety/human life perspective. Fatigue failures are among the most frequent causes of gear failure and include both contact fatigue related failures and bending stress related fatigue failures. Bending failures are catastrophic as they can result in almost instantaneous loss of torque transmission capability. Modeling and prediction of this failure is therefore necessary from both a crack propagation view and a cumulative damage perspective, as crack propagation can be a direct measure of fatigue damage. Current crack propagation model validation relies on post-mortem analysis of the crack path to match against model results. In this study and optical image-based technique using high speed imaging technology is developed to measure cycle to cycle crack propagation rates during a gear single tooth bending test. An image processing algorithm is developed to automatically measure the crack length at each relevant frame. The methodology is then used to measure cyclic crack propagation rates under various load levels and fatigue lives. Session
