ACOUSTIC EMISSION DAMAGE PARAMETER FOR CUMULATIVE FATIGUE DAMAGE PREDICTION IN GEAR SINGLE TOOTH BENDING FATIGUE

Power delivery in many industrial, automotive, and aerospace applications is subject to duty cycles based on the needs of the equipment over each mission. These blocks of usage at various power levels subjects the drivetrain to cyclic forces and stresses of variable mean and amplitude. Each block of applied cyclic stresses contributes some amount to the overall fatigue damage in the parts. It is critical that the design of the power transmission components such as gears accounts for the overall fatigue damage applied from the expected duty cycle loading. Contemporary cumulative fatigue damage models require experimental data of various proportions to regress required empirical parameters. At minimum, a constant amplitude stress life (SN) evaluation is necessary. Others require expansive multilevel load experimental programs to regress empirical material parameters. It is advantageous for all design engineers from a time and cost perspective to minimize the amount of fatigue testing required to regress empirical cumulative damage parameters. It is proposed here that measurement of Acoustic Emission (AE) in constant amplitude fatigue tests may serve as a suitable metric on which to base the regression of empirical cumulative damage parameters. AE hits, ringdown counts, and absolute energy is monitored during gear single tooth bending fatigue (STBF) tests. Material parameters as defined in the Manson and Halford Damage Curve Approach Model are then regressed using the AE metrics. A prediction of a set of multilevel STBF tests is made and compared to existing experimental results and predictions from other cumulative damage fatigue models.