Life Usage and Health Assessment of Drivetrain Splines in Support of Condition Based Maintenance (CBM)

Given the criticality of main- and tail-rotor spline couplings on rotorcrafts, there is a need for robust tools that will provide better design guidance, provide current health status as well as provide prognostic capabilities for spline couplings. To meet this need, Impact Technologies, LLC proposes to develop and demonstrate a spline health assessment and prognosis system that will utilize physics-based spline lifing models in conjunction with vibration data to produce actionable life usage and health assessment information. We intend to create a comprehensive technology suite that will accurately and quickly assess the impact of past and future vehicle usage on spline health status and therefore, provide the means of assessing mission readiness. The approach will consist of identifying and quantifying spline faults focusing on fretting-fatigue-induced crack initiation and subsequent crack propagation. Accurately characterizing the current health will allow improved estimates for remaining useful life. Development of spline health models will take into account physical material properties such as alloy composition, case hardness and surface finish in conjunction with local stress and displacement fields. As much as possible, current health state assessments will be made by leveraging existing on-board vibration sensors and utilizing novel data processing techniques.