Time-Varying Mesh Stiffness Modelling for Multi-Fault Spur and Helical Gear Diagnostics: An Integrated Analytical, Numerical, and Experimental Framework

Gear Time-Varying Mesh Stiffness (TVMS) is the primary internal excitation governing gear dynamic response. It is the physical bridge between fault severity and measurable vibration signatures. That is why its accurate modeling is important. An accurate model of TVMS may lead to accurate prediction of the gearbox system’s response. Most existing TVMS formulations are restricted to spur gears with single, idealized faults and limited experimental validation. This research aims to develop a physics-consistent, slice-coupled analytical TVMS framework for spur and helical gears, incorporating compound multi-location faults (pitting, tooth cracking), along with elastohydrodynamic (EHL) lubrication corrections, profile shift, and tooth lead deviations to accurately represent real gears used in practice. A three-phase methodology, comprising improved analytical model development, multi-source validation (Finite Element Analysis (FEA), Multibody simulations (MBS), precision test rig), and signal processing for fault diagnosis, establishes an experimentally grounded framework for vibration-based gear health monitoring, directly relevant to PHM practice.