Many chassis and powertrain components in the transportation and automotive industry experience multi-axial cyclic service loading. A thorough load-history leading to durability damage should be considered in the early vehicle production steps.
The key feature of rubber fatigue analysis discussed in this study is how to define local critical location strain time history based on nominal and complex load time histories. Material coupon characterization used here is the crack growth approach, based on fracture mechanics parameters. This methodology was utilized and presented for a truck engine mount. Temperature effects are not considered since proving ground (PG) loads are generated under isothermal high temperature and low frequency conditions without high amounts of self-heating.
This novel methodology for fatigue life calculation involves finding independent load channels and mapping all load history through converting single or multichannel load-displacement history into stress-strain history for a nonlinear elastic finite element model. After finding strain history, a critical plane approach, based on crack energy density, is used for life predictions. Rainflow cycle counting methodology and linear damage rules are used for load cycle characterization and damage accumulation, respectively.
This methodology is correlated with component proving ground vehicle testing under complete service conditions for the vehicle. Predictions are validated through analysis of hot spot high stress locations, life regime, and strain states. Comparative results of numerical predictions show reasonable correlation with experimental data.