Modeling & Simulation, Testing & Validation (MSTV)


by William V. Mars; Matthew Castanier; David Ostberg; William Bradford


In this work, Abrams tank track system T-158LL backer pad elastomer self-heating and fatigue behavior was characterized experimentally, and the backer pad design was digitally twinned to show how complex in-service conditions can be evaluated virtually. The material characterization included measurement of the thermal properties and dissipative characteristics of the rubber compound, as well as its fatigue crack growth rate curve and crack precursor size. The analysis included 1) a structural finite element analysis of the backer pad in operation to obtain the load history, 2) a thermal finite element analysis to obtain steady-state operating temperature distribution within the backer pad, and 3) a thermo-mechanical fatigue analysis using the Endurica CL fatigue solver to estimate the expected service life and failure mode of the backer pad. As validation, experiments were conducted on the backer pad to measure operating temperature, fatigue life, and failure mode over a matrix of loads and frequencies typical of service. Operating temperatures in a range from 125 °F to 350 °F were observed. Several failure modes occurred in backer pad tests, depending on the load and frequency. In cases where thermal runaway occurred, a thermal degradation mechanism was observed internally in the pad. Under less severe conditions, fatigue crack growth initiating near the “binocular” tubes was observed. Fatigue life was found in almost all cases to fall between 103 and 107 cycles. Thermal runaway predictions for the T-158LL backer pad were also validated against tests in cases where debonding of the rubber from the metal core occurred. The digital twin of the backer pad yielded failure modes quite similar to those observed in experiments, and gave realistic estimates of operating temperature and fatigue life. The fatigue analysis methods developed under this project have since been applied commercially, and have proven effective in a wide range of elastomer applications. Future applications of the tools will include durability improvement initiatives, light-weighting efforts, and remaining life tracking for reliability programs.