Analysis of low-frequency fatigue behavior of polyurethane elastomers under localized compressive loading using shear creep behavior

Abstract

Polyurethane elastomers are widely utilized in various industrial applications due to their exceptional flexibility, energy absorption, and long-term pressure resistance. However, their mechanical stability under extremely low-frequency cyclic loading remains poorly understood, particularly in terms of fatigue and creep behavior. This study investigates the failure mechanisms of thermoplastic polyurethane (TPU) and cross-linked TPU under long-term localized compressive stress under extremely low-frequency cyclic loading, simulating real-world conditions in the automotive sector. The experimental approach includes dynamic mechanical analysis, tensile, compression, shear, fatigue, and creep tests, complemented by finite element simulations using a visco-hyperelastic model. Our findings indicate that shear stress plays a more significant role in TPU failure compared to compressive stress, with fatigue behavior under extremely low-frequency conditions exhibiting characteristics similar to creep deformation. The time-temperature superposition method was employed to accelerate testing, validating predictive models for long-term elastomer durability. Furthermore, the introduction of SiO₂-reinforced TPU nanocomposites demonstrated enhanced shear creep resistance, effectively extending failure time under equivalent stress conditions. These results provide valuable insights for improving the design and reliability of polyurethane elastomers in applications requiring prolonged mechanical stability.