Dynamic compressive behavior and constitutive model of polyamide-6 at different temperatures and strain rates

This study investigates the quasi-static and dynamic compressive mechanical properties of polyamide-6 at different temperatures (25–85 ℃) and strain rates (2.6 × 10⁻⁴–3.2 × 10³ s⁻¹) by using a universal testing machine and a split Hopkinson pressure bar device. The variation of mechanical properties with temperature and strain rate is analyzed. The results show that the stress–strain response of polyamide-6 at different temperatures and strain rates includes viscoelastic deformation, yield behavior, and strain hardening behavior. Under some experimental conditions, polyamide-6 has constant stress flow states, which are related to temperature and strain rate. The mechanical properties of polyamide-6 are significantly affected by temperature and strain rate. The elastic modulus, yield strength, and energy absorption property increase with an increase of strain rate, but decrease with an increase of temperature. The formulas of yield strength and elastic modulus are given, and a modified constitutive model is given to describe the stress–strain response of polyamide-6. The predicted results of the model are in good agreement with the experimental data at different temperatures and strain rates.