A mixed strain rate and energy based fatigue criterion for short fiber reinforced thermoplastics

Multiple parameters influence the durability of reinforced thermoplastics under fatigue loading. Having models unifying as many of these parameters, while providing an accurate estimation of the fatigue lifetime, is thus key. This investigation on the evolution of multiple mechanical parameters under cyclic loading, and based on a large experimental database (more than 200 uniaxial fatigue tests over a wide range of load ratios), two cyclic strain rate based criteria are proposed. The second is more elaborated, introducing anelastic energy, to better account for mean stress effect and unify fatigue life predictions within scatter bands of factor two.