As they possess the qualities of high specific strength, high specific modulus, high specific energy absorption, and excellent designability, ultra-high molecular weight polyethylene (UHMWPE) fiber-reinforced composites have gradually replaced traditional materials such as ceramics and steel plates as the main ballistic protection materials. Using an improved test method, the uniaxial tensile tests of UHMWPE fiber-reinforced composites at two strain rates of 10⁻⁴ s⁻¹ and 10⁻² s⁻¹ and a temperature range from −20 °C to 80 °C are carried out to study the effects of strain rate and temperature on the tensile behavior of UHMWPE fiber-reinforced composites. The experimental results indicate that the tensile responses exhibit nonlinear characteristics and the sensitivity of strain rate and temperature. The yield strength and modulus decrease with increasing temperature and increase with the increase in strain rate. A phenomenological viscoelastic constitutive model composed of a nonlinear spring and a nonlinear Maxwell element is proposed to characterize the temperature and strain rate dependent deformation behavior of UHMWPE fiber-reinforced composites before yielding. The results show that the model can accurately predict the tensile nonlinear viscoelastic responses of UHMWPE fiber-reinforced composites before yielding over a wide temperature range under quasi-static loading.

Static and dynamic uniaxial tensile responses were investigated to accurately characterize and predict the mechanical properties of PEEK (polyether-ether-ketone) at strain rates ranging from 10⁻³ s⁻¹ to 200 s⁻¹ and temperatures ranging from 23 °C to 110 °C. The tensile responses showed dependences on the strain rate and temperature, and the dependences of the yield strength and elastic modulus on the temperature and strain rate were studied. A modified phenomenological Sherwood–Frost constitutive model considering a wide range of strain rates and temperatures was established to characterize the tensile mechanical response of PEEK material before yielding based on the experimental data. The results indicate that the model can accurately describe the pre-yield behavior of PEEK under different temperature and strain rate conditions, thus reducing the dependency on experimental data for subsequent researchers, thereby providing a theoretical foundation and modeling framework for the design and performance evaluation of CF/PEEK composite structures.