Investigation on the effects of temperature and strain rate on dynamic tensile fragmentation of PMMA using a novel electromagnetic-driven composite expansion ring test setup

The excellent optical transparency and mechanical properties of polymethyl methacrylate (PMMA) have led to its extensive utilization in the manufacture of transparent protective components, such as aircraft windshields. which are frequently exposed to complex thermal environments and at risk of impact-induced fragmentation. However, the temperature-dependent dynamic fragmentation behavior of PMMA remains poorly understood and requires further investigation. In this study, a combination of a novel electromagnetic-driven composite expansion ring test setup, ultra-high-speed imaging, Photon Doppler Velocimetry (PDV) and numerical simulation is employed to conduct dynamic one-dimensional tensile fragmentation test on PMMA specimen at different temperatures and strain rates. The distributions of stress states, fragmentation onset and progression, and fragment characteristics are systematically analyzed. The results obtained from the test indicate that the fragmentation process is predominantly governed by circumferential tensile stress. As the temperature decreases, the fragmentation strain progressively declines, and crack initiation occurs earlier. The degree of fragmentation intensifies, and a distinct trend of fragment refinement is observed, indicating a typical low-temperature embrittlement phenomenon. The strain rate significantly influences the fragmentation response and the final morphology of the fragments. It has been demonstrated that high strain-rate loading induces an explosive fragmentation mode, while low strain-rate loading leads to a more gradual fragmentation process. A statistical model based on the Gamma distribution is established to characterize the mass distribution of PMMA fragments following dynamic tensile fragmentation. The results showed that the scale parameter of the fragment distribution increases with rising temperature and decreasing strain rate, thus demonstrating the significance influence of loading conditions on fragmentation granularity. The research results of this paper provide guidance for the impact resistance design of PMMA structures under high temperature and high strain rate conditions.