Whether used as structural components in design or matrix materials for composites, the mechanical properties of polymers are increasingly important. The compressive response of extruded polymethyl methacrylate (PMMA) rod with aligned polymer chains and Al–Ni–PMMA particulate composites are investigated across a range of strain rates and temperatures. The particulate composites were prepared using an injection-moulding technique resulting in highly anisotropic microstructures. The mechanics of these materials are discussed in the light of theories of deformation for glassy polymers. The experimental data from this study are compared with PMMA results from the literature as well as epoxy-based composites with identical particulates. The PMMA exhibited the expected strain rate and temperature dependence and brittle failure was observed at the highest strain rates and lowest temperatures. The Al–Ni–PMMA composites were found to have similar stress–strain response to the PMMA with reduced strain softening after yield. Increasing volume fraction of particulates in the composite resulted in decreased strength.
Abstract. Polymers are increasingly used in impact and complex high rate loading applications. Generally, the mechanical response of glassy polymers under high strain rates has been determined in compression. Some research programs have studied the combined effects of temperature and strain rate, still primarily in compression, providing better understanding of the physics behind the observed response and enhancing the models for these materials. However, limited data are available in tension, and even more limited are data describing both the compressive and tensile response of the same glassy polymer. This paper investigates the compressive and tensile response of glassy polymers across a range of stain rates from quasi-static to dynamic. Experimental results from dynamic mechanical analysis, quasi-static compression and tension, and split Hopkinson tension/pressure bars on several representative glassy polymers will be presented. The pressure dependant yield in these materials will be discussed through comparison of the tensile and compressive yield stresses.
Abstract. Since the early 1990s, a range of experimental data has been generated describing the response of glassy polymers to high strain rate loading in compression. More recently, research programs that study the combined effects of temperature and strain rate have made significant steps in providing better understanding of the physics behind the observed response, and also in modeling this response. However, limited data are available in tension, and even more limited are data describing both the compressive and tensile response of the same polymer. This paper investigates the compressive and tensile response of glassy polymers, using poly(vinyl chloride) as a representative material, across a range of stain rates from quasi-static to dynamic. The pressure dependant yield in glassy polymers will be discussed through comparison of the tensile and compressive yield stresses.
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