The. Mdyb-3 Plexiglass Static And Dynamic Mechanical Behavior

In this paper, the mechanical behavior of MDYB-3 (milled-polished directional) aeronautic PMMA (polymethyl methacrylate) is systematically investigated over a temperature range from -55℃ to 120℃, and strain rates of 10^-3/S - 2×10³/S. Tests under lower strain rate are performed using mode CSS-55000 serials electronic controlling testing machine, and the split Hopkinson bar is used for higher strain-rate tests. In order to enhance the signal-noise ratio of strain gauges on transmission bar, aluminium bar with lower Young's modulus is designed and used. For dynamic tensile mechanical properties, the specimens are directly adhered to the ends of incident and transmission bar, to verify this method effectivity and reliability, dynamic tensile results by the split Hopkinson tension bar are compared with these with train gauge directly adhered to specimen, so that effective dynamic tensile properties ore obtained under different temperatures and different strain rates. Close-loop controlling system is used to get and keep the testing temperatures, it can make the temperature fluctuate less than ±2℃. The results show that, the Young's modulus and yield stress of MDYB-3 decrease with the increasing of temperatures at lower strain rates. When testing temperature reaches to the glass transition point, the Young's modulus and yield stress approach to constant value due to the state of polymer chain segments changing from "frozen" to "free". When the strain rate is over 10²/S, the dynamic compression modulus also approaches to a constant value at low temperatures. But at high temperatures the compression modulus doesn't approach to a constant value. The phenomena of plasticity flow and strain hardening are observed during dynamic tensile tests, whereas these phenomena are not observed during dynamic compression test. It is possible that, when the transformation reach to certain value, the orientation of the identical polymer chains or chain segments tropism trend to agreement, the transform resistance will increase. It is found that, the Young's modulus increases with increasing strain rates for compression or tension tests under the same temperatures. This phenomenon is directly related with temperature, the phenomenon of strain-rate sensitivity with increasing temperature become weak. Finally, based on the detailed test results and published viscoelastic constitutive relation basis, a displacement factor...