Evolution of dynamic fractures in PMMA : experimental and numerical investigations

摘要: A combined experimental/numerical study has been conducted to investigate dynamic fractures in poly(methyl methacrylate) (PPMA). The results obtained from single-edge-notched-tensile (SENT) fracture tests support the idea that evolution of PMMA is governed by nucleation, growth and coalescence penny-shaped micro-cracks. density microcracks therefore roughness surface increase with crack velocity. Both size process region length for a given specimen. Microscopy virgin material fractured surfaces showed no consistent evidence pre-existing flaws, dust particles or other impurities would provide nucleation sites Instead, it was observed molecular weight significantly affects fracture, must play an important role velocity measurements show rapid initial acceleration followed nearly constant mean velocity, which some cases well above previously reported terminal speed. found decreasing notch depth. Oscillations velocities were also they more pronounced at higher velocities. To large extent, degree oscillations dependent on filtering technique applied raw experimental data. Therefore, conclusive correlation between histories obtained. Finite Volume (FV) method developed numerical simulations experiments. Global behaviour approximated as linear elastic, while Cohesive Zone Model (CZM) used defining local separation material. Numerical predictions good agreement experimentally variations length. speed are predicted.