Dynamic stress intensity factors during viscoelastic crack propagation at various strain rates

Dynamic stress intensity factors K D were measured by the caustic method and crack propagation velocity Ċ by the velocity gauge techniques for PMMA [poly(methyl methacrylate)] during dynamic crack propagation at various strain rates \documentclass{article}\pagestyle{empty}\begin{document}$ \rm \dot \varepsilon $\end{document} . No definite applied strain rate effects on the dynamic stress intensity factor were observed for applied strain rates ranging from 8.33 × 10 −4 to 30/sec; however, the test results do show crack propagation velocity dependency in K D ∼ Ċ relations. The high local strain rate region may be realized at the running crack tip even under the quasi‐static loading case of \documentclass{article}\pagestyle{empty}\begin{document}$ \rm \dot \varepsilon $\end{document} = 8.33 × 10 −4 /sec, since all the crack propagation velocities obtained were greater than 50 m/sec even up to 450 m/sec.