Dynamic crack resistance of acrylic plastic

The dependence of the stress-intensity factor near the tip of a growing crack in an SO-120 acrylic plastic on the crack-propagation velocity $K_{\mathrm{I}}(v)$ within the range of 10$^{-5}$ – 300 m/sec is determined. Specific features of crack propagation associated with the shape of the curve $K_{\mathrm{I}}(v)$, which has discontinuities and nonuniqueness intervals, are discussed.