| Abstract: | Conclusions 1. We have studied the influence of previously formed surface SC of various orientations on the force and kinetic characteristics of a slowly growing arterial FC. The subject of investigation was industrial glass based on polymethyl methacrylate. Steady growth of the FC was achieved in our experiments by applying torque in order to split lamellar samples.2. We have found that for no mutual disposition of the two kinds of cracks do surface SC ease the conditions of FC growth. On the contrary, in a number of cases the presence of SC having linear dimensions of only 3–5% of the front length interrupt the steady growth of the FC, reduce its average velocity, and sometimes stop it altogether. For the growth of the FC to be renewed the load has to be augmented, so that the limiting specific work of fracture Wlim increases by 10–40%. The growth of an FC is opposed most strongly by SC lying at right angles to it.3. The results of our experiments indicate comparatively easy fracture of the SC, and also show that FC prefer to develop along earlier-formed SC, subject to appropriate mutual orientation.4. By virtue of the presence of elastic interactions between different sections, any action applied to a small part of the leading edge (front) will alter the conditions of material fracture along the whole FC front.Institute of High-Molecular-Weight Compounds, Academy of Sciences of the USSR, Leningrad. Translated from Mekhanika Polimerov, No. 4, pp. 609–615, July–August, 1976. |
