Anisotropy of the low-cycle tensile fatigue strength and deformability of a glass-reinforced plastic

Experimental results on the anisotropy of the strength and deformability of a 1:1 SVAM oriented glass-reinforced plastic in low-cycle tension in the directions =0, 15, 30, and 45° are discussed. The loading frequency was 1–1.5 cycles/minute. A three-dimensional fatigue strength diagram is constructed in _max - - log N coordinates. It is shown that in the direction =0° the fracture strain depends on stress, whereas at 0° the glass-reinforced plastic fails at almost the same maximum strain, the value of which depends on , but is invariant with respect to _max. It is established that the rate of development of the strain extrema on the linear part of the (N) graph and the stress _max are related by a power-law dependence, whose parameters are determined by the anisotropy of the mechanical properties of the composite.Institute of Mechanics, Academy of Sciences of the Armenian SSR, Erevan. Translated from Mekhanika Polimerov, No. 3, pp. 425–429, May–June, 1976.