炭素短繊維強化PPSの射出成形平板における疲労き裂進展に及ぼす試験温度の影響

Abstract

The temperature effect on the fatigue crack propagation behavior was studied with center-notched specimens which were cut from injection-molded plate of short fiber reinforced plastics, PPS, at three angles of the loading axis relative to the molding flow direction. The crack propagation behavior was investigated at four temperatures : room temperature (RT=298 K), 343K, 373 K and 403 K. In the relation between crack propagation rate, da/dN, and the stress intensity factor range, ΔK, the propagation rate of fatigue cracks was slowest for the zero angle, MD, and increased with increasing fiber angle at all temperatures. For each orientation, da/dN was nearly the same at RT and 345K, and increased greatly at temperatures of 373 K and 403K above Tg (=363 K). When da/dN was correlated to the J-integral range, ΔJ, the relations for different orientations became closer, and also the influence of temperature on da/dN was decreased. The inelastic deformation and the decrease of elastic constants are responsible for crack acceleration seen in da/dN vs ΔK relation at high temperatures.