|Budget Amount *help
¥3,400,000 (Direct Cost : ¥3,400,000)
Fiscal Year 1998 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1997 : ¥2,800,000 (Direct Cost : ¥2,800,000)
Studies on crack propagation behaviors and threshold properties of GFRP Laminates under an acid stress environment.
GF/epoxy specimens, which are made of E-glass fiber and epoxy resin, are investigated, and effects of the loading conditions arid the environmental conditions on crack propagation behaviors and threshold properties in HCI solution are researched.
Constant and cyclic loading tests are performed, so that the stress ratio and the frequency are changed for the cyclic loading tests. As a result, it is found that crack propagation depends on a time and the maximum stress intensity factor, K_<lmax>. There is no acceleration of crack propagation due to cyclic loading in a K_<lmax>-da/dt diagram. Furthermore, it is verified that the threshold stress intensity factors, K_<ISCC>, under both loading condition have a distinguished difference in the range of our study. From fractographic observations, interfacial crackings and pull-outs of fibers are remarkable under the cyclic loading condition.
As for the environment condition, changes in the crack propagation behaviors due to the alternations of acid concentration and temperature of the HCI solution are researched. As the acid concentration increases, the K_<ISCC> seems to be a constant under the constant loading conditions and the solution temperature of 303K.And it is noted that the K_<ISCC> takes its minimum value at lmoh/l under the cyclic loading conditions and the solution temperature of 303K.
Increase of the solution temperature lead to the quickening of crack propagation. Arrhenius' equation can be adopted in a stable crack propagation region according to Paris' power low. As for the threshold properties, there is little effect of temperature under the constant loading conditions. On the other hand, the K_<ISCC> decreases and its minimum value vanished under the cyclic loading conditions and the solution temperature of 343K.