2012 年 12 巻 2 号 p. 81-87
Residual strength after a creep loading is studied for open hole CFRP laminates. Accelerated tests are performed at the elevated temperatures. The test results show that the residual strengths are not always less than the static strength but sometimes greater than that, depending on the temperature. A digital image correlation (DIC) method is employed for the measurement of in-situ strain distribution around the open hole. DIC result implies splitting damage of loading directional layer has a role playing to enhance the residual strength after creep. Finite element analysis involving cohesive element is implemented in order to verify the splitting-induced residual strength enhancement. The cohesive element has time-dependent strength and toughness. Time-dependent internal damage propagation is thus analyzed. This study suggests the residual strength as a function of creep time once increases via stress-concentration mitigation by splitting damage and then decreases with time due to the degradation of material properties themselves.
