下限界応力拡大係数範囲ΔΚ_thの簡便な同定方法に関する一検討

抄録

It is necessary to identify relationship between the fatigue crack propagation rate and the stress intensity factor range, if the fracture mechanics approach is applied to evaluate the fatigue crack growth evolution. In addition, identification of the stress intensity factor range of fatigue crack growth threshold (ΔΚ_th) is important to evaluate the structural integrity from the view of fatigue performance. ASTM standard E647 "Standard Test Method for Measurement of Fatigue Crack Growth Rates" is widely known as a de fact standard to determine the value of ΔΚ_th. However, a considerably long time is required to perform the determination of ΔΚ_th value. Therefore, it is expected to cut the experimental period for ΔΚ_th determination. Efficient and time saving procedure for determining ΔΚ_th value comparing with ASTM-E647 is proposed in this study. Many fatigue crack propagation test data were applied to verify the validity of our proposed method. It is expected to be able to complete the experiment for determining ΔΚ_th value at a stage where the fatigue crack propagation rate is one order larger comparing with ASTM-E647.