The threshold stress intensity factor range ΔKth can be obtained using the ΔK decreasing method. Because ΔKth is dependent on the ΔK decreasing rate, the rate is regulated by the American Society of Testing Materials standard. However, the rate was derived under specific conditions, and its applicability to materials with physical properties different from ordinary steel has not been clarified. To address this issue, this study performed plasticity-induced-crack-closure analysis with the Dugdale model. The dependence of material properties on ΔKth of long crack was determined for steel, aluminum and magnesium. The results showed that the rate value proposed by the standard is valid for all materials with different yield strengths and different Young's moduli within 10% error.
- ASTM standard
- Plasticity-induced crack closure analysis
- Threshold stress intensity factor range
- ΔK-decreasing rate