Enhanced Apparent Toughness Approach to Tensile Strain Design

Tensile strain design is an essential element of the overall strain-based design methodology. This paper focuses on the apparent toughness approach and introduces the concept of apparent CTOD resistance curve (CTOD_R). The determination of apparent toughness, CTOD_A, from the apparent CTOD_R is demonstrated. The prediction of tensile strain capacity (TSC) using the CTOD_A and the traditional tangent method is conducted. Similar results are obtained from both approaches. The value of apparent CTOD_R is found to be relatively insensitive to the amount of flaw growth after some limited initial growth. This insensitivity allows the determination of CTOD_A at the small amount of flaw growth. This feature establishes the connection between CTOD_A and initiation-based toughness. Further work is under way to apply these findings.