MM504 Lecture 26: C*-integral, Creep crack growth

C* (pronounced "C-star") is a parameter used to quantify the rate of crack growth in a material subjected to constant stress over an extended period of time. It is defined as the product of the creep compliance and the square root of the crack length.

C* = J/σ√a

where J is the J-integral, σ is the applied stress, and a is the crack length.

C* is used to describe the rate of crack growth in materials that exhibit creep behavior, which is the tendency of a material to deform over time under a constant load or stress. Creep crack growth is a common mode of failure in high-temperature applications, such as gas turbines and steam generators, and is an important consideration in the design of such systems.