Measurement of J-Integral by Thermal Video System

The increase of temperature produced by the plastic deformation at the crack tip has been measured by a thermal video system (TVS). It has been found that the distribution of the temperature increase ΔT_p in the plastic zone is proportional to 1/r where r is the distance from the crack tip. The above result has been explained by the fact that the plastic strain energy at the crack tip, which is expressed by the HRR solution, has the singularity of 1/r. A method of measuring the J-integral by the TVS has been proposed and the subjects for the future improvements have been discussed.温度計測に基づくＪ積分測定法の提案