Thermal Stress Intensity Factor of Semi-Infinite Crack due to Crack Face Heating

The stress intensity factor of a semi infinite crack in an infinite plate under a transient and quasistatic thermal stress field generated by a point heat source acting on a crack surface was analyzed. A typical stress around a point heat source is severe compression in the vicinity of the point of heat, then it turns positive value as the distance from the point of heat increases and finally it becomes zero at infinity. Therefore, in the crack surface heating, a wide contact region of crack surface was found just around the heat source, but the crack surfaces gradually open each other due to the positive stress away from the point of heat and the singular stress appears at the crack tip. A crack tip stress intensity factor was obtained as a function of heating time and/or velocity of the moving heat source and the degree of heat dissipation from surfaces of thin plate to the atmosphere. Two types of different technique for determining an extent of the contact length and stress intensity factor were proposed. It was found that the SIF is significantly influenced by the degree of heat dissipation from the plate surfaces in the case of crack face heating with moving heat source.