Crack tip opening due to crack-face heating in an infinite plate

Time-dependent thermal stress field was analyzed when a crack-face was heated locally in an infinite plate. From the beginning of heating, the crack closes partly on each side of the heat source and bears the compressive stress. The closed region size, growing with time, depends on the heating location and heat dissipation from the surfaces. At the nearer crack tip to the heat source, tip-closing occurs at first and then at the other tip. As long as some part of the crack remains open, the stress field has singularity at the open crack tip. The stress intensity factor there varies with time and attains to its maximum after a certain duration, showing the similarity to the previous study where a point ahead of the crack tip is heated. By the optical interference method, crack opening displacement was measured experimentally using center-cracked glass plates heated by CO2 laser beam. Measured displacements, varing with time, were well approximated by the analysis.