ON THE USE OF NODE-SHIFTING TECHNIQUES FOR THE INTENSITY FACTOR OF TEMPERATURE GRADIENT AT A MACROCRACK TIP

Abstract

The node-shifting technique used in finite element analysis to achieve the required singularity of temperature gradient in the vicinity of a macrocrack tip is extended. The analytical expressions for the intensity factor of temperature gradient (IFTG) at the crack tip are derived for both the 8-node quadratic and 12-node quadrilateral isoparametric elements. Two numerical examples follow the analytical derivations. The first example, dealing with a central cracked panel subject to heat flux irradiation, is designed to reveal the critical size of the elements adjacent to the crack tip. In applying the derived expression for the 12-node quadrilateral elements, it has been found that the most appropriate size of the crack tip elements is approximately 2% of the half crack length. The second example is to study the effect of stacking sequence of material layers in composites on the reduction of the IFTG. An optimal stacking sequence has been determined that yields the smallest value of IFTG among all the possible cases.