Cracking in particulate composites due to thermalmechanical stress

Numerical computations of the strain energy release rate for cracks propagating around the interface between a spherical particle and a matrix have been used to determine the strain energy release rate function for the case where stresses arise due to differential thermal contraction. The strain-energy release rate function was found to exhibit a maximum as a function of crack length consistent with the theoretical conditions for crack extension and arrest proposed by Lange. The calculations show that a critical particle size exists below which crack extention does not occur for a given thermalmechanical stress. The predicted critical particle size correlates well with experimental results.