Multiple cracking in metal-ceramic laminates

Abstract

There have been observations showing that relatively thick metal layers in metal-ceramic laminates lead to the formation of multiple periodic cracks within a zone near a pre-crack, distributing damage and significantly enhancing the composite's toughness. Several models including linear elastic fracture mechanics and shear-lag analysis are developed in the present work in order to study the competition between multiple cracking and single-crack extension as damage modes. It is established that there is a critical thickness ratio for metal-ceramic layers above which multiple cracking dominates. Moreover, this critical thickness ratio is inversely proportional to the corresponding moduli ratio such that the competition between damage modes is governed by the metal-ceramic layer stiffness ratio. Plastic hardening of metals helps to activate the multiple-cracking damage mode, while plastic yielding does the opposite.