Fracture of metal/ceramic laminates. 1: Transition from single to multiple cracking

Journal Article · Fri Jan 15 04:00:00 EST 1999 · Acta Materialia

DOI:https://doi.org/10.1016/S1359-6454(98)00357-7· OSTI ID:329054

Hwu, K L; Derby, B ^[1]

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1. Univ. of Oxford (United Kingdom). Dept. of Materials

The transition from single crack extension to multiple laminate cracking near the crack tip has been studied over a range of metal/ceramic thickness ratios (t{sub m}/t{sub c}), in three metal/ceramic laminate systems: Al/alumina, Cu/alumina and Ni/alumina. Multiple cracking occurs above a critical value of t{sub m}/t{sub c}, with the critical value increasing with decreasing ratio of equivalent constrained metal yield stress to mean ceramic fracture stress, {sigma}{sub e}/{sigma}{sub c}. These results are shown to be inconsistent with the predictions of a linear elastic fracture mechanics (LEFM) model, which considers a cracked laminate as a bridged monolithic crack, for the lower metal yield strength Cu/alumina and Al/alumina laminates. A modified model considers a limiting case where the stress distribution in the ceramic layers in the crack wake is determined by shear-lag below a critical value of the ratio {sigma}{sub e}/{sigma}{sub c}. This combined model is shown to predict more accurately the transition from single to multiple cracking in the three laminate types and also to predict the ceramic layer crack spacing in the multiple cracked specimens.

• OSTI ID: 329054
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 2 Vol. 47; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM
ALUMINIUM OXIDES
COMPOSITE MATERIALS
COPPER
CRACKS
FRACTURE PROPERTIES
LAYERS
MATHEMATICAL MODELS
NICKEL
PREDICTION EQUATIONS