Effect of reinforcement morphology on matrix microcracking

Journal Article · Fri Mar 01 04:00:00 EST 1996 · Acta Materialia

DOI:https://doi.org/10.1016/1359-6454(95)00245-6· OSTI ID:215387

Sridhar, N; Srolovitz, D J ^[1]; Rickman, J M ^[2]

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1. Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Materials Science and Engineering
2. Lehigh Univ., Bethlehem, PA (United States). Dept. of Materials Science and Engineering

The authors quantitatively examine the conditions under which a particle matrix misfit leads to matrix crack growth as a function of inclusion shape. Such misfit stresses and cracks can be generated by thermal expansion mismatch, generated by cooling a brittle matrix containing ductile inclusions. Using fracture mechanics and perturbation theory, they analyze the case of a penny-shaped crack interacting with a misfitting spheroidal inclusion. A simple and direct relationship is established between the strain energy release rate and the physical and geometrical properties of the system including: the thermal expansion mismatch, temperature change, the crack and inclusion sizes, the elastic properties of the medium and the shape of the inclusion. In particular, the effects of inclusion shape on the stress intensity factors and strain energy release rate are analytically determined for nearly spherical inclusions. The authors use this information to determine the minimum crack size for crack growth to occur and the maximum size to which cracks may grown. The maximum crack size corresponds to the case where the elastic strain energy released upon crack growth is no longer sufficient to compensate for energy expended in extending the crack as the crack is growing into the rapidly decreasing stress field. The authors employ a nominally exact numerical procedure to study the effects of whiskers and platelets (i.e. spheroids very different from spheres) on matrix cracking. It is found that upon cooling a composite containing ductile inclusions, the propensity for matrix cracking is maximized for reinforcement shapes close to that of a sphere.

• OSTI ID: 215387
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 3 Vol. 44; ISSN XZ504Y; ISSN 1359-6454
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CERAMICS
COMPOSITE MATERIALS
CRACK PROPAGATION
CRACKS
DUCTILITY
ELASTICITY
FRACTURE MECHANICS
FRACTURE PROPERTIES
METALS
MICROSTRUCTURE
PARTICULATES
PERTURBATION THEORY
SHAPE
STRAINS
STRESS INTENSITY FACTORS
STRESSES
THERMAL EXPANSION