Mechanisms of fatigue-crack propagation in ductile and brittle solids

• Published in: International journal of fracture 1999-01, Vol.100 (1), p.55-83
• Main Author: RITCHIE, R. O
• Format: Article
• Language: English
• Subjects: Brittle materials; Brittleness; Condensed matter: structure, mechanical and thermal properties; Crack closure; Crack propagation; Crack tips; Cross-disciplinary physics: materials science; rheology; Dependence; Ductile fracture; Ductile-brittle transition; Exact sciences and technology; Fatigue failure; Fatigue, brittleness, fracture, and cracks; Fatigue, corrosion fatigue, embrittlement, cracking, fracture and failure; Fatigue, embrittlement, and fracture; Fracture mechanics; Intermetallic compounds; Materials science; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; Physics; Propagation; Shielding; Treatment of materials and its effects on microstructure and properties
• ISSN: 0376-9429; 1573-2673
• DOI: 10.1023/a:1018655917051

The mechanisms of fatigue-crack propagation are examined with particular emphasis on the similarities and differences between cyclic crack growth in ductile materials, such as metals, and corresponding behavior in brittle materials, such as intermetallics and ceramics. This is achieved by considering the process of fatigue-crack growth as a mutual competition between intrinsic mechanisms of crack advance ahead of the crack tip (e.g., alternating crack-tip blunting and resharpening), which promote crack growth, and extrinsic mechanisms of crack-tip shielding behind the tip (e.g., crack closure and bridging), which impede it. The widely differing nature of these mechanisms in ductile and brittle materials and their specific dependence upon the alternating and maximum driving forces (e.g., ΔK andKmax) provide a useful distinction of the process of fatigue-crack propagation in different classes of materials; moreover, it provides a rationalization for the effect of such factors as load ratio and crack size. Finally, the differing susceptibility of ductile and brittle materials to cyclic degradation has broad implications for their potential structural application; this is briefly discussed with reference to lifetime prediction.