Propagation and closure of small cracks in SiC particulate reinforced aluminum alloy in high cycle and low cycle fatigue

✍ Scribed by Keisuke Tanaka; Yoshiaki Akiniwa; Kenichi Shimizu

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 610 KB
• Volume: 55
• Category: Article
• ISSN: 0013-7944
• DOI: 10.1016/0013-7944(96)00009-4

✦ Synopsis

The propagation behavior of small fatigue cracks in smooth specimens of an aluminum alloy (2024-T6) reinforced with 20% volume of SiC particles was studied under load-and displacement-controlled cyclic conditions. The development of crack closure with crack extension was measured through the compliance method. An interferometric displacement gage was used to measure the opening displacement of surface cracks. When compared at the same stress amplitude, the life of reinforced material was longer than that of unreinforced material. On the other hand, when compared at the same strain amplitude, the life of reinforced materials was shorter than that of unreinforced material. In the relation between the crack propagation rate, dc/dN, and the stress intensity range, AK, the rate of surface cracks in reinforced materials is higher than that predicted from the relation for long cracks. When dc/dN is correlated to the effective stress intensity range, AK~r, the rate for surface cracks in both reinforced and unreinforced materials coincides with that for long cracks, except for the case of reinforced materials under displacement-controlled conditions. The relation between the crack propagation rate and the J-integral was almost identical for all cases examined in the present study.