Effect of prestrain on material and single tensile overload cycles on crack closure

✍ Scribed by Raghuvir Kumar; S.B.L. Garg

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 773 KB
• Volume: 32
• Category: Article
• ISSN: 0013-7944
• DOI: 10.1016/0013-7944(89)90180-x

✦ Synopsis

Ahstractxrack

closure experiments were performed on 6063-T6 Al-alloy, using COD gauge for various overload ratios (1.67, 1.87 and 2.06) and different prestrains (0, 3 and 6%). On the basis of these experiments some relations are developed. The delay period after application of single overload is also increased as magnitude of overload is increased. The retardation is less as prestrain increased for the same overload ratio. After overload cycle the decrease in U value is less in prestrain material as compared to as received material. CGR is also decreased after application of overload cycle, it attains the CAL CGR after a certain number of cycles. In general crack closure load increased after overload cycle and after a certain number of cycles it tends to attain its CAL closure value.

NOMENCLATURE

crack length fatigue crack propagation rate specimen thickness material constant crack opening displacement constant ampitude loading Young's modulus overload ratio (AP,,/AP) effective stress range ratio stress intensity range material constant number of cycles number of cycles to failure delay cycles load range load range of overload cycle stress ratio effective stress range ratio minimum effective stress range ratio effective stress range ratio at constant amplitude loading effective stress range ratio after overload width of the specimen maximum stress of load cycle minimum stress of load cycle crack opening stress of load cycle crack closing stress ultimate stress fracture stress