Study on modified J-integral range and its correlation with fatigue crack growth

✍ Scribed by Y.P Srivastava; S.B.L Garg

• Publisher: Elsevier Science
• Year: 1988
• Tongue: English
• Weight: 887 KB
• Volume: 30
• Category: Article
• ISSN: 0013-7944
• DOI: 10.1016/0013-7944(88)90217-2

✦ Synopsis

Ahatraet-The research work reported in this paper is concerned with the studies on J-integral range (AJ)/modi6ed value of J-integral range (AJ*) and to relate them to crack tip opening displacement (CTOD)/crack opening displacement (COD) and fatigue crack growth rate (da/dZV). Experiments were performed on 6063-T6 Al-alloy in both as-received and annealed states for different stress ratios (R). CTOD and COD were measured using surface measurement technique by a small COD gauge, by mounting it near a fatigue crack tip at different positions behind the crack tip and at the crack tip respectively. It was found that AJ is a function of CTOD/COD. When conventional concept of J-integral is modified by introducing notional crack concept for considering the plasticity at the crack tip, the experimental results are found to come closer to the AJ" values (found theoretically by notional crack concept). The fatigue crack propagation law though conventionally expressed as a function of stress intensity range (AK) can also be expressed as a function of AJ*. The experimental results for both states of the material (as-received and annealed) show that for large range of da/dN, AJ+ is able to provide a satisfactory correlation in the form of power law and the crack growth rate equation is found to be independent of R.