Damage Tolerant Analysis of Cracked Al 2024-T3 Panels repaired with Single Boron/Epoxy Patch
It is known that damage tolerant analysis has two objectives, namely, remaining life prediction and residual strength evaluation. To achieve the these objectives, determination of accurate and reliable fracture parameter is very important. XFEM methodologies for fatigue and fracture analysis of cracked aluminium panels repaired with different patch shapes made of single boron/epoxy have been developed. Heaviside and asymptotic crack tip enrichment functions are employed to model the crack. XFEM formulations such as displacement field formulation and element stiffness matrix formulation are presented. Domain form of interaction integral is employed to determine Stress Intensity Factor of repaired cracked panels. Computed SIFs are incorporated in Paris crack growth model to predict the remaining fatigue life. The residual strength has been computed by using the remaining life approach, which accounts for both crack growth constants and no. of cycles to failure. From the various studies conducted, it is observed that repaired panels have significant effect on reduction of the SIF at the crack tip and hence residual strength as well as remaining life of the patched cracked panels are improved significantly. The predicted remaining life and residual strength will be useful for design of structures/components under fatigue loading.
KeywordsXFEM Stress intensity factor Fatigue ABAQUS Interaction integral Remaining life
The authors are thankful to the staff of the Computational Structural Mechanics Group (CSMG) of CSIR- Structural Engineering Research Centre, Chennai, India for the co-operation and suggestions provided during the investigations.
- 2.Y. Murakami, Stress Intensity Factors Handbook (Pergamon Press, Oxford, 1988)Google Scholar
- 6.M.M. Ratwani, Characterization of Fatigue Crack Growth in Bonded Structures, Volume II, Analysis of Cracked Bonded Structure. AFFDL-TR-77-31, Air Force Flight Dynamics Laboratory, Ohio (1977)Google Scholar
- 9.R.J. Callinan, L.R.F. Rose, C.H. Wang, Three dimensional stress analysis of crack patching, in Proceedings of International Conference on Fracture ICF-9, pp. 2151–2158 (1997)Google Scholar
- 19.A.R.C. Murthy, G.S. Palani, N.R. Iyer, Residual strength evaluation of unstiffened and stiffened panels under fatigue loading. SDHM 5(3), 201–226 (2009)Google Scholar
- 20.Abaqus 6.10, Analysis User’s Manual, Dassaultsimulia, http://www.simulia.com