Open Access

ARTICLE

Multiple Interacting and Coalescing Semi-Elliptical Surface Cracks in Fatigue-Part-I: Finite Element Analysis

S. K. Patel¹, B. Dattaguru², K. Ramachandra¹

1 Gas Turbine Research Establishment, Bangalore
2 Department of Aerospace Engineering, Jain University, Bangalore (formerly at) Indian Institute of Science, Bangalore

Structural Longevity 2010, 3(1), 37-57. https://doi.org/10.3970/sl.2010.003.037

Abstract

Damage tolerance analysis is essential for evaluating life extension of aged structures which are in service beyond originally stipulated life. The major issue for such an analysis for aged aero-engines is the effect of multiple threedimensional flaws on the structural integrity. In this paper, an improved modified virtual crack closure integral technique is applied to investigate the interaction of twin coplanar semi-elliptical cracks in a finite body under both tension and bending. The specific configuration analysed and presented here is two semi-elliptical surface cracks for combinations of various aspect ratios, thickness ratios and combination of interspacing. The interaction effects are studied for both interacting and coalescing phases as observed to occur during the growth of multiple surface cracks under fatigue load. Empirical equations are formulated to estimate interaction factors which could be used in simulation of fatigue crack growth of three-dimensional multi-site damage.

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