Issue 22

R. K. Bhagat et alii, Frattura ed Integrità Strutturale, 22 (2012) 5-11; DOI: 10.3221/IGF-ESIS.22.01 5 Evaluation of stress intensity factor of multiple inclined cracks under biaxial loading R. K. Bhagat, V. K. Singh, P. C. Gope, A.K. Chaudhary College of Technology, G.B.P.U.A. & T, Pantnagar-263145, (Uttarakhand), INDIA vks2319@yahoo.co.in A BSTRACT . A finite rectangular plate of unit thickness with two inclined cracks (parallel and non parallel) under biaxial mixed mode condition are modelled using finite element method. The finite element method is used for determination of stress intensity factors by ANYSIS software. Effects of crack inclination angle on stress intensity factors for two parallel and non parallel cracks are investigated. The significant effects of different crack inclination parameters on stress intensity factors are seen for lower and upper crack in two inclined crack. The present method is validated by comparing the results from available experimental data obtained by photo elastic method in same condition. K EYWORDS . Stress intensity factor; Multiple cracks; Photoelasticity; Crack inclination angle. I NTRODUCTION he fracture mechanics theory can be used to analyze structures and machine components with cracks and to obtain an efficient design. The basic principles of fracture mechanics developed from studies of [1-3] are based on the concepts of linear elasticity. Westergaard [3] derived the general linear elastic solution for the stress field around a crack tip using complex stress functions. Irwin [4], proposed the description of the stress field ahead of a crack tip (front) by means of only one parameter, the so called stress intensity factor (SIF). The interaction between multiple cracks has a major influence on crack growth behaviours. This influence is particularly significant in stress corrosion cracking (SCC) because of the relatively large number of cracks initiated due to environmental effects. Wen Ye Tian and U Gabbert [5] have proposed pseudo – traction –electric – displacement – magnetic –induction method to solve the multiple crack interaction problems in magneto elastic material. The interaction of multiple cracks in a finite plate by using the hybrid displacement discontinuity method (a boundary element method) and detail solutions of the stress intensity factors (SIFs) of the multiple-crack problems in a rectangular plate are shown by Xiangqiao [6]. The numerical results reported by Xiangqiao [6] illustrates that the boundary element method is simple, yet accurate for calculating the SIFs of multiple crack problems in a finite plate. Flaw interaction effects were investigated and the importance of modelling multiple crack growth at high stress levels was presented by Walde [7]. Wang [8] studied the interactions of two collinear cracks, three collinear cracks, two parallel cracks, and three parallel cracks using finite element technique. The present investigation have been conducted keeping in mind the effect of crack inclination angle on facture parameters such as stress intensity factor for mode-I problem (K I ) and stress intensity factor for mode-II problem (K II ). Rectangular finite plate with double crack (parallel and non-parallel) inclined at different angles with the loading axis has been used in the present investigation for determination of mixed mode (mode I, mode II) stress intensity factors under biaxial loading condition by using ANSYS Software. The accuracy of the present method is validated by comparing the results obtained by photo elastic method. T