Journal of Mechanical Science and Technology 25 (2) (2011) 403~413 www.springerlink.com/content/1738-494x DOI 10.1007/s12206-010-1217-3 A numerical study of crack interactions under thermo-mechanical load using EFGM † Mohit Pant, I. V. Singh * and B. K. Mishra Department of Mechanical and Industrial Engineering, Indian Institute of Technology, Roorkee 247 667, UA, India (Manuscript Received September 21, 2009; Revised July 21, 2010; Accepted October 7, 2010) ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Abstract In this work, element free Galerkin method (EFGM) has been used to obtain the solution of various edge crack problems under thermo-mechanical loads as it provides a versatile technique to model stationary as well as moving crack problems without re-meshing. Standard diffraction criterion has been modified with multiple crack weight technique to characterize the presence of various cracks in the domain of influence of a particular node. The effect of crack inclination has been studied for single as well as two edge cracks, whereas the cracks interaction has been studied for two edge cracks lying on same as well as opposite edges under plane stress conditions. The values of mode-I and mode-II stress intensity factors have been evaluated by the interaction integral approach. Keywords: EFGM; LEFM; Edge cracks; Thermal loading; Mechanical loading; Cracks interaction ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 1. Introduction Many engineering components/parts are subjected to ther- mal as well as thermo-mechanical loads. The common exam- ples of such components are: piston of an engine, where the variation of temperature takes place with the piston move- ment; the connecting rod of an internal combustion engine, which is subjected to thermo-mechanical loading; high ther- mal shock prevails in aerospace components/parts due to ex- treme operating conditions; steam turbine blades, which are exposed to high temperature steam; in military applications, components are exposed to varying thermal loads e.g. gun chamber is subjected to very high temperature and pressure during shell firing and cools down to nominal temperature soon afterwards; walls of nuclear reactor, where severe tem- perature and pressure conditions exists; non-uniform heating of bi-material coatings; heating of ceramic linings used in furnaces and vessels; pressure vessels and boilers subjected to high temperature and pressure. It is well-known that the failure of engineering components is not only due to mechanical loads but also due to thermal stresses/thermal fatigue [1]. Thermo-mechanical loading may result in either the propagation of pre-existing cracks or may initiate new cracks in the structures. This may finally lead to catastrophic failure of the components resulting in the loss of property and lives. In general, multiple cracks exist in all components at macro/micro level. They interact with each other resulting in the change of stress distribution, stress intensity factor and direction of crack propagation. As such, all important failure phenomena such as stress corrosion cracking, hydrogen em- brittlement, and creep micro cracking are directly linked to crack interactions [2]. Thus, the study of crack interactions under thermo-mechanical [3-4] loading is of great importance as it helps us to understand some basic phenomenon such as: ●The effect of micro and macro cracks on the strength of non-uniform materials e.g. composites, concrete, piezo- electric; ●Amplification and shielding effect [4] of cracks; ●Direction of crack propagation and crack branching; To study the effect of crack interaction, a number of nu- merical tools such as finite element method (FEM), boundary element method and finite difference method are available. Among these numerical methods, FEM is found the most successful and powerful numerical method for the simulation of fracture mechanics problems. However, FEM often experi- ences difficulties in solving a class of problems such as large deformation involving element distortion, moving crack simu- lation, crack growth with arbitrary and complex path, dynamic impact, continuous casting, and breakage of material into large number of fragments, etc. Moreover, the accuracy of the solu- tion in FEM depends upon the quality of the mesh generated. To handle these difficulties, a new class of methods, known as mesh-free methods [5] has been developed over past ten years. † This paper was recommended for publication in revised form by Associate Editor Seong Beom Lee * Corresponding author. Tel.: +91 1332 285888, Fax.: +91 1332 285665 E-mail address: ivsingh@gmail.com © KSME & Springer 2011