Abstract—Explosive welding is a process which uses explosive detonation to move the flyer plate material into the base material to produce a solid state joint. Experimental tests have been carried out by other researchers; have been considered to explosively welded aluminium 7039 and steel 4340 tubes in one step. The tests have been done using various stand-off distances and explosive ratios. Various interface geometries have been obtained from these experiments. In this paper, all the experiments carried out were simulated using the finite element method. The flyer plate and collision velocities obtained from the analysis were validated by the pin-measurement experiments. The numerical results showed that very high localized plastic deformation produced at the bond interface. The Ls_dyna_971 FEM has been used for all simulation process. Keywords—Explosive Welding, Johnson-Cook Equation, Finite Element, JWL Equation. I. INTRODUCTION XPLOSIVE welding is an area of study that represents a truly multidisciplinary research as it deals with the dynamics of collision at high velocities and pressures, the transient fluid like behaviour of metals at extremely high strain rates, metallurgical and other physical aspects of colliding metals, modelling of material behaviour, sources of high rate energy and the geometrical parameters of colliding system of metals. To analyze the process, the hydrodynamic analogy was used by various authors [1, 2, and 3] due to the creation of the high localized pressure and the material fluid like behaviour at the collision zone. The process parameters are the impact velocity, the collision point velocity, the angle, the stand-off distance, the type of the explosive used and the detonation velocity, density and size and distributions of the explosive mix. Welding windows were proposed to show the weld ability ranges of process parameters i.e. impact velocity (or collision point velocity) versus the dynamic angle for various materials [3, 4, 5, and 6]. Nevertheless, the data were obtained by means of large number of experiments performed. However, the process could be simulated using the finite element method and most aspects of the welding process Roozbeh Alipour is with member of faculty of Islamic Azad University – Mahshahr branch, Iran, (Tel: +989166141452; e-mail: r.alipour@ mahshahriau.ac.ir). Farhad Najarian is a lecturer of faculty of Islamic Azad University – Saveh branch, Iran, (Tel: +989124267903; e-mail: farhad_nadjarian@ yahoo.com). could be obtained. Few attempts have been reported in the literature to simulate the process. Al-Hassani [7] treated the problem as a normal transient loading of plane stress elements of rectangular shape. In this analysis, cinematically equivalent concentrated loads at the nodes represented the uniformly distributed explosive load. Explosive welding process was simulated by Oberg [8] by means of Lagrangian finite Element computer code, but only produced jetting. The explosive welding process was also modeled by Akihisa [9]. He only produced waves but no jetting. In addition, the author assumed that symmetric or asymmetric shear flow distribution was generated in the flyer and parent plates and the modeling was performed based on this supposition. II. GENERAL SPECIFICATION Experimental tests have been performed to explosively welded aluminium 7039 and stainless steel 4340 tubes in one step. The welded tubes had an external diameter of 135mm and internal diameter of 123mm. The outer layer was made of 4340 steel, with the external diameter of 135 and thickness of 4.5mm. The inner tube was made of Al-7039 with 5mm thickness. The tests have been done using various stand-off distances and explosive ratios. Various interface geometries have been obtained from these experiments. The explosive material was positioned inside the inner tube. In this investigation, all the experiments were simulated using the finite element method. The JWL equation of state was used to describe the behavior of explosive. The JWL equation of state has been developed for high explosive burn materials. The explosive properties used were tabulated in Table 1. These equations were coded into the FEM software. The JWL equation was described as: V e r C e r C P v r v r ωψ ω ω + − + − = − − 2 2 1 1 ) 1 ( ) 1 ( 2 2 1 1 (1) Where C 1 , C 2 , r 1 , r 2 and ω are the constants of JWL equation. V is the ratio of the volume of the product gases to initial volume of undetonated explosive. The constant is given in Table 1 for the PETN used in this investigation [10]. TABLE I THE JWL CONSTANTS EQUATION OF PETAN Charge Type C 1 (Gpa) C 2 (Gpa) r 1 r 2 ω PETN 1032.158 90.57014 6 2.6 0.57 A FEM Study of Explosive Welding of Double Layer Tubes R. Alipour, F.Najarian E World Academy of Science, Engineering and Technology International Journal of Mechanical and Mechatronics Engineering Vol:5, No:1, 2011 183 International Scholarly and Scientific Research & Innovation 5(1) 2011 scholar.waset.org/1307-6892/3398 International Science Index, Mechanical and Mechatronics Engineering Vol:5, No:1, 2011 waset.org/Publication/3398