13th International Conference on Fracture June 16–21, 2013, Beijing, China -1- Structure responses in the riveted and the friction stir welded stringer panel under the tensile loading MA Yu E 1,*, ZHAO ZhenQiang 1 1 School of Aeronautics, Northwestern Polytechnical University, 710072, P.R. China, * Corresponding author: ma.yu.e@nwpu.edu.cn Abstract In this paper, applications of friction stir welding in the integral fuselage structure are studied. In order to compare with the traditional riveted stringer panel, the integral panels are joined by two ways: one is by single-row rivets and the other one is by friction stir welding. Two kind finite element models are built by Abaqus 6.10. Stress distributions are analyzed and compared. For welded panel, a FORTRAN program of the SIGINI subroutine is made to input the residual stress profile to the finite element model of friction stir welded panel. Compared with the rivet joint, friction stir welded joint can reduce the weight of fuselage. In the same applied stress, the sample joint with rivets has the higher stress areas around the rivet hole, the sample joint with friction stir welding avoids the stress concentration in junctions. Keywords Friction stir weld; riveted stringer panel; welded panel; stress distribution. 1. Introduction Friction stir welding (FSW) is a solid state welding process that has received the world wide attention, particularly for joining aluminum alloys. Because FSW has a lower heat input than the traditional fusion welding, the plastic shrinkage of joint induced by heat in FSW is also lower, which will help to reduce the welding residual stress and distortion of structure. Consequently, FSW has been widely used in modern aero structures. A significant amount of work has been conducted in the past few years to understand the properties of friction stir welding joints. Aidy studied the crack coalescence in 2024-T351 Al alloy friction stir welded joints and discussed the fatigue endurance of FSW joint [1]. Zhang established the two-dimensional numerical models of friction stir welding and gave the numerical simulation of FSW process [2]. Dinaharan studied the effect of friction stir welding on microstructure, mechanical and wear properties of AA6061/ZrB2 [3]. Xu studied the residual stress in thick aluminum friction stir welded butt joints [4]. 2. Numerical Simulation 2.1 Parameters settings Finite element analysis is run by Abaqus 6.10. The riveted stringer panel and the welded panel are of the same size (shown in Fig.1). The length of the panel is 1113mm, the width in the middle is 200mm and in both ends is 288mm, and the thickness is 2mm. There are three rows of rivet hole along the direction of the riveted stringer panel width, one of which is located in the middle and the other two rows are located on both sides, 150 mm from the middle rivet holes. Three stringers (shown in Fig.2) will be fixed on the panel by 30 rivets. The width of the surface of the stringer which contacts with the panel is 28mm, the height of the stringer is 28mm, and the thickness is always 2mm in every part of the stringer. The material of panel and stringers is aluminum-lithium alloy, the Young’s modulus is 77000 and the Poisson’s ratio is 0.33. The material of rivet is 45 steel; two parameters are 210000 and 0.269. Welded panel is joined by welding instead riveting to joint panel and stringers, and the size of the welded panel are the same with the riveted stringer panel except using 10 mm width weld zone to replace the three rows of rivet hole. The material parameters in the weld zone are 55000 and 0.33. After assembly, contact surface between different
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