In manufacturing sheet metal formed plates, panels and shells by welding, buckling distortions become substantial especially for aerospace structures with material thickness less than 4 mm. To prevent buckling, Low Stress No Distortion (LSND) welding techniques have been pioneered and developed at the Beijing Aeronautical Manufacturing Technology Research Institute. These innovative techniques have been applied successfully in manufacturing aerospace structural components. In this paper, the

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... hanisms of LSND welding techniques using either the whole cross-sectional thermal tensioning effect or the localized thermal tensioning effect are described and summarized in detail. The basic idea of LSND welding techniques is to perform active in-process control of inherent plastic (incompatible) strains and stresses formation during welding to achieve distortionfree results so that no costly post weld reworking operations for distortion correction is required. Emphasis is given to the finite element analysis to predict and optimize the localized thermal tensioning technique with a trailing spot heat sink coupled to the welding heat source. Selection of parameters for engineering solution are recommended. 21 Ref., 1 Tabl., 15 Fig.