Abstract
A multibody coupling finite element model, in which worktable, clamping strip, welding plate and fixture are included, is built to simulate the welding transient distortions under restraining forces. Overlaying welding experiments are also carried out to measure transient welding distortions and dynamic restraining forces to validate the model. The effects of the restraining force location and magnitude, release of restraining force and restraining moment on welding distortion are discussed. Results show that the variation of the restraining force is similar to that of the welding angular distortion during welding, and the minimum initial restraining force for a specified restraining location and the appropriate restraining distance from welding centreline for a specified restraining force to restrain the welding angular distortion can be optimised using the model. However, the welding plate would spring back to some extent after the restraining force release. The restraining moment plays an important role in controlling the welding angular distortion under the same welding parameters, the angular distortion almost the same with the same restraining moment no matter the location and magnitude of the restraining force, the angular distortion decreases rapidly with increasing restraining moment, the distortion before restraining force release can be fully restrained and the values of spring back keep almost the same when the restraining moment is larger than a threshold.