为了揭示夹具拘束距离对0.5 mm厚Hastelloy C-276薄板脉冲激光焊接变形的影响，基于有限元软件ANSYS建立了三维热力耦合有限元模型。采用位移约束假设代替实际夹具的拘束作用，研究了夹具拘束距离对Hastelloy C-276薄板焊接纵向挠曲变形及横向收缩变形的影响规律。实验测量了焊接热循环曲线和残余变形，验证了所建立有限元模型的可靠性。模拟结果表明，随着夹具拘束距离从8 mm增加到20 mm，焊接纵向挠曲变形及横向收缩变形均表现为近似线性增大的趋势，特别是焊接横向收缩变形增加了将近3.6倍，而减小夹具拘束距离可以控制焊接残余变形。该模型较准确地模拟了薄板脉冲激光焊接温度场及残余变形，为抑制薄板焊接变形提供了理论和实验依据。

A three-dimensional thermal-mechanical Finite Element Model (FEM) was established by the ANSYS code to reveal the influence of fixture restraint distance on Pulsed Laser Welding (PLW) distortion of Hastelloy C-276 thin sheet with a thickness of 05 mm. The influence laws of the restraint distance on welding longitudinal deflection and transverse shrinkage distortion were investigated by using the displacement restriction assumption instead of the actual restraint condition. Experiments were carried out to measure the welding thermal cycle curves and residual distortions. The simulation results are in good agreement with that of the corresponding experiment, which validates the reliability of the FEM. It shows that the welding longitudinal deflection and transverse shrinkage distortion increase linearly with the restraint distance increasing from 8 mm to 20 mm, especially the welding transverse shrinkage distortion increases by nearly 3.6 times. Furthermore, the welding residual distortions can be controlled by reducing the restraint distance. Results dennonstrate that the FEM can simulate accurately the temperature field and the residual distortion of PLW and can provide theoretical and experimental basis for suppression of the welding distortion of thin sheets.