利用MARC软件, 采用壳单元替代实体单元建立了健身自行车架的焊接有限元模型, 分析了壳单元替代实体单元模拟的误差并得到了修正系数,为1.136 7; 对车架的五道焊缝在两种焊接方案、十二种焊接顺序下进行了焊接模拟, 分析了车架的主要焊接变形,对焊接顺序进行了优化并进行了试验验证。结果表明: 车架的焊接变形主要表现为座垫套管的偏转变形; 采用非连续焊接方案, 不同焊接顺序下座垫套管的偏转变形量均小于连续焊接方案下的; 最佳焊接顺序为前斜管与套管环焊缝、前斜管与定位板内侧焊缝、套管与定位板外侧焊缝、套管与定位板内侧焊缝、前斜管与定位板外侧焊缝的依次非连续焊接; 不同顺序非连续焊接后座垫套管的偏转变形模拟值与实测值较吻合, 证明了有限元模型的准确性。

The welding finite element model of the gymnastic bicycle frame was built using shell elements instead of solid elements by software MARC. The errors between the simulation by shell elements and by solid elements were analyzed and the correct coefficient of 1.136 7 was obtained. The welding simulation by two welding schemes in twelve sequences of the five welds of the frame was conducted. The main welding deformation of the frame was analyzed, the welding sequence was optimized and verified by experiments. The results show that the deflection of the cushion tube was the main welding deformation of the frame. The deflections of the cushion tube after discontinuous welding in different sequences were lower than those after continuous welding. The optimal welding sequence was discontinuous welding in the order of the girth weld of anterior inclined tube and cushion tube, inner side weld of anterior inclined tube and locating plate, lateral weld of cushion tube and locating plate, inner side weld of cushion tube and locating plate, lateral weld of anterior inclined tube and locating plate. The simulated deflection values of the cushion tube after discontinuous welding in different sequences coincided well with the measured results, proving the accuracy of the finite element model.