Welding Sequence Optimization Of The Low-side Open Wagon Sidewall

Welding deformation is one of the most common problems in the structural manufacturi- ng process. Welding deformation injures the beauty of appearance of a structure and decreases its strength capability. In addition, the welding deformation will make the assembly and welding of next step become more difficult. Then, the correction of welding deformation decreases productivity and economic returns. Therefore, developing a precise method to predict the deformation is essential.The body of the low-side open wagon is composed of underframe, endwall, sidewall,and so on. As an important part of the wagon body, the welding quality of the sidewall affects the operation safety and quality of the wagon. In this paper, the three-dimensional heating-elastic-plastic finite element method is used to simulate the welding process of the low-side open wagon sidewall. Heating-elastic-plastic analysis of large structure, which faces with the problems as large scale computing time and convergence difficulty, can be solved by using segmented double ellipsoidal shaped moving heat source model and method of shell-solid elements combining modeling. Segmented double ellipsoidal shaped moving heat source model which divides the heat source into several segments, decreases time increments used to describe details of moving heat flux greatly, so that dramatically increases analysis efficiency. Moreover, Segmented double ellipsoidal shaped moving heat source model not only reflects the characteristics of the heat source—concentration and moving, but also possesses attractive accuracy contrasting with double ellipsoidal shaped moving heat source model, so it combines accuracy and efficiency perfectly. Method of shell-solid elements combining modeling is also used in this paper. In this method, welding structure can be divided into two zones—welding zone and non-welding zone. Three-dimensional solid elements are used in the welding zone, shell elements are used in the non-welding zone, this can further increase the computing efficiency.The impact of welding sequence to the deformation of the low-side open wagon sidewa- ll is studied using segmented double ellipsoidal shaped moving heat source model and method of shell-solid elements combining modeling. Six schemes are established in this paper. Through comparison of the welding deformation under each scheme, the optimum welding sequence is found out, which can provide some reference to imporve the welding process of the body of the wagon.