Dear all,
I am working on a 2D welding simulation. The welding plate is symmetric about the X-axis, and the welding is moving along the Z direction. The width of the plate is along the Y direction. I have applied the Dflux subroutine as the heat input in Abaqus software. When I use the X symmetry boundary conditions at the Symmetric plane, and the other two ends nodes are fixed along with all directions, the simulation works fine(but the percentage difference from results is more). But the end of the plate away from the heating side becomes more tensile. If I apply the Xsymmetry and encastering the bottom node in the same plane with the same mesh, the results are diverging. When I reduce the size of the mesh, the solutions will converge.
1.Why the solutions are converge when the mesh becomes finer?
2.Can anyone suggest the exact boundary conditions for the 2D welding analysis?
Dear Anoop,
Maybe you shouldn't use the same mesh for the whole structure, for each part of the structure you have to use a specific mesh to avoid deformation.
Best,
Hi, if I understood correctly you probably facing "Stress Singularity" issue. Its a FEM artifact. Sharp edge with Fixed end boundary cause this.
The best way to deal with this, is exclude that singular point from calculation or making Fillet.
Hi.
1. When you apply finer meshing to your domain, it will create more fine elements. Element size will become smaller as compared to coarse meshing elements. And total number elements in the domain will increase. So, when you will solve this with appropriate BC's and IC's, the solver will solve the governing equations for each element. You will get more accurate results at each node, which will also change your final solution. Therefore, in numerical analysis, it is advisable to perform a grid independence test. Grid independence test will enable us to know whether the size of the element is changing the solution results or not.
2. Without looking at your problem it is difficult to suggest BC's. What kind of analysis you are doing? Structural or thermal?
Sellami Khouloud its a 2 D rectangular plate .I tried more fine mesh at the point where the weld torch is applied and coarse mesh towards the end of plate
Subhabrata Mishra Its a coupled temperature-displacement analysis.I have done mesh convergence study.But I am not achieving the required results.The problem will solve with more constraints and I will get the results.But when we compare with the practical welding boundary condition the BC's I am applying seems to be over constrained.
Dear Anoop Pillai,
Selecting the appropriate element and creating an optimal network of elements has the greatest impact on the accuracy of finite element analysis and the convergence of its results. Improper element selection and large element size lead to high errors in the numerical model and in contrast to the high mesh density increase the analysis time, accumulation of rounding error and ultimately induces stiffness in the structure. Various methods and algorithms have been proposed to create an optimal mesh in the finite element method.
I suggest you make sure that the results are independent of the mesh size with the convergence test.
For Better Idea Read this
https://abaqus-docs.mit.edu/2017/English/SIMACAEGSARefMap/simagsa-c-ctmmeshconverg.htm
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