Metal forming

I think spring back prediction by using implicit is not realistic. What is your opinion regarding the convergence issue?

Implicit spring back analysis is better if converged solution can be obtained. However, over the past two years, I have done over sixty forming simulations, and I only got two converged solutions for spring back simulation. So I think spring back prediction by using implicit is not realistic. What is your opinion regarding the convergence issue?

I tried to use LSPOST to compare the strain state with FLD. When I selected the element and clicked the plot button, nothing was plotted. What was the problem?

If a converged solution from springback prediction cannot be obtained after trying many different combinations of parameters, what else can I do?

If I didn’t find wrinkling and strain localization in from my simulation, can I say that my design is good?

If I use very coarse mesh for the pre-deformation (such as pre-bending, gravity loading etc), and then refine the mesh in the later forming analysis. Will it result in obvious numerical error for the final results?

If localized necking occurs what can I do to get rid of it?

If wrinkling occurs, what can I do to get rid of it?

In implicit analysis of springback process, there are both linear and non-linear methods. Can you advise which one is better?

In implicit forming analysis, I found that the friction force was not properly applied, what could have been the problem?

In LS-DYNA, there are different material models and I’ve found it difficult to choose the proper material model. Would you please give me some suggestions in selecting the proper material model?

In my analysis of the sheet metal forming process, I frequently found that the calculation could not continue and it terminated unexpectedly. Is there a way to avoid this?

In my simulation, some of the corner nodes can be put in the wrong place. Can you advise what the problem is?

In springback analysis I don't have enough memory or the analysis takes too much time. What can I do ?

In springback analysis I’ve found I have two problems: 1) When I use the implicit method I don’t have enough memory and can’t continue the calculation; and 2) At other times springback analysis takes too much time. Are there any methods available to solve these problem?

In springback analysis, I found that my constraint hasn’t been taken into account during the simulation, what was the problem?

In springback analysis, I just changed the constrained nodes a little bit away from the original node. The convergence then became very different and the predicted result seems not to be reasonable. What can be the problem?

In springback analysis, we had no problem when gravity effect is not considered. However, after gravity effect is included in the input deck, there were some strange error messages. What might be the cause?

Is it possible to allow separation/gap between elements within one part?

Is it possible to coarsen a uniformly refined mesh, as well as an adaptively generated mesh?

Is it possible to do forming simulation by using both implicit and explicit method in the same run?

Is the order relevant in which I do triming and coarsening of the mesh?

When I do springback analysis after trimming, I need to coarsen the mesh to decrease the memory requirement and increase the computation speed. We can trim the mesh first and then do coarsen the mesh; we also can coarsen the mesh first, and trim the mesh later. Is there any difference between the above two methods?

Is there a way to prevent distortion?

When the constraint contact is used, the mesh is distorted in the forming analysis. Is there a way to prevent this distortion?

Is there a way to reduce the penetration problem?

When I do a forming analysis there is large penetration of the blank into the rigid tools. Is there a way to reduce the penetration problem?

Is there any limitation for LSDYNA3D to be applied to Metal-Forming analysis?

I’ve found that when I use several CPUs with the SMP code that only one CPU is working and the other CPUs are idle. What is the problem and how can it be corrected?

No matter how I’ve tried, I can’t trim the elements with the IGES line data. Is there any alternative to do trimming?

There are several linear solvers for implicit analysis. Can you tell me which one is the fastest and most accurate?

There are several non-linear solvers for implicit analysis - which one is better?

There is no load applied to the blank when I used *LOAD_MASK. What might be the problem?

When I used *LOAD_MASK for hydro-forming analysis, first I have no problem in applying the load, but the load is in the wrong direction. I used negative value for the load curve to reverse the load direction. However, there was no load applied to the blank anymore. What might be the problem?

What are the differences between smooth and non-smooth trimming?

There are two methods in trimming, i.e. smooth and non-smooth trimming. In smooth trimming, the boundary element will be cut exactly along the trimming curve; while in non-smooth trimming, the boundary element can be either kept or removed from the model and it will not be cut in half. What is the advantage of each method?

What can I do if the direction of the pressure is not reasonable after the mesh had been refined adaptively?

When I used adaptive mesh in hydro forming simulation, there was no problem in the initial stage. However, I found that the direction of the pressure wasn’t reasonable after the mesh had been refined adaptively. What was the problem and how can it be fixed?