Dynaform 难题

我想和大家探讨DYNAFORM里的一个问题.在使用DYNAFORM进行模拟时,我发现最后成型的壁厚大于模具的间隙
(DIE和PUNCH).比如,圆柱形PUNCH的直径为0.5mm,DIE内径为0.8mm,(在PROE里分别生成,没有用DYNAFORM教材里的OFFSET方法),PUNCH将BLANK完全PUSH到DIE里面, 那么,最大的壁厚事实上一定小于(0.8-0.5)/2=0.15mm.但是最后模拟结果部分地方大于0.15mm,尤其是上面部分. 请各位高手指教.万分感谢!!

:L0.15mm

   老兄! 你那是不是太厚了!!???  能说说你的板料的厚度吗?? 还有上下模的间隙是多汪??

Thanks. Actually not. The simulation I am now doing is a real project according to the production process. The
clearance between the die and punch for each side is 0.254mm, and the original blank thickness is 0.211mm. So, in
reality, the thickness of the final can should be smaller or less than 0.254 mm. I have discussed this issue with some of
the guys in working in LSTC, which is the company developed LS-DYNA, the solver of Dyanform, they still can not
provide good and clear answer.

兄弟 看来我见识太少了 敬候你的分析结果  其实看过你的贴子过后我也试了试，不过不是你那样做的，是想通过在dynaform 里生成的冲模凹模的曲面，导出到ＰＲＯ／Ｅ里做成模具，但是现在还没有成功，先在
ＳimWe里问了一下，但是现在还没有得出那间隙能否生成，精确度有多高？还在试验啊　

Hi, there,
I think creating the surface with curvature of the die and punch in Dynaform is more difficult than
doing it in CAD software, e.g. ProE, but should be successful. There are lot of questions in the
solver of Dynaform ---- LS-DYNA. Maybe I am wrong. I was trying to give different scale factor
(SLSFAC), normaly it is between 0.01 to 0.1 (default value) in "Control Parameters" of Dynaform,
such as 0.2, 0.1, 0.5, and the reason that I gave the bigger value than 0.1 came up from the
LS-DYNA Theory Manual that increasing the scale factor in penalty method could reduce the
penetration possibility when the pressure is too high between contact surfaces (slave and master), while I got relatively smaller difference between results of thickness. But with 0.2, it seems that
the bigger thickness of the final can is only 0.257795 mm, which is a little bit bigger than the
clearance 0.254mm.
I am going to have a Dynaform training next month and hopefully they could answer me the
question. And then I will put it on.

我查了查Ls-DYNA的帮助手册，我想想要解决你的问题是Dyna的接触定义问题，　我看了一下资料介绍有四十多种接触，看资料显示应该是出现了渗透，让单元滑动到了接触厚度中去了，要修改分析的参数的关键字扩充接触面

没用过

Hi, dmdongmin, thanks a lot for your suggestion. In the beginning, I thought it should be the problem of contact since there could only be the contact surface penetration that can lead to big thickness with big minor or major strain. So, I tried to use several different contact type including "FORMING_ONE_WAY_SURFACE_TO_SURFACE", "FORMING_SURFACE_TO_SURFACE", "ONE_WAY_SURFACE_TO_SURFACE" and "SURFACE_TO_SURFACE", but they seems not working. Since I am now
working alone on this project and got nobody to discuss with, I really don't know how to do next. According to your advice
"要修改分析的参数的关键字扩充接触面", could you please explain a  little more or give me some example keywords?
Thanks a lot!

我看了一下是在K文件里的*Contact中的SST和MST两个参数可以控制，但是我也没有用过，试试吧！显示说当壳单元的厚度小于1Mm时就要增加它们的接触厚度，现在正在学习研究中