非线性模态分析的内容怎么在帮助里没有？
非线性模型如何求模态的那部分内容？ 在理论帮助中是有的在ADINA的Theory and Modeling Guide之Volume I: ADINA Solids & Structures中（8.3版本）的下面就有这样一段话：
If the structure is nonlinear and is preloaded, you must perform the analysis in two runs.
In the first run, you apply the preload(gravity loads, thermal loads, initial strains, etc.) in a nonlinear
static analysis. This run can contain one or more solution steps.
In the second run, you restart from the last solution of the first
run, then perform a frequency analysis. The frequency analysis is,
as stated above, performed based on the stiffness and mass matrix
corresponding to the time of solution start; in this case the time of
solution start is the time corresponding to the restart analysis.
Therefore the stiffness and mass matrices include all geometric and
material nonlinearities corresponding to the end of the nonlinear
static analysis.
[ 本帖最后由 runinwind 于 2006-8-25 09:37 编辑 ] 多谢，终于找到了 ：）
我的是8.2版，相同的内容在
Chapter 6: Eigenvalue problems
6.2 Frequency analysis
... ....
! If the structure is nonlinear and is preloaded, you must perform
the analysis in two runs. In the first run, you apply the preload
(gravity loads, thermal loads, initial strains, etc.) in a nonlinear
static analysis. This run can contain one or more solution steps.
In the second run, you restart from the last solution of the first
run, then perform a frequency analysis. The frequency analysis is,
as stated above, performed based on the stiffness and mass matrix
corresponding to the time of solution start; in this case the time of
solution start is the time corresponding to the restart analysis.
Therefore the stiffness and mass matrices include all geometric and
material nonlinearities corresponding to the end of the nonlinear
static analysis.
... ...
一直以为ADINA的非线性模态分析有独到之处 ：（
看来ADINA的非线性模态也是加了预应力的模态分析，跟ANSYS一样，ADINA可以卸载了：）
再次感谢 runinwind ！ 呵呵，
感到有点遗憾......
其实ADINA真的是一款不可多得的好有限元软件
不过，还是俗话说得好：萝卜白菜各有所爱嘛。
我们现在的科学不正是鼓励百家争鸣、百花齐放吗？
也许只有这样，我们的科学才能在探索中不断前进！
最后对wsjxaut 会员表示理解和支持！
:D:handshake
[ 本帖最后由 runinwind 于 2006-8-28 09:35 编辑 ] 下面是我做的几个关于接触问题模态分析的东西，前后处理是用ANSYS完成的，求解器是我的：
http://www.simwe.com/forum/viewthread.php?tid=740835&highlight=%B7%C7%CF%DF%D0%D4%2B%C4%A3%CC%AC
http://www.simwe.com/forum/viewthread.php?tid=737234&highlight=%BD%D3%B4%A5%2B%C4%A3%CC%AC
http://www.simwe.com/forum/viewthread.php?tid=740495&highlight=%BD%D3%B4%A5%2B%C4%A3%CC%AC 支持!
自己写求解器，好厉害啊! 这是关于MARC的接触模态分析的讨论：
http://www.simwe.com/forum/thread-215057-1-107.html 相关的讨论都放在这里了：
http://www.simwe.com/forum/viewthread.php?tid=737234&highlight=%C4%A3%CC%AC%2Bwsjxaut
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