RIKS法：A ZERO DISPLACEMENT SOLUTION WAS FOUND IN THE FIRST

zjd819

对于大变形，我想用riks求解，为什么会出现这个问题？从abaqus说的原因是我将所有的自由度进行约束了，这是指我的那个monitor结点嘛？
  
怎么才算约束呢？我把所有有关他的约束都去了也还是不行！
    INCREMENT     1 STARTS. ATTEMPT NUMBER  1
  

  ***ERROR: A ZERO DISPLACEMENT SOLUTION WAS FOUND IN THE FIRST ITERATION OF A RIKS STEP. THE ANALYSIS CANNOT PROCEED. THE MOST LIKELY CAUSE IS THAT ALL DISPLACEMENT DEGREES-OF-FREEDOM ARE CONSTRAINED TO BE ZERO.

yogayoga

First of all, I do not think you really need RIKS method. Risk method is designed for unstable problem like snap and buckling. In those cases, you can have softening and even negative displacement increments (negative is in the sense it is opposite to the boundary condition you applied.) This will cause problem no matter what kind of control you are using.  Rike just use arc length in force and displacement space in a broad sense. So zero displacemnet just mean your arch length increments only come from stress.
  
Back to your problem, most large deformation problem do not require RIKS method, which actually cause trouble if it's not nessessary. As I said, make sure your problem physically have a unstable nature before you want to use it.

wydyyh

材料考虑软化，我的计算过程也出现同样的问题

wydyyh

这是zsq-w斑竹发给我的：[url]http://www.simwe.com
还是不很懂

shineee

材料考虑软化什么意思？该怎么做呢？
我用riks出现以下错误：A zero displacement solution was found in the first iteration of a riks step. The analysis cannot proceed. The most likely cause is that all displacement degrees-of-freedom are constrained to be zero.
可是我的边界条件没有限制所有自由度呀？奇怪～～

fuboxiao

不明白，搭车问一下

shicongcsy

shineee 发表于 2009-6-3 11:32
材料考虑软化什么意思？该怎么做呢？
我用riks出现以下错误：A zero displacement solution was found in t ...

问题解决了吗  我今天也碰到一样的问题了

yrhzjh

有人出来解决这个问题没有，我也碰到了

yrhzjh

找出解决的问题，荷载没有施加如果，检查施加的荷载

only73

同样遇到了，关于riks的问题，我总是步长到某一时刻increment突然开始变小，也就是buckling刚粗线的时候，看了好几天论坛，有很多搂主遇到这种问题，但是请问如何解决呢？

yang930619

求问出现解决方法了吗

superturkey

yogayoga 发表于 2004-10-11 07:36
First of all, I do not think you really need RIKS method. Risk method is designed for unstable probl ...

具体解决问题怎么操作

zhangda

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