请问出现负特征值和单元过度扭曲怎么解决

whua8

请问出现负特征值和单元过度扭曲怎么解决? 请大侠指教
The system matrix has 22 negative eigenvalues.

Excessive distortion at a total of 1857 integration points in solid (continuum) elements

Excessive distortion at a total of 22263 integration points in solid (continuum) elements

Excessive distortion at a total of 5314 integration points in solid (continuum) elements

The strain increment has exceeded fifty times the strain to cause first yield at 4 points

likuiming

可能是计算不收敛。尤其是进行非线性分析时，由于本构关系不恰当更会如此。

[ 本帖最后由 likuiming 于 2006-9-4 11:46 编辑 ]

bb20040291

你应该看看你材料本构 单元出现了大变形 导致不收敛 或者是结构中各种材料应力应变关系相差过大

whua8

我模型中的材料弹性模量和泊松比都是实际值, 请问这个时候还出现上述过度扭曲和负特征值 怎么办啊.请兄弟帮忙啊

***WARNING: THE SYSTEM MATRIX HAS 70 NEGATIVE EIGENVALUES.
   ELEMENT PART-1-1.65 IS DISTORTING EXCESSIVELY.
   ELEMENT PART-1-1.111 IS DISTORTING EXCESSIVELY.
   ELEMENT PART-1-1.168 IS DISTORTING EXCESSIVELY.
   ELEMENT PART-1-1.169 IS DISTORTING EXCESSIVELY.
   ELEMENT PART-1-1.170 IS DISTORTING EXCESSIVELY.
   ELEMENT PART-1-1.181 IS DISTORTING EXCESSIVELY.
   ELEMENT PART-2-1.2 IS DISTORTING EXCESSIVELY.
   ELEMENT PART-2-1.3 IS DISTORTING EXCESSIVELY.
   ELEMENT PART-2-1.4 IS DISTORTING EXCESSIVELY.
   ELEMENT PART-2-1.7 IS DISTORTING EXCESSIVELY.
   ELEMENT PART-2-1.8 IS DISTORTING EXCESSIVELY.

likuiming

请上传模型。

hehewo

<<求助>>
    请问:TIE约束中定义的SLAVE SURFACE 上的节点还可以定义边界约束吗?
    还有就是,在CAE中建模型定义约束的时候,选择的是几何区域,施加了边界条件以后,导入INP文件中的边界条件怎么是施加在了单元和节点上NODE+ELEMENT,而不只是节点上呢.

likuiming

原帖由 hehewo 于 2006-9-11 20:25 发表
<<求助>>
    请问:TIE约束中定义的SLAVE SURFACE 上的节点还可以定义边界约束吗?
    还有就是,在CAE中建模型定义约束的时候,选择的是几何区域,施加了边界条件以后,导入INP文件中的边界条件怎么是 ...

第一个问题没做过，你可以试试就知道了。这样的面一般情况不需要再加约束了。
第二个问题属于正常情况。如果你一定要加到节点上，可以在inp文件中编辑一下即可。
另外有问题请单独发帖，不要这样跟帖。

[ 本帖最后由 likuiming 于 2006-9-12 09:53 编辑 ]

whua8

The system matrix has 2 negative eigenvalues.

The system matrix has 87 negative eigenvalues.

Excessive distortion at a total of 125 integration points in solid (continuum) elements

The system matrix has 2 negative eigenvalues.

The system matrix has 87 negative eigenvalues.

Excessive distortion at a total of 124 integration points in solid (continuum) elements

The system matrix has 2 negative eigenvalues.

The system matrix has 87 negative eigenvalues.

Excessive distortion at a total of 122 integration points in solid (continuum) elements

The system matrix has 2 negative eigenvalues.

The system matrix has 87 negative eigenvalues.

Excessive distortion at a total of 124 integration points in solid (continuum) elements

The system matrix has 2 negative eigenvalues.

The system matrix has 87 negative eigenvalues.

Excessive distortion at a total of 130 integration points in solid (continuum) elements
兄弟 我的计算 又出现问题？   计算不下去   能否帮帮忙兄弟

likuiming

whua8  这是不收敛的典型报错，请上传你的模型。否则没法进一步讨论。

hanqinhu

正如上面那位仁兄所说，这个错误是不收敛的典型出错信息，造成不收敛的问题很多，不上船模型，如何讨论呢？

t_y2004

[quote]原帖由 hehewo 于 2006-9-11 20:25 发表
<<求助>>
    请问:TIE约束中定义的SLAVE SURFACE 上的节点还可以定义边界约束吗?
  

可能不行，至少在standard中是不行的。如下所述：The surface-based tie constraint is imposed in ABAQUS/Standard by eliminating the degrees of freedom on the slave surface; therefore, nodes on the slave surface should not be used to apply boundary conditions。