huazi071783 发表于 2009-5-31 22:35

怎么设置铰支

我在做一个梁的模态试验,要设置梁为两端铰支,请问怎么设置?

16443 发表于 2009-6-1 08:57

作实验还是软件算?

huazi071783 发表于 2009-6-1 09:41

回复 沙发 16443 的帖子

就是用软件模拟

zhouxman 发表于 2009-6-1 15:00

可以设置 节点自由度耦合来模拟这样的情况
比如说,看、耦合x y 方向自由度,保留RZ
不知道说的对不对,以前在那里看到过的

16443 发表于 2009-6-1 16:48

还可以使用mpc单元

zhouxman 发表于 2009-6-16 08:48

mpc单元是是嘛单元?
简要介绍一下可以么? 谢谢

16443 发表于 2009-6-16 14:16

原帖由 zhouxman 于 2009-6-16 08:48 发表 http://www.chinavib.com/forum/images/common/back.gif
mpc单元  是是嘛单元?
简要介绍一下可以么? 谢谢
自己学help去吧。:lol

huazi071783 发表于 2009-6-16 21:55

谢谢各位了

zhouxman 发表于 2009-6-17 10:24

yooo大哥
你所说一句胜读我们张金才十年书哦呵
还是谢谢

zhouxman 发表于 2009-6-17 10:38

MPC184 Element Description
MPC184 comprises a general class of multipoint constraint elements that implement kinematic constraints. The elements are loosely classified here as “constraint elements” and “joint elements.” You can use these elements in situations that require some type of kinematic constraint to be imposed. The constraint may be as simple as that of identical displacements at a joint. Constraints can also be more complicated, such as those involving modeling of rigid parts, or kinematic constraints that transmit motion between flexible bodies in a particular way. The type of constraint used depends on the desired application. For example, a structure may consist of some rigid parts and some moving parts connected together by some rotational or sliding connections. The rigid part of the structure may be modeled using the MPC184 Link/Beam elements, while the moving parts may be connected with the MPC184 slider, spherical, revolute, slot, or universal joint element.

The kinematic constraints are imposed using one of the following two methods:

The direct elimination method, wherein the kinematic constraints are imposed by internally generated MPC (multipoint constraint) equations. The degrees of freedom of a dependent node in the MPC equations are eliminated in favor of an independent node.

The direct elimination method should be used whenever it is available since the degrees of freedom at the dependent nodes are eliminated, thereby reducing the problem size and solution time.

Since the dependent degrees of freedom are eliminated, the constraint forces and moments are not available from the element output table (ETABLE) for output purposes. However, the global constraint reaction forces are available at independent nodes in the results file, Jobname.rst (PRRSOL command, etc.).

The Lagrange multiplier method, wherein the kinematic constraints are imposed using Lagrange multipliers. In this case, all the participating degrees of freedom are retained.

The Lagrange multiplier method should be used when the direct elimination method is not available or not suitable for the analysis purposes.

In this method, the constraint forces and moments are available from the element output table (ETABLE).

The disadvantage of the Lagrange multiplier method is that the Lagrange multipliers are additional solution variables and, hence, the problem size and solution time become larger when compared with the direct elimination method.

Currently, the rigid beam/link MPC184 elements can use the direct elimination method or the Lagrange multiplier method. All other MPC184 element options use the Lagrange multiplier method only.

Constraint Elements
The following types of constraint elements are available:link/beam
slider
spherical


Link/Beam
Figure 184.1MPC184 Geometry

zhuweihong2004 发表于 2009-6-18 11:30

回复 地板 zhouxman 的帖子

这个在msc里面是这么设置的,在ansys中可以这么设置么
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