【求助】柔性体仿真出错的原因

xiaotiger

我在做门式起重机的刚性四连杆机构仿真,我想大家都见过吧.在ANSYS里对小拉杆建模，共有三个外部结点（一端与臂架连接，另一端两头分别与平衡梁两头连接,这里是否会引进虚约束？）导入ADAMS，连接仿真，出错结果如下：
   
   ERROR:      The simulation is terminating at time = 0.0.
  
   ADAMS can not solve the equations of motion because the mechanism has
   "locked up."    At least one constraint  can  no longer be satisfied.
   ADAMS is unable to satisfy the constraint for: JOINT  MODEL_2.JOINT_23 .
ERROR:      Symbolic refactorization failed.  The matrix is structurally singular
   at time = 0.0.
WARNING:    On iteration 1, the Jacobian matrix for the initial values of
   the displacements (for the assembly analysis) is singular, a condition
   usually caused by over specification of EXACT coordinates.  Since
   ADAMS/Solver employs a penalty-function method to assemble the mechanism,
   the approach becomes less effective as more and more EXACT initial
   conditions are specified.  If the user labels too many initial values
   as EXACT, the Jacobian matrix can become ill-conditioned or even
   singular.  Although the analysis will continue, the simulation could
   fail or produce inaccurate results due to inconsistent initial conditions.
  
里面的“MODEL_2.JOINT_23”为小拉杆与平衡梁上两个施转副中的一个？
我百思不得其解，因为我用刚体做结果很好没有这样的错误为什么改用柔性体后会有这样的错误，是柔性体导入的问题吗？是虚约束的问题吗？但用刚体这样联接没有问题？
  
  请教各位大侠及斑主！！！！急盼回复

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