Learning Forum

[Gijoys4v]

when large deflection off, it is able to converge a solution by the solver.

but when I made it on, it shows an error message that 

The solver engine was unable to converge on a solution for the nonlinear problem as constrained.  Please see the Troubleshooting section of the Help System for more information.

what might be the reason?

[peteroznewman]

With large deflection off, the stiffness matrix is inverted and multiplied by the force vector to compute the displacements. This is called a linear solution. As long as the stiffness matrix is not singular, you get a result. If deflections are small, the result will be accurate. If they are large, the result will have a significant error from the nonlinear solution.

With large deflection on, convergence criteria are used to decide if the solution is in equilibrium. If it is not, the solver updates the stiffness matrix and tries again, which is called iteration. This is called a nonlinear solution. If a large load is applied all at once, the solver will fail to satisfy the convergence criteria and give up iterating. If the large load is divided into small increments, the solver will successfully iterate to convergence on the first increment, then add the next increment, iterate and converge and so on until the full load is applied.

[Gijoys4v]

thanks a lot

[Gijoys4v]

one more doubt regarding this. 

For this whether we have to increase the substeps or increase the number of steps in which load is applying?

[Gijoys4v]

I tried both ways: means I tried increasing the substep and also I increased the no: of steps and at each step the required load is applied in steps. but still getting the error message

[Gijoys4v]

 As this is a nonlinear problem I increased the no: of elements by refining the mesh, but then this message appeared

 

The number of ERROR and WARNING messages exceeds 10000.                
  Use the /NERR command to increase the number of messages.             
  The ANSYS run is terminated by this error.