Pivot Element Error 1

[engg35mechie]

Hello Group,

I am trying to simulate simple bending of a hat-stiffened panel. I calculated A, B, D matrices with Equvivalent formulation as in Colliers Papers and used 3 MAT2 cards to define them. In P-shell element for equivalent formulation i referred the corresponding bending, coupling and Membrane Matrices to this three MAT2 cards and left shear as blank.

by Fix supporting the edges of plate and applying load in middle , I get Excessive Pivot Ratios , the reason being all element show negative matrix diagonal.

whats could be possible error?do i need to give shear values in PSHELL card?..I tried to use PARAM Bailout -1 but that is also not working.

thanks and regards

 

[engg35mechie]

Update:

I tried for isotropic material and i could solve by staic subcase but it fails for equivalent panel

 

[engg35mechie]

and isotropic case

 

[olduser]

Hi there,

The system is unconstrained. I added constraints at x = 0. and used isotropic materials. Runs fine on my modified nasa nastran.

Best

 

[engg35mechie]

Hello olduser,

Can you suggest why I get such hight pivot ratios when I used the equivalent formulation for same boundary and load conditions?

Best Regards