Error during anisotropic

[khush8319]

Hi,
I am trying to calculate stresses and strains in the thin film deposited on substrate by ABAQUS.

I am getting this error message when I am using anisotropic in place of isotropic in materials properties:

"Stiffness matrix defined by type=anisotropic is singular. Check the anisotropic stiffness matrix"

Can anyone tell me what is this means and how can I remove this error?

Thanks in advance

Waiting for reply

 

[InvariantL]

Singular means that in at least one direction, there is no resistance to force and the displacement solution "blows up".

I assume you entered some nonzero stiffness values in the matrix for the thin film. If the film is much different in stiffness than the substrate or other materials in the model (several orders of magnitude) Abaqus can view this as "near-singular" and terminate the analysis because it may lead to roundoff error.

Another possibility is that your thin film might not be adequately attached to the substrate, but I think if that were the case, you would get a different error from the one you're reporting.

If those suggestions don't help, use Matlab or hand calculation to calculate the determinant of the stiffness matrix you entered. If it's zero or very small, there is probably an error in the matrix.

http://www.invariantlabs.com

 

[khush8319]

Thanks for the reply

Could you please tell me where is the option in ABAQUS to assign stiffness values to the model?

Also I am making a shell and partitioning into substrate and coating & after that assigning different material properties. Is it right way?

because I don't know how to join two shells in ABAQUS as I have recently started working with ABAQUS.

Thanks in advance

waiting for the reply

 

[InvariantL]

Based on your description I'm guessing that CAE is generating a *SHELL GENERAL SECTION, COMPOSITE card to define the properties. Look at that line(s) in your input file to make sure a material with a reasonable stiffness is being assigned to each layer.

http://www.invariantlabs.com