mixed element for anisotropic hyperelastic material at finite strain

[zha]

Hello,

I am working with a generally anisotropic hyperelastic material.  With the ''disp'' element formulation, I have run into some convergence errors.  I then read from Chapter 7. , Mixed Finite Element Methods, to learn that the ''mixed'' formulation is also available for anisotropic linear elastic or inelastic materials.  I tested it just by switching the keyword from 'disp' to 'mixed'.  The stress results became wrong.  Could there be examples that demonstrate the application of the mixed method on anisotropic materials to help me better understand?

I have typed in the example, Plasticity Problem, from Chapter 9 of the FEAP problem manual.  I have been getting a ''log (SING) error''.  Please see the attached file.     

Thanks,

Zhang

[Prof. R.L. Taylor]

Zhang,

Before you run any solution you need to make sure the mesh is correct.   Never run a batch job before you check that the problem is correctly defined.  This means plotting the mesh, boundary conditions, etc. to make sure you have what you want.

Your input file has an error -- no END of mesh!