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Dear all,

      I want to model crack initiation and propagation for a user defined material, using Abaqus. When I try to model , I get the following error:

A MATERIAL PROPERTY THAT IS NOT ALLOWED WITH A USER MATERIAL HAS BEEN SPECIFIED

when I take out critical damage initiation, the model works fine; which means that it doesnt allow me to couple UMAT with crack initiation. Does anyone know how to handle this problem?

All the best,

         Panos

HI,
I am performing a non linear buckling analysis in ansys using shell 181 element. My geometry is made up of composite material and has a shell structure. The shell is subjected to torsion at one end so as to buckle throughout it length. the other end is fully constraint.
My problem is how to apply this torsional moment at the free end.
anybody please help me.

I was going through these papers:

1.P.K. Sarkar and S.K. Maiti, 'Prediction of mode-1 fracture toughness of unidirectional fibre composites with arbitrary crack fibre orientation from its lowest or matrix fracture toughness'. int. J. Fracture, vol. 40. pp. R91-R96, (1989).

2.S.K. Maiti and P.K. Sarkar, 'A method of calculation of total strain energy release rate and its layer-wise distribution for an arbitrary through the thickness crack extension in a composite laminate', Engg. Fracture Mechanics, vol. 36, pp. 639-646,(1990).

I am currently having difficulty modelling fatigue analysis on a wheelchair frame with hollow circular sections (pipe 16). When assigning the stress locations it says that the stress is not available for that node. 

Any help would be appreciated!