Hi everyone,

    I am not a student majoring in the mechanics. But I have found that: the element eroding method is so powerful in numerical simulation (i.e. using ls-dyna) if we reduce the mesh size, then we can get a very perfect fracture process of material. So why we need fracutre mechanics?

In my opioion, the traditional concrete model is taking the smeared cracking concept to deal with the tensile cracking and using the elastoplastic method to deal with the compressive softening.

We can find that recently the CDM based concrete model become a hot research subject.

But what are the advantages of the CDM-based?

Thank you very much!

Hi all, 

I find that the umat in Abaqus doesn,t support the stiffness damping. How can I introduce the stiffness damping into my subroutine?

Thank you very much!

    This days, I am working on the dynamics analysis using the Abaqus. the implicit dynamic integration method in abaqus is HHT-alpha. I found that a very strange parameter about the method is the half-step residual tolerance . I don't know the parameter is whether important or not and how to determine it.

thank you very much :)

I am confused about apply BC of a model in abaqus. because I find that if I apply the accelaration of earthquake on BC, I must remove the fixed constraints applied on BC in previous step in abaqus. so the model become a free body without any constraints.

 any expert can give me some detailed suggestions?thank you very much!^_^