Hi,

I am reading the book on-Non linear finite element analysis by M.A.Crisfield-as some of you know(as I've posted questions earlier too),it's more of a self study that I am doing-I have got some fundamental questions in chapter 3-the topic on:

Section 3.3 A Truss element based on Green's strain.

Basically the author has divided into 3 sections wherein we have:

Section 3.3.1 Geometry and stress strain relationships

Section 3.3.2 Equilibrium and internal force vector

Section 3.3.3 The tangent stiffness matrix

Dear All,



Could you suggest any literature or online step by step tutorial on how to create your own subroutines in ABAQUS like umeshmotion or umat. Any relevant information would be much appreciated. I am looking for information that are not covered in the ABAQUS manual.

Thanks very much in advace,



Nicholas

Consider attached file.It lists the details of the Timoshinko method for geometric non linear analysis.

Can anyone tell me how is it diiferent from incremental analysis conceptually?

Is it used commercially?Which method is more sophisticated-Timoshinko,incremental or Newton Raphson?

Please help

I am trying to use finite element modeling of indentation experiments
to extract hyperelastic material parameters. I am having a dilemma,
when the tissue has residual strain, the model couldn't achieve the
high nonlinear relationship between displacement vs reaction force as
measured in the experiments.



I have tried several strain energy potentials,

1) W=A/B*{exp[B(I1-3)]-1}

2) W=C10(I1-3)+C01(I2-3) 

3) W=C10(I1-3)+C20(I1-3)^2+C30(I1-3)^3

4) Arruda-Boyce type model