Computational Mechanics Forum

In Dr. Ted Belytschko's book, Nonlinear Finite Elements for continua and Structures, he uses two formulations to describe the Lagrangian mesh, i.e., Total Lagrangian formulation(TL) and Updated Lagrangian formulation(UL). For TL formulation, he derives the weak form using the principle of virtual work, which will result in a finite element formulation whose unknowns are displacement. For UL formulation, he gets the weak form using the principle of virtual power, which leads to a finite element formulation whose unkowns are velocity.

My question is:

Hi,

I am currently working on a FEM  2d plane strain elastic model in matlab. The next step would be to use a non linear constiutive law (Mohr-Coulomb). As far as I have been reading non linearities, are solved with iteration schemes. My question is how to compute the tangent matrix with the N.Raphson method? I have seen only case for polynomials, but not for matrices.

Regards!

Anna

<p>What is static riks solver?? Please explain in details.. As I am a learner of abaqus I get problem understanding some things, like arc length, &nbsp;increment in static riks etc.. I find that it is very useful for simulating collaps behaiour.. I wish to do a thrust experiment regarding geological setup... Please help and guide me..&nbsp;</p>
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<p>Thank you&nbsp;</p>

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Hello everybody,

 UPDATE :   Question can be deemed as closed.. :)

                       I have a very simple doubt in 3D model simplification. I believe plane stress and plane strain conditions are the two extreme states to simplify a 3D model to 2D case.

Hello, 
I have to model finite number of springs with point masses on a soil layer in Abaqus representing resonators. I tried to use Reference Points on the soil layer and some Reference point above the layer and connect them with Spring/Dashpots using connecting two nodes option, I chose Line of action for the spring, then I add stiffness. In the next step I applied Point mass as inertia to the reference points above the soil. 

Hi everyone, 

I am doing airplane impact problem. In my simulation, I need to have an airplane and a wall. The material of the wall is concrete. I utilized the LS-DYNA concrete damage
model (keyword *MAT_CONCRETE_DAMAGE) to describe the wall and also added *DEFINE_CURVE for tabulated strain/pressure data. I kept getting error messages:

*** Error 20450 (STR+450)
Material model 72 (CONCRETE_DAMAGE)
Only eos 8, eos 9 and eos 11 are valid

*** Error 20018 (STR+18)
input phase completed with 1 fatal errors
please check messag file

Dear friends

I'm modelling a large penetration of a strip footing in clay soil. I'm using a Python script (Abaqus 6.13) for this.

Hello everyone,

A quick question: how to report a unique nodal RF(Reaction Force)/U(Displacement) in a different coordiante system in ABAQUS? It seems it always output in the default coordinate system that ABAQUS is set based on.