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I try to program the GTN model in a UMAT with isotropic hardening and anisotropic Hill yield criterion. I just want to know if someone has an example of UMAT dealing with the original GTN model (Von Mises criterion). This example would help me a lot in order to compare my code and perhaps to find my mistakes. 

Hi Guys,



I am facing the following error in the execution of a job in ABAQUS: 

'Error in job ModalTest_2: 27 elements have missing property definitions. The elements have been identified in element set ErrElemMissingSection.

Error in job ModalTest_2: SECTION DEFINITIONS ARE MISSING OR INCORRECT FOR THE ELEMENTS INDICATED ABOVE. FURTHER PROCESSING OF THE INPUT FILE IS NOT POSSIBLE UNTIL THIS INPUT ERROR IS FIXED.'

Recently,I made a model of two parts

1. a circle pad (deformed)

2.a discrete rigid line (move upwords)

the problem is I want to get the reaction force in the rigid surface,but I can not.

 I must get it from the pad because I must make the rigid part more well meshed,I want to get better data.

Could you tell me how to get data in rigid part when contact occur?

Thanks a lot.

Nowadays, we are talking about multiscale simulation. I am surprising that we discussed about multiscale modeling while units are still exist. In my point of view, the multiscale only be achieved if units in general equations were treated.

When use matlab or mathematica integrate this y = int(cos(m*pi*x/a)*cos(n*pi*x/a)/(x+a0)^2,x,0,a); (m,n=0,1,2,3,4,5...)

There is some explicit integral. I try to solve this problem. But the result is complex.

Is there some effective way to solve this problem.  

Thanks! 

The advance of mechanics towards the frontiers of biology and soft matter necessitates an understanding of entropic forces which manifest themselves as thermal fluctuations at length scales of a micron and below. The effects of these fluctuations can be easily seen in biofilaments at thermodynamic equilibrium under the action of forces and moments as they fluctuate around their minimum energy configuration due to Brownian motion. This remains true of filaments in networks and gels such as those of actin, spectrin, fibrin or other biopolymers.

I'm trying to implement a superplastic material constitutive equation by UMAT subroutine but don't know how i use subrouties specially UMAT.

Pls help me out or introduce me to some refrences.

pls don't tell me to go to Abaqus User manual :-)

Thanks guys,

Regards

M.Hedayati

Hello Sir's,