non-linear material specification

Hengre

Hello all,

Is there a way to enter a technical stress-strain curve in Mecway to describe a non-linear material behavior.

I thought that would work?

Thanks in advance

Victor

You can enter a piecewise stress-strain curve in CCX -> custom model definition. See the manual section 13.1 Custom model definition for an example using 3 points.

Hengre

Thank you for your answer.
Are there any plans to integrate that oportunity in the Material Properties --> Plastic card
as new Point:
Strain-Strss-curve

Hengre

I tried your suggestion, but didn't get the expected results :-(

If I follow your suggestion the inp. file contains the following, but it seems nonlinear material is not taken...

...

*MATERIAL,NAME=Alu
*ELASTIC,TYPE=ISOTROPIC
70000000000,0.3
*DENSITY
2750
*MATERIAL,NAME=Stahl
*ELASTIC,TYPE=ISOTROPIC
210000000000,0.3
*DENSITY
7850
*MATERIAL,NAME=Kupfer
*ELASTIC,TYPE=ISOTROPIC
125000000000,0.3
*MATERIAL,NAME=Rotguss
*ELASTIC,TYPE=ISOTROPIC
95000000000,0.3
*DENSITY
8700
*MATERIAL,NAME=Bronze
*ELASTIC,TYPE=ISOTROPIC
111000000000,0.3
*DENSITY
8730
*MATERIAL,NAME=Messing
*ELASTIC,TYPE=ISOTROPIC
90000000000,0.3
*DENSITY
8500
*SOLID SECTION,ELSET=innen,MATERIAL=Rotguss
*SOLID SECTION,ELSET=aussen,MATERIAL=Stahl
...

other stuff
...

*AMPLITUDE,NAME=Aconstant
0,1
*MATERIAL,NAME=Stahl
*ELASTIC
210000000000,0.3
*PLASTIC
350e6,0
400e6,0.01
410e6,0.1
*DENSITY
7850
*MATERIAL,NAME=Kupfer
*ELASTIC
125000000000,0.3
*MATERIAL,NAME=Rotguss
*ELASTIC,TYPE=ISOTROPIC
95000000000,0.3
*PLASTIC
250e6,0
300e6,0.01
310e6,0.1
*DENSITY
8700
*STEP,NLGEOM=YES,INC=100
*STATIC

Victor

It looks like you already have materials named Stahl and Rotguss which are conflicting with the new ones. Use different names and remove any Mecway-defined materials from the components that are getting the new plastic material.

Don't forget to enter the *SOLID SECTION cards too since Mecway will no longer generate them with no materials on the components.

Yes, I hope to add this to the UI soon to make it easier.

gemada

Hi Victor. That would be great. I've been away for a while...can you tell when this feature will be available?

Hengre

Hi Victor, I would also apreciate that feature very much and i guess many other's, too

Victor

The next version (14) will have a stress-strain curve.

Could you two, and anyone else here, tell me if you prefer the strain input to be plastic strain (0 at yield) like CCX does or total strain (yield strain at yield)?

mmartin

I vote for “ total strain. “

Hengre

I am not really sure. I am a bit closer to CCX, why I prefere more for CCX definition

gemada

Thank you Victor. I'd prefer total strain!

Sergio

I prefer to be plastic strain only to keep in line with CalculiX documentation

MikeMcMullen

Thank you as well! I would like total strain as well, especially with the recent speedups. Having a linear part to speed up calculations as well as a non-linear part does not seem as important with the speeding up of the computers, solvers, Mecway and Calculix in recent times. Probably more speed up on the way due to larger memory on GPU cards and faster Pcie busses and different (more adaptive) software models. Can't even go get a cup of coffee while waiting for a solution with Mecway and Calculix. Also most of the materials I use are not precisely linear at all (carbon fiber is close), just defined that way by code to simplify calculations.

gemada

Hi. Could we get both?

Hengre

make it selectable :-)