Learning Forum

[Astro45]

Hello everyone,

I am attempting to do an impact analysis for a wood based structure in explicit dynamics. But i dont know how to model or map the orthotropic material properties of wood in ansys. I have incorporated the  young's modulus (in all three directions), shear modulus (in all three directions) and poission ratio  (in all three directions). But still errror comes up solving the explicit dynamic analysis namely as Solver initialization error . if anyone knows how to map the wood properties specially for the explicit analysis,please let me know.

Thanks in advance.

[peteroznewman]

Please insert a screen snapshot of the material definition you created in Engineering Data.

[jj77]

I tried this and you get this error when using the standard engineering data.

 

If one uses ACP on shell bodies and define the data there then it is OK - hope this helps. 

 

 

If you are doing 3D analysis (3Dsolid parts) then it might be more tricky. Then go from explicit to an autodyn system, that will let you define an equation of state (EOS) and thus material that is orthotropic (like wood). The EOS is called Ortho. Of course you might just be able to add it to your orthotropic material (equation of state), and that might work also directly in WB without going to AUTODYN//. I am not familiar with the explicit models so I do not know what equation to use. Perhaps you will find something on the Internet (e.g., ls-dyna and wood).

 

 

[Astro45]

These are the properties that i have mapped in the engineering data.

[Astro45]

i tried  sharing the setup of the expicit dynamics to the autodyn,and defined the equation of state as Ortho  but that  also yields the same error.

[jj77]

Is it a 3D analysis using 3D bodies and 3d say brick elements, or are using surface bodies and shell elements?

For shells we need to use I think ACP see here:

 

For 3D I am not really sure anymore (I never used the autodyn gui so I do not know anything about it).

 

The only way I can make it work is if I do as shown below, this I link it up like that (only steel defined in engineering data), I create ortho material in autodyn (say just loaded from a library a ortho-material called kfrp or kevlar), reassigned that to the component (via a fill operation, so setup, component,fill, and material).

 

I run that and it worked - I do not have a clue how to post process in autodyn, and it is not straightforward to find.

 

Perhaps someone else has some better tips - or write to ansys support and ask on how to best model this.

[Astro45]

sir, 

   i added the equation of state  linear model to my material and the ansysis started without any error.but the time taken to compete the anaysis is quite large.please help me to reduce the time.My system has 64 gb of RAM poewered with XEon processor.

[jj77]

How did you do that. When I tried adding eos linear to an orthotropic material say s glass, the the orthotropic properties are crossed out, there is a line across orthotropic.

[Astro45]

I just created my a new material adding the density and orthotropic elasticity and then the EOS. is that the correct method? if i am wrong please correct me.

Thanks in advance

 

[jj77]

I did that to and then one or the other gets crossed out - so there is a line on top of the word EOS or Orthotropic - see yellow marking in the image below, you probably get the same. Can you confirm, and include a screen shot of your material like the one below showing all properties (ortho.+eos).

[Astro45]

ya i too have that kind of the cross mark on my orthotropic easticity.if the cross mark comes,is that the property wil not be taken into account for the analysis.

[jj77]

I really believe so - look on explicit library in eng. data and one can see there is no isotropic/ortho. elasticity + eos, it is only eos with strength and failure models.

So the only way as I can see is to use AUTODYN as I did. 

[Astro45]

Is there any way to solve it in LS Dyna extension.If possible Please tell me how to add the orthotropic material properties in that.

Thanks in advance

[jj77]

I do not know that.

 

What I can tell you is that you can do it as shown below:

 

[jj77]

I have spoken to people that know autodyn and ansys very well, and you can do orthotropic elasticity in Engineering data for Explicit dynamics + orthotropic stress limits for failure but you can not use the nonlinear EOS options or the orthotropic plasticity as you can in Autodyn (as shown above). So unless you do high vel. impact or blast that should be OK. If you do blast or high vel. impact then use autodyn gui as mentioned.

[Astro45]

Thanks for the reply sir.