How to create isotropic wood?

[Anonymous]

Greetings all,

It appears that wood cannot be used in simulations because it's "nonlinear"? I get a warning icon next to wooden materials (which should actually be an error icon because it's an error not a warning), after some clicking I see in red letters "nonlinear".

Non-linear is already taken as an engineering term and it doesn't mean 'anisotropic' which I'm assuming was meant by the red text. Support team should correct this if that's the case.

Nevertheless I'm looking for a workaround. I tried making a custom material called "Isotropic plywood" in which I copied the existing plywood material and then forced all the properties to be isotropic (yes, bad practice but we're not building rockets here), anyways I still get the error. I am guessing that there's a flag on the material data somewhere which I can't remove from within the GUI that tells the FEA tool not to bother. Modifying advanced properties doesn't seem to do anything.

The majority of all structures in the world have wood, Fusion 360 really ought to be able to handle it! Just assume the grain goes along the longest axis of the part- that assumption will work for like 95% of cases.

Further, I don't see the ability to just create a material from scratch. I must be missing something, is it really not possible to do this?

What are my options here?

[MoshiurRashid]

You have to collect the available properties for the wood you'll be using. Then you have to create a material in the environment.

Select a 3D object in the viewport, then right-click, select "Physical material".

If the material you are looking for is not available in the library you should duplicate an existing one with similar properties and edit that duplicate. Then save it.

Nonlinear simulation is  available in fusion 360. I can suggest you a Lars tutorial. It is very basic of nonlinear. Also a Autodesk University session (free for now)

https://youtu.be/Qe_7UR87p-o

https://www.autodesk.com/autodesk-university/class/Nonlinear-Simulation-Autodesk-Fusion-360-2017

Also, 

[spencerhiscox]

Seems an aweful lot like you didn't read his question at ALL. Thanks for the *completely useless* cut-and-paste answer. Paid per post are we?

[TheCADWhisperer]

@spencerhiscox 

Exactly what problem are you having in creating an isotropic “wood” material?

[spencerhiscox]

The issue is this: It would seem that fusion has some sort of 'behind-the-scenes' 'flag' on materials which defines them as anisotropic (or orthotropic) or isotropic. So, duplicating a wood material from the library (which you want to use in a simulation) -- so that the properties are 'correct' -- and simply editing anisotropic properties such that they all have the same value regardless of axis / orientation with respect to the grain, doesn't actually work. If you try to run the simulation after that, you'll simply get the same error.

I found a work-around (based on the assumption there was a 'hidden flag' described above) -- which is simply to duplicate a metal (or other isotropic material) and do your best to fudge the material properties to match whatever type of wood you wanted to use. Obviously, anything you do to 'force' a simulation using wood isn't going to be perfect and some care needs to be taken in selecting which property values from the wood to use to populate properties in your custom material -- which will always be the case until fusion supports simulating anisotropic materials. The issue with this work around is just tedium. -- Obviously, happy to hear about a better solution if you have one. I also don't understand why fusion isn't set up with a 'material creation wizard' or something to allow you to just define a new material from scratch (rather than having to duplicate an existing material). Could reverse-engineer the software to find a work-around for THAT -- but, I mean, you want to talk about tedium... how many hoops do we need to jump through AutoDesk?

As to the initial reply to OP's question above. A cursory explanation of how to duplicate a material and edit the copy (which OP clearly already knows how to do -- if he'd bothered to read OP's question) and then linking a completely irrelevant video which *barely* deals with creating non-linear simulations is basically just spam / trash. If you don't know the answer / don't have anything valuable to contribute which might help / LEAD to an eventual answer .. OR just can't be bothered to read the question AT ALL -- then DON'T ANSWER? Right? I mean really....

[yasmughal]

Hi, Did you ever find the solution for this issue? I'm currently stuck in the same pit and cant find the answer...