simulation Error: Some components are using a material with invalid properties.

[Anonymous]

While doing a thermal simulation (no stress) I get an "Error: Some components are using a material with invalid properties.
Click here to select 'Study Materials' to set a material." while trying to set up the simulation.  Looking at the materials, I don't see anything that looks out of line.  All the materials were drag and drop straight from the fusion 360 library.  Can anyone suggest how to tell what values need attention?

Image of the properties:

https://goo.gl/4l7Znx

Original File (for Autodesk employee only, email for password)

http://a360.co/1UgQ0S2

[Mike.Grau]

Hi @Anonymous,

Thank you for sharing your file. Could I send you a private message for the password to download your file?

I have seen in the picture, that you have applied "wood" as a physical material. This might have a real "Thermal Conductivity" value but it is very low in comparison to metal.

These pictures may help, where you can see the highlighted thermal properties for "Thermal Conductivity", "Thermal Expansion Coefficient" and "Specific Heat" in the pictures here:

You have probably noticed the exclamation mark in the "Study Material" column

that indicates, this material can not be used in a thermal analysis. This link here to our learning content explains this bit more in detail.

A work-around to use the "Thermal_Conductivity" of "Plywood" in a thermal simulation could be achieved by following these steps:

1. You can open the "Manage Physical Materials" Library in the Material dropdown menu, with the link here
2. Here you Add a material like Aluminum or Steel to your favorites and rename it
3. Now you can edit the "Physical Properties" of your Material by click on the Pencil on the right and navigate to "Physical"
4. You have now the option to change the "Basic Thermal" values to the values of your preferred material
5. Once you go back to your study materials you are now able to select your custom material and the exclamation mark disappears

I have created a screen cast for you, that probably helps to create your custom material, with the link here.

I hope this information helps that you can run simulation. I´ll be excited to see the results.

Thanks,

[Mike.Grau]

Hi @Anonymous,

I have send you a private message to share the password for your design.

Thanks,

[Anonymous]

In the documentation it says that "the material cannot be used in simulations mostly because its limit values for Poisson's Ratio are out of the limits"  What limits can the solver manage?  For a thermal study, does Poissons Ratio even get used?  Is there a way to edit the non functioning Plywood material instead of having two Plywoods?

[jan.vonasek · Accepted solution]

Hi Eric,

Current solver requires isotropic material behavior. This is the main reason why orthotropic wood materials are treated as invalid. Therefore if you still need to work with wood materials the only way is to create copy of these materials, change material behavior to isotropic and may be also adjust some physical properties. Note: In this case calculated results may not be accurate.

Regards,

Jan Vonasek

[Anonymous]

Hi Jan,

Great post! I'm a highschool teacher trying to get my students to use inventor to test balsa wood bridges. I've tried going through the process of making a Balsa Wood Material. I originally used Maple and changed the properties of everything based off what I could find on the internet. When running a simulation it is still saying that there is an error. 

Would you have any insight as to anything else I need to change?

Thank you in advance,

Steve

[jan.vonasek]

Hi Steve,

As I wrote before orthotropic materials are not supported. You have to change material behavior to isotropic and may be also parameters like Shear Modulus to be non zero.

Probably best way is to duplicate any valid material and start to modify parameters one by one and verify it is still valid.

Regards,

Jan

[Noah_Katz]

I'm trying to use maple.

I duplicated the material and don't see an option to choose orthotropic or isotropic.

I changed all mechanical and thermal properties to the same X/Y/Z values and still get the error.

[jan.vonasek]

Hi Noah,

I can recommend to duplicate some valid material like steel and then modify parameters.