Hi @Anonymous -
Thanks for reaching out with your issue.
I will first point out that what you are seeing, is simply a warning, letting you know that the material you have defined for your Simulation does not include nonlinear properties that will be needed to actually predict nonlinear behavior in your Simulation. This will not prevent you from running your analysis, however, it is important to note that the results you get will assume the material behaves in a linear elastic manner. We do this because we want users to be very aware that nonlinear material information is required to simulate nonlinear behavior and because our nonlinear library is currently, not that large, and will require users to create nonlinear materials specific to their needs.
Using nonlinear materials in Fusion 360 can be done in a few different ways. Let me explain...
1. Nonlinear materials are supported in both Nonlinear Static Stress and Event Simulation.
2. Fusion 360 includes a nonlinear material library titled Fusion 360 Nonlinear Material Library and can be accessed from within the Study Materials command. I think you have already found this, as you noted that this library is currently limited to a small number of metal materials. When looking at the material models that Fusion 360 supports, these fall into the Nonlinear Plastic category, as they include stress and strain data beyond the yield point. Further, the Nonlinear Static and Event Simulation study types will work with various types of nonlinear materials (metals, plastics, rubbers, etc,), however, the user would need to create these materials and add them to the library on their own.
3. Another nonlinear material model that is supported in Fusion 360 is Nonlinear Elasto-Plastic, also known as bi-linear. This material model behaves such that it has a single value for the linear region (Young's Modulus or Elastic Modulus) and a single value for the post-yield region (Tangent Modulus). When using this material model, by default, the Tangent Modulus is assume to be 10% of the Young's Modulus. You will find that this will work for most all of the materials in the Fusion 360 Material library, you simply need to copy that material to your Favorites or Custom Library, activate the Advanced Physical Properties and define the material model as Nonlinear Elasto-Plastic (bi-linear).
4. As mentioned in item 2 above, Fusion 360 also supports a Nonlinear Plastic material model, which allows the user to define the post-yield behavior as a stress vs. strain curve. For these types of materials, users must create a new material in Fusion 360 and define the required properties.
To learn more about the material models that Fusion 360 supports and the process for creating nonlinear materials for use in Nonlinear Static Stress or Event Simulation, please refer to the following section of our Help documentation. Be sure to read the sub-sections on defining material properties.
http://help.autodesk.com/view/fusion360/ENU/?guid=GUID-011D96B0-9681-41C5-8A53-F6D557E19AB5
Let us know if you have any other questions.
Thanks,
Mike Smell,
Product Manager, Fusion 360 - Simulation
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