Nonlinear Materials (Partial Differential Equations Toolbox)

Hello,

For those familiar to the topic. How can I use the following function:

structuralProperties(structuralmodel,'PoissonsRatio',0.3, ...

'YoungsModulus',210E3);

For nonlinear materials? Meaning the value of the Young's modulus varies after the yield strenght of the material is surpassed.

[William Rose]

@Pablo, structuralmodel() only does linear stress-strain problems. For a nonlinear model you will have to do more coding on your own. If I were solving a static loading problem, I would try writing the equations for the relevant nonlinear PDEs as a relaxation problem. Good luck with this challenging problem.

[William Rose]

@Pablo, I would also search the File Exchange. For example:

https://www.mathworks.com/matlabcentral/fileexchange/54226-fem-matlab-code-for-linear-and-nonlinear-bending-analysis-of-plates

[Pablo]

Oh that's a pity...

Thank you for the response!

[William Rose]

@Pablo, you're welcome.

[Thomas]

Agree'd it's a shame - something I'd like to see included / become a little easier in future.

For the structural mech documentation the Youngs Modulus has to be a positive number.

https://uk.mathworks.com/help/pde/ug/pde.structuralmodel.structuralproperties.html#d126e138802

For the unified workflow (which appears how things are going) under Material Property Assignments the Youngs Modulus can be of type: positive number | three-element vector of positive numbers | function handle the catch here is that it can only depends on space then - not local elemental stress.

https://uk.mathworks.com/help/pde/ug/pde.materialproperties.html

Still, function handles can be useful, I'm currently trying to see if I can relate a third variable to this spatial field, i.e. temperature and damage and then use that to indirectly vary the stiffness. For details, see Nonconstant Parameters of Finite Element Model.