Is it possible to optimize parameters in the constraints section of the FEB file

[Fisher]

What I want to run is something like this

<?xml version="1.0"?>
<febio_optimize version="2.0">
<Options>
<obj_tol>0.001</obj_tol>
<f_diff_scale>0.001</f_diff_scale>
</Options>
<Parameters>
<param name="fem.material(’BM’).custom_material.material_ constant">0.99, 0.9, 0.99999, 1</param>
<param name="fem.constraint[0].constraint_constant_1">1e-5, 1e-9, 0.1, 1</param>
<param name="fem.constraint[0].constraint_constant_2">1, 0, 20, 1</param>
</Parameters>
<Objective type="data-fit">
<fnc type="parameter">
<param name="fem.mesh.node[690].position.y"/>
</fnc>
<data>
<point>0.0, 0</point>
<point>400.0, 1</point>
</data>
</Objective>
</febio_optimize>

When I try to run this I just get the message "failed initializing the task: optimise" (in febio 2.8.5)
I don't know if the syntax is wrong or if what I'm trying to do is not supported.
(Im using a custom material plugin that has constants in the constraints section that influence how the material evolves)

[maas]

Hi,

This should work. I've attached an optimization problem that uses a parameter of the constraint. (This example doesn't do anything useful, but it just illustrates the syntax. I tried this with FEBio2.9 and FEBio3.)

I don't see anything obviously wrong with your syntax. Of course, I don't know your custom material's interior structure, so it could be a syntax error? Also, perhaps try to use an index for the material, instead of the name.

<param name="fem.material[0].custom_material.material_constant">0.99, 0.9, 0.99999, 1</param>

If that doesn't work, can you share your input file, or at least the Materials section?

Thanks,

Steve

[Fisher]

Thanks
my material is a mixture and what I was using before was
<param name="fem.material(’material_name’).mixture_compon ent_name.material_constant">0.99, 0.9, 0.99999, 1</param>
what worked is
<param name="fem.material[X].elastic_solid[Y].material_constant">0.99, 0.9, 0.99999, 1</param>

perhaps what I should have used in the original style was this :
<param name="fem.material(’material_name’).elastic_solid( 'mixture_component_name').material_constant">0.99, 0.9, 0.99999, 1</param>

regardless, it's working now