Discussion Forum

Dear COMSOL Support,

I’m working on a Solid Mechanics project involving a thermally deformed 2D cantilever. I have introduced a reference temperature of 393.15 K (~20 C), and an elevated temperature of 273.15 K (~100 C).

Under the Solid Mechanics section of my component, I have declared my solid to be a Linear Elastic Material, and have added a Thermal Expansion to it. I have added a Fixed Constraint to one edge (boundary) of the cantilever. Under this Fixed Constraint, I have also added Thermal Expansion such that the constraint is allowed to expand in one direction and prevent additional stress along that direction. I’m using aluminum as my material with a coef. of thermal expansion of 2.3E-5.

My first question pertains to analysis of the logarithmic strain component in the x direction (true strain). Using the expression [alpha*(Televated-Tref)], I would expect a true strain value of 1.84E-3. Instead, I am looking at ~2.45E-3 on my strain results surface (see COMSOL model), for most of the x direction.

My second question involves the thermal expansion of my fixed constraint. Despite adding this thermal expansion to the fixed boundary, why do I still see additional stresses and strains near the x=0 boundary in my surface plots? Is there something I am missing in the Linear Elastic Material equation formulations that is pre-straining the solid?

Thanks, Ben

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