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Defining material properties as a function of frequency
Posted Nov 4, 2016, 8:18 a.m. EDT Materials, Structural Mechanics Version 5.1 0 Replies
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I am trying to model a simple asphalt slab (a normal block with complex material properties) in COMSOL 5.1 to do a modal analysis.
To do so, I am using HN model to define the Young's modulus as a function of frequency: E(freq) = E_e[MPa]+((E0[MPa]-E_e[MPa])/(1+(j*2*pi*freq[Hz]*tau[s])^alpha)^beta)
The analysis works as long as values of alpha and beta in this formula are high! So my way of defining the function shoud be fine! But when I set them as realistic values (which are for instance alpha=0.563, beta=0.212) I get this error:
Error in user-defined function.
- Function: dcomp1.mat1.def.an1_dan1__x__internalArgument
Failed to evaluate expression.
- Expression: simplify((-1)*(d(d(d((-comp1.solid.Sl11*test(comp1.solid.el11)-2*comp1.solid.Sl12*test(comp1.solid.el12)-2*comp1.solid.Sl13*test(comp1.solid.el13)-comp1.solid.Sl22*test(comp1.solid.el22)-2*comp1.solid.Sl23*test(comp1.solid.el23)-comp1.solid.Sl33*test(comp1.solid.el33))*(dvol),{test@4}),comp1.vZ),lambda)))
- Feature: Eigenvalue Solver 1 (sol1/e1)
Any idea what is going wrong?
Thank you,
Navid
Hello Navid Hasheminejad
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