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How to make equations nonlinear in PZD interface?
Posted Aug 7, 2012, 7:40 a.m. EDT Modeling Tools & Definitions, Parameters, Variables, & Functions, Structural Mechanics Version 4.3 1 Reply
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I have made a model of piezo resonator on base of piezoelectric interface. Now I try to take into account the nonlinearity.
So Comsol use formula1(attach) to calculate stress tensor from stain tensor. I want to use formula2 or formula3 to get nonlinearity and temperature dependence of model.
I cant find the way to change piezoelectric interface equations because there is no place to add new material properties as third order elastic constants (Cijklmn).
I tried to use physics builder to make my own piezoelectric interface, but the problem is I cant multiply elasticity matrix (6x6 matrix) by strain matrix (3x3 matrix). I know, that elasticity matrix is tensor 4th order (3x3x3x3) but Comsol use 6x6 matrix.
Thanks in advance
Konstantin
So Comsol use formula1(attach) to calculate stress tensor from stain tensor. I want to use formula2 or formula3 to get nonlinearity and temperature dependence of model.
I cant find the way to change piezoelectric interface equations because there is no place to add new material properties as third order elastic constants (Cijklmn).
I tried to use physics builder to make my own piezoelectric interface, but the problem is I cant multiply elasticity matrix (6x6 matrix) by strain matrix (3x3 matrix). I know, that elasticity matrix is tensor 4th order (3x3x3x3) but Comsol use 6x6 matrix.
Thanks in advance
Konstantin
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1 Reply Last Post Aug 9, 2012, 6:38 a.m. EDT
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Posted:
1 decade ago
I ran into one more problem.
I try to declare new variable "strain" in physics builder. It should be symmetric matrix 3x3.
When I make definition of this variable
0.5*(gradient(u)+transpose(gradient(u)))
I get error "Variable definition is non-symmetric for a symmetric variable", although i believe this definition is symmetric.
How can I correct this definition?
I try to declare new variable "strain" in physics builder. It should be symmetric matrix 3x3.
When I make definition of this variable
0.5*(gradient(u)+transpose(gradient(u)))
I get error "Variable definition is non-symmetric for a symmetric variable", although i believe this definition is symmetric.
How can I correct this definition?