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Modeling constitutive equations
Posted Jan 26, 2011, 7:41 p.m. EST Modeling Tools & Definitions, Parameters, Variables, & Functions Version 3.5a, Version 4.0a 0 Replies
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I am using Comsol 3.5a/4.0a general PDE mode for my research work. I used a conservation equations to model the physics. Now I need to add the additional constitutive equation in the model.
I will illustrate it with the dummy example from the structural physics. The momentum conservation equation is
rho * d^2(u)/dt^2 = d(Stress)/dx + f, -- (1)
where rho is the density, u is displacement variable, and f is body force. The Stress is function of dependent variable "u".
In addition, there is a following rate dependent constitutive equation:
d(e)/dt = C * d(Stress)/dt, -- (2)
where e = d(u)/dx is a strain and C is constant.
It is easy to model Eq.(1) using PDE mode with dependent variable "u". The question is where and how to model Eq.(2)?
The global equations only allow modeling of ODEs (dependent on time only).
Please suggest me some way to model Eq.(2), which is dependent on "u" and time, in comsol ?
Thanks and regards,
Rakesh
Hello Rakesh Dhote
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