MATLAB Matlab: transfer function determination

AI Thread Summary
To determine the transfer function of a 2 dof vibration system in MATLAB, start by rearranging the Laplace-transformed differential equation to express the relationship between external forces and displacement. This allows for the transfer function to be derived directly from the equation. MATLAB functions such as tf, bode, and ltview can be utilized for analysis, even in multi-degree-of-freedom systems. While symbolic solutions using dsolve are possible, they may not be necessary for simpler systems. Understanding how to manipulate the equations is key to efficiently using MATLAB for transfer function analysis.
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I have a 2 dof vibration system, I have determined the differential equation of the model, can I determine the trasfer function readily with matlab, without using manual algebra operation?
In other word, I have that differential equation system:

[m]x''+[c]x'+[k]x=[f]

where:
[m] mass matrix
[c] damping matrix
[k] stiffness matrix
[f] external forces matrix

through laplace transformation I obtain:

s^[m]x(s)+s[c]x(x)+[k]x(s)=[f]

where s is the laplace variable, how can I find [f]/[x]?
I'm searching a way for estimating readily the transfer function of mechanical system, it is a loss of time to perform the calculation every time
 
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may anyone help me?
 
You've pretty much got the TF. Rearrange the laplace you've done above so you get f/x = tf (factorise the left side wrt to X). From there, you can use MATLAB to analyse the TF.
MATLAB tools(look in help): tf, bode, ltview.
The time required to manually calculate the TF is trivial for systems like this. You can use dsolve to get a symbolic solution to the ODE but it's not really necessary
 
ddarvil said:
You've pretty much got the TF. Rearrange the laplace you've done above so you get f/x = tf (factorise the left side wrt to X). From there, you can use MATLAB to analyse the TF.
MATLAB tools(look in help): tf, bode, ltview.
The time required to manually calculate the TF is trivial for systems like this. You can use dsolve to get a symbolic solution to the ODE but it's not really necessary

I know the tf, bode function, but how can I use them when the system has more than one dofs?
 
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