I'm using the data available in the literature, I calculated the frequency but the same results can not be obtained.
I used lumped mass matrix for calculating Mass matrix.
M=ro*A*L/2*[1 0 0 0 0 0
0 1 0 0 0 0
0 0 1 0 0 0
0 0 0 1 0 0
0 0 0 0 1 0
0 0 0 0 0 1];
Do you want to verify and validate results obtained from numerical analysis with experiments?
No is not my purpose. I wan't to optimize 52 bar truss. but i can't calculate exactly natural frequency. I got dizzy....
Dear Mostafa,
I hope that the below file was attached help to you. You could be compute the mass and stiffness matrices of 2D. Truss structure based on 8 and 9 pages (File Name: Structural Elements). After making these matrices you should product the eigen value equation and finally, derived the eigen values of truss structure (Natural Frequencies). The number of eigen value is equal to the number of modes (DoFs).
Good Luck,
Milad
Dear Mostafa
In order to find the natural frequency of a truss, you need the mass and stiffness matrices. Was lumped mass matrix considered in the literature? How do you use the natural frequency of the system to optimize it? To find the optimize design of a system, you need the objective function and some constraints such as allowable strain, stress and deflection. For example, the objective function could be the weight of truss. I worked on truss optimization previously in the MATLAB software using PSO, FA, SOS and SA algorithms. I can help you to solve your problem. Please contact me.
Dear Mohammad
I don't have any problem about Optimization process. My problem is that I can not calculate the frequency correctly.
I send to yo matlab code that analyze 52 bar truss. for example for initial design of 52 bar truss the weight is 338.69 . so i calculate correctly the weight. but the frequency of system have little different from initial design. so i can't find my mistake. i use both of the lumped and consistent mass matrix. but i don't get result
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