Frequency & Eigenvalue from dynamic eqn

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SUMMARY

The discussion focuses on determining the natural period of a vertical cantilever beam using the characteristic polynomial derived from the global mass (M) and stiffness (K) matrices. The matrices are square symmetric and of rank 6, leading to the equation [M] - ω²[K] = 0, where ω² represents the cyclic frequency. A numerical eigensolution is required, with tools such as MATLAB, NAG, and EisPack recommended for solving the characteristic polynomial. The solution involves transforming the matrices into diagonal form for simplification.

PREREQUISITES
  • Understanding of structural dynamics and cantilever beam theory
  • Familiarity with matrix algebra and eigenvalue problems
  • Experience with numerical analysis software, particularly MATLAB
  • Knowledge of mass and stiffness matrix formulation in finite element analysis
NEXT STEPS
  • Explore MATLAB's eig function for numerical eigensolutions
  • Study the process of diagonalizing matrices in numerical analysis
  • Research finite element methods for dynamic analysis of structures
  • Learn about the NAG library for advanced numerical computations
USEFUL FOR

Structural engineers, mechanical engineers, and researchers involved in dynamic analysis of structures, particularly those working with cantilever beams and eigenvalue problems.

rk81
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Hi, i am trying to find the natural period of a vertical cantilever beam which is fixed at bottom and free at other end., i worked out the global M & K matrices and i have the eqn in the form [M]-w^2[K] = 0, the M & K are not diagonal matrices, but square symetric matrices of rank 6. i understand that w2 is the cyclic frequency, how do i solve this characteristic polynomial the matrix way.. thanks in advance,
 
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You need a numerical eigensolution, such as is available in many numerical analysis packages (NAG, EisPack, etc.). I think MatLab probably has one as well, and there are many other sources as well.
 
thanks, i think i found the answer.. i need to make the matrix to diagonal form, and then the soln is simple.
 

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