The theoretical foundation for this analysis lies in the Euler-Bernoulli beam theory. The partial differential equation governing the transverse vibration ( w(x,t) ) of a uniform beam is ( EI \frac{\partial^4 w}{\partial x^4} + \rho A \frac{\partial^2 w}{\partial t^2} = f(x,t) ), where ( EI ) is the flexural rigidity, ( \rho ) is density, and ( A ) is the cross-sectional area. For a cantilever beam, the boundary conditions are zero displacement and zero slope at the fixed end (( x=0 )), and zero bending moment and zero shear force at the free end (( x=L )). Solving this equation analytically yields an infinite set of natural frequencies and mode shapes. However, real-world engineering requires a finite, computable solution, which is where MATLAB's numerical capabilities become invaluable.
The core of the dynamic analysis is the solution of the eigenvalue problem ( ([K] - \omega^2[M]) {\phi} = 0 ). MATLAB's eig function efficiently computes the natural frequencies (( f_i = \omega_i / 2\pi )) and the corresponding mode shapes (( {\phi_i} )). The code can then plot the first few mode shapes, visually confirming that the first mode is bending, the second mode shows a node (point of zero displacement) along the beam, and so forth. An example output for a steel beam (L=1m) might show natural frequencies around 15 Hz, 95 Hz, and 265 Hz, aligning closely with the theoretical values from the characteristic equation ( \cos(\beta L) \cosh(\beta L) = -1 ). Dynamic Analysis Cantilever Beam Matlab Code
Beyond free vibration analysis, advanced MATLAB code can simulate forced vibration. By employing modal superposition and numerical integration (e.g., the Newmark-beta method via ode45 ), the code can compute the beam's time-domain response to arbitrary forces. For instance, applying a harmonic force at the free end and sweeping the frequency reveals the classic resonance peaks. Similarly, an impulse response calculation yields the beam's dynamic amplification factor. The theoretical foundation for this analysis lies in