Each modal equation: (\ddot{q} r + 2\zeta_r \omega {nr} \dot{q} r + \omega {nr}^2 q_r = Q_r(t))
"Fundamentals of Vibrations" is a textbook written by Leonard Meirovitch, a renowned expert in the field of vibrations. The book provides a thorough introduction to the principles of vibrations, covering topics such as free and forced vibrations, vibration of discrete systems, and continuous systems. The text is designed for undergraduate and graduate students in engineering, as well as practicing engineers who need to analyze and design systems involving vibrations.
By the end, you will understand how to approach any vibration problem systematically — and why a solutions manual shortcut often backfires in exams and design projects.
Meirovitch’s Fundamentals of Vibrations is a masterwork that teaches deep analytical skills. Problem 230 (or similar) is designed to test your understanding of modal analysis with proportional damping and harmonic forcing — a core skill in vibration engineering. Avoid the temptation to download an illegal solutions manual; it often contains errors, and more importantly, you rob yourself of the ability to solve real-world vibration problems where no manual exists.
Divide by (m^2): (2\omega_n^4 - 9\frac{k}{m}\omega_n^2 + 5\left(\frac{k}{m}\right)^2 = 0)
[ (3k - \omega_n^2 m)(3k - 2m\omega_n^2) - (4k^2) = 0 ]
Then: (\mathbf{U}^T \mathbf{M} \mathbf{U} = \mathbf{I}) (identity) (\mathbf{U}^T \mathbf{K} \mathbf{U} = \text{diag}(\omega_{n1}^2, \omega_{n2}^2)) (\mathbf{U}^T \mathbf{C} \mathbf{U} = \text{diag}(2\zeta_1\omega_{n1}, 2\zeta_2\omega_{n2}))