Mechanical Vibration is the study of oscillatory motions of mechanical system. It is both useful and harmful for engineering systems. Sometimes, it is profitably used in musical instruments, propagation of sound etc. On the other hand, excessive vibration causes damage to buildings and rapid wear of machine parts such as gear & bearing. At the stage of resonance, it may even lead to the shutdown of the turbine units which directly disturbed the economical system, time management, employment system of a nation. Resonance is the stage where the natural frequency of the system is equal to the external excitation frequency. Due to this, the amplitude of vibration is excessive at resonance. So, determination of first few modes of natural frequency of a system is a must for design point of view. So, it is essentially required to have the knowledge of vibration (natural frequency) for a designer. Это и многое другое вы найдете в книге Mechanical Vibration of Plates (Subodh Kumar Sharma and Ashish Kumar Sharma)