In recent decades, the use of sandwich plates as structural members has increased significantly due to their low specific weight, fatigue resistance, and high bending strength. Also, composite materials that are composed of two or more independent materials have enhanced and improved characteristics, which in this sense have a role in machines and aerospace industries and parts that are exposed to high heat. It is an undeniable material. If the members of a complex structure including beams, plates and shells are affected by strong dynamic stimulation, they vibrate with large amplitudes. eva‎luation of free vibration behavior is a fundamental consideration in structure design. Understanding the frequency parameter of the plates will be useful in the design of the structural members and in the early stages of the design. In the present study, the static analysis, stability and free vibration of the plates in linear mode are investigated for the main purpose, which is the non-linear free vibration analysis of sandwich plates with a viscoelastic core. For this purpose, the finite strip method and the first order shear theory based on van Karman's assumptions are used. It should be noted that the viscoelastic properties of the core follow the Boltzmann integral law with a constant bulk modulus. Laplace transform is used to convert equations from time domain to Laplace domain. Finally, by solving an eigenvalue problem in the Laplace-Carson domain, nonlinear frequencies are obtained for this type of sheets.

نسرين جعفري , سعيد صرامي

مجتبي ازهري , مهدي زندي آتشبار