December 4, 2024
Mohammad Reza Golbahar

Mohammad Reza Golbahar

Academic Rank: Associate professor
Address: -
Degree: Ph.D in -
Phone: -
Faculty: Faculty of Engineering

Research

Title
Nonlinear vibration analysis and control of conical panels reinforced by functionally graded graphene platelets
Type Thesis
Keywords
ارتعاش خطي و غيرخطي، بارگذاري انفجاري، تحليل ديناميكي، پلاكت هاي گرافن، پوسته ها و پنل هاي مخروطي، پيزوالكتريك، كنترل ارتعاش، كنترل مرزي.
Researchers Parviz Malekzadeh (Primary advisor) , Mohammad Reza Golbahar (Advisor)

Abstract

In this thesis, linear and nonlinear vibration analysis of conical shells and panels reinforced by functionally graded graphene platelets (GPLs) with piezoelectric layers, and, the dynamic analysis of the structures was studied. Blast force was considered for dynamic analysis. The higher-order shear deformation theory (HSDT) was utilized to model the linear behavior. Furthermore, the first-order shear deformation theory (FSDT) together with nonlinear von Karman's strain-displacement assumptions were employed to derive the nonlinear governing equations. The differential quadrature method (DQM) was employed to discretize the equations in the space. Besides, harmonic balance method and direct iterative method was used to achieve the nonlinear frequencies. In addition, the responses of dynamic analysis were obtained by utilizing Newmark's method. Afterward, a boundary control algorithm was designed and applied on the system under blast force. After verifying the accuracy and convergence behavior of the method, the effects of geometrical shape parameters like different distributions and volume fractions of GPLs, and boundary conditions, thickness-to-length ratio, apex angle, subtended angle, thickness of piezoelectric layers, on the linear/nonlinear vibration and dynamic response and efficiency of the control algorithm were studied. The results illustrated that by increasing volume fractions of GPLs, addition of the piezoelectric layer and increase of its thickness, decreasing apex angles and decreasing of subtended angle, independently, the frequency of the system will be raised. Furthermore, the role of the boundary control in the reduction of the vibration amplitude under blast force was demonstrated.