Vedat Dogan

Vibration of anti‐symmetric angle‐ply composite plates under random excitation

Purpose – The transverse shear deformation and rotary inertia effects need to be included for an accurate analysis in the response of the relatively thick plates. This paper seeks to use, one of the refined theories which takes into account those effects, The First Order Shear Deformation Theory, to obtain linear and non‐linear responses for anti‐symmetric angle‐ply composite plates under random excitation.Design/methodology/approach – The random excitation is assumed to be stationary, ergodic and Gaussian with zero‐mean. A Monte Carlo Simulation of stationary random process is used. A multi‐mode Galerkin approach and numerical integration procedure are employed to find linear and non‐linear response solutions. Laminated composite plate is taken to be simply‐supported along four edges.Findings – The vibration of composite plates at elevated temperatures is also investigated. The linear and non‐linear deflections root‐mean‐square (RMS) are obtained for various input levels, the different lamination angles ...

Design and Manufacturing of a Composite Drive Shaft

In this study, a composite drive shaft for heavy commercial vehicles is designed and manufactured. The carbon/epoxy composite material is used for the shaft tube and the end joints are made of steel. The material properties of the carbon/epoxy composite are obtained by performing coupon tests. The shaft tube is modeled using ANSYS finite element software. The static, buckling and modal analysis are achieved to obtain the Tsai-Wu strength ratio, the critical buckling torque and free vibration frequencies, respectively. The shaft tube is manufactured by using filament winding method. The steel end connections are bonded to the shaft tube during the filament winding process.

Active vibration control of functionally graded plates under random excitation

In this study, the active control of the nonlinear vibration of the functionally graded material plate under random excitation is presented. The functionally graded material plates considered are mixture of two materials such as metal and ceramic. The mechanical properties of the functionally graded material plate are graded in the thickness direction only according to a simple power-law distribution in terms of volume fraction of constituents. The temperature dependencies of the constituents of the functionally graded material plates are also considered. The plate governing equations are due to the classical plate theory with von Karman–type geometric nonlinearities. Discrete piezoelectric materials are symmetrically bonded to top and bottom surfaces of the functionally graded material plate as sensors and actuators. A velocity feedback control technique is employed. The external pressure is considered as stationary Gaussian random process and simulated by using Monte Carlo technique. Parametric studies are conducted to investigate the viability of the lead zirconate titanate sensors/actuators to control the nonlinear random vibrations of the functionally graded material plates.

Vibration of sandwich panels using {3,2}-order plate theory

This paper concerns the evaluation of fundamental natural frequencies and mode shapes of simply-supported sandwich panels using Navier-type solutions within the {3,2}-order equivalent single-layer theory. The kinematic assumptions of the theory are cubic in-plane displacements and a quadratic transverse displacement. The theory also assumes a cubic distribution of the transverse normal stress that is continuous across the laminate. The Euler-Lagrange equations of motion and consistent boundary conditions are obtained from Hamilton’s principle. The predictive capability of the theory is assessed for homogeneous, laminated composite, and sandwich panels. The fundamental natural frequencies are compared with previously published results for varying plate aspect ratio, length-tothickness ratio, and material modulus.

THE NONLINEAR AXISYMMETRIC VIBRATIONS OF CIRCULAR PLATES WITH LINEARLY VARYING THICKNESS UNDER RANDOM EXCITATION

In this study, the nonlinear axisymmetric behavior of circular isotropic plates with linearly varying thickness under random excitation is investigated. It is assumed that plate response is axisymmetric when plate is subjected to axisymmetric random loading. The Berger type nonlinearity is used to obtain the governing equations of motion for clamped circular plates. A Monte Carlo simulation of stationary random processes, single-mode Galerkin-like approach, and numerical integration procedures are used to develop nonlinear response solutions. Response time histories, root mean squares and spectral densities are presented for different random pressure levels. Parametric results are also presented. Linear responses are included to investigate the nonlinear effects.