Out-of-plane and in-plane free vibrations of angle-ply and cross-ply laminated composite beams with different boundary conditions are studied. The effect of fiber angle on out-of-plane bending, torsional, in-plane bending, and axial natural frequencies are investigated separately. The beam is modeled and analyzed by the finite element method (FEM). The finite element software package ANSYS is u...

In this study, flapwise bending vibration analysis of a tapered Timoshenko beam mounted on the periphery of a rotating rigid hub is performed. The governing differential equations of motion for pure bending are derived using the Hamilton’s principle and solved using the Differential Transform Method, DTM. During the derivation of the equations, effects of rotary inertia, shear deformation and h...

Orientation accuracy is a key factor in the design of mechanisms for antenna pointing. Our design uses a redundantly actuated parallel mechanism which may provide an effective way to solve this problem, and even can increase its payload capability and reliability. The presented mechanism can be driven by rotary motors fixed on the base to reduce the inertia of the moving parts and to lower the ...

We consider a shape optimization problem in rotordynamics where the mass of a rotor is minimized subject to constraints on the natural frequencies. Our analyis is based on a class of rotors described by a Rayleigh beam model including effects of rotary inertia and gyroscopic moments. The solution of the equation of motion leads to a generalized eigenvalue problem. The governing operators are no...

1. Formulation of the Problem Consider an elastic rod simply supported at both ends. Let L be the length of the rod. We assume that the rod is loaded by an axial force P (t) that is a known function of time and has a fixed direction coinciding with the rod axis in the initial (undeformed) state. In this work we shall generalize our previous analysis [1] in two directions. First, we assume here ...

This paper investigates the development of a novel framework and its implementation for the nonlinear tuning of nano/microresonators. Using geometrically exact mechanical formulations, a nonlinear model is obtained that governs the transverse and longitudinal dynamics of multilayer microbeams, and also takes into account rotary inertia effects. The partial differential equations of motion are d...

A helicopter is not possessed of an ability to fly fast compared with fixed-wing counterparts. This is a result of considerations with the main rotor. The main rotor moves in a direction very close to its plane of rotation which naturally divides it into two halves which operate under different aerodynamic conditions. One side (called the advancing side) has the rotation and translation velocit...