Investigation of a Hollow Shaft to Determine the Maximum Angular Velocity Regarding the FGM Properties

Abstract

To determine the maximum velocity of a rotating hollow shaft it is mandatory to understand the effects of material & geometrical properties variations. In this paper, mechanical behavior & maximum rotational speed of a hollow FGM shaft in elastic zone is investigated. The analysis is based on small deformation in plane-strain state. Young's modulus, density & yield stress are assumed to vary as a power-law function of radial coordinate. Introducing dimensionless parameters, the equilibrium equation has been analytically solved. For the case of equal exponent parameters, numerical results compared the effect of density & yield stress variation on displacement, strain & stress elements. The results are compared with a homogeneous shaft & a variable material properties case. It shows material properties’ variation may have a considerable effect on the stress & strain components & radial displacement & causes yielding onset from the inner radius of the shaft.

A string-driven rotor for efficient energy harvesting from ultra-low frequency excitations

“…In recent years, researchers have explored rotational energy harvesters (REHs) with various rotors to capture energy from ultralow frequency excitations. 3,26 The conventional rotor structure has been investigated widely and developed well in the macro scale, 27,28 but their efficiency drops quickly after being miniaturized. 29 Moreover, since the naturally available excitations (such as mechanical vibrations, linear reciprocating motions, swing motions) cannot trigger the rotation of the conventional rotor, additional eccentric mass has to be attached to the rotor, which enables the (eccentric) rotor to do swing motion with respect to the stator under ambient excitations.…”

Characterization of Functionally Graded Timoshenko Beams with Variable Rotational Speed

“…The vibration analysis of a rotating tapered shaft in Functionally Graded Material (FGM) is modeled using the Timoshenko beam theory (FSDBT) with consideration of gyro-scopic effect and rotary inertia. The equations of motion are expressed by the hierarchical finite element method based on bi-articulated boundary conditions [15][16][17][18]. Usually the FGM beams are subjected to higher rotational speeds, but ahead of their complete break down the incidence of vibration, plastic failure or creep relaxation can create serious damages which finally prevent the increase of the rotational speed.…”