Studies of the Dynamic Responses of Pre-twisted and Tapered Rotating Composite Beams Attached to a Movable Disk

• Main Authors: Chun-Nan Chen, 陳俊男
• Other Authors: 張銘永
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/20262125383056272350

碩士 === 國立中興大學 === 機械工程學系所 === 99 === The main objective of this thesis is to develop a finite element model based on an improved beam theory for studying the vibration characteristics and dynamic responses of the pre-twisted and tapered rotating beams made of isotropic materials or composite materials. The transverse shear deformation, torsion, cross-sectional warping, chordwise curvature, sidewise bending, pre-twisted angle and the width-tapered effects of the beam are considered. The finite element method is applied to derive equations of motion of the system, where one-dimensional three-node element with 23 degrees of freedom are used. Hence, it allows one to predict more accurately the vibration behavior of pre-twisted and tapered rotating beams. To derive the equations of motion, first, a displacement field is assumed to represent the flexible deformation of the beam. Based on the linear strain theory, the expressions of strain energy, kinetic energy as well as the work done by the centrifugal force of the pre-twisted and tapered rotating composite beam mounted on a movable disk are obtained. Next, by evoking the Hamilton’s principle employed together with the finite element method, the equations of motion are then derived. In the studied examples, the effects of the stagger angle, precone angle and the rotational speed on the natural frequencies of the pre-twisted and tapered rotating beams made of isotropic materials or composite materials are investigated. Moreover the dynamic responses of the rotating beams attached to a movable disk are analyzed by using the Newmark-β method. The influences of the parameters such as the breadth taper ratio, rotational speed and acceleration, pre-twisted angle, stagger angle and precone angle on the dynamic responses are investigated.