Research On The Coupled Flexural-Torsional Vibration Characteristics Of Periodic Beams | | Posted on:2009-06-27 | Degree:Master | Type:Thesis | | Country:China | Candidate:J Y Fang | Full Text:PDF | | GTID:2132360278457014 | Subject:Mechanical engineering | | Abstract/Summary: |  PDF Full Text Request | | Controlling vibrations in structures has been one of the pop research topics in academic and engineering for a long time. However, the philosophy of Phononic crystals (PCs) is introduced into engineering structures design and the characteristics of band gaps are used to control vibration in structures, which will be a new theoretical and technical way to control vibration.Under this circumstance, with the extended Transfer Matrix Method (TMM), hanging together Finite Element Method (FEM), this dissertation addresses to investigate the characteristics of the coupled flexural-torsional vibration band gaps in periodic beams which are applied widely in engineering basing on the Phononic crystals theory deeply and systemically. The main work and achievements are as follows:1.The TMM is modified and improved to deal with different type of periodic beams. And the characteristics of coupled flexural-torsional vibration band gaps of Euler-Bernoulli and Timoshenko beams including warping effect are investigated. The accurate results of coupled flexural-torsional band structures of periodic beams are obtained.2.The effect of axial load on coupled flexural-torsional vibration band gaps in periodic beams is investigated. Beginning from coupled flexural-torsional vibration equations of axially loaded beam, the required transfer matrices are deduced to calculate the band gaps to deal with different types of beams. And coupled flexural-torsional vibration band structures of periodic monosymmetrical Timoshenko beam and asymmetrical Euler-Bernoulli beam with different axial load are obtained. The laws how coupled flexural-torsional vibration band gaps of different type of periodic beams varied with the change of axial load are concluded.3.The characteristic of vibration band gaps of periodic composite beam is researched. The material is assumed unidirectional fiber-reinforced composite, and the beam member model is based on the classical lamination theory. The band structure of axially loaded periodic composite beam is calculated with TMM. The mechanism of coupled bending and torsion of periodic composite beam is opened out. And the effects of material parameters and geometrical parameters on vibration band gaps of composite beam are studied. In addition, the effect of axial load on band gaps of composite beam is investigated.In summary, this dissertation addresses to investigate the characteristic of the coupled flexural-torsional vibration band gaps in periodic beams extensively. It can be obtained much closer result compared to the result calculated from FEM with the improved TMM. It is meaningful for engineering application to study the effect of axial load on coupled bending-torsional band gaps. Research on the mechanism of coupled bending and torsion and the characteristic of its band gaps of periodic composite beam establishes the theoretical foundation to study the composite material extensively. These studies which are valuable for periodic beams in stimulating its engineering application to vibration/noise control are of significant value in the theory as well as its application to vibration/noise control. | | Keywords/Search Tags: | Periodic beams, Band gap, Coupled flexural-torsional vibration, Warping, Axial load, Composite material | | PDF Full Text Request | Related items |
| |
|
