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Structural Engineering and Mechanics
  Volume 63, Number 4, August25 2017, pages 551-565
DOI: http://dx.doi.org/10.12989/sem.2017.63.4.551
 


Free vibration analysis of cracked Timoshenko beams carrying spring-mass systems
Guojin Tan, Jinghui Shan, Chunli Wu and Wensheng Wang

 
Abstract
    In this paper, an analytical approach is proposed for determining vibration characteristics of cracked non-uniform continuous Timoshenko beam carrying an arbitrary number of spring-mass systems. This method is based on the Timoshenko beam theory, transfer matrix method and numerical assembly method to obtain natural frequencies and mode shapes. Firstly, the beam is considered to be divided into several segments by spring-mass systems and support points, and four undetermined coefficients of vibration modal function are contained in each sub-segment. The undetermined coefficient matrices at springmass systems and pinned supports are obtained by using equilibrium and continuity conditions. Then, the overall matrix of undetermined coefficients for the whole vibration system is obtained by the numerical assembly technique. The natural frequencies and mode shapes of a cracked non-uniform continuous Timoshenko beam carrying an arbitrary number of springmass systems are obtained from the overall matrix combined with half-interval method and Runge-Kutta method. Finally, two numerical examples are used to verify the validity and reliability of this method, and the effects of cracks on the transverse vibration mode shapes and the rotational mode shapes are compared. The influences of the crack location, depth, position of spring-mass system and other parameters on natural frequencies of non-uniform continuous Timoshenko beam are discussed.
 
Key Words
    non-uniform Timoshenko beam; free vibration; crack; spring-mass system; numerical assembly technique
 
Address
Guojin Tan, Jinghui Shan, Chunli Wu and Wensheng Wang : College of Transportation, Jilin University, Renmin Street 5988, Changchun 130022, China
 

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