Dynamic analysis of beams with breathing crack using finite element method

Özkan, Berkay
Non-linear dynamic characteristics of a beam with a breathing crack are investigated using finite element method. This thesis has two main objectives: (1) to obtain a foresight for the vibration based crack detection by using finite element method (2) to investigate the effects of crack location, crack depth, excitation frequency, excitation amplitude and boundary conditions on the indications of crack presence. Two dimensional finite element approach is used to model a square cross sectional beam subjected to dynamic loading. Frictionless contact is introduced to avoid any penetration between the crack faces. Time histories and Fourier spectra are obtained for nodal acceleration at specified sensor locations on the beam. On the basis of the results of this research, the capability of finite element method on the crack detection is evidenced by the generation of sub- and higher-harmonics in the Fourier spectra. Both time and frequency domain responses deviate considerably from vibration response of an intact beam. The depth and position of the crack change the amplitude of the harmonics, which can be interpreted as an indicator on the severity of the damage. Furthermore, exciting the beam with frequency of first natural mode of the beam, makes the harmonics more detectable on the frequency domain.  


Non-linear dynamic analysis for the lateral vibration of beams with breathing crack under harmonic excitation using finite element method
Özkan, Berkay; Ciğeroğlu, Ender; Özgen, Gökhan Osman; Kadıoğlu, Fevzi Suat (null; 2017-06-09)
Non-linear dynamic characteristics of beam with breathing crack were investigated using finite element method. Capability of detecting cracks is demonstrated by observing the sub and super harmonics on the forced vibration response of the beam. Moreover, changes in frequency response of lateral displacement and acceleration of the beam due to depth and location of crack are exhibited.
Computational Modeling of the Effects of Viscous Dissipation on Polymer Melt Flow Behavior During Injection Molding Process in Plane Channels
Tutar, M.; Karakuş, Ali (2013-02-01)
The present finite volume method based fluid flow solutions investigate the boundary-layer flow and heat transfer characteristics of polymer melt flow in a rectangular plane channel in the presence of the effect of viscous dissipation and heat transfer by considering the viscosity and density variations in the flow. For different inflow velocity boundary conditions and the injection polymer melt temperatures, the viscous dissipation effects on the velocity and temperature distributions are studied extensive...
Numerical modelling and finite element analysis of stress wave propagation for ultrasonic pulse velocity testing of concrete
Yaman, İsmail Özgür; Aktan, Haluk (2006-12-01)
Stress wave propagation through concrete is simulated by finite element analysis. The concrete medium is modeled as a homogeneous material with smeared properties to investigate and establish the suitable finite element analysis method (explicit versus implicit) and analysis parameters (element size, and solution time increment) also suitable for rigorous investigation. In the next step, finite element analysis model of the medium is developed using a digital image processing technique, which distinguishes ...
Reduced order modeling of helicopter substructures for dynamic analysis
Hayırlı, Uğur; Kayran, Altan; Department of Aerospace Engineering (2018)
Dynamic analysis of a structure is generally conducted by the finite element method in aerospace structures. The models usually contain large number of elements to be able to obtain more accurate results. Although the most computers are capable of solving the large and complex problems, the analysis problems such as dynamic optimization, aeroelastic, frequency and time response may take long time due to involving iterative and multi-step processes. In this study, various model reduction methods are describe...
Induced current magnetic resonance electrical impedance tomography (ICMREIT) with low frequency switching of gradient fields
Eroğlu, Hasan Hüseyin; Eyüboğlu, Behçet Murat; Department of Electrical and Electronics Engineering (2017)
In this thesis, it is aimed to investigate induced current magnetic resonance electrical impedance tomography (ICMREIT) starting from modeling and analysis to experimental validation. Forward and inverse problems of ICMREIT are formulated. A magnetic resonance imaging (MRI) pulse sequence is proposed for the realization of ICMREIT using the slice selection (z) gradient coil of MRI scanners. Considering the proposed MRI pulse sequence, relationship between the low frequency (LF) MR phase and the secondary ma...
Citation Formats
B. Özkan, “Dynamic analysis of beams with breathing crack using finite element method,” M.S. - Master of Science, Middle East Technical University, 2017.