Zeki Kiral

Simulation and analysis of vibration signals generated by rolling element bearing with defects

Abstract Dynamic loading of a rolling element bearing structure is modeled by a computer program developed in Visual Basic programming language. The vibration response of the structure to the dynamic loading is obtained using a standard finite element package I-DEAS. A force model is proposed to model the localized rolling element bearing defects. Time and frequency domain analyses are performed for diagnostics of rolling element bearing structures. Statistical properties of the vibration signals for healthy and defected structures are compared. The envelope (HFRT) method is employed in the frequency domain analysis. The effect of the rotational speed on the diagnostics of rolling element bearing defects is investigated. An optimum sensor location on the structure is sought. Effect of the structure geometry on the monitoring techniques is studied. An optimum monitoring method can be employed by analyzing the rolling element bearing structure following the procedure proposed in this study. The present commercial computer aided engineering packages can be used in special engineering applications such as condition monitoring of rolling element bearings.

Dynamic Analysis of A Symmetric Laminated Composite Beam Subjected to a Moving Load with Constant Velocity

This study deals with the dynamic behavior of a symmetric laminated composite beam subjected to a concentrated force traveling at a constant velocity. The dynamic analyses for a fixed-fixed composite beam under the action of a moving load are carried out by the finite element method. A three-dimensional finite element model based on the classical lamination theory is used. The Newmark integration method is employed in order to calculate the dynamic response. A computer code is developed using MATLAB to perform the finite element vibration analysis. The dynamic magnification, which is defined as the ratio between the dynamic and static displacements is obtained for different load velocities and ply orientations. The results reported in this paper show that load velocity and ply orientation have significant effect on the dynamic response, especially for those with [90]2s lay-up. For a fixed-fixed beam, the maximum mid-point deflection is observed when the total traveling time is equal to the first natural period of the beam.

Damped Response of Symmetric Laminated Composite Beams to Moving Load with Different Boundary Conditions

The aim of this study is to present the damped dynamic response of a symmetric laminated composite beam with different boundary conditions. A three-dimensional finite element model based on the classical laminated plate theory is used together with the Newmark integration method in order to obtain the dynamic response of the beam. A computer code written in MATLAB® was developed in order to perform the dynamic analyses. The proportional damping which is referred to as Rayleigh damping is employed in the dynamic analyses. The impulse, step and moving load responses of the composite beam are presented for different damping ratios. The effect of the damping ratio on the dynamic magnification value, which is defined as the ratio between the dynamic and static displacements calculated for the mid point of the beam, is investigated. The normalized time values at which the maximum mid-point displacements occur are presented. The results reported in this article show that the largest dynamic magnification values are recorded for a pinned—pinned beam and the dynamic magnification values decrease as the damping ratio increases.

Interior acoustics of a truck cabin with hard and impedance surfaces

Abstract Interior acoustics of a truck cabin is determined and the consequences of an attempt, which was performed with acoustic linings in order to improve the interior comfort, are presented. Acoustic field generated from the harmonic vibrations of the cabin floor panel was expressed by the Helmholtz integral equations. Numerical results were obtained by a computer code which was developed in Visual Basic programming language in order to solve the integral equations by using boundary element method. The effects of the linings on the levels and distributions of the sound pressure in the cabin are presented by means of the comparison of the results calculated from two different boundary conditions: hard wall and impedance wall.

Effect of Elastic Foundation on the Dynamic Response of Laminated Composite Beams to Moving Loads

The aim of this study is to present the dynamic behavior of a symmetric laminated composite beam with localized elastic supports. The dynamic response of a clamped—clamped composite beam to a moving point load with constant velocity is calculated by using the finite element method. A three-dimensional finite element model based on the classical lamination theory is used in order to define the structural stiffness. The Newmark integration method that is widely used in structural dynamics is employed in order to calculate the dynamic response of the beam. The finite element vibration analyses are performed by a computer program written in MATLAB. The dynamic magnification, which is defined as the ratio between the dynamic and the static displacements, is obtained for different load velocities, ply orientations, and spring locations. The effect of the spring number in the elastic foundation on the dynamic magnification is also investigated. The results reported in this article show that load velocity, ply orientation, and the location of the elastic support have significant effect on the dynamic response, especially for [45/-45] s and [90]2s lay-ups.

Experimental Investigation of the Dynamic Response of a Symmetric Laminated Composite Beam Via Laser Vibrometry

This article reports the experimental analysis of free and forced vibrations of a cantilever symmetric laminated composite beam with different lay-up sequences. The free vibrations generated due to initial displacements are recorded by two laser displacement sensors. The damping ratios for different ply orientations are determined by using the ratios between the successive peaks in the free vibration responses and the corresponding envelope curves. The dynamic response of the beam to a moving load with constant velocity is also investigated. The pressured air is blown out onto the beam to create the load and the movement of the load is achieved by an industrial robot manipulator. The moving load mechanism is peculiar to this study. The free and moving load responses are also examined by the finite element method. A commercial finite element package ANSYS® is used for numerical analyses. The results reported in this study show that the lay-up sequence has an important role on the dynamic response of the laminated composites and the velocity of the moving load affects the dynamic response considerably, especially for [90]2s lay-up.

Effect of interface crack on lateral buckling behavior and free vibration response of a sandwich composite beam

The aim of this study is investigation of the effect of interface crack on lateral buckling load and free vibration response of a sandwich composite beam using experimental methods and finite element solutions. The lateral buckling load and natural frequencies in a thin sandwich composite cantilever beam with crack were considered. The crack was opened between the face sheets and foam core. The length of the crack was selected, such as 100, 150, 200, and 250 mm. Lateral buckling and vibration tests were applied on these samples and then the critical lateral buckling load and natural frequencies were found using experimental and finite element method. In the experimental studies, in-house test mechanisms were used. For the numerical analysis, ANSYS finite element software was used. Close results were obtained between both two methods.

DYNAMIC ANALYSIS OF ELASTICALLY SUPPORTED CRACKED BEAM SUBJECTED TO A CONCENTRATED MOVING LOAD

This study deals with the dynamic behavior of a cracked beam subjected to a concentrated force traveling at a constant velocity. Dynamic analyses for a hinged-hinged cracked beam resting on elastic supports under the action of a moving load are carried out by the finite element method. For the beam having rectangular cross-section, element formulation for crack element is developed by using the principles of fracture mechanics. In the numerical analysis, Newmark integration method is employed in order to calculate the dynamic response of the beam. The effects of crack depth, crack location, elastic support and load velocity on the dynamic displacements calculated for different locations on the beam are investigated. The results related to the dynamic response of the beam are presented in 3D graphs.

Monitoring and Determination of Wind Energy Potential by Web Based Wireless Network

In this paper, we develop a web based interface which performs a wireless communication with ZigBee protocol for monitoring wind energy potential and also gathering custom reports for determination of the interested wind field. A custom printed circuit board layer is designed for interfacing with all the sensors that are in use. Web based interface is a product of responsive design for platform and device independency. This system enables scalable, accessible, reliable, low cost and low power consumption solution for renewable energy systems.

Harmonic response analysis of symmetric laminated composite beams with different boundary conditions

Abstract This study deals with the determination of the harmonic response of symmetric laminated composite beams by the finite element method. The structural stiffness of the composite beam is determined by the classical laminated plate theory. Four different ply orientations, namely, [0]2s, [0/90]s, [45/-45]s, and [90]2s are used to examine the effect of the stacking sequence on the harmonic response of the beam. Proportional damping is used to model the structural damping, and the damped harmonic responses of the composite beams are obtained to show the effect of the damping on the harmonic response. The effect of the boundary conditions on the harmonic response is also investigated. The displacement maps calculated for varying excitation points are obtained for different boundary conditions and damping ratios at different vibrational modes. The numerical results presented in this study show that the magnitudes of the harmonic response of the composite beam increase as the flexural rigidity decreases, and the vibration magnitudes reduce considerably with damping. The vibration patterns created for varying excitation and observation locations change as the damping ratio and excitation frequency change.