Applied Mechanics and Materials Vols. 592-594

Abstract: A numerical investigation is performed to study the free vibration responses of a width tapered composite beam. The finite element simulation is performed to investigate the effect of taper angle along the longitudinal plane of the beam on the free transverse vibration responses. Experimental investigations are also performed to demonstrate the effectiveness of the developed finite element formulation (FEM) in identifying the free vibration responses of the uniform and tapered composite beam. Further, various parametric studies are performed to investigate the effect of taper angle and boundary conditions on natural frequencies of the uniform and tapered composite beams. It is shown that the natural frequencies of the taper configurations at all the modes considered are higher than those obtained from the uniform composite beam. It is concluded that the stiffness of the composite structures could be tailored according to the requirement by changing the taper angle of the composite along longitudinal plane to obtain the desired natural frequencies.

Abstract: Structural vibrations problems presents a major hazard and design limitation for a wide range of engineering problems. A comprehensive study of vibration phenomena includes determining the nature and extent of vibration response levels. This paper focuses in determining suitability of composite material in replacement of metallic material for assessing the dynamic characteristics of the blade. This study reviews the natural frequencies and associated mode shapes for a pre twisted composite propeller blade for marine applications. MAB and composite are used .composite with symmetric and balanced stacking sequence were analyzed. From the results it can be concluded that by further changing the layup sequence composite materials can be made much stiffer than MAB propeller.

Abstract: A Hydraulic circuit is a group of components such as pumps, actuators, and control valves so arranged that they will perform a useful task. When analyzing or designing a hydraulic circuit, the following three important considerations must be taken into account.Safety of operation,Performance of desired function, Efficiency of operation.It is very important for the fluid power ( Hydraulics and Pneumatics ) designer to have a working knowledge of components and how they operate in a circuit. Hydraulic circuits are developed through the use of graphical symbols for all components. Keywords: damper,hydraulic circuit,

Abstract: The paper summarizes a complete analysis about vibrational characteristics of a spinning simply supported cracked shaft with fluid medium at finite region. The damping effect occurs due to external fluid is integrated in the existing analysis, with the help of navier - stokes equation. The simply supported cracked shaft is analyzed by the influence coefficient strain energy method. Here we have changing the parameter of shaft i.e. damping viscosity of fluid and the length of the shaft which accountable for the alteration of the amplitude of vibration.

Abstract: The objective of the study is to measure the whole body vibration (WBV) transmitted to the driver as well as the passengers during the operation of bus and to compare results with ISO 2631-1(1997) comfort chart and health guidance criteria. In this study, vibration exposure of the driver, passenger in the mid row seat and passenger in the rear row seat were measured at different operating conditions (static and dynamic). The BMI (Body Mass Index) was maintained for driver and passengers. The results of static test showed that the driver seat produced more vibrations compared to the passenger's mid row and rear row seat. This is due to the fact that driver seat was positioned close to the engine cabin. The results of dynamic test showed that, in all cases, the rear seat produced maximum vibrations. At 40 km/h speed the vibration magnitude exceeded the exposure limit at all tested seats. This high vibration magnitude might be due to the resonance effect caused between engine and chassis vibrations.

Abstract: The constitutive equations of MEE materials are used to derive the finite element equations involving the coupling between mechanical, electrical and magnetic fields. The candidate materials for this study are piezoelectric (BaTiO₃) and magnetostrictive (CoFe₂O₄) material. The linear buckling and vibration behavior of layered MEE beam under uniform magnetic field is carried out using finite element method. The present study is limited to clamped-clamped boundary conditions. The influence of stacking sequences and piezoelectric coupling on critical buckling magnetic field and vibration behaviour is investigated.

Abstract: This paper deals with two frequency parametric excitation in presence of internal resonance. The cubic nonlinearity is inserted into the equation of motion by considering the mid-line stretching of the beam. The perturbation method of multiple scales is applied directly to the governing nonlinear fourth order integro-partial differential equation of motion. This leads to a set of first order differential equations known as the reduced equations or normalized reduced equations, which are utilized to determine the additional instability zones, appeared in the trivial state stability plot, the bifurcation and stability of fixed-points, periodic, quasi-periodic, mixed mode and chaotic responses. The transition of system behaviour from stable periodic to unstable chaotic occurs through intermittency route

Abstract: A simple and robust methodology is presented to identify damages in a structure using changes in vibration data. A comparison is made among damage indicators such as natural frequencies, mode shape data, curvature damage factors and flexibility matrices to study their efficacy in damage assessment. Continuous ant colony optimization (ACO_R) technique is used to solve the inverse problem related to damage identification. The outcome of the simulated results demonstrates that the flexibility matrix as a damage indicator provides better damage identification.

Abstract: s: In this article, results of an analysis is investigated by using a data mining tool called ‘SPSS’, to identify the flow characteristics and response of an elastically mounted circular cylinder at different interference conditions. Numerical investigation is performed on a range of longitudinal gap ratios (2.0 ≤ L/D ≤ 4) and transverse gap ratios (2.0 ≤ T/D ≤ 4) between the cylinders arranged in tandem and staggered configuration. The effects of the interference cylinders were analyzed at specific relative positions were observed and it has been identified that the parameters, reduced velocity (U/fD) and relative positions were significantly influences the flow induced vibration excitation. Hence, in this article, an accent is laid on the efficient of ‘SPSS Tool’ for analyzing the results of flow induced vibration excitation in an elastically mounted circular cylinder at different interference conditions. From the results, it is observed that, reduced velocity must be lesser than the threshold value and also the observed that the relative positions (spacing ratios) is playing a significant role when compared to the reduced velocity. Further, the results shows that, at the fluid flow characteristics of elastically mounted circular cylinder in staggered arrangement with two interfering cylinders in upstream conditions the oscillatory amplitude ratio (A/D=0.250) is found to be minimum.

Abstract: This work employs the wavelet transform for reading the fault diagnosis in a rotor-bearing system. Initiating with literature review with some relevant studies of bearing fault and the signal processing techniques used followed by the theory of wavelet transform. A bearing test rig is shown which is used for implementing wavelet transform. A faulty bearing vibration signal is measured from the test rig; thereafter the fast Fourier transform is plotted to show the critical frequencies, bearing characteristics frequency and its harmonics. A scalogram showing the energy levels of signal is plotted as result. Faulty signal is analyzed using wavelet transform.