Shock and Vibration

https://www.hindawi.com/journals/sv/

List of Papers (Total 989)

Far-Field Power Transmissions in Orthotropic Plates: A New Approach

The structural intensity (SI) technique is an essential tool for locating and ranking vibration sources and sinks on structures. It can quantify vibration fields by plotting a vector map of energy transmission on the structures. In this paper, a different strategy, changing coordinate systems of plate equations, is used to develop an intensity equation from shear force components...

Structural Damage Detection Using Energy Flow Models

The presence of a crack in a structure modifies the energy dissipation pattern. As a consequence, damaged structures can present high localized damping. Experimental tests have revealed that crack nucleation and growth increase structural damping which makes this phenomenon useful as a damage locator. This paper examines the energy flow patterns caused by localized damping in...

Simple Models for the Dynamic Modeling of Rotating Tires

Large Finite Element (FE) models of tires are currently used to predict low frequency behavior and to obtain dynamic model coefficients used in multi-body models for riding and comfort. However, to predict higher frequency behavior, which may explain irregular wear, critical rotating speeds and noise radiation, FE models are not practical. Detailed FE models are not adequate for...

New Approach for the Analysis of Damped Vibrations of Fractional Oscillators

The dynamic behavior of linear and nonlinear mechanical oscillators with constitutive equations involving fractional derivatives defined as a fractional power of the operator of conventional time-derivative is considered. Such a definition of the fractional derivative enables one to analyse approximately vibratory regimes of the oscillator without considering the drift of its...

Numerical and Experimental Study on Integration of Control Actions into the Finite Element Solutions in Smart Structures

Piezoelectric smart structures can be modeled using commercial finite element packages. Integration of control actions into the finite element model solutions (ICFES) can be done in ANSYS by using parametric design language. Simulation results can be obtained easily in smart structures by this method. In this work, cantilever smart structures consisting of aluminum beams and lead...

Hybrid Secondary Suspension Systems

Passive fluid mounts are used in the fixed wing applications as engine mounts. The passive fluid mount is placed in between the engine and the fuselage to reduce the cabin's structure- borne noise and vibration generated by the engine.

Transient Response of Partially-Bonded Sandwich Plates Subject to Underwater Explosions

This paper investigated the influence of interfacial bonding on the transient response of sandwich plates subject to underwater explosions. It was found that un-bonded sandwich plates receive lower impact energy, and are able to dissipate more energy through plastic deformation of the foam core, than perfectly bonded plates. Consequently, interfacial de-bonding leads to lower net...

Analytical Stationary Acoustic Wave in a Liquid over Which a Moving Pressure Runs

This paper presents an analytical study of the stationary response of a liquid loaded on its free surface by an ideal pressure step moving in a constant direction at a constant velocity. The acoustic pressure in the liquid is found, in four different examples, by means of the Fourier Transform. Two loading regimes are considered; subsonic and supersonic. Two configurations of...

Some Remarks on Experimental Estimation of Damping for Seismic Design of Civil Constructions

Experimental estimation of damping is currently not a comprehensively solved problem. Although modal frequencies and mode shapes can be measured confidently and quite easily by means of dynamic tests on civil structures, an accurate identification of damping ratios needs further development. Experimental values can be characterized by large error bounds mainly because damping is...

Dynamical Response of a Multi-Laminated Periodic Bar: Analytical, Numerical and Experimental Study

This article presents a study on the use of the dynamical response of multi-laminated periodic bars to create resonance band gaps within useful frequency ranges. The objective is to control, in a passive form, the longitudinal vibration transmissibility in specific and wide enough frequency ranges of interest. This is achieved by the separation of two adjacent eigenfrequencies. A...

Free Vibration Analysis of Composite Plates via Refined Theories Accounting for Uncertainties

The free vibration analysis of composite thin and relatively thick plates accounting for uncertainty is addressed in this work. Classical and refined two-dimensional models derived via Carrera's Unified Formulation (CUF) are considered. Material properties and geometrical parameters are supposed to be random. The fundamental frequency related to the first bending eigenmode is...

Free Vibration and Stability of Axially Functionally Graded Tapered Euler-Bernoulli Beams

Structural analysis of axially functionally graded tapered Euler-Bernoulli beams is studied using finite element method. A beam element is proposed which takes advantage of the shape functions of homogeneous uniform beam elements. The effects of varying cross-sectional dimensions and mechanical properties of the functionally graded material are included in the evaluation of...

Identification of Flap Motion Parameters for Vibration Reduction in Helicopter Rotors with Multiple Active Trailing Edge Flaps

An active control method utilizing the multiple trailing edge flap configuration for rotorcraft vibration suppression and blade loads control is presented. A comprehensive model for rotor blade with active trailing edge flaps is used to calculate the vibration characteristics, natural frequencies and mode shapes of any complex composite helicopter rotor blade. A computer program...

Dynamic Stress and Displacement in an Elastic Half-Space with a Cylindrical Cavity

The dynamic response of an elastic half-space with a cylindrical cavity in a circular cross-section is analyzed. The cavity is assumed to be infinitely long, lying parallel to the plane-free surface of the medium at a finite depth and subjected to a uniformly distributed harmonic pressure at the inner surface. The problem considered is one of plain strain, in which it is assumed...

Fault Diagnosis in Industrial Systems Based on Blind Source Separation Techniques Using One Single Vibration Sensor

In the field of structural health monitoring or machine condition monitoring, most vibration based methods reported in the literature require to measure responses at several locations on the structure. In machine condition monitoring, the number of available vibration sensors is often small and it is not unusual that only one single sensor is used to monitor a machine. The aim of...

Optimal Design and Control of Mechanical Systems with Uncertain Input

This paper presents an integrated approach to optimize for design and control of mechanical systems with random input parameters. Random parameters are represented by probability density functions. A numerical technique defining directly the representative values and the associated probabilities is implemented by modeling the stochastic parameters as generalized Wiener processes...

He’s Variational Iteration Method for Nonlinear Jerk Equations: Simple but Effective

The variational iteration method (VIM) for determining periodic solutions of non-linear jerk equations involving third-order time-derivative is presented. This method is based on the use of Lagrange multipliers for identification of optimal value of a parameter in a functional. We propose first-order approximate VIM solution for this equation and we compare this solution with the...

An Improved Beam Element for Beams with Variable Axial Parameters

The traditional beam element was improved to consider the variable axial parameters. The variable axial parameters were formulated in terms of a power series, and the general forms of elementary mass and stiffness matrices which depend on the power order were derived. The mass and stiffness matrices of the improved beam element were obtained in terms of an elementary matrix...

Multi-Fault Feature Extraction and Diagnosis of Gear Transmission System Using Time-Frequency Analysis and Wavelet Threshold De-Noising Based on EMD

gear transmission system is a complex non-stationary and nonlinear time-varying coupling system. When faults occur on gear system, it is difficult to extract the fault feature. This paper researches the threshold principle in the process of using the wavelet transform to de-noise the system, and combines EMD (empirical mode decomposition) with wavelet threshold de-noising to...

Study on Dynamic Characteristics of Aerostatic Bearing with Elastic Equalizing Pressure Groove

Microvibration has an important influence on the dynamic performance of aerostatic bearings. Dynamic stiffness and equivalent damping coefficient are the main indexes to evaluate the dynamic characteristics of the aerostatic bearing. In order to study the dynamic characteristics of a new type of aerostatic bearing with the elastic equalizing pressure groove (EEPG), the dynamic...

Global Sensitivity Analysis of the Vibration Reduction System with Seated Human Body

The paper deals with the global sensitivity analysis for the purpose of shaping the vibroisolation properties of suspension systems under strictly defined operating conditions. The variance-based method is used to evaluate an influence of nonlinear force characteristics on the system dynamics. The proposed sensitivity indices provide the basis for determining the effect of key...

Investigation of Energy Mechanism and Acoustic Emission Characteristics of Mudstone with Different Moisture Contents

Characteristics of energy accumulation, evolution, and dissipation in conventional triaxial compression of mudstones with different moisture contents were explored. Stress-strain relations and acoustic emission (AE) characteristics of the deformation and failure of rock specimens were analyzed. The densities and rates of stored energy, elastic energy, and dissipated energy under...

Parameter and State Estimation of Shear Buildings Using Spline Interpolation and Linear Integral Filters

A parameter identification method and a high gain observer are proposed in order to identify the model and to recover the state of a seismically excited shear building using acceleration responses of the ground and instrumented floors levels, as well as the responses at noninstrumented floors, which are reconstructed by means of cubic spline shape functions. The identification...

Composites Bond Inspection Using Heterodyne Effect and SuRE Methods

With increasing utilization of the composite materials in commercial and military applications, the longevity of composite bonds has become a crucial concern of the aerospace industry. In spite of the previous studies in the literature for characterization of bonding condition in composite materials, implementation of more advanced structural health monitoring (SHM) techniques...

Hybrid Filtered-x Adaptive Vibration Control with Internal Feedback and Online Identification

Active control is an effective way to suppress low-frequency mechanical vibration. However, with applications to submarine equipment, there are still some shortcomings due to vibration coupling and multifrequency complex excitation. In this paper, a novel hybrid improved adaptive control strategy, feedback and online identification filtered-x LMS, namely, FOFxlms, is proposed...