Shock and Vibration

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

List of Papers (Total 1,258)

Structural Damping with Friction Beams

In the last several years, there has been increasing interest in the use of friction joints for enhancing damping in structures. The joints themselves are responsible for the major part of the energy dissipation in assembled structures. The dissipated work in a joint depends on both the applied normal force and the excitation force. For the case of a constant amplitude excitation...

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...

Lessons Learned in Applying Accelerometers to Nuclear Effects Testing

Exoatmospheric nuclear effects, such as those that would be encounter by reentry bodies, provide instantaneous (near zero-duration), impulsive loading of structures. Endoatmospheric nuclear effects possess an impulse that is finite in duration, but whose rise time is still instantaneous. The commonality of these loadings is that they initiate waves propagating through structures...

Dynamic Instability of Pile-Supported Structures in Liquefiable Soils during Earthquakes

Piles are long slender columns installed deep into the ground to support heavy structures such as oil platforms, bridges, and tall buildings where the ground is not strong enough to support the structure on its own. In seismic prone zones, in the areas of soft soils (loose to medium dense soil which liquefies like a quick sand) piles are routinely used to support structures...

Reliability Analysis of Electronic Equipment Subjected to Shock and Vibration – A Review

Increasingly modern electronic equipment is expected to provide more functionality whilst still being able to withstand shock and vibration loads. The process of reliability prediction has been hampered by the complicated response and failure characteristics of electronic equipment, with the currently available methods being a compromise between accuracy and cost. A process to...

Control of 2D Flexible Structures by Confinement of Vibrations and Regulation of Their Energy Flow

In this paper, we investigate the control of 2D flexible structures by vibration confinement and the regulation of their energy flow along prespecified spatial paths. A discretized-model-based feedback strategy, aiming at confining and suppressing simultaneously the vibration, is proposed. It is assumed that the structure consists of parts that are sensitive to vibrations. The...

Design Optimization for Vibration Reduction of Viscoelastic Damped Structures Using Genetic Algorithms

Due to the large number of design variables that can be present in complex systems incorporating visco-elastic damping, this work examines the application of genetic algorithms in optimizing the response of these structures. To demonstrate the applicability of genetic algorithms (GAs), the approach is applied to a simple viscoelastically damped constrained-layer beam. To that end...

A Study on the Hybrid Mount against Vibration and Shock for Naval Ships

In naval ships, some methods or devices are acquired both to cut off the transmission of vibration from shipboard machineries and to protect them from external shock loading. One of the approaches is to install the passive mountings between machinery and a flexible supporting structure. More advanced performance has become necessary recently so far as at high frequencies in order...

Damping Prediction of Structures with Bolted Joints

Friction in joints significantly contributes to the observed overall damping of mechanical structures. Especially if the material damping is low, the frictional effects in joints and clamping boundary conditions dominate the structural damping. The damping and the stiffness of the structure are nonlinear functions of the system states and consequently of the excitation signal and...

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...

Modal Characteristics of Two Operating Power Transmission Poles

Unique conductor-pole couplings complicate the dynamic behaviors of electric transmission pole line systems. Finite element modeling is performed on two typical transmission poles used in southeastern USA – a steel pole and a prestressed concrete pole. The two poles are representative of unique structure types: a heavy rod-like structure and a lightweight, shell-type structure...

Particle Damping with Granular Materials for Multi Degree of Freedom System

A particle damper consists of a bed of granular materials moving in cavities within a multi degree-of-freedom (MDOF) structure. This paper deals with the damping effects on forced vibrations of a MDOF structure provided with the vertical particle dampers. In the analysis, the particle bed is assumed to be a single mass, and the collisions between the granules and the cavities are...

Simulation and Experimental Study on Vibration and Sound Radiation Control with Piezoelectric Actuators

FEM/BEM is adopted to model the interaction between the fluid and structures. In the modeling, modal truncation and inertial coupling are applied to sufficiently reduce the coupled model order. This approach is adopted for the purpose of constructing a modal model in the time domain. Active vibration control is realized with piezoelectric actuators and an adaptive method. In the...

Nonlinear Dynamic Analysis of an Inclined Timoshenko Beam Subjected to a Moving Mass/Force with Beam’s Weight Included

In this study, the nonlinear vibrations analysis of an inclined pinned-pinned self-weight Timoshenko beam made of linear, homogenous and isotropic material with a constant cross section and finite length subjected to a traveling mass/force with constant velocity is investigated. The nonlinear coupled partial differential equations of motion for the rotation of warped cross...

Detection and Estimation of Damage in Structures Using Imperialist Competitive Algorithm

This paper presents a method for detection and estimation of structural damage on the basis of modal parameters of a damaged structure using imperialist competitive algorithm. The imperialist competitive algorithm was developed over the last few years in an attempt to overcome inherent limitations of traditional optimize method. In this research, imperialist competitive algorithm...

Time-Varying Uncertainty in Shock and Vibration Applications Using the Impulse Response

Design of mechanical systems often necessitates the use of dynamic simulations to calculate the displacements (and their derivatives) of the bodies in a system as a function of time in response to dynamic inputs. These types of simulations are especially prevalent in the shock and vibration community where simulations associated with models having complex inputs are routine. If...

Analysis of Shearing Viscoelastic Beam under Moving Load

In this paper the dynamic behavior of a viscoelastic beam subjected to a moving distributed load has been studied analytically. The viscoelastic properties of the beam have been considered as the linear standard model in shear and incompressible in bulk. The stress components have been separated to the shear and dilatation components then, the governing equation in viscoelastic...

Improvement of Accuracy in Damage Localization Using Frequency Slice Wavelet Transform

Damage localization is a primary objective of damage identification. This paper presents damage localization in beam structure using impact-induced Lamb wave and Frequency Slice Wavelet Transform (FSWT). FSWT is a new time-frequency analysis method and has the adaptive resolution feature. The time-frequency resolution is a vital factor affecting the accuracy of damage...

Vibration Attenuation by a Combination of a Piezoelectric Stack and a Permanent Magnet

The present work proposes a non-contact vibration attenuator made up of a permanent magnet mounted on a piezoelectric stack. Two such actuators are made to work simultaneously in a 'twin-actuator

Uncertainty in Loading and Control of an Active Column Critical to Buckling

Buckling of load-carrying column structures is an important design constraint in light-weight structures as it may result in the collapse of an entire structure. When a column is loaded by an axial compressive load equal to its individual critical buckling load, a critically stable equilibrium occurs. When loaded above its critical buckling load, the passive column may buckle. If...

Experimental Dynamic Analysis of Nonlinear Beams under Moving Loads

It is well known that nonlinear systems, as well as linear time-varying systems, are characterized by non-stationary response signals. In this sense, they both show natural frequencies that are not constant over time; this variation has however different origins: for a time-varying system the mass, and possibly the stiffness distributions, are changing over time, while for a...

Improved Riccati Transfer Matrix Method for Free Vibration of Non-Cylindrical Helical Springs Including Warping

Free vibration equations for non-cylindrical (conical, barrel, and hyperboloidal types) helical springs with noncircular cross-sections, which consist of 14 first-order ordinary differential equations with variable coefficients, are theoretically derived using spatially curved beam theory. In the formulation, the warping effect upon natural frequencies and vibrating mode shapes...

Liquid Self-Balancing Device Effects on Flexible Rotor Stability

Nearly a century ago, the liquid self-balancing device was first introduced by M. LeBlanc for passive balancing of turbine rotors. Although of common use in many types or rotating machines nowadays, little information is available on the unbalance response and stability characteristics of this device. Experimental fluid flow visualization evidences that radial and traverse...

The Study on Free Vibration of Elastically Restrained Beams Carrying Various Types of Attachments with Arbitrary Spatial Distributions

The flexible beams carrying attachments often appear in engineering structures, modal analysis of those structures is important and necessary in structural design. This manuscript develops a proposed analytical method as a general tool for solving the free vibration of varying cross-section beams carrying various types of attachments with different distributions and arbitrary...

Damage Identification in Bars with a Wave Propagation Approach: Performance Comparison of Five Hybrid Optimization Methods

The formulation and solution of the inverse problem of damage identification based on an one-dimensional wave propagation approach are presented in this paper. Time history responses, obtained from pulse-echo synthetic experiments, are used to damage identification. The identification process is built on the minimization of the squared residue between the synthetic experimental...