Reduction Of Vibration Response Research Articles

Vibration response analysis and hoop layout optimization of spatial pipeline under random excitation

PurposeIn many cases, the external pipelines of aero-engine are subjected to random excitation. The purpose of this paper is to reduce the vibration response of the pipeline system effectively by adjusting the hoop layout.Design/methodology/approachIn this paper, a spatial pipeline supported by multi-hoops is taken as the object, the methods of solution of the vibration response of the pipeline system by using pseudo excitation and hoop layouts optimization with amplitude reduction of vibration response as the goal are presented. First, the finite element model of the spatial pipeline system is presented. Then, an optimization model spatial pipeline is established. Finally, a case study is carried out to prove the rationality of the random vibration response analysis of the pipeline system. Furthermore, the proposed optimization model and genetic algorithm are applied to optimize the hoop layout.FindingsThe results show that the maximum response variance after optimization is reduced by 32.8%, which proves the rationality of the developed hoop layout optimization method.Originality/valueThe pseudo excitation method is used to solve the vibration response of aero-engine pipeline system, and the optimization of the hoop layout for aero-engine spatial pipelines under random excitation to reduce random vibration response is studied systematically.

Use of viscoelastic material and design parameter optimization for optimum reduction of vibration response of primary system

Studies on vibration responses of a beam (both ends fixed) with a cantilever as absorber have been carried out. The objective is to generate the theoretical model to optimally control the beam vibrations using viscoelastic material and find the optimum parameters for the same. Constrained and unconstrained damping treatments are considered in this model. Theoretical model using different theories have been reported. Experiments have been conducted to validate the theoretical model and the results have been compared with the theoretical result. The theoretical and experimental, results depict that the use of viscoelastic material for damping of absorber system gives optimum reduction of vibration responses of main system. It is also found that the working frequency range between two resonant frequencies in the case of constrained treated absorber system is wider than in the case of absorber without damping and unconstrained treated absorber system.

Experimental Investigations and Numerical Simulations of the Vibrational Performance of Wood Truss Joist Floors with Strongbacks

This paper provides an experimental study and computer modeling analysis of vibration performance of full-scale wood truss joist floors, related to the static deflection and vibration mode/frequency and single-person-induced vibration. The vibration behavior of full-scale truss joist floors was investigated and the influences of the strongbacks on the vibration behavior were assessed. The results showed that the simulated predictions agreed well with the measured results. Strongbacks do not significantly affect the fundamental frequency of the truss joist floors but influence the second and third modal frequencies. The use of strongback rows at mid-span effectively decreased the maximum deformation of point loading at floor center. The effect of adding strongbacks at one-third of each span on decreasing maximum deformation at the floor center was minimal. The case of walking parallel to the joist produced higher acceleration response at the floor center than that of walking perpendicular to the joist. The closer the placements of strongbacks were to the mid-span, the more significant reduction of the vibration at floor center was. Two strongback rows at mid-span performed the best effect on reduction of vibration response at floor center. However, the use of strongbacks had limits of reduction peak acceleration of the sheathing between the joists. The study provides a valuable guide for future vibration serviceability study and design optimization of wood truss joist floors.

Parametric Study on Vibration Response for Automobile Crankshaft

In the interest of utilized more stable automobile components at high speed for reduction the vibration of mechanical system, dynamic characteristics analysis plays a vital role in complex mechanical parts. Factors influencing on the level of vibration response were determined and optimized by the approach of experimental design. Based on golbal and local proerties of crankshaft structural properties, it was found that main journal diameter and Young’s modulus were recommended as inital values. Modification of crankshaft structure was performed carefully with the aspect of compatitablity for engine equipment. The reduction of vibration response was achieved and structure resonance has been shifted toward higher frequency domain. This approach proposed for the optimizing the structural parameters and would provide potential value basis to qualitative measure of parameters and determination of optimized structure.

Experimental and Numerical Investigation of Engine Foundation for Vibration Reduction

<p>The purpose of this study is to minimise frequency response of engine foundation using topology optimisation. The study involves vibration response estimation of an existing marine engine foundation, validation of estimations with measurements and estimation of reduction in vibration response after optimisation. Initially, solid model of baseline model is generated using dimensions of the existing foundation measured by a laser line probe coordinate measuring machine. Harmonic analysis is used to find the vibration response of the foundation. These results are experimentally validated by the measurements on the foundation using the vibration testing. Frequency response topology optimisation is then carried out on the baseline model to reduce vibration response with specified constraints and objective function. Subsequently, harmonic analysis is performed on the topology optimised design to verify the reduction in vibration response. From these results, it is observed that considerable frequency response is reduced with modified design compared to baseline model.</p>

Reduction of vibration response of structures to earthquake by inertial mass damper

Reduction of vibration response of structures to earthquake by inertial mass damper

Experimental study of sound radiation by plates containing circular indentations of power-law profile

In this paper, the results of the first experimental investigation into sound radiation of rectangular plates containing tapered indentations of power-law profile are reported. Such tapered indentations materialise two-dimensional acoustic black holes for flexural waves in plates that result in absorption of a large proportion of the incident wave energy. A multi-indentation plate was compared to a plain reference plate of the same dimensions, and the radiated sound power was determined according to ISO 3744. It was demonstrated that not only do such multiple indentations provide substantial reduction in the damping of flexural vibrations within the plates, but also cause a substantial reduction in the radiated sound power. As the amplitudes of the flexural vibrations of a plate are directly linked to the amplitudes of radiated sound from the same plate, this paper also considers the effect of redistribution of the amplitude of the plate’s response due to the presence of acoustic black holes on the amplitudes of the radiated sound. The results show that, in spite of some increase in the amplitudes of the displacements at the centres of black holes (circular indentations), the overall reduction of vibration response over the plate is large enough to cause a substantial reduction in the resulting sound radiation from plates containing indentations of power-law profile.

Vibration response of exposed gas pipeline placed to temporary structure

In this study, the vibration responses of exposed gas pipelines that are subject to vehicle loads are quantitatively estimated through experimental and analytical methods. To achieve this, a term here after called Scaled Weight (SW), which is a multiplication of the weight and the velocity of the testing vehicles, was defined, and vibration response equation using thisSW as a source of vibration was suggested. According to the equation, practitioners and researchers can decide anSW that satisfies vibration criteria. Furthermore, the isolation devices that can reduce the vibration response of gas pipelines placed to temporary structure and a set of systems that can quantify the reduction of vibration response were suggested.

Laser effects on the dynamic response of laminated composites

Transient response of a moving composite laminate suddenly subjected to combined mechanical load and high intensity laser irradiation was investigated. The three thermal effects, which are caused by rapid laser heating and influence the structure's dynamic behavior, are material property degradation, burn-out and induced thermal loading. To determine temperature distribution and material burn-out due to the high laser energy deposition, a modified Crank-Nicholson finite difference scheme, which includes the effects of surface ablation, degradation of thermophysical properties at elevated temperatures and heat losses from radiation and convection, was employed. The predicted thermal results were then used for thermal loading calculation and, subsequently, forced vibration analysis. Both small and large deflection composite plate theories were adopted. The inclusion of temperature-dependent mechanical properties in the analysis was also of particular importance. It was shown that the escalation or reduction of vibration response of a laminated composite subjected to transverse loads by laser irradiation depends not only upon the laser intensity, but also, which plate surface is irradiated. It was also found that a higher power laser irradiation ensures neither greater escalation not reduction of the vibration.

Active acceleration canceling for directional hydrophones

Directional transducers which are suspended from surface floats or moorings are subjects to suspension cable strumming and flow induced vibration. These inputs can mask the desired acoustical signals at low frequencies. A dynamic acceleration canceling system which senses case vibration and removes its response from the output of the acoustical sensor has been developed and tested. A reduction of vibration response by 14 dB has been measured in the laboratory with an additional acoustic sensitivity increase of 1 to 2 dB. The system comprises a simple piezoelectric accelerometer and associated electronics in addition to the usual hardware associated with the acoustic sensor. It can be used with any direct acting acoustic transducer scheme but not with geophone-type hydrophones.