Vibration Of Column Research Articles

Semi-active omnidirectional liquid column vibration absorber with rapid frequency adjustment capability

This paper explores the semi-active omnidirectional liquid column vibration absorber, a unique tuned liquid column damper consisting of multiple circularly distributed columns for the control of vibrations in all lateral directions. Each column features actuator-controlled cells that can trap liquid and adjust column cross-sections, facilitating a rapid shift in natural frequency during operation. Unlike previous semi-active tuned liquid column dampers, this design can modulate its natural frequency without altering the total liquid mass and eliminate the need for overpressure or additional springs. Validation is conducted on a full-scale omnidirectional prototype. However, the trapped liquid mass plays a crucial role in determining the damper’s optimal tuning parameters and affects the resulting restoring force, emphasizing its significance in the design process. This research introduces a comprehensive mathematical model of the absorber, accompanied by a control algorithm, and proposes a corresponding design approach. Moreover, a shape function informed by experimental damping is developed to address complexities arising from geometry and cell arrangements. The focus of the study is the lateral vibration control of high-rise civil engineering structures. Numerical and experimental analyses demonstrate the superior adaptability of the absorber to fluctuating structural properties, marking a significant improvement over its passive counterpart in various loading scenarios.

Full-field Modal Analysis of a Tensegrity Column Using a Three-dimensional Scanning Laser Doppler Vibrometer with a Mirror

Abstract Tensegrity structures become important components of various engineering structures due to their high stiffness, light weight, and deployable capability. Existing studies on their dynamic analyses mainly focus on responses of their nodal points while overlook deformations of their cable and strut members. This study proposes a non-contact approach for experimental modal analysis of a tensegrity structure to identify its three-dimensional (3D) natural frequencies and full-field mode shapes, which include modes with deformations of its cable and strut members. A 3D scanning laser Doppler vibrometer is used with a mirror for extending its field of view to measure full-field vibration of a novel three-strut metal tensegrity column with free boundaries. Tensions and axial stiffnesses of its cable members are determined using natural frequencies of their transverse and longitudinal modes, respectively, to build its theoretical model for dynamic analysis and model validation purposes. Modal assurance criterion (MAC) values between experimental and theoretical mode shapes are used to identify their paired modes. Modal parameters of the first 15 elastic modes of the tensegrity column identified from the experiment, including those of the overall structure and its cable members, can be classified into five mode groups depending on their types. Modes paired between experimental and theoretical results have MAC values larger than 78%. Differences between natural frequencies of paired modes of the tensegrity column are less than 15%. The proposed non-contact 3D vibration measurement approach allows accurate estimation of 3D full-field modal parameters of the tensegrity column.

The reasonableness and feasibility of replacing standing wave vibration with air piston mode vibration in thermoacoustic refrigerator

On the basis of analyzing the longitudinal forced vibration of the gas column in the resonator of a half-wavelength standing wave thermoacoustic refrigerator, the idea of replacing the standing wave vibration with the first-order piston mode vibration of the gas column in the thermoacoustic refrigerator was proposed, so as to increase the vibration amplitude of the gas in the resonator, realize the large alternating flow of gas, and improve the working efficiency of the thermoacoustic refrigerator. At the same time, its rationality and feasibility are discussed from the aspects of modal vibration, pressure distribution of gas column piston, and temperature variation of gas microcluster vibration in equilibrium position. Combined with the existing research results, the superiority of the application of the first-order piston mode vibration of the gas column in the thermoacoustic refrigerator is further explained. The results provide a new research idea and direction for further reducing the cold end temperature of thermoacoustic refrigerator.

Transverse Free Vibration of Pre-stressed Heavy Columns Laminated from Two-Hybrid Materials with Circular Cross-Section

Transverse Free Vibration of Pre-stressed Heavy Columns Laminated from Two-Hybrid Materials with Circular Cross-Section

Review on Energy Harvesting from Wind-Induced Column Vibrations: Theories, Mechanisms, and Applications

This paper presents an extensive review of energy harvesting from the column vibrations of wind turbines under the influence of wind. The study investigates the underlying theories, mechanisms, and potential applications of such a system. By tapping into the vibrational energy otherwise dissipated in wind turbines, the study proposes an innovative approach to enhance renewable energy generation. Furthermore, the potential benefits of the technology, such as powering remote sensors, vibration damping, structural health monitoring, and increasing wind turbine efficiency and lifespan, are discussed. While the study acknowledges the promise of such an approach, it also emphasizes the need for further research to optimize and integrate these systems effectively into the renewable energy landscape.

RETRACTED: Using the method of differential equations by quadratic to solve the free vibrations of columns under the effect of axial load and column weight

This paper investigates various techniques used to solve the differential equations governing the free vibration of columns. The present work focuses on the study of the free vibration of Euler’s Bernoulli column of equal strength in compression, considering its own weight and the axial load in compression and tension while subjected to symmetrical boundary conditions. The investigation utilizes the differential quadrature method to examine the fifth natural frequency parameters of the column in different states of column boundary conditions and varying geometric section shapes, including pin-pin and clamp-clamp configurations. The results of this work contribute valuable insights for informed decisions on selecting the cross-section types and appropriate boundary conditions for ensuring the stability of such columns in civil constructions.

Method for Simulating the Anti-Damage Performance of Consolidation Soil Balls at the Roots of Seedlings during Transportation Using Consolidated Soil Columns.

In the process of landscaping or afforestation in challenging terrain, in order to improve the survival rate of transplanted seedlings, it is necessary to transplant seedlings with a mother soil ball attached. During transportation, the soil ball at the root of the seedlings is very susceptible to breakage due to compression, bumps, and collisions. In order to ensure the integrity of the soil ball of the transplanted seedlings and improve the survival rate of seedlings, a method of chemically enhancing the soil surface strength was employed. Specifically, a polymer-based soil consolidating agent was used to solidify the root balls of the seedlings. To examine the abrasion resistance performance of the soil balls formed by consolidating the surface with polymer adhesive during the transportation process, we utilized a polymer-based consolidating agent to prepare test soil columns and developed a method to simulate the damage resistance performance of seedling root balls during transportation using these soil columns. The method primarily encompasses two aspects of testing: compressive strength testing of the consolidated soil columns and resistance to transportation vibration testing. The first method for testing the resistance to transportation vibration of the consolidated soil columns is a combination test that includes three sets of tests: highway truck transportation vibration testing, combined wheel vehicle transportation vibration testing, and impact testing. Although the method is cumbersome, testing is more accurate. The second method for testing the resistance to transportation vibration of the consolidated soil columns involves simultaneously testing multiple consolidated soil columns using a simulated transportation vibration test platform. The testing method is concise and efficient, and the test results are more intuitive. The combined assessment of the resistance to transportation vibration and compressive strength testing of the consolidated soil columns allows for a comprehensive evaluation of the soil columns' resistance to damage during transportation. This study mainly provides a quick and effective method for detecting the damage resistance of consolidated soil columns/balls during transportation, providing technical support for the application of polymer-based consolidation agents in the field of seedling transplantation.

Vibrations of columns in the thermal postbuckling state accounting for temperature effect on material properties

The article is concerned with natural frequencies of thermally buckled columns. The analysis accounts for the effect of temperature on the modulus of elasticity and the coefficient of thermal expansion of the material of the column. The columns are simply supported and two cases of axial boundary conditions include an elastic axial constraint and prescribed axial displacements. It is demonstrated that neglecting the effect of temperature on material properties leads to a significant quantitative mistake at low temperatures and a qualitative mistake at high temperatures. In flexible columns with axially constrained boundaries subject to a prescribed thermal loading the frequencies increase with an increasing temperature, but this trend is reversed at high temperatures due to the sharp drop of the modulus of elasticity. In the contrary, in the columns subject to a prescribed axial displacement in addition to thermal loading, frequencies remain relatively stable and subsequently decrease at high temperatures. It is demonstrated that the frequencies of columns with a low or moderate slenderness ratio are affected by the axial constraint to a much larger degree than those in more flexible columns.

An efficient three-dimensional dynamic stiffness-based model for predicting subway train-induced building vibrations

The prediction of train-induced vibration in buildings constructed above the subway is a challenging problem due to its sophisticated system and time-consuming calculation. This paper proposes an efficient three-dimensional (3D) dynamic stiffness-based model (DSM) to predict subway train-induced building vibrations. The DSM has the capability to analytically explore the axial, bending, and torsional vibrations of columns and beams, as well as the flexural and in-plane vibrations of floors and walls induced by the moving train, which few studies have focused on before, and has high computational efficiency compared to the traditional finite element method (FEM). In the DSM, the dynamic stiffness matrices of floors, walls, columns and beams are formulated by the stiffness theory firstly. Then, the global dynamic stiffness matrix of the building is determined following an assembly procedure and the vibration responses of the building can be calculated by the dynamic stiffness equation in the frequency domain. Further, the calculation accuracy and efficiency of the DSM are validated by comparison with a 3D finite element model. Finally, the DSM is used to predict the train-induced vibrations of a building constructed at a subway station based on a subway train-slab track coupled dynamics model. Results show that the building vibrations induced by the moving train are significant in both vertical and horizontal directions and the steel-spring floating-slab track can effectively suppress the train-induced building vibrations.

Influence of the specific load on stability and vibrations of the multimember column with internal cracks

Influence of the specific load on stability and vibrations of the multimember column with internal cracks

METHODS, MEANS AND TECHNOLOGY OF VIBRATION DIAGNOSTICS OF MAIN GAS PIPELINES SUBJECT TO STRESS CORROSION CRACKING

Computational and experimental methods, tools and technology for monitoring the technical condition of main gas pipelines during their underground laying according to the parameters of technological and geodynamic vibrations are proposed. To identify potentially hazardous (risk-sensitive) sections of main gas pipelines, the parameters characterizing the microseismic field directly above the gas pipeline routes, the energy forms of natural acoustic vibrations of the natural gas column of the gas pipeline section, the natural frequencies of the pipe of the gas pipeline section as a beam/shell and the soil containing it are used. The results obtained make it possible to reduce operating costs.

Omnidirectional liquid column vibration absorbers for multi-story buildings

With non-identical cross sections, liquid column vibration absorbers (LCVAs) have expanded the versatility of tuned liquid column dampers (TLCDs) that are well-known vibration control devices in alleviation of resonant vibrations. In comparison, LCVAs present natural frequencies and control forces in wider ranges. However, LCVAs still suffer from unidirectionality so that their performance deteriorates when the resultant excitation deviates from their axis. This paper introduces an omnidirectional class of LCVAs, so called O-LCVAs, that have n (integer n ≥ 3 ) number of liquid columns with non-identical cross sections. Based on the Euler–Lagrange equation, the theory for application of multiple O-LCVAs in control of multi-story building structures with translational degree of freedoms (DoFs) in plane are developed. O-LCVAs can be set in any arbitrary orientations and attached to the same or different DoFs on the floors. A formal solution to involve excitations in disparate directions in the equation of motion is introduced. A designing process is proposed for multiple O-LCVAs tuned to multiple structural modes. The coupled control system is represented in state-space, employed in the simulation of a multi-story building exposed to a set of load cases including harmonic and seismic loadings. Additional study is conducted to investigate the role of distribution of multiple dampers when the liquid mass is the same. Moreover, experiments are carried out to verify the mathematical model. Investigations show the dynamic characteristics and the control performance of O-LCVAs are independent from the orientations of the dampers, which brings useful flexibility, for example, in limited architectural spaces. Consequently, O-LCVAs with random orientations can be tuned to resonant modes optimally and control them regardless of the excitation direction. Thanks to omnidirectionality, O-LCVAs can also detect the direction of resultant excitation like a physical sensor. • Omnidirectional liquid column vibration absorber (O-LCVA) is introduced. • The analytical model is derived for multi-story buildings. • The state-space formulation and a parameter optimization scheme are provided. • Experimental studies are conducted for the validation of the theory. • Control performance of multiple O-LCVAs is investigated numerically.

An experimental study on the damping characteristics and tuning of the liquid column vibration absorber

This paper deals with an experimental investigation of the damping characteristics of the liquid column dynamic vibration absorber. The laboratory test rig of a single degree of freedom system integrated with a liquid column dynamic vibration absorber was designed and manufactured to study the efficiency of this type of dynamic absorbers. The system response has been measured and recorded by using a (DXL-345) accelerometer and data acquisition system. The effects of mass ratio, length ratio, and the opening ratio of the central orifice on the vibration reduction of the main structure in free vibration mode were evaluated. The results showed that the tuned liquid column vibration absorber has a good ability to reduce or eliminate unwanted vibration by the suitable selection of the combination of its design parameters. The maximum damping of the main system was achieved at the mass, length and orifice opening ratios equal to 7.7 %, 87% and 74% respectively.

Analysis on the mechanism of sound production and effects of musical flue pipe

String instruments, wind instruments and percussion instruments are three traditional categories of musical instruments, among which wind instruments play an important role. Usually, pitches of wind instruments are determined by the vibrating air column, and the musical pitches will be affected by multiple factors of the air flow. In this article, the mechanism of sound production by a pipe is analysed in terms of the coupling of the edge tone and the air column's vibration in the tube. Experiments and computational fluid dynamics numerical calculations are combined to study the influence of the jet velocity on the oscillation frequency of the edge tone and the musical sound produced by the tube, which help to gain deeper insight into the relation between physics and music.

Oscillating Frequencies Generated by Combustion Oscillation in a Combustor Tube Fueled by Natural Gas and a Hydrogen Mixture

Abstract From previous combustion oscillation experiments using a simulated gas turbine combustor, oscillation frequencies around 350 Hz were measured in only natural gas-fired, and around 200 and 400 Hz were measured in the case of hydrogen-containing fuel. In this study, the axial gas column vibration mode was assumed, and the method to reproduce the change of oscillating frequency due to the difference of fuel was investigated. In the previous study, the temperature distribution in the combustor was divided into only two regions, and there were problems in terms of parameter estimation for modeling the flame dynamics. Therefore, the transfer matric method that incorporates a linear temperature gradient was employed. Also, the temperature distributions obtained from computational fluid dynamics, and experiments were reduced to one dimension to reproduce the difference in combustion characteristics due to the difference in fuel composition; four methods were proposed, the axial representative temperatures. The Nyquist plot method was used to calculate up to 10 combinations of resonant frequency and growth rate simultaneously. Furthermore, the oscillation frequency was determined in which the resonance frequency with the growth rate was maximum. As a result, the value of the oscillating frequency obtained differed depending on creating the representative temperature distribution.

Free vibration and buckling of heavy column with regular polygon cross-section

This paper deals with the free vibration and buckling of heavy column, considering its own self-weight. The column has a regular polygonal cross-section with a constant area. The column is applied to an external axial load as well as the self-weight. The five end conditions of the column are considered. Based on equilibrium equations of the column element, differential equations governing the vibrational and buckled mode shapes of column are derived. In solution methods, differential equations are numerically integrated by the direct integration method and eigenvalues of the natural frequency, buckling load and self-weight buckling length are calculated by the determinant search method. The numerical results of this study were in good agreement with those of the reference. Parametric study of the end condition, side number and self-weight on the natural frequency and buckling load was carried out.

Analysis of the vibrations of a console column made on a base with non-line protection in gin

The article presents a constructive scheme and the principle of operation of the cantilever grate of a saw gin installed in the housing by means of a rubber gasket consisting of two rubber elements having different stiffness. The results of the study show that when sawing raw cotton, the saws touch the working part of the chimneys, causing blockages, which leads to damage to the fiber, as well as a decrease in the overall quality of the fiber. In this case, the total stiffness was obtained with a nonlinear characteristic. A mathematical model and its solution by an approximate analytical method. A numerical solution of the problem constructed graphical dependencies and on the basis of their analysis, the necessary values were recommended.

Vibration characteristic analysis of transformers influenced by DC bias based on vibration half-wave energy method

More and more DC bias problems caused by monopole operation of HVDC are appeared in grid which leads to efficiency droop or potential risk of transformers. This paper proposes a new method, Vibration half-wave energy (VHE), based on core deformation characteristics of magnetostriction in silicon steel which can accurately reflect the abnormal flux distribution caused by DC bias. Firstly, Magnetostriction model of transformer core is derived and the VHE method is proposed on the basis of the asymmetric deformation on transformer core. Secondly, the transformer DC bias experiment platform is set up and the transformer vibration signals are measured. Meanwhile, the optimal selection method of vibration test point is analyzed. Thirdly, the VHE values of the DC bias vibration signals are obtained and compared with the DC excitation which verifies that the VHE can express the DC degree in the transformer. Lastly, the VHE method is applied to an operated main transformer in substation and it is proved that is also applicable under actual operation. Results show that the VHE values of vibration signals which on axial vibration of the iron core column and at the top of the transformer shell increase with the increase of DC bias. Therefore, the VHE is an innovative method which can effectively reflect the DC bias condition of transformers and diagnose the abnormal vibration of transformers.

ПОБУДОВА ЗОН ДИНАМІЧНОЇ НЕСТІЙКОСТІ ДЛЯ ВИСОТНИХ БУДІВЕЛЬ У РАЗІ СЕЙСМІЧНИХ ДІЙ

Seismic impacts create the possibility of parametric resonances, i.e. the possibility of the appearance of intense transverse vibrations of structure elements (in particular, of high-rise structures) from the action of periodic longitudinal forces. As a design model of a high-rise structure, a model is used which adopted in the calculation of high-rise structures for seismic effects, - a weightless vertical rod (column) rigidly restrained at the base with a system of concentrated masses (loads) located on it (Fig. 1). By solving the differential equation of the curved axis influence function for a rod is constructed by means of which influence coefficients are determined for the rod points, in which the concentrated masses are situated. These coefficients are elements of the compliance matrix . Next, the elements of the stiffness matrix are determined by inverting the matrix . Using a diagonal matrix of the load masses and matrix a system of differential equations of free vibrations of a mechanical system, consisting of concentrated masses, is constructed, and the frequencies and forms of these vibrations are determined. From the vertical component of the seismic impact, its most significant part is picked out in the form of harmonic vibrations with the predominant frequency of the impact. Column vibrations are considered in a moving coordinate system, the origin of which is at the base of the column. The forces acting on the points of the mechanical system (concentrated masses) are added by the forces of inertia of their masses associated with the translational motion of the coordinate system. The forces of the load weights and forces of inertia create longitudinal forces in the column, periodically depending on time. Further, the integro-differential equation of the dynamic stability of the rod, proposed by V. V. Bolotin in [8], is written. The solution to this equation is sought in the form of a linear combination of free vibration forms with time-dependent factors. Substitution of this solution into the integro-differential equation of dynamic stability allows it to be reduced to a system of differential equations with respect to the mentioned above factors with coefficients that periodically depend on time. For some values of the vertical component parameters of the seismic action, namely the frequency and amplitude, the solutions of these equations are infinitely increasing functions, i.e. at these values of the indicated parameters, a parametric resonance arises. These values form regions in the parameter plane called regions of dynamic instability. Next, these regions are being constructed. A concrete example is considered.

Experimental and numerical analysis on the limited ductility of H-shaped concrete cable-stayed bridge tower

When a cable-stayed bridge is subjected to strong ground motions during an earthquake, the vibration of the tower column is much stronger and more severe in the transverse direction than the longitudinal direction, due to the lateral restriction between the tower and the main girder. To address this issue, the current seismic design of cable-stayed bridge recommends that a larger reinforcement ratio in tower column be used to achieve the target seismic performance (i.e., remaining elastic). This entails an increased number of the piles and the reinforcement volume as well and thus such a design is often not cost-effective. Alternatively, the tower column can be designed to have allowable ductile behaviour for saving costs. Therefore, this study aimed to verify the ductility margin and the allowable ductile performance of the H-shaped concrete tower, by studying its lateral elastic-plastic behaviour and damage mechanism through incremental dynamic analysis, and its limited ductility against the lateral inertial forces based on quasi-static test.