Vibration Table Research Articles

Specific modes of vibratory technological machines: mathematical models, peculiarities of interaction of system elements

The methodological basis of constructing mathematical models of vibratory technological machines is developed in the article. An approach is proposed that makes it possible to introduce a vibration table in a specific mode that provides conditions for the dynamic damping of oscillations for the zone of placement of a vibration exciter while providing specified vibration parameters in the working zone of the vibration table. The aim of the work is to develop methods of mathematical modeling, oriented to technological processes with long cycles. The technologies of structural mathematical modeling are used with structural schemes, transfer functions and amplitude-frequency characteristics. The concept of the work is to test the possibilities of combining the conditions for reducing loads with working components of a vibration exciter while simultaneously maintaining sufficiently wide limits in variating the parameters of the vibrational field.

Three-Dimensional Identification for Unbalanced Mass of Rotor Systems in Operation

Unbalanced mass identification is important for rotor systems. Current methods normally use sensors, which only detect vibration in two-dimensional (2D) space. Actually, the rotor systems vibrate in three-dimensional directions. In this paper, a non-contact method is developed to identify unbalanced mass of rotor systems in 3D space. A stereo video system with a pair of synchronized high-speed cameras is established and a feature point is employed to replace traditional contact transducer for measurement. Checkerboard target on a vibration table is used to implement dynamic calibration. The proposed method is compared with eddy current method and laser displacement method. The comparison experiments verify the detection ability of the unbalanced mass for the proposed method. Overall, the proposed method can provide more information than 2D detection methods, which has the great potential for fault diagnosis of rotating machinery.

Analysis of Vibration of Roadheader Rotary Table Based on Finite Element Method and Data from Underground Coalmine

The intense vibration of a roadheader rotary table damages the cutting system of the roadheader and reduces the efficiency. This paper analyzes the vibration of a rotary table by combining the finite element model with tested data from an underground coalmine. First, the force of the rotary table during the cutting procedure was analyzed, and the finite element model was built using Pro/E and ADAMS. The tested data were then imported into the model after selection, procession, and combination were conducted. Next, the six lowest‐order parameters of the rotary table were calculated. A vibration analysis of the rotary table under certain working conditions was conducted, and the results were compared with those from a modal experiment using a single‐point excitation method. According to the comparison between the simulation result and experiments, it is clear that this method is both reasonable and feasible. And it could supplement the theoretical foundation of the analysis of other roadheader components, providing reference for the improvement of the structure and dynamic properties of a roadheader. In addition, other vibration components of a roadheader such as the cutting head and the cutting arm could also be analyzed through the proposed method, with very reliable precision.

Application of passive damping fixture to the improvement of CNC drilling

High precision and high efficiency are the essential competition conditions for multi-axis machine. However, machine vibration problems are always plagued by equipment manufacturers. This study focuses on solving or eliminating the multi-angle drilling vibration of processing machines. By the design and experiment combining CNC multi-axis machine tools with vibration tables, the surface roughness in the multi-angle drilling holes is discussed for the reference of the industry or the academia. The results indicated that adding proper vibration factors could effectively improve the bore surface roughness and smoothness. Roughness Ra with the vibration interval time 0.5 sec, could improve the surface roughness 48.95% of the processing hole, comparing to it without vibration. Besides, the resonance phenomenon disappears at the feed to generate good effect. It is expected to reduce various vibration problems faced by processing with machine tools in order to enhance the international competitiveness of processing tool manufacturers.

CaSO4Scale Formation on Vibrated Piping System in the Presence Citric Acid

Vibration in many industries commonly generated by the operation mechanical equipment such as extruder, mixer, blower, compressor, turbine, generator etc. Vibration propagates into the floor and attacks the pipe around those mechanical equipment. In this paper, the influence of vibration in a pipe on the CaSO4scale formation was investigated to understand the effect of vibration on the kinetics, mass of scale, crystal phases and crystal polymorph. To generate vibration force, mechanical equipment was prepared consisted of electrical motor, crankshaft, connecting rod and a vibration table at where test pipe section mounted. Deposition rate increased significantly when the vibration affected to the system i.e. 0.5997 and 1.6705 gr/hr for vibration frequency 4.00 and 8.00 Hz. The addition 10.00 ppm of citric acid declined the deposition rate of 8 Hz experiment from 3.4599 gr/hr to 2.2865 gr/hr.

Optimization of Moulding Technology of Polymer Concrete Used for Manufacture Precision Tool Machine Bases

Aspects of moulding technology have a great effect on the mechanical properties and curing behaviour of polymer concrete used to manufacture the base of precision tool machine. In this paper, the results and the analysis are both presented of an experimental investigation on the effects of moulding technology on polymer concrete (PC) used for manufacture the base of precision tool machine. Effect of voids population on compressive strength of polymer concrete was examined. Various frequencies were applied during the packing operation of the polymer concrete samples using the vibration table. The optimum frequency for vibration and for producing a PC sample with the highest compressive strength was found to be 18.9375 Hz, which resulted in 109 MPa compressive strength for basalt, sand and chalk composition. In addition influence of Dimethyl aniline (DMA) amount and moulding temperature on mixing process and the strength of matrix domain were experimented. The relation between time of viscosity build-up t (min), temperature T (°C) and DMA content C (%) were correlated. This relation was used to obtain the suitable time required for mixing to prevent the mixing while the polymeric binder reach the gelling time through the copolymerization process. Also mixing technology and its influence on mechanical properties of PC were investigated. The optimized mixing technology was reached. Enhancing certain aspects of moulding technology could lead to an elevation of the mechanical strength of PC that may assist in producing polymer concrete with a high level of compliance with the optimisation criteria for PC used in manufacturing bases for precision tool machinery.

Evaluation of the dynamic characteristics of a super tall building using data from ambient vibration and shake table tests by a Bayesian approach

The Shanghai Tower is a newly built 127-story and 632 m high super tall building. As of April 2017, it was ranked as the second tallest building in the world. Its main structural system is a mega-frame-tube-outrigger system with six outrigger trusses along the height. Due to its unique structural configuration, a series of field and laboratory model tests have been conducted to better understand its dynamic characteristics. Before its construction, a scaled model of the tower was tested on a shake table, and the results were used to refine the design of the tower. At the completion of the construction, full-scale ambient vibration tests were performed. A Bayesian method was used to perform operational modal analysis from the shake table and full-scale ambient vibration tests. The most probable value of the modal parameters and the associated posterior uncertainties were calculated using this method. The first eight modes were identified, including three translational modes in each principal direction and two torsional modes. Using these results, the dynamic characteristics and associated uncertainties obtained from the two tests were investigated and compared in this paper. Due to the scaling of the model, there are some discrepancies between the natural frequencies obtained from two different tests, but the identified mode shapes matched very well. Although the structure was designed in a very innovative manner, its dynamic characteristics are similar to regular tall buildings. The results from this investigation provide valuable information for an ongoing condition assessment of this super tall building.

Influence of linear vibration on the errors of three-axis FOGs in the measurement while drilling systems

At present, the single-axis FOG has a good anti-vibration performance when being tested with the linear vibration table. However, when the three FOGs are installed into the Initial Navigation System orthonormal, the anti-vibration performance of the FOGs becomes deteriorated. This paper discovers that the sampling rate of the gyros is a critical factor that influences their anti-vibration performance greatly. When the FOGs-based MWD is vibrating linearly, the MWD also involve with an angular vibration which is given rise by the linear vibration. This angular vibration has the same frequency with the linear vibration. As the angular sensor, the FOGs installed in the MWD can sense this angler vibration. According to the Nyquist sampling theorem, a continuous signal should be sampled at a rate greater than 2 times the maximum frequency of the signal. If the sampling rate of the FOGs is lower than 2 times of the maximum frequency of angular vibration, their measurements couldn’t recover the real vibration signal accurately which will result in a drift. In this paper, this phenomenon is explained theoretically. And the quantitative relation between the linear vibration and the effect on FOGs is established for the first time. In order to validate this innovative idea, a 10 Hz frequency linear vibration of the MWD was simulated using trajectory generator. This continuous vibration signal was sampled by inertial sensors with different sampling rate (1 KHz, 20 Hz and 12.5 Hz). When the sampling rate of the FOG installed in the MWD was lower than 2 times of the vibration frequency, the measurements of the FOGs drifted 0.25°/h. While the sampling rate was greater than 2 times of the vibration, it barely drifted. Additionally, three linear vibration experiments were performed under the condition of the lab. The fix-frequency vibration along Y axis verified that the linear vibration truly incur the angular vibration with same frequency. The linear sweep-frequency vibration along X axis verified that with the higher sampling rate, the error of FOGs measurements was reduced dramatically. The random vibration along Z axis proved that the attitude errors were reduced more than 50% when the FOGs sampling rate was greater than 2 times of the maximum frequency of the vibration.

High frequency large stroke design and simulation experimental research on shaking table

Firstly, this paper introduces the design of high frequency large stroke vibration table according to the applicable environment. Secondly, the three-dimensional solid model is established which is based on solidworks2012 environment. The kinematics and dynamics simulation of the shaking table model are carried out. The vibration test curve of the vibrating table is obtained, and the reason of the change of the vibration curve under different vibration frequency is analyzed. Finally, this paper concludes that this exciting scheme is feasible and effective.

A new type of high frequency mechanical vibration table

This paper puts forward a new type of mechanical vibration table. First of all, the structure and working principle of this vibration table is described. Then the kinetic equation and the three-dimensional model of the eccentric exciter are established, the simulation experiments are carried out, and the displacement curves, velocity curves and acceleration time curves at different frequencies are analyzed. Finally, finite element analysis of eccentric wheels is carried out based on solidwork2012. The simulation results show that the mechanical vibration of this new mechanical vibration table is achievable at 0-100 Hz.

The Simulation Realization of Pavement Roughness in the Time Domain

As the needs for the dynamic study on the vehicle-pavement system and the simulated vibration table test, how to simulate the pavement roughness actually is important guarantee for whether calculation and test can reflect the actual situation or not. Using the power spectral density function, the simulation of pavement roughness can be realized by Fourier inverse transform. The main idea of this method was that the spectrum amplitude and random phase were obtained separately according to the power spectrum, and then the simulation of pavement roughness was obtained in the time domain through the Fourier inverse transform (IFFT). In the process, the sampling interval (Δl) was 0.1m, and the sampling points(N) was 4096, which satisfied the accuracy requirements. Using this method, the simulate results of pavement roughness (A~H grades) were obtain in the time domain.

Some problems of control of dynamical conditions of technological vibrating machines

The possibility of control of dynamical condition of the shakers that are designed for vibration treatment of parts interacting with granular media is discussed. The aim of this article is to develop the methodological basis of technology of creation of mathematical models of shake tables and the development of principles of formation of vibrational fields, estimation of their parameters and control of the structure vibration fields. Approaches to build mathematical models that take into account unilateral constraints, the relationships between elements, with the vibrating surface are developed. Methods intended to construct mathematical model of linear mechanical oscillation systems are used. Small oscillations about the position of static equilibrium are performed. The original method of correction of vibration fields by introduction of the oscillating system additional ties to the structure are proposed. Additional ties are implemented in the form of a mass-inertial device for changing the inertial parameters of the working body of the vibration table by moving the mass-inertial elements. The concept of monitoring the dynamic state of the vibration table based on the original measuring devices is proposed. Estimation for possible changes in dynamic properties is produced. The article is of interest for specialists in the field of creation of vibration technology machines and equipment.

A new compound control method for sine-on-random mixed vibration test

Vibration environmental test (VET) is one of the important and effective methods to provide supports for the strength design, reliability and durability test of mechanical products. A new separation control strategy was proposed to apply in multiple-input multiple-output (MIMO) sine on random (SOR) mixed mode vibration test, which is the advanced and intensive test type of VET. As the key problem of the strategy, correlation integral method was applied to separate the mixed signals which included random and sinusoidal components. The feedback control formula of MIMO linear random vibration system was systematically deduced in frequency domain, and Jacobi control algorithm was proposed in view of the elements, such as self-spectrum, coherence, and phase of power spectral density (PSD) matrix. Based on the excessive correction of excitation in sine vibration test, compression factor was introduced to reduce the excitation correction, avoiding the destruction to vibration table or other devices. The two methods were synthesized to be applied in MIMO SOR vibration test system. In the final, verification test system with the vibration of a cantilever beam as the control object was established to verify the reliability and effectiveness of the methods proposed in the paper. The test results show that the exceeding values can be controlled in the tolerance range of references accurately, and the method can supply theory and application supports for mechanical engineering.

On the extraction technique of the single-coil self-feedback signal on a standard vibration table

In the process of calibration on vibration and shock transducers, it is necessary for the vibration table to generate a small sine-function form distortion as the excitation signal, and the closed-loop servo feedback technology is one of the proven effective ways to reduce low-frequency motion signal distortion of the vibration table. In this paper, we report a method based on the principle of closed-loop servo feedback that can directly extract induction electromotive force of the vibrator coil. This method solves the problems caused by using sensors in the process of getting the vibration signals. Furthermore, this device has some advantages such as small size, light weight, low cost and simple maintenance. In this article, the system components and technical indexes and analyzis of the control method of the vibration table are described. Next, we compare the wave distortion obtained using monocoil signal extraction technology and that obtained using relative speed sensor. Finally, the error analysis of monocoil signal extraction technology is carried out, and the experiment is finished to prove this analysis.

Seismic response analysis on shear lag effect of continuous curved box girder with three spans

Shear lag effect of continuous curved box girder with three spans under seismic excitation is studied in this paper. Firstly, spatial shell finite element model is founded by ANSYS, and EL-centro seismic wave is chosen as seismic excitation. Secondly, the shear lag effect at different cross sections are investigated with dynamic time-history analysis, the results show that under seismic excitation there is prominent shear lag effect in continuous curved box girder, the maximum shear lag coefficient is 3.02, shear lag effect is severe, shear lag effect at mid-span cross sections are prominent than support cross sections, and inside peak shear lag coefficients are generally greater than outside. Finally, the numeric results are compared with the experimental results from a vibration table testing, which shows great consistencies.

A New Approach for Road‐Vehicle Vibration Simulation

A new approach for road‐vehicle vibration simulation is proposed and demonstrated feasible by testing with three express‐road vehicle‐vibration records, that is, record A, two‐wheel electric bicycle, 80% loaded, traveling on urban road; record B, median van, 50% loaded, traveling on urban road; and record C, minivan, 80% loaded, traveling on urban road too. This method decomposes the original signal into a series of approximate Gaussian‐vibration segments and a shock segment with high kurtosis by moving crest factor and one‐tenth peak‐value method. Simulate Gaussian‐distribution vibration one by one from the power spectral density (PSD) of each decomposed segments. The overall signal is simulated by concatenating of each decomposed Gaussian segment. The simulated signal has not only the same overall root‐mean‐square (RMS), duration as the original signal, but also has a similar PSD to the original signal, without incurring excessive acceleration levels. This allows an improved and more representative simulated input signal to be generated that can be use in the current generation of vibration table.

Novel methods to apply micro dynamic stimulations on cultured adhesive cells and its application in constructing gel-embedded three-dimensional neuronal structures differentiated from human iPS cells

In cellular engineering, device system to apply active dynamic stimulations on cultured adhesive cells or cell colonies is highly needed in order to control cellular functions as well as morphologies prior to clinical treatment such as cell transplantation in regenerative medicine. In this study, simple but effective cantilever-type three-dimensional micro vibration table as well as two-dimensional one to be used within limited space and environment inside the cell incubator is newly developed to stimulate cultured adhesive iPS cells colony directly to promote their differentiation into objective cells. The finite element method is utilized in developing process. Also, together with the dynamic stimulation, a method of gel-embedded culture for neurons is proposed to construct three-dimensional neuronal structures. Effects of the dynamic stimulations on the differentiation and growth process of the human iPS cells into neuronal cells are investigated by measuring the immunostained areas of βIII-tubulin of the differentiated neural cells with or without the dynamic stimulations. It is found that there is significant difference in differentiation and growth efficiency of the human iPS cells into neurons between the statically cultured cells and the dynamically stimulated ones. Furthermore, it is confirmed that the gel-embedded culture together with the dynamic stimulations is a promising strategy to construct the three-dimensional neuronal structures.

Based on the traffic system tools magneto electric equipment design and application

In transportation, the road is rough, the engine operation, the instability of the transmission system, and large vibration of the vibration system is to collect the vibration energy, and transformed into stable electricity, provide extra energy for transportation. Experiment device of the system is composed of three parts: simulate vibration test rig, vibration generating device, rectifier voltage regulator circuit. Vibration table is to simulate vehicle vibration in the road, cars, for example, through the check information that cars drive in ordinary road driving axle of some vibration data, thus to calculate all parameters of the vibration table. Vibration generating device is placed on the simulation vibration table, it can convert vibration energy into cars can use electricity. Rectifier voltage regulator circuit is generated by power generation device with a range of random variation of amplitude of electric energy through the rectifier voltage into a stable power output, for car use. The final design and making the vibration system, obtained by the method of experiment proved that the vibration of system feasible.

Моделирование процессов испытаний виброопор на экспериментальном стенде

The mathematical model of the experimental stand for vibration damping is described in the article. Vibration table is used as a source of vibration of different frequencies. Asynchronous motors are attached to the vibrating table from below. These motors are frequency-controlled and have eccentric disks on the shafts. Due to imbalance, the motors create a vibration that is transmitted to the upper table through the samples of the damping devices being examined. The upper table is equipped with measuring equipment. Additional sources of vibration are the harmonic components of the voltage generated by power electronic converters at the terminals of the stators of two asynchronous motors. Modeling allows obtaining quantitative characteristics of damping of the studied devices in wide ranges of material properties, geometric parameters and control algorithms. The mathematical model of a mechanical system is based on the Lagrange equations and electromechanical energy conversion by electric motors. This model allows analyzing various variants of dampers with various external and control impacts.

MEMS-based seismic intensity instrument for earthquake early warning

Micro-electro-mechanical systems (MEMS)-based tri-axial seismometer can be employed to design intensity instrument and construct early warning network. Using average period τc and peak amplitude of displacement Pd methods, the estimation relationships between seismometer and magnitude can be calculated. This work outlines the algorithm and first-hand experience using low-cost MEMS-based seismometer in seismic intensity instrument. τc and Pd methods are employed to calculate magnitude estimation and STA/LTA trigger algorithm is used to identify seismic event. A set of simulated earthquake wave experiments on a horizontal vibration table are used to testify the ability of P-wave identification. The results show that the accuracy of P-wave identification and seismic intensity judgement is over 95%, which proves the usability of improving implementations for the MEMS-based seismometer in the earthquake early warning application.