scholarly journals Composite synchronization on two pairs of vibrators in a far super-resonant vibrating system with the single rigid frame

2021 ◽  
pp. 146134842110215
Author(s):  
Xueliang Zhang ◽  
Wenchao Hu ◽  
Zhiguo Gao ◽  
Yunshan Liu ◽  
Bang-Chun Wen
Keyword(s):  
Structural Parameters ◽  
Vertical Direction ◽  
System Stability ◽  
Stable Phase ◽  
Balance Equations ◽  
Rigid Frame ◽  
Vibration Responses ◽  
Exciting Forces ◽  
Gear Mechanism ◽  
Theory Condition

In the present work, a new dynamical model with a single rigid frame driven by two pairs of vibrators, of which each pair of vibrators is engaged with each other by gear mechanism, is proposed to explore the composite synchronization of the system. The motion differential equations and vibration responses of the system are given first. The theory condition for achieving composite synchronization of the system is obtained, by using the average method to deduce the average torque balance equations of the two pairs of vibrators. According to the Hamilton’s theory, the system stability condition is presented, and it is mainly determined by the structural parameters of the system. The synchronous stable regions and stability ability versus the key parameters of the system are qualitatively discussed in numeric, and further quantitatively verified by simulations. It is shown that, in engineering, the reasonable working points of the system, should be selected in the region where the stable phase difference of the two pairs of vibrators is stabilized in the vicinity of zero. Only in this way, can the exciting forces of the two pairs of vibrators be positively superposed, and the linear motion of the system in the vertical direction be realized.

scholarly journals Stability and motion characteristics in a vibrating system with five rigid frames driven by two counter-rotating exciters

2021 ◽  
pp. 146134842110196
Author(s):  
Wenchao Hu ◽  
Xueliang Zhang ◽  
Wei Zhang ◽  
Weihao Chen ◽  
Shiju Cui
Keyword(s):  
Phase Difference ◽  
Vertical Direction ◽  
Stable Phase ◽  
Resonant Effect ◽  
Rigid Frames ◽  
The Difference ◽  
Motion Characteristics ◽  
The Stability ◽  
Region Ii ◽  
Theory Condition

A new dynamical model with five rigid frames (RFs), driven by two counter-rotating exciters, is proposed to explore the synchronization, stability, and motion characteristics of the system in this paper. The motion differential equations and the corresponding responses of the system are given firstly. Using the average method, the average torque balance equations for the two exciters are deduced. According to the relationship between the difference of the dimensionless effective output electromagnetic torques for the two motors and the coupling torques of the system, the theory condition of realizing synchronization is obtained. Based on the Hamilton’s theory, the theory condition of stability of the system is deduced. The stability and motion characteristics of the system for different resonant regions are qualitatively discussed in numeric, including the stable phase difference of the two exciters, relative phase relationships among the five rigid frames, amplitude-frequency characteristics, stability coefficients, and the effective load torque between the two exciters. Simulations are carried out to further quantitatively validate the feasibility of the above theoretical and numerical qualitative results. It is shown that in engineering the reasonable working points of the system should be selected in Region II, only in this way, can the synchronous and stable relative linear motion of the system with the zero stable phase difference in vertical direction be realized, and in this case, the vibrations of the four inner rigid frames (IRFs) in the horizontal direction are compensated with each other, and the energy is also saved due to utilizing the resonant effect. Based on the present work, some new types of vibrating coolers/dryers or vibrating screening machines can be designed.

scholarly journals Study on dynamic characteristics of leaf spring system in vibration screen

2021 ◽  
pp. 146134842110229
Author(s):  
Jiacheng Zhou ◽  
Chao Hu ◽  
Ziqiu Wang ◽  
Zhengfa Ren ◽  
Xiaoyu Wang ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Vertical Direction ◽  
Maximum Amplitude ◽  
Exciting Force ◽  
Mode Shapes ◽  
Leaf Spring ◽  
Amplification Factors ◽  
Simulation And Experiment ◽  
Exciting Forces ◽  
Spring System

By studying dynamic characteristics of the leaf spring system, a new elastic component is designed to reduce the working load and to a certain extent to ensure the linearity as well as increase the amplitude in the vertical and horizontal directions in vibration screen. The modal parameters, amplitudes, and amplification factors of the leaf spring system are studied by simulation and experiment. The modal results show that the leaf spring system vibrates in horizontal and vertical directions in first and second mode shapes, respectively. It is conducive to loosening and moving the particles on the vibration screen. In addition, it is found that the maximum amplitude and amplification factor in the horizontal direction appear at 300 r/min (5 Hz) while those in the vertical direction appear at 480 r/min (8 Hz), which are higher than those in the disc spring system. Moreover, the amplitude of the leaf spring system increases proportionally with the increase of exciting force while the amplification factors are basically the same under different exciting forces, indicating the good linearity of the leaf spring system. Furthermore, the minimum exciting force occurs in the leaf spring system under the same amplitude by comparing the exciting force among different elastic components. The above works can provide guidance for the industrial production in vibration screen.

Structural Optimization of the Telescopic Boom of a Certain Type of Truck-Mounted Crane

2014 ◽  
Vol 548-549 ◽  
pp. 383-388
Author(s):  
Zhi Wei Chen ◽  
Zhe Cui ◽  
Yi Jin Fu ◽  
Wen Ping Cui ◽  
Li Juan Dong ◽  
...  
Keyword(s):  
Finite Element ◽  
Static Analysis ◽  
Cross Sections ◽  
Optimization Design ◽  
Structural Parameters ◽  
Vertical Direction ◽  
Element Model ◽  
Shape Parameters ◽  
Conventional Design ◽  
Design Variables

Parametric finite element model for a commonly used telescopic boom structure of a certain type of truck-mounted crane has been established. Static analysis of the conventional design configuration was performed first. And then an optimization process has been carried out to minimize the total weight of the telescopic structures. The design variables include the geometric shape parameters of the cross-sections and the integrated structural parameters of the telescopic boom. The constraints include the maximum allowable equivalent stresses and the flexure displacements at the tip of the assembled boom structure in both the vertical direction and the circumferential direction of the rotating plane. Compared with the conventional design, the optimization design has achieved a significant weight reduction of up to 24.3%.

The Dynamic Characteristics of Rigid Frame Single-Rib Arch Bridge

2013 ◽  
Vol 368-370 ◽  
pp. 1426-1430
Author(s):  
Li Xiong Gu ◽  
Rong Hui Wang
Keyword(s):  
Dynamic Characteristics ◽  
Bending Strength ◽  
Dynamic Properties ◽  
Structural Parameters ◽  
Bending Stiffness ◽  
Torsional Stiffness ◽  
Lateral Stiffness ◽  
Arch Bridge ◽  
Vertical Stiffness ◽  
Rigid Frame

In this paper, by establishing the finite element model to study the dynamic characteristics of rigid frame single-rib arch bridge. By respectively changing structural parameters of the span ratios, and the compressive stiffness of arch, and the bending stiffness of arch, and the bending stiffness of bridge girder, and the layout of boom to find out the regularity of the structure on lateral stiffness, and vertical stiffness, and torsional stiffness as well as dynamic properties, it come out the results of that lateral stiffness of the structure is weaker, and increasing the span ratios and the compressive strength of arch are conducive to the improvement of the overall stiffness, and improving the bending strength of arch and layout of boom are less effect on the overall stiffness and mode shape.

scholarly journals Influence of different biomass ash additive on anthracite pyrolysis process and char gasification reactivity

2020 ◽  
Vol 7 (3) ◽  
pp. 464-475 ◽  
Author(s):  
Xiaoming Li ◽  
Caifeng Yang ◽  
Mengjie Liu ◽  
Jin Bai ◽  
Wen Li
Keyword(s):  
Coal Gasification ◽  
Structural Parameters ◽  
Vertical Direction ◽  
Pyrolysis Process ◽  
Biomass Ash ◽  
Inhibition Effect ◽  
Gasification Reactivity ◽  
Char Gasification ◽  
High K ◽  
The Cost

Abstract Catalytic coal gasification technology shows prominent advantages in enhancing coal gasification reactivity and is restrained by the cost of catalyst. Two typical biomass ash additions, corn stalk ash (CSA, high K–Na and low Si) and poplar sawdust ash (PSA, high K–Ca and high Si), were employed to study the influence of biomass ash on pyrolysis process and char gasification reactivity of the typical anthracite. Microstructure characteristics of the char samples were examined by X-ray diffraction (XRD). Based on isothermal char-CO2 gasification experiments, the influence of biomass ash on reactivity of anthracite char was determined using thermogravimetric analyzer. Furthermore, structural parameters were correlated with different reactivity parameters to illustrate the crucial factor on the gasification reactivity varied with char reaction stages. The results indicate that both CSA and PSA additives hinder the growth of adjacent basic structural units in a vertical direction of the carbon structure, and then slow down the graphitization process of the anthracite during pyrolysis. The inhibition effect is more prominent with the increasing of biomass ash. In addition, the gasification reactivity of anthracite char is significantly promoted, which could be mainly attributed to the abundant active AAEM (especially K and Na) contents of biomass ash and a lower graphitization degree of mixed chars. Higher K and Na contents illustrate that the CSA has more remarkable promotion effect on char gasification reactivity than PSA, in accordance with the inhibition effect on the order degree of anthracite char. The stacking layer number could reasonably act as a rough indicator for evaluating the gasification reactivity of the char samples.

Self-synchronization theory of tri-motor excitation with double-frequency in far resonance system

2020 ◽  
Vol 234 (16) ◽  
pp. 3166-3184 ◽  
Author(s):  
Min Zou ◽  
Pan Fang ◽  
Yongjun Hou ◽  
Guodong Chai ◽  
Jinsong Chen
Keyword(s):  
Drilling Fluid ◽  
Structural Parameters ◽  
Rapid Development ◽  
Low Frequency ◽  
Single Frequency ◽  
Stable Phase ◽  
Resonance System ◽  
Double Frequency ◽  
Differential Motion ◽  
Motor Excitation

With the rapid development of petroleum exploitation industry, vibrating screen actuated with a single frequency is unsuitable to separate cuttings from drilling fluid, since it usually results in screen blocking. Hence, for solving the above-mentioned problem, tri-motor excitation with double-frequency in far resonance system is introduced. This paper aims to explore the self-synchronization mechanism of the proposed system. First, dynamic equation is established according to physical model of the system. Then, displacement response of the system in steady state is obtained with dynamic formulas. Subsequently, synchronous condition among the three exciters is determined by small parameters method, and criterion of synchronous stability among the three exciters is derived by Poincare-Lyapunov method. Finally, in light of the differential motion equation, Runge-Kutta principle is assigned to validate the reliability of self-synchronous theory and the stability of the double-frequency system. The results indicate that electromagnetic torques of low-frequency motors are dynamically antisymmetric in synchronous operation, and synchronous ability of the system is determined by the mass ratio among the rotors. In addition, stable phase difference among the rotors is significantly influenced by the structural parameters of the system. And this study will be helpful for the improvement of separation technology.

scholarly journals A Comparative Study of Regularization Method in Structure Load Identification

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Bingrong Miao ◽  
Feng Zhou ◽  
Chuanying Jiang ◽  
Xiangyu Chen ◽  
Shuwang Yang
Keyword(s):  
Structural Parameters ◽  
Railway Track ◽  
Load Identification ◽  
Noise Levels ◽  
Beam Structure ◽  
Identification Procedure ◽  
Vibration Data ◽  
Vibration Responses ◽  
Curve Method ◽  
Quantitative Indicators

This study aims to correlate the vibration data with quantitative indicators of structural health by comparing and validating the feasibility of identifying unknown excitation forces using output vibration responses. First, numerical analysis was performed to investigate the accuracy, convergence, and robustness of the load identification results for different noise levels, sensors numbers, and initial estimates of structural parameters. Then, the laboratory beam structure experiments were conducted. The results show that using the two identification methods Tikhonov (L-curve) and TSVD (GCV-curve) can successfully and accurately identify the different excitation forces of the external hammer. The TSVD based on GCV method has more advantages than the Tikhonov based on L-curve method. The proposed two kinds of load identification procedure based on vibration response can be applied to the safety performance evaluation of the railway track structure in future inverse problems research.

Modeling and Dynamics of Magnetically Repulsive Negative Stiffness Permanent Magnetic Array for Precision Air/Magnetic Composite Vibration Isolation

2021 ◽  
Author(s):  
Yamin Zhao ◽  
Junning Cui ◽  
Limin Zou ◽  
Zhongyi Cheng
Keyword(s):  
Vibration Isolation ◽  
Permanent Magnets ◽  
Structural Parameters ◽  
Low Frequency ◽  
Vertical Direction ◽  
High Amplitude ◽  
Negative Stiffness ◽  
Magnetic Composite ◽  
Experimental Systems ◽  
Vibration Transmissibility

To reduce the natural frequency of air isolators and realize low or ultra-low frequency air/magnetic composite vibration isolation with large payloads, a magnetically repulsive negative stiffness permanent magnetic array (MRNSPMA) is proposed. Specifically, we utilize cuboidal permanent magnets to form a spatial array that is mechanically repulsive in the horizontal direction and structurally parallel in the vertical direction. The superiority of MRNSPMA in achieving high amplitude negative stiffness is verified. Furthermore, the effects of structural parameters on vibration transmissibility under the base and force excitations are investigated with the introduction of MRNSPMA. The displacement transmissibility, the force transmissibility and the frequency corresponding to the peak transmissibility are significantly reduced, validating the promise of MRNSPMA for improving the isolation performance of cutting-edge scientific experimental systems and facilities.

Flow Field Theoretical Optimization and Experimental Verification of Centrifugal Pump

2014 ◽  
Vol 716-717 ◽  
pp. 627-630 ◽  
Author(s):  
Yuan Sheng Lin ◽  
Quan Zhang ◽  
Lu Dai ◽  
Xu Hu
Keyword(s):  
Flow Field ◽  
Centrifugal Pump ◽  
Pressure Pulsation ◽  
Vibration Level ◽  
Noise Emission ◽  
Vibration Responses ◽  
Exciting Forces ◽  
Field Excitation ◽  
Cfd Method ◽  
Base Structure

Researches on vibration of centrifugal pump induced by fluid exciting forces are significant for reducing equipment faults, which are caused by the vibration transferring from the base, and noise emission of shells which connected with the base. Fluid exciting forces are the main vibration sources in centrifugal pump systems. The vibration of impellers is generated by fluid exciting forces, and transferred to mechanical systems through pump shell and shaft bearings. By optimizing of inner flow filed of centrifugal pump, not only the fluid exciting forces can be reduced, but also the vibration level of the pump can be improved. In this paper, based on reducing noise and isolating vibration, the inner flow field of the centrifugal pump was emulated by CFD method. The flow field was optimized by controlling the impellers cutting process. The optimizing results were shown by comparing the pressure pulsation of the optimized flow field with those of the original flow field. The improvement of optimization was verification by measuring the vibration responses of the centrifugal pump base structure. The experimental results shows that: the level of flow field excitation and the pressure pulsation of flow field under the blade frequencies and multiplication frequencies are declined to some degree by cutting impellers; the vibration responses of pump base decreased 4.5 dB after cutting impeller.

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