Transient response analysis of the variable frequency cropping system

2007 ◽  
Vol 221 (7) ◽  
pp. 769-778
Author(s):  
Z W Wang ◽  
S D Zhao ◽  
Y T Yu ◽  
L J Zhang
Keyword(s):  
Dynamic Analysis ◽  
Cropping System ◽  
Green Manufacturing ◽  
Element Model ◽  
Vibration Characteristics ◽  
Test Method ◽  
Response Analysis ◽  
Variable Frequency ◽  
Lumped Mass ◽  
Orthogonal Test Method

Variable frequency cropping is a new type of green manufacturing technology that utilizes the forced vibration of a cropping machine and the stress concentration effect of a V-shaped notch to produce crack initiation and propagation. In this paper, dynamic analysis of a variable frequency vibration cropping system is performed. First, the working principle and components of a variable frequency cropping system are explained. Further analysis shows that vibration characteristics are the main subject of variable frequency cropping. Second, the orthogonal test method is adopted to assess the influence of geometric parameters of the V-shaped notch on the vibration characteristics of metal bars. The results indicate that a V-shaped notch has little effect on the vibration mode frequency. Third, a finite-element model of the cropping system is constructed, which is composed of rigid bar elements, a beam element, a lumped mass element, and spring elements. Then the modal and dynamic analyses are conducted. The vibration characteristics and the ideal cropping frequency range are obtained on the basis of the results of the dynamic analysis. Finally, cropping experiments on bars made of Al-Cu4MgSi, C45e, C20e, and TC80 are carried out under conditions of three variable frequency curves.

scholarly journals Optimal Design for the Structure Parameters of Long Raster Engraving Air-floating Platform

Mechanika ◽  
2020 ◽  
Vol 26 (1) ◽  
pp. 55-63
Author(s):  
Deyun Mo
Keyword(s):  
Film Thickness ◽  
Element Model ◽  
Structure Design ◽  
Test Method ◽  
Loading Capacity ◽  
Three Dimension ◽  
Floating Platform ◽  
Range Analysis ◽  
Orthogonal Test Method ◽  
Air Film

Air-floating platform is the core component of long raster engraving system. In order to design an air-floating platform to greatly meet the demands of long raster engraving, this paper, based on the validation of simulation model accuracy by test platform, proposes a three-dimension finite element model about gas film, and investigates the influence of the gas film thickness, air pressure and width of bottom guideway on the loaded capacity and air consumption by orthogonal test method. Then the best design plan of air-floating platform structure was determined by range analysis method. The results showed that air film thickness H=0.02 mm, gas supply pressure Ps=0.15 MPa, width of bottom guideway Bx=140 mm, the loading capacity of single-sided guideway is about 3177 N, its air consumption is 191487 mm3/s. Hence, this plan can not only meet the requirements of the loading capacity but also reduce air consumption of air-floating platform so as to provide a basis for optimum structure design about air-floating platform.

The Vibration Characteristics of the Hydropower Plant with a Certain Cross Flow Hydro-Turbine Generating Units and its Earthquake Response Analysis

2014 ◽  
Vol 577 ◽  
pp. 541-545
Author(s):  
Zhen Yu Ouyang
Keyword(s):  
Cross Flow ◽  
Element Model ◽  
Vibration Characteristics ◽  
Hydropower Plant ◽  
Earthquake Response ◽  
Response Analysis ◽  
Plant Structure ◽  
Hydro Turbine ◽  
Earthquake Load ◽  
Earthquake Response Analysis

To consider the safety of a certain cross flow hydro-turbine generating units and the hydropower plant, the finite element model of the plant and units are established by ANSYS, with which the resonance check is carried out. Meantime, the spectrum analysis method is used to present an earthquake response analysis according to the relative specifications, and the earthquake reaction condition in different directions of the characteristic monitoring points in main height is obtained, then the vibration characteristics of the hydropower plant and the effect of the earthquake load are analyzed. The research gives evidence and reference to make sure of the plant structure safety and the healthy operation for hydro-turbine.

Optimization of the Frontal Rail Based on Composite Material

2012 ◽  
Vol 229-231 ◽  
pp. 321-324
Author(s):  
Hong Tao Yu ◽  
Lei Liu ◽  
Gui Fan Zhao ◽  
Zi Peng Zhang
Keyword(s):  
Composite Material ◽  
Head Injury ◽  
Element Model ◽  
Test Method ◽  
Vehicle Safety ◽  
Frontal Crash ◽  
Sled Test ◽  
Full Vehicle ◽  
Orthogonal Test Method ◽  
The Finite Element Model

Frontal rail constructed of composite material was researched, in order to improving vehicle safety performance in frontal crash as well as lightweight of vehicle. Compliance to FMVSS 208, the vehicle frontal crash was simulated using the finite element model of the full vehicle. The occupant head injury was analyzed by sled test using crash pulse. Then, the composite material parameters which have the best function of reducing the occupant head injury value were studied by using orthogonal test method. Using this kind of composite materials, the occupant safety protection was effectively improved and the weight of the frontal rail was greatly reduced.

scholarly journals Research on Radial Motion Characteristic of the Cropping Hammer in Radial-Forging Cropping Method

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Lijun Zhang ◽  
Shengdun Zhao ◽  
Zhenwei Wang
Keyword(s):  
Cross Section ◽  
Cropping System ◽  
Test Method ◽  
Radial Forging ◽  
Equivalent Stiffness ◽  
Steel Bars ◽  
Orthogonal Test Method ◽  
Motion Characteristic ◽  
Radial Loading ◽  
The Impact

The radial loading form applied to the bar is very important for reducing or avoiding the impact and vibration of the radial-forging cropping system and obtaining the high-quality cross section. A new radial stroke loading curve of the cropping hammer based on the cycloid form is proposed and the dynamic model of radial stroke loading mechanism is built. With the aim of obtaining the equivalent stiffness of the bar with V-shaped notch, which is a key parameter affecting the dynamic characteristic of radial stroke loading mechanism, the analytic model of the bar is built and the simulation experiments are designed by means of the orthogonal test method. The analytical results show that the diameter of the bar has the significant influence on the equivalent stiffness of the bar. Furthermore, the equivalent stiffness of the bar with V-shaped notch can be directly calculated according to the equivalent stiffness of smooth bar whenh/d<0.05andr>0.15. By using the cycloid stroke curve, the cropping experimental results for 45 steel bars and 20 steel bars show that the radial impact and vibration of the cropping system are decreased and the bar cross-section qualities have been significantly improved.

Dynamic analysis of a helical gear reduction by experimental and numerical methods

2020 ◽  
Vol 68 (1) ◽  
pp. 48-58
Author(s):  
Chao Liu ◽  
Zongde Fang ◽  
Fang Guo ◽  
Long Xiang ◽  
Yabin Guan ◽  
...  
Keyword(s):  
Numerical Methods ◽  
Dynamic Analysis ◽  
Dynamic Behavior ◽  
Fourth Order ◽  
Numerical Models ◽  
Helical Gear ◽  
Operating Conditions ◽  
Dynamic Responses ◽  
Lumped Mass ◽  
Gear Mesh

Presented in this study is investigation of dynamic behavior of a helical gear reduction by experimental and numerical methods. A closed-loop test rig is designed to measure vibrations of the example system, and the basic principle as well as relevant signal processing method is introduced. A hybrid user-defined element model is established to predict relative vibration acceleration at the gear mesh in a direction normal to contact surfaces. The other two numerical models are also constructed by lumped mass method and contact FEM to compare with the previous model in terms of dynamic responses of the system. First, the experiment data demonstrate that the loaded transmission error calculated by LTCA method is generally acceptable and that the assumption ignoring the tooth backlash is valid under the conditions of large loads. Second, under the common operating conditions, the system vibrations obtained by the experimental and numerical methods primarily occur at the first fourth-order meshing frequencies and that the maximum vibration amplitude, for each method, appears on the fourth-order meshing frequency. Moreover, root-mean-square (RMS) value of the acceleration increases with the increasing loads. Finally, according to the comparison of the simulation results, the variation tendencies of the RMS value along with input rotational speed agree well and that the frequencies where the resonances occur keep coincident generally. With summaries of merit and demerit, application of each numerical method is suggested for dynamic analysis of cylindrical gear system, which aids designers for desirable dynamic behavior of the system and better solutions to engineering problems.

scholarly journals Probabilistic seismic response analysis of coastal highway bridges under scour and liquefaction conditions: does the hydrodynamic effect matter?

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Xiaowei Wang ◽  
Yutao Pang ◽  
Aijun Ye
Keyword(s):  
Seismic Response ◽  
Seismic Design ◽  
Highway Bridges ◽  
Element Model ◽  
Response Analysis ◽  
Hydrodynamic Effect ◽  
Strong Earthquakes ◽  
Influence Of Water ◽  
Scour Hazard ◽  
Ground Motion Records

AbstractCoastal highway bridges are usually supported by pile foundations that are submerged in water and embedded into saturated soils. Such sites have been reported susceptible to scour hazard and probably liquefied under strong earthquakes. Existing studies on seismic response analyses of such bridges often ignore the influence of water-induced hydrodynamic effect. This study assesses quantitative impacts of the hydrodynamic effect on seismic responses of coastal highway bridges under scour and liquefaction potential in a probabilistic manner. A coupled soil-bridge finite element model that represents typical coastal highway bridges is excited by two sets of ground motion records that represent two seismic design levels (i.e., low versus high in terms of 10%-50 years versus 2%-50 years). Modeled by the added mass method, the hydrodynamic effect on responses of bridge key components including the bearing deformation, column curvature, and pile curvature is systematically quantified for scenarios with and without liquefaction across different scour depths. It is found that the influence of hydrodynamic effect becomes more noticeable with the increase of scour depths. Nevertheless, it has minor influence on the bearing deformation and column curvature (i.e., percentage changes of the responses are within 5%), regardless of the liquefiable or nonliquefiable scenario under the low or high seismic design level. As for the pile curvature, the hydrodynamic effect under the low seismic design level may remarkably increase the response by as large as 15%–20%, whereas under the high seismic design level, it has ignorable influence on the pile curvature.

scholarly journals Time and Frequency Domain Dynamic Analysis of Offshore Mooring

2021 ◽  
Vol 9 (7) ◽  
pp. 781
Author(s):  
Shi He ◽  
Aijun Wang
Keyword(s):  
Dynamic Analysis ◽  
Frequency Domain ◽  
Time Domain ◽  
Linearization Method ◽  
Euler Method ◽  
Single Component ◽  
Hydrodynamic Drag ◽  
Lumped Mass ◽  
Mooring Lines ◽  
The Time Domain

The numerical procedures for dynamic analysis of mooring lines in the time domain and frequency domain were developed in this work. The lumped mass method was used to model the mooring lines. In the time domain dynamic analysis, the modified Euler method was used to solve the motion equation of mooring lines. The dynamic analyses of mooring lines under horizontal, vertical, and combined harmonic excitations were carried out. The cases of single-component and multicomponent mooring lines under these excitations were studied, respectively. The case considering the seabed contact was also included. The program was validated by comparing with the results from commercial software, Orcaflex. For the frequency domain dynamic analysis, an improved frame invariant stochastic linearization method was applied to the nonlinear hydrodynamic drag term. The cases of single-component and multicomponent mooring lines were studied. The comparison of results shows that frequency domain results agree well with nonlinear time domain results.

The Finite Element Analysis and Optimization for the Grinder Based on the Joint Surface

2013 ◽  
Vol 281 ◽  
pp. 165-169 ◽  
Author(s):  
Xiang Lei Zhang ◽  
Bin Yao ◽  
Wen Chang Zhao ◽  
Ou Yang Kun ◽  
Bo Shi Yao
Keyword(s):  
Finite Element ◽  
Natural Frequency ◽  
Element Model ◽  
Joint Surface ◽  
Weak Links ◽  
Response Analysis ◽  
Element Analysis ◽  
Static And Dynamic Analysis ◽  
Harmonic Response Analysis ◽  
Grinding Machine

Establish the finite element model for high precision grinding machine which takes joint surface into consideration and then carrys out the static and dynamic analysis of the grinder. After the static analysis, modal analysis and harmonic response analysis, the displacement deformation, stress, natural frequency and vibration mode could be found, which also helps find the weak links out. The improvement scheme which aims to increase the stiffness and precision of the whole machine has proposed to efficiently optimize the grinder. And the first natural frequency of the optimized grinder has increased by 68.19%.

A Simplified Model of SSI Dynamic Analysis

2012 ◽  
Vol 446-449 ◽  
pp. 334-339
Author(s):  
Zhi Ying Zhang ◽  
Ying Li ◽  
Qing Sun
Keyword(s):  
Dynamic Analysis ◽  
Soil Structure ◽  
Design Method ◽  
Simplified Model ◽  
Lumped Mass ◽  
Foundation Soil ◽  
Linear Elastic ◽  
Lumped Mass Method ◽  
Actual Mechanism ◽  
Seismic Design Method

Aiming at the problem of dynamic analysis of SSI system, the dynamic influence of different parts of foundation soil is studied on the linear elastic assumption according to the actual mechanism of Soil-Structure Interaction (SSI); in addition, a simplified model on the condition of the lumped mass method is put forward and the corresponding motion equations of SSI system are built, which can be a reference for the structural seismic design method considering SSI effect.

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