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,&63 3URFHHGLQJVHarmonic Response Analysis On Cutting Part of Shearer Physical Simulation System Paper TitleFang RenˈZhengyan Liu and Zhaojian Y angCollege of Mechanical Engineering, Taiyuan University of Technology, TaiY uan , ChinaRenfang67@Abstract—Coal-rock interface recognition system mainly meanscollecting various response signals available from multi-sensorsequipped in shearer and further analyzing and those response signals to see if it is cutting coal or rock. For this purpose, the shearer equips total five types of various distinguishing sensors to pick up these signals. Both the optimized configuration of sensorsmeasuring points and the choices of the sensors properties are thekey factors to correctly and completely collecting the manifolddynamic characteristic signals of cutting part of physicalsimulation system. Therefore, it is important and necessary tocarry out the harmonic response dynamics analysis of shearer cutting part. The vibration characteristics based on frequencyresponse is analyzed. The study not only optimizes the dispositionof the vibration sensor for the maximum output amplitude signals, but also identifies the frequency range of the vibrationsensor, so that it not only satisfies the condition for undistortedmeasurements, but also avoids that the sensors are interfered dueto resonance.Keywords—cutting part ˈfinite element dynamics ˈ harmonic response ˈcoal-rock interface recognitionI. I NTRODUCTIONCoal-rock interface recognition system mainly collects response signals of cutting force of shearer by multi-sensor and analyses this response signal for the recognition of cutting coal or rock. Therefore, it is basic premise to pick up signals. Generally there are two methods to pick up these signals: one is to collect data at the coal interface, which, however, brings a lot of difficulties as a result, and is limited to certain extent by many factors. Another method is, under meeting the similarity condition, to establish physical simulation system in the laboratory, including media and the simulation of shearer traction-cutting mechanism. This way can adjust structural parameters, mechanical and physical performance parameters of coal or rock in large range; meanwhile, this way can strictly shaft, torsional vibration signal of drum shaft and cutting electrical current accordingly reflect changes in the state of cutting. So the five types of sensors to pick up these signals are equipped with. In recent years ˈthe researches of coal- 978-1-4244-5900-1/10/$26.00 ?010 IEEErock interface recognition are mostly focused on fusion research[1]-[3], unfortunately, little concerns about thevalidity2509 and correctness of the data itself is given, which involvesthedisposition optimization of sensors measuring points andthechoice of the sensor performances. In view of this,thevibration states of arm will be analyzed and summarized upinthis paper. So the cutting part of shearer physical simulationsystem for finite element harmonic analysis is made,thevibration response characteristics of cutting part fromtheperspective of frequency response is analyzed to obtainthebest point of picking-up vibration of arm, optimizethe disposition of the vibration sensor measuring pointand determine the due working frequency range of sensor.II. P HYSICAL SIMULA TION SYSTEM OF SHEARERThe testing model of shearer is based on the prototypeofelectric traction shearer (model:MGTY400/900-3.3D)according to the similarity theory, and is designed bythegeometric ratio of one to eight. Based on the foundation ofthis,it is optimized and remodeled to highlight the simplesofmodel and meet the performance, low cost, simple structure.The physical simulation system of shearer[4]is shown asfigure1.Fig.1: Physical simulation system of shearerShearer model is composed of drum, arm, torsionalmoment sensor, motor, cylinder and body. The cutting partofmodel needs to complete two actions: the motor aspowerinput mechanism drives the drum to finish cutting; andtheheight of arm is adjusted successively by the cylinder fromthetop position(angle is α=48.96? to the bottom position (angleFigure 3 mesh graphics Figure 2 height schematic of armIII. H ARMONIC RESPONSE AT LEVEL POSITIONHarmonic response analysis is a method used to determinethe steady-state response of a linear structure to loads that varysinusoidally (harmonically) with time. The input is theharmonic load for the known size and frequency. The idea isto calculate the structure's response at several frequencies andobtain a curve graph of some response quantity versusfrequency[5].A. Establishment of three-dimensional modelFigure 4 local distribution of nodes When we ensure the original structure size, the quality ofstructure, simplify these parts what are not the focus of the study, A model of cutting part is established by three- dimensional modeling software Pro/E. The main parts' sizes are drum diameter 225 mm, arm length 490 mm, height 150 mm, width 154 mm, width 735 mm and so on.B. Definition of element type and material properties,meshingAfter completion in three-dimensional modeling, model is imported ANSYS11.0 finite element analysis software. Based on the structure of shearer, the type of solid element solid92 is selected. This element type is suitable for meshing of the irregular grid of model established by a variety of CAD / CAM. Element is defined by 10 nodes, and is the quadratic tetrahedron element of pure displacement shape function. Second , the laboratory model of shearer is steel material, so material property is defined isotropic materials, elastic modulus is 206 Gpa, Poisson's ratio is 0.3,density is 3 C. Boundary conditions and Apply loadsBecause the stand plate of laboratory shearer hinges on the fuselage, while the model is built to remove the fuselageˈthe displacement constraints of all degrees of freedom are imposed on the hinged earrings. In working process of shearer cutting one coal level, the rocker arm position is fixed by the cylinder, it is equivalent to the all degrees of freedom constraints imposed hinged earrings for a cutting height of shearer.In the harmonic response analysis, loads applied isharmonic load as F= F o coswt. There are two ways to apply load: one is real-imaginary part, the other is amplitude-phase[6],in this paper, real-imaginary part is selected. The peak of loadexcitation force is F o=300N, and it’s frequency range is generally 0 to 500 Hz, this is selected based on the testing datafrom the laboratory. The points of applying load are selectedin the front face parallel to drum axis, five points are applied load in downward direction, as shown in figure 3.7800 kg / m .As tetrahedron element types is selected, mesh is a free meshing. Meshes density meet the requirements of optimization of sensor location. the meshed model as shown in Figure 3 ,from top to bottom for the Y direction ,and up is positive; The horizontal direction for the X direction , the right is positive; forward and afterward for the Z direction ,forward is positive .the local distribution of nodes shown in Figure 4 D. Results of harmonic analysisThe purpose which the cutting part for harmonic analysis is made is to obtain its frequency response state, to test the transmission characteristic of mechanism for excitation force, to study vibration displacement in each frequency, and to acquire natural frequency and band in distortion measuring condition.Nodes 1157ǃ20060ǃ20044ǃ3388ǃ583 are selected to be investigated. The frequency-displacement curve ofvibration in Y direction is shown in figure 5, it is drawn from the figure that the largest vibration displacement is of node 1157, the vibration form of the other nodes is similar to the node 1157. The resonant frequency of node 1157 appears in the 38Hz, 278Hz, and 324Hz. The distorted frequency range is nearly 38Hz to 278Hz. By analyzing the displacement of each frequency corresponding to the three nodes, the displacement of node 1157 is generally larger than other two nodes. It shows that the region of nodes 1157 possesses excellent amplification for the excitation signal, and maintains good transmission characteristics of the excitation force.Figure 5 the frequency-displacementcurve of vibration in Y directionFigure 6 the frequency-displacementcurve of vibration in Z directionIt is drawn from the figure 6 that the largest vibration displacement is of node 1157 when it vibrates in Z direction. The resonant frequency of node 1157 appears in the 38Hz, 98Hz, 202Hz, 250Hz, 276Hz, and 324Hz. By the analysis above, the distorted frequency range is nearly 96Hz to 202Hz. In these three nodes, by analyzing the displacement of each frequency, node 1157 also possesses larger displacement than other two nodes, excellent amplification for the excitation signal, and maintains good transmission characteristics of the excitation force.IV. H ARMONIC RESPONSE ANALYSIS AT TOP POSITIONA. Preprocess model and solutionThe cutting part at top position for harmonic analysis is done when load is changed but other conditions. Loads are decomposed into X and Y axis respectively, it is equivalent to vertical downward load imposed on drum at top position. The equivalent load force is 300N, and is decomposed into Y axis as 196.96N, the downward of Y direction is negative based on model coordinate system, into X axis as 226.29N, the right of X direction is positive based on model coordinate system. Load is applied on model shown in figure 7.Figure 7 apply load at top positionB. Results of harmonic response and analysisNodes 1157ǃ 20060ǃ 20044 are still selected to be investigated, the frequency-displacement curve of vibration in Y direction as shown in figure 8, it is drawn from the figure that the largest vibration displacement is of node 1157, the vibration form of the other nodes is similar to the node 1157. The resonant frequency of nodes 1157ǃ 20060ǃ 20044 appears in the 38Hz, 278Hz, and 324Hz. The distorted frequency range is nearly 38Hz to 278Hz. It is shown in figure 8 that the cutting part of shearer at top position only appears third-order resonance, and the displacement of low-frequency resonance is the largest. So the cutting part of shearer mainly avoids noises signals of low-frequency, particularly in the three resonant frequencies. By analyzing the displacement of each frequency corresponding to the three nodes, it is shown that the region of nodes 1157 possesses excellent amplification for the excitation signal, and maintains good transmission characteristics of the excitation force as the level position.Figure 8 the frequency-displacement curveof vibration in Y direction at top positionFigure 9 the frequency-displacement curveof vibration in Z direction at top positionIt is drawn from the figure 9 that the largest vibration displacement is of node 583 when it vibrates in Z direction at top position. The resonant frequency of node 1157 appears in the 38Hz, 98Hz, 202Hz, 250Hz, 278Hz, 324Hz and 424Hz. By the analysis above, the distorted frequency range is nearly 98Hz to 202Hz. For vibration in Z direction at top position, node 1157 possesses larger displacement than other two nodes except individual frequency. So with regard to vibration in Z direction at top position, node 1157 can still be selected to be the picking-up point for good transmission characteristics. V. H ARMONIC RESPONSE ANALYSIS AT BOTTOM POSITION$ Preprocess model and solutionThe cutting part at bottom position for harmonic analysis is still done when load is changed but other conditions. Loads are also decomposed into X and Y axis respectively, it is equivalent to vertical downward load imposed on drum at top position. The equivalent load force is 300N, and is decomposed into Y axis as -148.59N, the downward of Y direction is negative based on model coordinate system, into X axis as -260.62N, the left of X direction is negative based on model coordinate system. Load is applied on model shown in figure 10.Figure 10 apply load at bottom positionB Results of harmonic response and analysisFigure 11 the frequency-displacement curveof vibration in Y direction at bottom positionFigure 12 the frequency-displacement curveof vibration in Z direction at bottom positionNodes 1157ǃ 20060ǃ 20044 are still selected to be investigated, the frequency-displacement curve of vibration in Y direction as shown in figure 11, it is drawn from the figure that the largest vibration displacement is of node 1157, the displacement value is 1.11cm, the vibration form of the other nodes is similar to the node 1157. The resonant frequency of nodes 1157ǃ20060ǃ20044 appears in the 38Hz, 278Hz, and 324Hz. The distorted frequency range is nearly 38Hz to 278Hz. It is shown in figure 11 that the cutting part of shearer imposed sinusoidal excitation force at bottom position only appears third-order resonance, and the displacement of low- frequency resonance is the largest. So the cutting part of shearer mainly avoids noises signals of low-frequency, particularly in the three resonant frequencies.It is drawn from the figure 12 that the largest vibration displacement is of node 583 when it vibrates in Z direction at bottom position. The resonant frequency of node 1157 appears in the 40Hz, 98Hz, 202Hz, 250Hz, 276Hz, 324Hz and 424Hz. By the analysis above, the distorted frequency range is nearly 98Hz to 202Hz, the displacement unit is meter.VI C ONCLUSIONThe cutting part of shearer for harmonic response analysis at level, top, and bottom position is done to acquire the vibration displacement law corresponding to frequency. It concluded:(1) With the vibration in Y direction, node 1157 retains excellent amplification for the excitation signal, and maintains good transmission characteristics of the excitation force. So the region of node 1157 is suitable picking-up point monitoring the vibration in Y direction.(2) The sensors installed for vibration in Y direction should possess good transmission characteristics of the excitation force in the frequency range of 0 to 265Hz, for vibration in Z direction, the frequency range should be 0 to 200Hz.(3) It is shown that output signals for harmonic response analysis zoom out unlimitedly in the resonant frequencies, yet the signals of other frequencies retain good amplification; meanwhile, the signals of resonant frequencies should be filtered to avoid zooming out unlimitedly and interfering the normal output signals of coal-rock state.It is drawn that the picking-up point of the largest amplitude is obtained, and the placement point of accelerometer sensor is optimized; meanwhile. Frequency band of sensors is studied, the sensor also possesses the filtering effect. The reliability of physical experiment is well verified in the simulation testing.AcknowledgmentThe work was financially supported by NSF of ShanXi China. (2008011051)R EFERENCES[1] Ren Fang; Yang Zhaojian; Xiong Shibo. Chinese Journal of MechanicalEngineering [J]. 2003ˈV ol16ˈ3ˈˈ321-324.[2]Zhao ShuanFeng.Coal-rock interface recognition based on multiwaveletpacket energy[J]. Journal of Xi an University of Science and Technology, 2009ˈV ol. 29ˈ5ˈˈ584-588.[3]Zhang YanLi, Zhang ShouXiang, Jiao LinY ue, Wang YongQiang.Application on ICA in coal and rock interface identification of the fully mechanized mining[J]. Coal Science and Technology, 2007. V ol35 ˈ8ˈˈ22-24.[4]Ren Fang. Study on the Theory and Method of Coal-Rock InterfaceRecognition Based on Multi-Sensor Data Fusion Technique [D].TaiY uan: TaiY uan University of Technology,2003.[5] Sheng HeTai, Yu HaiLiang, Fan XunYi. 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