A virtual sieving experimental simulation system was built using physical simulation principles.The effects of vibration frequency and amplitude,the inclination angle of the screen-deck and the vibration direction ang...A virtual sieving experimental simulation system was built using physical simulation principles.The effects of vibration frequency and amplitude,the inclination angle of the screen-deck and the vibration direction angle of screen on single particle kinematics were predicted.Properties such as the average velocity and the average throw height were studied.The results show that the amplitude and the angle of vibration have a great effect on particle average velocity and average height.The vibration frequency and the screen-deck inclination angle appear to have little influence on these responses.For materials that are difficult to screen the vibration frequency and amplitude,the screen-deck inclination angle and the vibration angle should be set to 14 Hz,6.6 mm,6° and 40°,respectively,to obtain optimal particle kinematics.A screening process can be simulated reliably by means of a virtual experiment and these results provide references for both screening theory research and sieving practice.展开更多
Demand for large vibrating screen is huge in the mineral processing industry. As bending and random vibration are not considered in a traditional design method for beam structures of a large vibrating screen, fatigue ...Demand for large vibrating screen is huge in the mineral processing industry. As bending and random vibration are not considered in a traditional design method for beam structures of a large vibrating screen, fatigue damage occurs frequently to affect the screening performance. This work aims to conduct a systematic mechanics analysis of the beam structures and improve the design method. Total motion of a beam structure in screening process can be decomposed into the traditional followed rigid translation(FRT), bending vibration(BV) and axial linear-distributed random rigid translation(ALRRT) excited by the side-plates. When treated as a generalized single-degree-of-freedom(SDOF) elastic system analytically, the BV can be solved by the Rayleigh's method. Stochastic analysis for random process is conducted for the detailed ALRRT calculation. Expressions for the mechanics property, namely, the shearing force and bending-moment with respect to BV and ALRRT, are derived, respectively. Experimental and numerical investigations demonstrate that the largest BV exists at the beam center and can be nearly ignored in comparison with the FRT during a simplified engineering design. With the BV and FRT considered, the mechanics property accords well with the practical situation with the maximum error of 6.33%, which is less than that obtained by traditional method.展开更多
A new concept of banana vibrating screen which has the same effect as traditional banana vibrating screen in a new way was put forward.The dynamic model of vibrating screen was established and its working principle wa...A new concept of banana vibrating screen which has the same effect as traditional banana vibrating screen in a new way was put forward.The dynamic model of vibrating screen was established and its working principle was analyzed when the action line of the exciting force did not act through the centroid of screen box.Moreover,the dynamic differential equations of centroid and screen surface were obtained.The motions of centroid and screen surface were simulated with actual parameters of the design example in Matlab/Simulink.The results show that not only the amplitude has a significant decrease from 9.38 to 4.10 mm,but also the throwing index and vibrating direction angle have a significant decrease from 10.49 to 4.59,and from 58.10° to 33.29°,respectively,along the screen surface,which indicates that motion characteristics of vibrating screen are consistent with those of traditional banana vibrating screen only by means of a single angle of screen surface.What's more,such banana vibrating screen of variable linear trajectory with greater processing capacity could be obtained by adjusting the relative position of force center and the centroid of screen box properly.展开更多
By ANSYS, dynamic simulation analysis of rubber spring supporting equipment used in vibrating screen was made. The modal frequency, mode, and harmonic displacement under working frequency were obtained. Variation of r...By ANSYS, dynamic simulation analysis of rubber spring supporting equipment used in vibrating screen was made. The modal frequency, mode, and harmonic displacement under working frequency were obtained. Variation of rubber spring supporting equipment＇s dynamic performance was discussed first, which is under the condition of existing spring stiffness difference and exciting force bias. Also, the quantitative calculation formulas were given. The results indicate that the performance of vibrating screen is closely related with rubber spring supporting equipment＇s dynamic performance. Differences of springs＇ stiffness coefficients reduce the modal frequency reduced, decrease the dynamic stiffness, and increase vibration displacement. Exciting force bias induces a larger lateral displacement. When rubber springs＇ stiffness coefficients exist, differences and lateral force accounts for 5% in total exciting force; rubber spring supporting equipment＇s side swing is larger than 1 mm, exceeding the side swing limit.展开更多
Based on the statics theory, a novel and feasible twice-suspended-mass method(TSMM) was proposed to deal with the seldom-studied issue of fault diagnosis for damping springs of large vibrating screen(LVS). With the st...Based on the statics theory, a novel and feasible twice-suspended-mass method(TSMM) was proposed to deal with the seldom-studied issue of fault diagnosis for damping springs of large vibrating screen(LVS). With the static balance characteristic of the screen body/surface as well as the deformation compatibility relation of springs considered, static model of the screen surface under a certain load was established to calculate compression deformation of each spring. Accuracy of the model was validated by both an experiment based on the suspended mass method and the properties of the 3D deformation space in a numerical simulation. Furthermore, by adopting the Taylor formula and the control variate method, quantitative relationship between the change of damping spring deformation and the change of spring stiffness, defined as the deformation sensitive coefficient(DSC), was derived mathematically, from which principle of the TSMM for spring fault diagnosis is clarified. In the end, an experiment was carried out and results show that the TSMM is applicable for diagnosing the fault of single spring in a LVS.展开更多
A large model of the screen was mounted in the laboratory for studying its modal performance. The model is suspended with steel ropes. Modal test was carried out with artificially exciting by 500 g impacting hammer an...A large model of the screen was mounted in the laboratory for studying its modal performance. The model is suspended with steel ropes. Modal test was carried out with artificially exciting by 500 g impacting hammer and 100 kg exciting force shaker respectively. Synthesis and correction of the modal parameters are obtained from both testing methods. Design faults of vibrating screen were determined based on the analy-sis and dynamic correction of structure approaches about the screen was put forward finally.展开更多
Based on Autodesk Mechanical Desktop (MDT), three main. approaches of parametric part design including program-drive, table-drive and interactive-drive were studied. By using Visual Basic and ActivesX automation compo...Based on Autodesk Mechanical Desktop (MDT), three main. approaches of parametric part design including program-drive, table-drive and interactive-drive were studied. By using Visual Basic and ActivesX automation component programming, access database, parametric drawing and mechanism analysis were integrated. h probes into how to design mechanical products quickly and effectively by means of CAD.展开更多
The particles’ motion on screen surface was studied by the way of nonlinear dynamics. It was found that the particles’ motion may be changed from one form to another with its vibration strength. When the vibration s...The particles’ motion on screen surface was studied by the way of nonlinear dynamics. It was found that the particles’ motion may be changed from one form to another with its vibration strength. When the vibration strength K is bigger than 1 and smaller than 1. 33, the particles’ motion is the bifurcating type;when K is bigger than 1. 33 and smaller than 1. 67, its motion becomes the double bifurcation type; when K is bigger than 1. 67, its motion changes into chaos motion type. On basis of studying all effects of large vibration strength on particles penetrating, it was pointed out that a larger vibration strength K of screen surface will increase the strength of particles’ motion, and then increase their probability of penetrating screen surface. A primary theory of particles’ motion under large vibration strength for moisture fine coal was established.展开更多
The screening of particles with different vibration modes was simulated by means of a 3D discrete element method (3D-DEM). The motion and penetration of the particles on the screen deck were analyzed for linear, circu...The screening of particles with different vibration modes was simulated by means of a 3D discrete element method (3D-DEM). The motion and penetration of the particles on the screen deck were analyzed for linear, circular and elliptical vibration of the screen. The results show that the travel velocity of the particles is the fastest, but the screening efficiency is the lowest, for the linear vibration mode. The circular motion resulted in the highest screening efficiency, but the lowest particle travel velocity. In the steady state the screening efficiency for each mode is seen to increase gradually along the longitudinal direction of the deck. The screening efficiency increment of the circular mode is the largest while the linear mode shows the smallest increment. The volume fraction of near-mesh size particles at the underside is larger than that of small size particles all along the screen deck. Linear screening mode has more near-mesh and small size particles on the first three deck sections, and fewer on the last two sections, compared to the circular or elliptical modes.展开更多
A kind of novel multi-layer piezoelectric actuator is proposed and integrated with controllable constrained damping treatment to perform hybrid vibration control.The governing equation of the system is derived based o...A kind of novel multi-layer piezoelectric actuator is proposed and integrated with controllable constrained damping treatment to perform hybrid vibration control.The governing equation of the system is derived based on the constitutive equations of elastic,viscoelastic and piezoelectric materials,which shows that the magnitude of control force exerted by multi-layer piezoelectric actuator is the quadratic function of the number of piezoelectric laminates used but in direct proportion to control voltage.This means that the multi-layer actuator can produce greater actuating force than that by piezoelectric laminate actuator with the same area under the identical control voltage.The optimal location placement of the multi-layer piezoelectric actuator is also discussed.As an example,the hybrid vibration control of a cantilever rectangular thin-plate is numerically simulated and carried out experimentally.The simulated and experimental results validate the power of multi-layer piezoelectric actuator and indicate that the present hybrid damping technique can effectively suppress the low frequency modal vibration of the experimental thin-plate structure.展开更多
In order to improve the screening efficiency of vibrating screen and make vibration process smooth,a new type of magnetorheological (MR) damper was proposed. The signals of displacement in the vibration process during...In order to improve the screening efficiency of vibrating screen and make vibration process smooth,a new type of magnetorheological (MR) damper was proposed. The signals of displacement in the vibration process during the test were collected. The trispectrum model of autoregressive (AR) time series was built and the correlation dimension was used to quantify the fractal characteristics during the vibration process. The result shows that,in different working conditions,trispectrum slices are applied to obtaining the information of non-Gaussian,nonlinear amplitude?frequency characteristics of the signal. Besides,there is correlation between the correlation dimension of vibration signal and trispectrum slices,which is very important to select the optimum working parameters of the MR damper and vibrating screen. And in the experimental conditions,it is found that when the working current of MR damper is 2 A and the rotation speed of vibration motor is 800 r/min,the vibration screen reaches its maximum screening efficiency.展开更多
Vibrating flip-flow screens are widely used in the field of screening;its actual operation is affected by the impact force of materials,but existing research usually ignores this effect.Based on this background,consid...Vibrating flip-flow screens are widely used in the field of screening;its actual operation is affected by the impact force of materials,but existing research usually ignores this effect.Based on this background,considering the influence of material impact force and moment on vibrating flip-flow screens,this paper develops a dynamic model and a vibration differential equation of a vibrating flip-flow screen,performs the analysis of material movement and calculation of the material impact force,and includes the material impact force in the dynamic characteristic analysis of a vibrating flip-flow screen.The results indicate the following:(1)The impact forces F_(x) and F_(y) account for 29%and 57.58%of the excitation force amplitude,respectively,indicating that they are of the same magnitude as the excitation force.Material impact increases the vibration amplitudes of the main and floating frames,and therefore,cannot be ignored in vibrating flip-flow screen design.(2)By comparing the vibrating flip-flow screen's responses with and without the impact,it is found that impact force significantly influences the system response,causing the displacement curve to shift and the amplitude–frequency curve to have periodic fluctuations and peak values.(3)The effects of impact parameters on the dynamic characteristics of a vibrating flip-flow screen are studied.The results show that increases in material mass and material binding coefficient lead to a decrease in the system natural frequencies.Due to the impact force,the amplitude–frequency curve of the main frame peaks at a frequency lower than the first order of the natural frequency,and the amplitude–frequency curve of the floating frame peaks in the intervals of 5–10Hz and 20–25 Hz.The results provide a theoretical reference for the design of vibrating flip-flow screens.The operating frequency of vibrating flip-flow screens should be selected to avoid the peak value due to the impact force,which helps extend the working life.展开更多
Screening is an important process in mineral industry. In this paper, a study has been made to simulate the screening process based on a high-performance MATLAB/Simulink software, with an example of simulating the sie...Screening is an important process in mineral industry. In this paper, a study has been made to simulate the screening process based on a high-performance MATLAB/Simulink software, with an example of simulating the sieving process of a vibrating screen. A simulation model of the sieving process with a vibrating screen （SMSPVS） was proposed, using correlative mathematical models and Simulink blocks. The results show that the simulation data was very close to the actual data, The minimum errors of size distribution of oversize and undersize are 0.65% and 0.20%, resoectivelv. The sieving orocess can be accurately simulated by the SMSPVS.展开更多
A feasible method to improve the reliability and processing efficiency of large vibrating screen via the application of an elastic screen surface with multiple attached substructures （ESSMAS） was proposed. In the ES...A feasible method to improve the reliability and processing efficiency of large vibrating screen via the application of an elastic screen surface with multiple attached substructures （ESSMAS） was proposed. In the ESSMAS, every screen rod, with ends embedded into elastomer, is coupled to the main screen structure in a relatively flexible manner. The theoretical analysis was conducted, which consists of establishing dynamic model promoted from the fuzzy structure theory as well as calculating for the equivalent stiffness of each attached structure. According to the numerical simulation using the NEWMARK-fl integration method, this assembling pattern significantly leads to the screen surface/rod having larger vibration intensity than that of the corresponding position on screen structure, which specifically, with an averaged acceleration amplitude increasing ratio of 11.37% in theoretical analysis and 20.27% in experimental test. The experimental results, within a tolerant error, also confirm the established model and demonstrate the feasibility of ESSMAS.展开更多
Based on the analysis of the piano wire’s vibration characteristics, the authors estab lished the mechanical model of piano wire proba bility screen , obtained the analytic so lution of thestable forced vibration...Based on the analysis of the piano wire’s vibration characteristics, the authors estab lished the mechanical model of piano wire proba bility screen , obtained the analytic so lution of thestable forced vibration of screen wires , and developed the para meter designfor m ula of the piano wire screen . The para meter design form ula has been used in coalpreparation industry .展开更多
The working frequency selection of the ZK30525 vibrating screen was studied using ANSYS. Integrating the dynamic performance simulation analysis of the vibrating screen structure, the variation laws of beams＇ vibrati...The working frequency selection of the ZK30525 vibrating screen was studied using ANSYS. Integrating the dynamic performance simulation analysis of the vibrating screen structure, the variation laws of beams＇ vibration displacements changing with different exciting frequencies were researched. These beams include six beams, with one discharging beam and one in-material beam. Results indicate that vibration displacements in the middle of these beams increase with the augmenta- tion of exciting frequency. When exciting frequency exceeds a certain value, there exists a flat change region for vibration displacement. According to vibrator characteristics, the vibrating screen＇s working frequency should be selected in the flat change region, and be far away from modal frequencies. The study provides theoretical guidance for the reasonable working frequency selection of the large-scale vibrating screen.展开更多
A feasible method was proposed to improve the vibration intensity of screen surface via application of a new type elastic screen surface with multi degree of freedom(NTESSMDF). In the NTESSMDF, the primary robs were c...A feasible method was proposed to improve the vibration intensity of screen surface via application of a new type elastic screen surface with multi degree of freedom(NTESSMDF). In the NTESSMDF, the primary robs were coupled to the main screen structure with ends embedded into the elastomers, and the secondary robs were attached to adjacent two primary robs with elastic bands. The dynamic model of vibrating screen with NTESSMDF was established based on Lagrange's equation and the equivalent stiffnesses of the elastomer and elastic band were calculated. According to numerical simulation using the 4th order Runge-Kutta method, the vibration intensity of screen surface can be enhanced substantially with an averaged acceleration amplitude increasing ratio of 72.36%. The primary robs and secondary robs vibrate inversely in steady state, which would result in the friability of materials and avoid stoppage. The experimental results validate the dynamic characteristics with acceleration amplitude rising by62.93% on average, which demonstrates the feasibility of NTESSMDF.展开更多
Vibration failure of piping is a serious problem and a matter of concern for safety and reliability of plant operations. Fatigue is the main cause of such failures. Due to the complexity of the phenomenon no closed fo...Vibration failure of piping is a serious problem and a matter of concern for safety and reliability of plant operations. Fatigue is the main cause of such failures. Due to the complexity of the phenomenon no closed form design solutions are available. In our study an analytical technique based on the theory of vibrations in the time domain has been presented. Using the inverse theory, the problem has been reduced to a system of Volterra Integral equations to be solved simultaneously at every time step. The solution of the inverse problem may be used in the conventional method to calculate stresses and end reactions which are important from the perspective of engineering design and condition monitoring. The method is robust, simple and can be easily adopted by practicing engineers.展开更多
基金support from the Innovative Research Groups of the National Natural Science Foundation of China (No.50921002)the National Natural Science Foundation of China (Nos.50574091 and 50774084)+1 种基金the "333 Project" Foundation of Jiangsu Provincethe Key Laboratory of Coal Processing & Efficient Utilization,Ministry of Education Foundation (No.CPEUKF 08-02) for this work
文摘A virtual sieving experimental simulation system was built using physical simulation principles.The effects of vibration frequency and amplitude,the inclination angle of the screen-deck and the vibration direction angle of screen on single particle kinematics were predicted.Properties such as the average velocity and the average throw height were studied.The results show that the amplitude and the angle of vibration have a great effect on particle average velocity and average height.The vibration frequency and the screen-deck inclination angle appear to have little influence on these responses.For materials that are difficult to screen the vibration frequency and amplitude,the screen-deck inclination angle and the vibration angle should be set to 14 Hz,6.6 mm,6° and 40°,respectively,to obtain optimal particle kinematics.A screening process can be simulated reliably by means of a virtual experiment and these results provide references for both screening theory research and sieving practice.
基金Project(51221462) supported by the National Natural Science Foundation of ChinaProject(20120095110001) supported by the Ph D Programs Foundation of Ministry of Education of China
文摘Demand for large vibrating screen is huge in the mineral processing industry. As bending and random vibration are not considered in a traditional design method for beam structures of a large vibrating screen, fatigue damage occurs frequently to affect the screening performance. This work aims to conduct a systematic mechanics analysis of the beam structures and improve the design method. Total motion of a beam structure in screening process can be decomposed into the traditional followed rigid translation(FRT), bending vibration(BV) and axial linear-distributed random rigid translation(ALRRT) excited by the side-plates. When treated as a generalized single-degree-of-freedom(SDOF) elastic system analytically, the BV can be solved by the Rayleigh's method. Stochastic analysis for random process is conducted for the detailed ALRRT calculation. Expressions for the mechanics property, namely, the shearing force and bending-moment with respect to BV and ALRRT, are derived, respectively. Experimental and numerical investigations demonstrate that the largest BV exists at the beam center and can be nearly ignored in comparison with the FRT during a simplified engineering design. With the BV and FRT considered, the mechanics property accords well with the practical situation with the maximum error of 6.33%, which is less than that obtained by traditional method.
基金Projects(50574091, 50774084) supported by the National Natural Science Foundation of ChinaProject(50921001) supported by the Innovative Research Group Science Foundation,ChinaProject supported by Jiangsu Scientific Researching Fund Project ("333" Project),China
文摘A new concept of banana vibrating screen which has the same effect as traditional banana vibrating screen in a new way was put forward.The dynamic model of vibrating screen was established and its working principle was analyzed when the action line of the exciting force did not act through the centroid of screen box.Moreover,the dynamic differential equations of centroid and screen surface were obtained.The motions of centroid and screen surface were simulated with actual parameters of the design example in Matlab/Simulink.The results show that not only the amplitude has a significant decrease from 9.38 to 4.10 mm,but also the throwing index and vibrating direction angle have a significant decrease from 10.49 to 4.59,and from 58.10° to 33.29°,respectively,along the screen surface,which indicates that motion characteristics of vibrating screen are consistent with those of traditional banana vibrating screen only by means of a single angle of screen surface.What's more,such banana vibrating screen of variable linear trajectory with greater processing capacity could be obtained by adjusting the relative position of force center and the centroid of screen box properly.
文摘By ANSYS, dynamic simulation analysis of rubber spring supporting equipment used in vibrating screen was made. The modal frequency, mode, and harmonic displacement under working frequency were obtained. Variation of rubber spring supporting equipment＇s dynamic performance was discussed first, which is under the condition of existing spring stiffness difference and exciting force bias. Also, the quantitative calculation formulas were given. The results indicate that the performance of vibrating screen is closely related with rubber spring supporting equipment＇s dynamic performance. Differences of springs＇ stiffness coefficients reduce the modal frequency reduced, decrease the dynamic stiffness, and increase vibration displacement. Exciting force bias induces a larger lateral displacement. When rubber springs＇ stiffness coefficients exist, differences and lateral force accounts for 5% in total exciting force; rubber spring supporting equipment＇s side swing is larger than 1 mm, exceeding the side swing limit.
基金Project(20120095110001)supported by the PhD Programs Foundation of Ministry of Education of ChinaProject(51134022,51221462)supported by the National Natural Science Foundation of China+1 种基金Project(CXZZ13_0927)supported by Research and Innovation Program for College Graduates of Jiangsu Province,ChinaProject(2013DXS03)supported by the Fundamental Research Funds for Central Universities of China
文摘Based on the statics theory, a novel and feasible twice-suspended-mass method(TSMM) was proposed to deal with the seldom-studied issue of fault diagnosis for damping springs of large vibrating screen(LVS). With the static balance characteristic of the screen body/surface as well as the deformation compatibility relation of springs considered, static model of the screen surface under a certain load was established to calculate compression deformation of each spring. Accuracy of the model was validated by both an experiment based on the suspended mass method and the properties of the 3D deformation space in a numerical simulation. Furthermore, by adopting the Taylor formula and the control variate method, quantitative relationship between the change of damping spring deformation and the change of spring stiffness, defined as the deformation sensitive coefficient(DSC), was derived mathematically, from which principle of the TSMM for spring fault diagnosis is clarified. In the end, an experiment was carried out and results show that the TSMM is applicable for diagnosing the fault of single spring in a LVS.
基金Supported by Provincial Natural Science Foundation of Shanxi(20031046)
文摘A large model of the screen was mounted in the laboratory for studying its modal performance. The model is suspended with steel ropes. Modal test was carried out with artificially exciting by 500 g impacting hammer and 100 kg exciting force shaker respectively. Synthesis and correction of the modal parameters are obtained from both testing methods. Design faults of vibrating screen were determined based on the analy-sis and dynamic correction of structure approaches about the screen was put forward finally.
文摘Based on Autodesk Mechanical Desktop (MDT), three main. approaches of parametric part design including program-drive, table-drive and interactive-drive were studied. By using Visual Basic and ActivesX automation component programming, access database, parametric drawing and mechanism analysis were integrated. h probes into how to design mechanical products quickly and effectively by means of CAD.
文摘The particles’ motion on screen surface was studied by the way of nonlinear dynamics. It was found that the particles’ motion may be changed from one form to another with its vibration strength. When the vibration strength K is bigger than 1 and smaller than 1. 33, the particles’ motion is the bifurcating type;when K is bigger than 1. 33 and smaller than 1. 67, its motion becomes the double bifurcation type; when K is bigger than 1. 67, its motion changes into chaos motion type. On basis of studying all effects of large vibration strength on particles penetrating, it was pointed out that a larger vibration strength K of screen surface will increase the strength of particles’ motion, and then increase their probability of penetrating screen surface. A primary theory of particles’ motion under large vibration strength for moisture fine coal was established.
基金financial support from the National Natural Science Foundation of China (No. 51204181)the Research Fund for the Doctoral Program of Higher Education of China (No.20110095120004)+1 种基金the Fundamental Research Funds for the Central Universities (Nos. 2011QNA10 and 2010QNB17)the China Postdoctoral Science Foundation (No. 20110491485) for this work
文摘The screening of particles with different vibration modes was simulated by means of a 3D discrete element method (3D-DEM). The motion and penetration of the particles on the screen deck were analyzed for linear, circular and elliptical vibration of the screen. The results show that the travel velocity of the particles is the fastest, but the screening efficiency is the lowest, for the linear vibration mode. The circular motion resulted in the highest screening efficiency, but the lowest particle travel velocity. In the steady state the screening efficiency for each mode is seen to increase gradually along the longitudinal direction of the deck. The screening efficiency increment of the circular mode is the largest while the linear mode shows the smallest increment. The volume fraction of near-mesh size particles at the underside is larger than that of small size particles all along the screen deck. Linear screening mode has more near-mesh and small size particles on the first three deck sections, and fewer on the last two sections, compared to the circular or elliptical modes.
基金This project is supported by National Natural Science Foundation of China(No.50275114,No.10476020).
文摘A kind of novel multi-layer piezoelectric actuator is proposed and integrated with controllable constrained damping treatment to perform hybrid vibration control.The governing equation of the system is derived based on the constitutive equations of elastic,viscoelastic and piezoelectric materials,which shows that the magnitude of control force exerted by multi-layer piezoelectric actuator is the quadratic function of the number of piezoelectric laminates used but in direct proportion to control voltage.This means that the multi-layer actuator can produce greater actuating force than that by piezoelectric laminate actuator with the same area under the identical control voltage.The optimal location placement of the multi-layer piezoelectric actuator is also discussed.As an example,the hybrid vibration control of a cantilever rectangular thin-plate is numerically simulated and carried out experimentally.The simulated and experimental results validate the power of multi-layer piezoelectric actuator and indicate that the present hybrid damping technique can effectively suppress the low frequency modal vibration of the experimental thin-plate structure.
基金Project(50975098) supported by the National Natural Science Foundation of ChinaProject(2008HZ0002-1) supported by the Major Scientific and Technological Program of Fujian Province,China
文摘In order to improve the screening efficiency of vibrating screen and make vibration process smooth,a new type of magnetorheological (MR) damper was proposed. The signals of displacement in the vibration process during the test were collected. The trispectrum model of autoregressive (AR) time series was built and the correlation dimension was used to quantify the fractal characteristics during the vibration process. The result shows that,in different working conditions,trispectrum slices are applied to obtaining the information of non-Gaussian,nonlinear amplitude?frequency characteristics of the signal. Besides,there is correlation between the correlation dimension of vibration signal and trispectrum slices,which is very important to select the optimum working parameters of the MR damper and vibrating screen. And in the experimental conditions,it is found that when the working current of MR damper is 2 A and the rotation speed of vibration motor is 800 r/min,the vibration screen reaches its maximum screening efficiency.
基金supported by the National Natural Science Foundation of China(Grant No.12272259).
文摘Vibrating flip-flow screens are widely used in the field of screening;its actual operation is affected by the impact force of materials,but existing research usually ignores this effect.Based on this background,considering the influence of material impact force and moment on vibrating flip-flow screens,this paper develops a dynamic model and a vibration differential equation of a vibrating flip-flow screen,performs the analysis of material movement and calculation of the material impact force,and includes the material impact force in the dynamic characteristic analysis of a vibrating flip-flow screen.The results indicate the following:(1)The impact forces F_(x) and F_(y) account for 29%and 57.58%of the excitation force amplitude,respectively,indicating that they are of the same magnitude as the excitation force.Material impact increases the vibration amplitudes of the main and floating frames,and therefore,cannot be ignored in vibrating flip-flow screen design.(2)By comparing the vibrating flip-flow screen's responses with and without the impact,it is found that impact force significantly influences the system response,causing the displacement curve to shift and the amplitude–frequency curve to have periodic fluctuations and peak values.(3)The effects of impact parameters on the dynamic characteristics of a vibrating flip-flow screen are studied.The results show that increases in material mass and material binding coefficient lead to a decrease in the system natural frequencies.Due to the impact force,the amplitude–frequency curve of the main frame peaks at a frequency lower than the first order of the natural frequency,and the amplitude–frequency curve of the floating frame peaks in the intervals of 5–10Hz and 20–25 Hz.The results provide a theoretical reference for the design of vibrating flip-flow screens.The operating frequency of vibrating flip-flow screens should be selected to avoid the peak value due to the impact force,which helps extend the working life.
文摘Screening is an important process in mineral industry. In this paper, a study has been made to simulate the screening process based on a high-performance MATLAB/Simulink software, with an example of simulating the sieving process of a vibrating screen. A simulation model of the sieving process with a vibrating screen （SMSPVS） was proposed, using correlative mathematical models and Simulink blocks. The results show that the simulation data was very close to the actual data, The minimum errors of size distribution of oversize and undersize are 0.65% and 0.20%, resoectivelv. The sieving orocess can be accurately simulated by the SMSPVS.
基金Projects(50574091,50774084) supported by the National Natural Science Foundation of China
文摘A feasible method to improve the reliability and processing efficiency of large vibrating screen via the application of an elastic screen surface with multiple attached substructures （ESSMAS） was proposed. In the ESSMAS, every screen rod, with ends embedded into elastomer, is coupled to the main screen structure in a relatively flexible manner. The theoretical analysis was conducted, which consists of establishing dynamic model promoted from the fuzzy structure theory as well as calculating for the equivalent stiffness of each attached structure. According to the numerical simulation using the NEWMARK-fl integration method, this assembling pattern significantly leads to the screen surface/rod having larger vibration intensity than that of the corresponding position on screen structure, which specifically, with an averaged acceleration amplitude increasing ratio of 11.37% in theoretical analysis and 20.27% in experimental test. The experimental results, within a tolerant error, also confirm the established model and demonstrate the feasibility of ESSMAS.
文摘Based on the analysis of the piano wire’s vibration characteristics, the authors estab lished the mechanical model of piano wire proba bility screen , obtained the analytic so lution of thestable forced vibration of screen wires , and developed the para meter designfor m ula of the piano wire screen . The para meter design form ula has been used in coalpreparation industry .
文摘The working frequency selection of the ZK30525 vibrating screen was studied using ANSYS. Integrating the dynamic performance simulation analysis of the vibrating screen structure, the variation laws of beams＇ vibration displacements changing with different exciting frequencies were researched. These beams include six beams, with one discharging beam and one in-material beam. Results indicate that vibration displacements in the middle of these beams increase with the augmenta- tion of exciting frequency. When exciting frequency exceeds a certain value, there exists a flat change region for vibration displacement. According to vibrator characteristics, the vibrating screen＇s working frequency should be selected in the flat change region, and be far away from modal frequencies. The study provides theoretical guidance for the reasonable working frequency selection of the large-scale vibrating screen.
基金Project(51221462)supported by the National Natural Science Foundation of China for Innovative Research GroupProject(20120095110001)supported by the Doctoral Fund of Ministry of Education of China+1 种基金Project supported by the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions,ChinaProject(CXJJ201303)supported by the Innovation Foundation of Xuyi Research and Development Center of Mining Equipment and Materials,China University of Mining and Technology,China
文摘A feasible method was proposed to improve the vibration intensity of screen surface via application of a new type elastic screen surface with multi degree of freedom(NTESSMDF). In the NTESSMDF, the primary robs were coupled to the main screen structure with ends embedded into the elastomers, and the secondary robs were attached to adjacent two primary robs with elastic bands. The dynamic model of vibrating screen with NTESSMDF was established based on Lagrange's equation and the equivalent stiffnesses of the elastomer and elastic band were calculated. According to numerical simulation using the 4th order Runge-Kutta method, the vibration intensity of screen surface can be enhanced substantially with an averaged acceleration amplitude increasing ratio of 72.36%. The primary robs and secondary robs vibrate inversely in steady state, which would result in the friability of materials and avoid stoppage. The experimental results validate the dynamic characteristics with acceleration amplitude rising by62.93% on average, which demonstrates the feasibility of NTESSMDF.
文摘Vibration failure of piping is a serious problem and a matter of concern for safety and reliability of plant operations. Fatigue is the main cause of such failures. Due to the complexity of the phenomenon no closed form design solutions are available. In our study an analytical technique based on the theory of vibrations in the time domain has been presented. Using the inverse theory, the problem has been reduced to a system of Volterra Integral equations to be solved simultaneously at every time step. The solution of the inverse problem may be used in the conventional method to calculate stresses and end reactions which are important from the perspective of engineering design and condition monitoring. The method is robust, simple and can be easily adopted by practicing engineers.
