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RSS2013 Vol. 32, No. 12
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2013, 32(12): 1717-1721.
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Abstract:
In the numerical prediction of transonic wing buffet boundary( i. e. buffet onset incidence) using steady aerodynamic parameters,it is difficult to determine the buffet boundary according to the aerodynamic parameters near the buffet onset incidence because the variations of these parameters are not obvious. A precise approach,called maximum curvature method,to predict the transonic wing buffet onset incidence is proposed. The flow field is simulated by solving steady N-S equation at different wing incidence,and the lifting coefficient curve,pitching moment coefficient curve and the trailing edge pressure coefficient curve are acquired and each curve is fitted by a quartic polynomial to get its curvature equation. Then the buffet onset incidence can be determined by solving its extremum. The transonic buffet onset incidence of a NACA 0012 airfoil at Mach 0. 775 is predicted by the present method. And the predicted transonic buffet onset incidence is compared to that obtained by wind tunnel tests cited from literature and good agreement is achieved. It is illustrated that the method can predict wing transonic buffet boundary with high precision because it utilizes more information from aerodynamic parameters in the vicinity of buffet onset incidence.
In the numerical prediction of transonic wing buffet boundary( i. e. buffet onset incidence) using steady aerodynamic parameters,it is difficult to determine the buffet boundary according to the aerodynamic parameters near the buffet onset incidence because the variations of these parameters are not obvious. A precise approach,called maximum curvature method,to predict the transonic wing buffet onset incidence is proposed. The flow field is simulated by solving steady N-S equation at different wing incidence,and the lifting coefficient curve,pitching moment coefficient curve and the trailing edge pressure coefficient curve are acquired and each curve is fitted by a quartic polynomial to get its curvature equation. Then the buffet onset incidence can be determined by solving its extremum. The transonic buffet onset incidence of a NACA 0012 airfoil at Mach 0. 775 is predicted by the present method. And the predicted transonic buffet onset incidence is compared to that obtained by wind tunnel tests cited from literature and good agreement is achieved. It is illustrated that the method can predict wing transonic buffet boundary with high precision because it utilizes more information from aerodynamic parameters in the vicinity of buffet onset incidence.
2013, 32(12): 1722-1727.
Abstract:
To predict the damping force characteristics of a hydraulic vibration absorber,the dynamic fluidstructure interaction( FSI) simulation system was developed and tested. The test results show that the dynamic effects of the vibration absorber can be ignored when its velocity reaches the peak. The formula for calculating the damping force was developed. The explicit Dytran algorithm and the FSI computation theory were discussed. We also probed the ways of promoting the computational speed and precision. Then,the Dytran algorithm was employed to conduct the simulation. Through a series of simulations,we obtained the fluid field and the damping force vs.velocity characteristics. The simulation results show a good accordance with the test data.
To predict the damping force characteristics of a hydraulic vibration absorber,the dynamic fluidstructure interaction( FSI) simulation system was developed and tested. The test results show that the dynamic effects of the vibration absorber can be ignored when its velocity reaches the peak. The formula for calculating the damping force was developed. The explicit Dytran algorithm and the FSI computation theory were discussed. We also probed the ways of promoting the computational speed and precision. Then,the Dytran algorithm was employed to conduct the simulation. Through a series of simulations,we obtained the fluid field and the damping force vs.velocity characteristics. The simulation results show a good accordance with the test data.
2013, 32(12): 1728-1732.
Abstract:
For a light rail vehicle,a suspension is a vital subsystem that influences its drive safety and ride comfort. By analyzing the structure of a conventional light rail vehicle,its ride comfort index( i. e.,vehicle vertical acceleration) is employed as a target function for evaluating the vibration response performance of the suspension.To further improve the vibration response performance,the novel suspension of a light rail vehicle with a twoterminal mass is suggested. A mechanical model is established to represent the novel suspension. The state-space model approach is proposed to design the parameters of the light rail vehicle. The results show that,with the optimal design,the vibration response performance of the novel suspension of the light rail vehicle improves 0. 696% ~1. 942% over that of the conventional one.
For a light rail vehicle,a suspension is a vital subsystem that influences its drive safety and ride comfort. By analyzing the structure of a conventional light rail vehicle,its ride comfort index( i. e.,vehicle vertical acceleration) is employed as a target function for evaluating the vibration response performance of the suspension.To further improve the vibration response performance,the novel suspension of a light rail vehicle with a twoterminal mass is suggested. A mechanical model is established to represent the novel suspension. The state-space model approach is proposed to design the parameters of the light rail vehicle. The results show that,with the optimal design,the vibration response performance of the novel suspension of the light rail vehicle improves 0. 696% ~1. 942% over that of the conventional one.
2013, 32(12): 1733-1737.
Abstract:
The simulation systems of carbon-carbon composite materials are independent. The process,microstructure and properties of C/C composites have no relationship. To solve the problem,the comprehensive simulation of CVI( Chemical vapor infiltration),microstructure-analysis and properties-forecast of C/C composite materials was investigated based the experimental database. Many disciplines such as C/C composite materials、database、software programming and computer simulation were used. The simulation system that utilized experimental database of C/C composite materials as data engine was established by VC + + platform,and the framework about propertiesforecast was built. The paper united TCVI,microstructure-analysis and properties-forecast as one system. The system achieves TCVI process simulation and microstructure-analysis. It has important guiding significance for researching integrated simulation of C/C composite materials.
The simulation systems of carbon-carbon composite materials are independent. The process,microstructure and properties of C/C composites have no relationship. To solve the problem,the comprehensive simulation of CVI( Chemical vapor infiltration),microstructure-analysis and properties-forecast of C/C composite materials was investigated based the experimental database. Many disciplines such as C/C composite materials、database、software programming and computer simulation were used. The simulation system that utilized experimental database of C/C composite materials as data engine was established by VC + + platform,and the framework about propertiesforecast was built. The paper united TCVI,microstructure-analysis and properties-forecast as one system. The system achieves TCVI process simulation and microstructure-analysis. It has important guiding significance for researching integrated simulation of C/C composite materials.
2013, 32(12): 1738-1742.
Abstract:
The finite element modal-parameter model was critical to the reliable and accurate analysis of the structural dynamics performance of spur gear. Comparing with the natural frequency of the initial finite element model to the experimental modal,the modification of finite element modal-parameter model was converted into the issue of solving the minimum relative errors of the natural frequency between the calculated and experimental results of spur gear based on the ANSYS optimization module. The results showed that the maximum relative error of the first six natural frequency was reduced from 2. 99% to 1. 24% after modifying the finite element modal-parameter model and the accuracy of the finite element modal-parameter model of spur gear was significantly improved with the corresponding damping characteristic supplied to the finite element modal-parameter model,ensuring the precise of the furthermore dynamics performance prediction analysis.
The finite element modal-parameter model was critical to the reliable and accurate analysis of the structural dynamics performance of spur gear. Comparing with the natural frequency of the initial finite element model to the experimental modal,the modification of finite element modal-parameter model was converted into the issue of solving the minimum relative errors of the natural frequency between the calculated and experimental results of spur gear based on the ANSYS optimization module. The results showed that the maximum relative error of the first six natural frequency was reduced from 2. 99% to 1. 24% after modifying the finite element modal-parameter model and the accuracy of the finite element modal-parameter model of spur gear was significantly improved with the corresponding damping characteristic supplied to the finite element modal-parameter model,ensuring the precise of the furthermore dynamics performance prediction analysis.
2013, 32(12): 1743-1747.
Abstract:
The hole centers distance is difficult measured by using the conventional measurement method. In this paper,new detection method which combine a machine tool probe based on laser displacement sensor is proposed.With the machine tool coordinate system,the centers' relative coordinates are quickly and accurately gotten by using the approximation hole center location,and then the hole centers distance for the measured work piece can be also gotten. Comparing with the traditional measurement method,the present method is rapid,convenient,high precision,non-contact,on-line measurement. Finally,using a pair of standard ring gauge to verify the correctness of the method,checking measurement accuracy of the hole centers distance in the three coordinates measuring machine,measurement errors can reach micron level. The experiment prove the present method can efficiently applied to measure the hole center distance online.
The hole centers distance is difficult measured by using the conventional measurement method. In this paper,new detection method which combine a machine tool probe based on laser displacement sensor is proposed.With the machine tool coordinate system,the centers' relative coordinates are quickly and accurately gotten by using the approximation hole center location,and then the hole centers distance for the measured work piece can be also gotten. Comparing with the traditional measurement method,the present method is rapid,convenient,high precision,non-contact,on-line measurement. Finally,using a pair of standard ring gauge to verify the correctness of the method,checking measurement accuracy of the hole centers distance in the three coordinates measuring machine,measurement errors can reach micron level. The experiment prove the present method can efficiently applied to measure the hole center distance online.
2013, 32(12): 1748-1751.
Abstract:
In order to improve the riding comfort and the strength properties of motorcycle,the finite element model for a motorcycle frame is established. The computational modal analysis is conducted and then the calculated modes are compared with those obtained by experimental modal tests. Base on the modal analysis,the motorcycle frame is optimized by using the MSC. Nastran software. In the optimization,the diameter and the thickness of the beam element were taken as variables and the first-order modal frequency of the motorcycle is maximized with the strength and weight constraints. The results show that the first-order mode frequency is increased by 8. 66% with a decreasing of the maximum stress by 22. 14%.
In order to improve the riding comfort and the strength properties of motorcycle,the finite element model for a motorcycle frame is established. The computational modal analysis is conducted and then the calculated modes are compared with those obtained by experimental modal tests. Base on the modal analysis,the motorcycle frame is optimized by using the MSC. Nastran software. In the optimization,the diameter and the thickness of the beam element were taken as variables and the first-order modal frequency of the motorcycle is maximized with the strength and weight constraints. The results show that the first-order mode frequency is increased by 8. 66% with a decreasing of the maximum stress by 22. 14%.
2013, 32(12): 1752-1757.
Abstract:
To reduce the non-uniform illumination and high light caused by the coaxial annular LED array light used for a vision-guided automatic guided vehicle,an image processing technique for non-uniform illumination with illumination constraints is proposed. Firstly,the illumination model of the coaxial annular LED array light is established; the parameters of the model are estimated by using the nonlinear least squares Levenberg-Marquardt algorithm for the monochromatic diffuse reflection template image. Another method based on irradiance average normalization is proposed to remove the influence of non-uniform illumination. In order to reduce the high light,the chrominance of color image that should be enhanced is complemented. The experimental results show that our method can effectively improve the reliability of feature extraction for guide path.
To reduce the non-uniform illumination and high light caused by the coaxial annular LED array light used for a vision-guided automatic guided vehicle,an image processing technique for non-uniform illumination with illumination constraints is proposed. Firstly,the illumination model of the coaxial annular LED array light is established; the parameters of the model are estimated by using the nonlinear least squares Levenberg-Marquardt algorithm for the monochromatic diffuse reflection template image. Another method based on irradiance average normalization is proposed to remove the influence of non-uniform illumination. In order to reduce the high light,the chrominance of color image that should be enhanced is complemented. The experimental results show that our method can effectively improve the reliability of feature extraction for guide path.
2013, 32(12): 1758-1761.
Abstract:
Applying the finite element method,the front sub-frame for the multi-purpose vehicle is analyzed on the cornering and braking conditions. The calculated rigidity,stresses and natural modes are compared between the original front sub-frame structure with the connected reinforcing rod and the new designed front sub-frame structure,with the disconnected reinforcing rod. The results show that the stress of the new designed sub-frame is lower than that of the original front sub-frame on the cornering and braking condition; the stiffness of the new front sub-frame structure is higher than that of the original sub-frame structure; the modal frequencies of the new designed front sub-frame structure is almost the same as those of the original sub-frame structure. It is predicted that the improved design for the sub-frame structure with the connected reinforcing rod can meet the request of the new developed vehicle.
Applying the finite element method,the front sub-frame for the multi-purpose vehicle is analyzed on the cornering and braking conditions. The calculated rigidity,stresses and natural modes are compared between the original front sub-frame structure with the connected reinforcing rod and the new designed front sub-frame structure,with the disconnected reinforcing rod. The results show that the stress of the new designed sub-frame is lower than that of the original front sub-frame on the cornering and braking condition; the stiffness of the new front sub-frame structure is higher than that of the original sub-frame structure; the modal frequencies of the new designed front sub-frame structure is almost the same as those of the original sub-frame structure. It is predicted that the improved design for the sub-frame structure with the connected reinforcing rod can meet the request of the new developed vehicle.
2013, 32(12): 1762-1766.
Abstract:
It is necessary to control radial force of non-contact electromagnetic loading device according to actual load in reliability experiments of high speed motorized spindle. To realize closed loop control of radial force,analytical model of dynamic electromagnetic field is built under high speed loading. In this model,the production of eddy currents magnetic field and its effects on original magnetic field are considered,and the analytical formula of radial electromagnetic force is acquired. The analytical calculation results show that the main influence factors are original magnetic field and the loading disc speed. To verify the effectiveness of the analytical calculation,the finite element method( FEM) is adopted to build three-dimensional simulation model of dynamic electromagnetic field. And the accurate calculation results are acquired. To further validate the accuracy of analysis of radial electromagnetic force,radial electromagnetic force measuring tests are conducted with different disc speeds. It is shown that the calculation results are in good agreement with those of measurement.
It is necessary to control radial force of non-contact electromagnetic loading device according to actual load in reliability experiments of high speed motorized spindle. To realize closed loop control of radial force,analytical model of dynamic electromagnetic field is built under high speed loading. In this model,the production of eddy currents magnetic field and its effects on original magnetic field are considered,and the analytical formula of radial electromagnetic force is acquired. The analytical calculation results show that the main influence factors are original magnetic field and the loading disc speed. To verify the effectiveness of the analytical calculation,the finite element method( FEM) is adopted to build three-dimensional simulation model of dynamic electromagnetic field. And the accurate calculation results are acquired. To further validate the accuracy of analysis of radial electromagnetic force,radial electromagnetic force measuring tests are conducted with different disc speeds. It is shown that the calculation results are in good agreement with those of measurement.
2013, 32(12): 1767-1770.
Abstract:
Automatic assembly is the key function for the rapid design system of semi-trailer. Based on the analysis of whole structural characteristics for the semi-trailer and the each parts,through the assembly sequence planning,specification of assembly constraints relations,suitable for semi-trailer assembly constraints types and realization method are put forward,specification of main parts of the semi-trailer rapid design assembly datums and matching type setting,realization of automatic assembly,greatly improve the speed and efficiency of the design,and based on the UG verifies that the method is effective and practical.
Automatic assembly is the key function for the rapid design system of semi-trailer. Based on the analysis of whole structural characteristics for the semi-trailer and the each parts,through the assembly sequence planning,specification of assembly constraints relations,suitable for semi-trailer assembly constraints types and realization method are put forward,specification of main parts of the semi-trailer rapid design assembly datums and matching type setting,realization of automatic assembly,greatly improve the speed and efficiency of the design,and based on the UG verifies that the method is effective and practical.
2013, 32(12): 1771-1774.
Abstract:
Aiming at the problem that the traditional morphology filter and wavelet de-noising algorithms cannot very well reduce the noise of rotor bearing load signal,a new wavelet morphology filter method was proposed in this paper. The methods of wavelet morphology filter and the generalized morphology filtering were used to simulation and experiment signals,respectively,and the results of the two methods were compared. It was demonstrated that the wavelet morphology filter method could depress the random signal more effectively,and it also can improve the SNR( signal-noise ratio). In addition,this new method can inhibit the de-noising signal distortion and accomplish the processing of the signal de-noising.
Aiming at the problem that the traditional morphology filter and wavelet de-noising algorithms cannot very well reduce the noise of rotor bearing load signal,a new wavelet morphology filter method was proposed in this paper. The methods of wavelet morphology filter and the generalized morphology filtering were used to simulation and experiment signals,respectively,and the results of the two methods were compared. It was demonstrated that the wavelet morphology filter method could depress the random signal more effectively,and it also can improve the SNR( signal-noise ratio). In addition,this new method can inhibit the de-noising signal distortion and accomplish the processing of the signal de-noising.
2013, 32(12): 1775-1779.
Abstract:
By employing an improved crank rocker mechanism,a new propulsion mechanism of caudal fin of bionic robotic fish is designed. By using the motion analysis module of Pro/E and ANSYS software,the conditions to achieve straight swimming are given for this mechanism. Meanwhile,three manners for this mechanism to achieve turning movement are given and the applicable situations are also proposed. Based on this,the control strategy is presented for this mechanism to carried out straight swimming and turning movement with multiple modules. In addition,simulation results show that the centroid of mechanism changed within a limited range; and the inertia force has little influence on the dynamic balance of the propulsion mechanism. The present study verifies the validity of the design and provids the theory basis for the experiments of the bionic robotic fish.
By employing an improved crank rocker mechanism,a new propulsion mechanism of caudal fin of bionic robotic fish is designed. By using the motion analysis module of Pro/E and ANSYS software,the conditions to achieve straight swimming are given for this mechanism. Meanwhile,three manners for this mechanism to achieve turning movement are given and the applicable situations are also proposed. Based on this,the control strategy is presented for this mechanism to carried out straight swimming and turning movement with multiple modules. In addition,simulation results show that the centroid of mechanism changed within a limited range; and the inertia force has little influence on the dynamic balance of the propulsion mechanism. The present study verifies the validity of the design and provids the theory basis for the experiments of the bionic robotic fish.
2013, 32(12): 1780-1784.
Abstract:
Parameter optimization is the ultimate goal in the Delta robot design. Therefore,dynamics analysis is done for the Delta robot in this paper. Based on the virtual work principle,kinematic equation in the Delta robot is built,and the singular value decomposition theory is adopted. Based on the dynamic performance index that the single axle's maximum output torque of the terminal unit acceleration in the whole workspace is minimum,a group of the optimal scaling parameters fitting the design demand is acquired. The present theory supports the theoretical basis for the physical prototype design of parallel robot.
Parameter optimization is the ultimate goal in the Delta robot design. Therefore,dynamics analysis is done for the Delta robot in this paper. Based on the virtual work principle,kinematic equation in the Delta robot is built,and the singular value decomposition theory is adopted. Based on the dynamic performance index that the single axle's maximum output torque of the terminal unit acceleration in the whole workspace is minimum,a group of the optimal scaling parameters fitting the design demand is acquired. The present theory supports the theoretical basis for the physical prototype design of parallel robot.
2013, 32(12): 1785-1788.
Abstract:
An improved three-cell model,which includes warp-weft cell,warp tying cell and contact cell,is proposed based on the geometry characteristics of the yarns for 3D orthogonal woven composite. The deformation and structural characteristics of yarns in cells are considered. The cross-section of yarns,especially extrusion yarns,is equivalently deal with so that the present model is common and the corresponding calculation is simple. The effective elastic properties of cells are obtained by using the homogenization method. Then based on the stiffness volume average method,the elastic stiffness of 3D orthogonal woven composite is calculated. Comparing with the available experimental data,the result of numerical example shows the present model is effective and reasonable. Also,the effect of the woven angle on the elastic stiffness of 3D orthogonal woven composite is discussed,i. e.,the increase of the woven angle leads to the increase of the transverse modulus and the decrease of the longitudinal modulus.
An improved three-cell model,which includes warp-weft cell,warp tying cell and contact cell,is proposed based on the geometry characteristics of the yarns for 3D orthogonal woven composite. The deformation and structural characteristics of yarns in cells are considered. The cross-section of yarns,especially extrusion yarns,is equivalently deal with so that the present model is common and the corresponding calculation is simple. The effective elastic properties of cells are obtained by using the homogenization method. Then based on the stiffness volume average method,the elastic stiffness of 3D orthogonal woven composite is calculated. Comparing with the available experimental data,the result of numerical example shows the present model is effective and reasonable. Also,the effect of the woven angle on the elastic stiffness of 3D orthogonal woven composite is discussed,i. e.,the increase of the woven angle leads to the increase of the transverse modulus and the decrease of the longitudinal modulus.
2013, 32(12): 1789-1791.
Abstract:
In order to make the computer vision technology for comprehensive,reliable measurement of part size,and to ensure the accuracy and stability of the measurement data requirements. In this paper,CMOS camera,optical lens,parallel light source,such as the core hardware,build and develop a set of dimensional measurement system based on computer vision. The experimental analysis of repeatable accuracy,linearity,system stability and ambient light effects by using the measuring system to standard gauge block shows that measuring system has the high accuracy of measurement,which can reach 0. 005 mm precision measurement requirements,in the case of small size transform range.
In order to make the computer vision technology for comprehensive,reliable measurement of part size,and to ensure the accuracy and stability of the measurement data requirements. In this paper,CMOS camera,optical lens,parallel light source,such as the core hardware,build and develop a set of dimensional measurement system based on computer vision. The experimental analysis of repeatable accuracy,linearity,system stability and ambient light effects by using the measuring system to standard gauge block shows that measuring system has the high accuracy of measurement,which can reach 0. 005 mm precision measurement requirements,in the case of small size transform range.
2013, 32(12): 1792-1796.
Abstract:
The influence of the variation of parameters in sludge mixed liquor was studied through simulating the running condition of the SBR( sequencing batch reactor activated sludge process) in the sewage treatment plant in this paper. The test result indicated as follows: with the increase of ozone dosage,MLSS( mixed liquid suspended solids) and MLVSS( mixed liquor volatile suspended solids) of SBR always tend to decrease,and the activity of sludge was reduced significantly. Ozone oxidation could break the sludge microbial cells,which could increase the concentration of SCOD( soluble chemical oxygen demand),TOC( total organic carbon),TN( total nitrogen) and TP( total phosphorus) in the mixed liquor,whose maximum values could reach 1 366. 5 mg/L,420. 50 mg/L,31. 89 mg/L and 19. 54 mg/L,respectively. NH4+-N content and pH of the sludge mixed liquor also decreased.Both NO2--N content and NO-3-N content increased in the same way at first,but NO2--N content showed a downward trend with the constant increase of ozone dosage.
The influence of the variation of parameters in sludge mixed liquor was studied through simulating the running condition of the SBR( sequencing batch reactor activated sludge process) in the sewage treatment plant in this paper. The test result indicated as follows: with the increase of ozone dosage,MLSS( mixed liquid suspended solids) and MLVSS( mixed liquor volatile suspended solids) of SBR always tend to decrease,and the activity of sludge was reduced significantly. Ozone oxidation could break the sludge microbial cells,which could increase the concentration of SCOD( soluble chemical oxygen demand),TOC( total organic carbon),TN( total nitrogen) and TP( total phosphorus) in the mixed liquor,whose maximum values could reach 1 366. 5 mg/L,420. 50 mg/L,31. 89 mg/L and 19. 54 mg/L,respectively. NH4+-N content and pH of the sludge mixed liquor also decreased.Both NO2--N content and NO-3-N content increased in the same way at first,but NO2--N content showed a downward trend with the constant increase of ozone dosage.
2013, 32(12): 1797-1801.
Abstract:
This paper studies the water-jacket exhaust manifold on a certain engine. With the help of the 3D modeling UG software,the 3D models of the wall,inner gas and inner cooling water of the water-jacket exhaust manifold are established separately; then,the 3D models are assembled. This paper also divides a mesh by using the GAMBIT software and simulates the fluid flow,heat transfer and coupled heat transfer between the water-jacket exhaust manifold and its fluid by using the FLUENT software,thus obtaining the inner flow field distribution and the temperature field distribution. The simulation results show that the surface temperature of the water-jacket exhaust manifold does not reach 423 K. This meets the explosion-proof requirement.
This paper studies the water-jacket exhaust manifold on a certain engine. With the help of the 3D modeling UG software,the 3D models of the wall,inner gas and inner cooling water of the water-jacket exhaust manifold are established separately; then,the 3D models are assembled. This paper also divides a mesh by using the GAMBIT software and simulates the fluid flow,heat transfer and coupled heat transfer between the water-jacket exhaust manifold and its fluid by using the FLUENT software,thus obtaining the inner flow field distribution and the temperature field distribution. The simulation results show that the surface temperature of the water-jacket exhaust manifold does not reach 423 K. This meets the explosion-proof requirement.
2013, 32(12): 1802-1806.
Abstract:
Considering the inspection requirements for urban drainage pipelines as well as the advantages and disadvantages of traditional pipeline inspection methods,a kind of wheel municipal pipeline inspection robot with the endoscopic detection function was developed in this paper. According to the design parameter requirements for pipeline robots,UG software was used to design mechanical structures of the robot,meanwhile,the performances of the transmission structure and the critical subversion state were also further analyzed. And then,in order to verify the movement stability of the robot,ADAMS software was used to do the kinematics simulation. After that,visual C++ 6. 0was used to prepare the numerical control system based on the PMAC( Programmable Multi-Axis Controller) card.Finally,the traction and climbing performances of physical prototype were tested and the results effectively verified the rationality of the design,and the design goal for urban drainage pipeline detection was achieved.
Considering the inspection requirements for urban drainage pipelines as well as the advantages and disadvantages of traditional pipeline inspection methods,a kind of wheel municipal pipeline inspection robot with the endoscopic detection function was developed in this paper. According to the design parameter requirements for pipeline robots,UG software was used to design mechanical structures of the robot,meanwhile,the performances of the transmission structure and the critical subversion state were also further analyzed. And then,in order to verify the movement stability of the robot,ADAMS software was used to do the kinematics simulation. After that,visual C++ 6. 0was used to prepare the numerical control system based on the PMAC( Programmable Multi-Axis Controller) card.Finally,the traction and climbing performances of physical prototype were tested and the results effectively verified the rationality of the design,and the design goal for urban drainage pipeline detection was achieved.
2013, 32(12): 1807-1811.
Abstract:
The unit cell model for predicting elastic properties of 3D orthogonal C /C composite was established based on the micro-structure in this paper,and nine engineering constants of this material were evaluated with homogenization method,the prediction results agee well with experimental results. In order to further validate the proposed model,finite element analysis was carried to open hole tensile specimen with the engineering constants calculated,and strain around the hole coincides well with experimental results. In addition,the off-axis elastic properties were discussed,and the effect of properties of components on the elastic properties of this material was also investigated. The results indicate that the axial tensile modulus of the material is dominated by the fiber and shear modulus depends on that of matrix,however,the dominant constituent of in-plane shear modulus switches to fiber when the deflection angle increases to 45 degrees.
The unit cell model for predicting elastic properties of 3D orthogonal C /C composite was established based on the micro-structure in this paper,and nine engineering constants of this material were evaluated with homogenization method,the prediction results agee well with experimental results. In order to further validate the proposed model,finite element analysis was carried to open hole tensile specimen with the engineering constants calculated,and strain around the hole coincides well with experimental results. In addition,the off-axis elastic properties were discussed,and the effect of properties of components on the elastic properties of this material was also investigated. The results indicate that the axial tensile modulus of the material is dominated by the fiber and shear modulus depends on that of matrix,however,the dominant constituent of in-plane shear modulus switches to fiber when the deflection angle increases to 45 degrees.
2013, 32(12): 1812-1816.
Abstract:
Aiming at the measurement requirement for the filling level of ball mill,a new monitoring approach for vibration signals of the mill shell is proposed. Firstly,the type and install position for sensors are determined combining the distribution of filling level in ball mill. Secondly,the main structure of wireless sampling system is given. Finally,the sampling frequency,number and region for the vibration signal of mill shell are obtained based on the steel ball impact model and the ideal layered model of the steel ball combining the practical vibration data of power plant. The results demonstrate that the present monitoring method is effective.
Aiming at the measurement requirement for the filling level of ball mill,a new monitoring approach for vibration signals of the mill shell is proposed. Firstly,the type and install position for sensors are determined combining the distribution of filling level in ball mill. Secondly,the main structure of wireless sampling system is given. Finally,the sampling frequency,number and region for the vibration signal of mill shell are obtained based on the steel ball impact model and the ideal layered model of the steel ball combining the practical vibration data of power plant. The results demonstrate that the present monitoring method is effective.
2013, 32(12): 1817-1820.
Abstract:
Hydraulic decoking is a decoking method widely used in delayed coking process. But generally in the hydraulic decoking process,operators need to determine the decoking state according to observation constantly for the coke water from the bottom of tower in the chute and work experience. Because of the operating conditions,weather,night and many other factors,operators are sometimes unable to accurately observe and judge the decoking state. In this paper,an automatic detection project is put forward to detect the decoking situation automatically based on the fact that the vibration strengths such as the amplitude and the frequency of the tower wall vibration signal are different during the whole decoking process. Also a human-computer interface is made by LabVIEW to show the decoking process on real-time. The test result shows that: the amplitude change of the vibration signal on the tower can reach 100 times during and after the decoking. The frequencies of the signal are mainly located at 400 Hz and 1 200 Hz during and after the decoking respectively. The detection system can detect whether the decoking work finished or not effectively and it can show the process on human-computer interface.
Hydraulic decoking is a decoking method widely used in delayed coking process. But generally in the hydraulic decoking process,operators need to determine the decoking state according to observation constantly for the coke water from the bottom of tower in the chute and work experience. Because of the operating conditions,weather,night and many other factors,operators are sometimes unable to accurately observe and judge the decoking state. In this paper,an automatic detection project is put forward to detect the decoking situation automatically based on the fact that the vibration strengths such as the amplitude and the frequency of the tower wall vibration signal are different during the whole decoking process. Also a human-computer interface is made by LabVIEW to show the decoking process on real-time. The test result shows that: the amplitude change of the vibration signal on the tower can reach 100 times during and after the decoking. The frequencies of the signal are mainly located at 400 Hz and 1 200 Hz during and after the decoking respectively. The detection system can detect whether the decoking work finished or not effectively and it can show the process on human-computer interface.
2013, 32(12): 1821-1824.
Abstract:
Magneto rheological( MR) damper of aircraft landing gear has better adaptability and wider adjusted range than the changed pin cross-section one. The smaller size of MR damper improves the strength of aircraft structure. A MR damper and its test method are designed in this paper. The magnetic field and mechanics of MR damper are modeled,and the test simulation is done. The fuzzy controlled damping properties perform better than the non-controlled and fulfill the designing demand of that the load increases to the peak gradually.
Magneto rheological( MR) damper of aircraft landing gear has better adaptability and wider adjusted range than the changed pin cross-section one. The smaller size of MR damper improves the strength of aircraft structure. A MR damper and its test method are designed in this paper. The magnetic field and mechanics of MR damper are modeled,and the test simulation is done. The fuzzy controlled damping properties perform better than the non-controlled and fulfill the designing demand of that the load increases to the peak gradually.
2013, 32(12): 1825-1828.
Abstract:
The interaction between the fluid-filled pipes and its support structure bring about complexity in its vibration analysis. Based on the finite element method,the liquid-filled pipe and its supporting structure are modeled separately and then the two models are combined together using the condition of the same displacement for their common nodes. Based on the coupled equation,the vibration characteristics of the liquid-filled pipe and the supporting structure system are analyzed. The results show that,due to the fluid-structure interaction effect,the modal frequencies of the system are reduced obviously and the higher order modal shapes are influenced evidently. The strong coupling vibration modes exist in the support structure and liquid-filled pipe system.
The interaction between the fluid-filled pipes and its support structure bring about complexity in its vibration analysis. Based on the finite element method,the liquid-filled pipe and its supporting structure are modeled separately and then the two models are combined together using the condition of the same displacement for their common nodes. Based on the coupled equation,the vibration characteristics of the liquid-filled pipe and the supporting structure system are analyzed. The results show that,due to the fluid-structure interaction effect,the modal frequencies of the system are reduced obviously and the higher order modal shapes are influenced evidently. The strong coupling vibration modes exist in the support structure and liquid-filled pipe system.
2013, 32(12): 1829-1834.
Abstract:
Owing to the complicate configuration of cylindrical gear tooth,the present method of mesh gear tooth is difficult to apply to simulate the stress induced by laser shock processing,so a new mesh technique is presented to mesh the gear tooth into the regular three-dimensional finite elements. On the basis of analyzing the tooth profile feature,the end surface of gear tooth is divided firstly into different regions,and then these regions are meshed into the plane elements with different density controlled. Finally,the solid elements can be generated by the drag method,which is suitable for the laser shock waves propagation. Comparing with the known mesh methods,the new technique has clear improvement in grid density,elements form,length-width ration and the same direction of elements,and effectively avoids the abnormal shape of elements,which can ensure calculating successfully and obtain a relatively accurate residual stresses. Moreover,an experiment of gear tooth laser shock processing is performed to validate the mesh method and simulation accuracy,and the mesh size 0. 125 mm is selected for further evaluation.
Owing to the complicate configuration of cylindrical gear tooth,the present method of mesh gear tooth is difficult to apply to simulate the stress induced by laser shock processing,so a new mesh technique is presented to mesh the gear tooth into the regular three-dimensional finite elements. On the basis of analyzing the tooth profile feature,the end surface of gear tooth is divided firstly into different regions,and then these regions are meshed into the plane elements with different density controlled. Finally,the solid elements can be generated by the drag method,which is suitable for the laser shock waves propagation. Comparing with the known mesh methods,the new technique has clear improvement in grid density,elements form,length-width ration and the same direction of elements,and effectively avoids the abnormal shape of elements,which can ensure calculating successfully and obtain a relatively accurate residual stresses. Moreover,an experiment of gear tooth laser shock processing is performed to validate the mesh method and simulation accuracy,and the mesh size 0. 125 mm is selected for further evaluation.
2013, 32(12): 1835-1840.
Abstract:
The parts built by three dimensional printing( 3DP) will contract in different direction after drying and post-treatment,which will significantly affect the dimensional accuracy. Based on the experimental platform of ZP310,the central composite design( CCD) is used to design the experimental program for printing parameters in this paper. Response surface methodology( RSM) is also used to analyze the effect of printing parameters such as the power thickness and saturation level on the contraction ratio of mixed powder of starch based. A mathematical model is established to represent the relationship between the contraction ratio in X,Y and Z three directions and the printing parameters. According to the contraction ratio,the reasonable error compensation is made to improve the accuracy in each direction
The parts built by three dimensional printing( 3DP) will contract in different direction after drying and post-treatment,which will significantly affect the dimensional accuracy. Based on the experimental platform of ZP310,the central composite design( CCD) is used to design the experimental program for printing parameters in this paper. Response surface methodology( RSM) is also used to analyze the effect of printing parameters such as the power thickness and saturation level on the contraction ratio of mixed powder of starch based. A mathematical model is established to represent the relationship between the contraction ratio in X,Y and Z three directions and the printing parameters. According to the contraction ratio,the reasonable error compensation is made to improve the accuracy in each direction
2013, 32(12): 1841-1845.
Abstract:
Based on the bending stress analysis of the elliptical cross section of an elbow pipe with wall thickness variation,we use the triple-shear yield criterion to derive the plastic limit load formula that considers the variation of the wall thickness of the elbow pipe under external pressure and the bending elliptical variation. The plastic limit load of the elbow pipe changes with the wall thickness and ovality of the elbow pipe.
Based on the bending stress analysis of the elliptical cross section of an elbow pipe with wall thickness variation,we use the triple-shear yield criterion to derive the plastic limit load formula that considers the variation of the wall thickness of the elbow pipe under external pressure and the bending elliptical variation. The plastic limit load of the elbow pipe changes with the wall thickness and ovality of the elbow pipe.
2013, 32(12): 1846-1849.
Abstract:
In order to obtain the excitation inputs for vibration simulation and test of operator suspension seat,the vibration excitations in time-domain,such as acceleration,velocity and displacement,are reconstructed in this paper based on the inverse discrete Fourier transform( IDFT) and frequency domain integration methods,according to the excitation input spectral specified in national standards. Compared with the power spectral densities( PSDs) in national standards,the PSDs of the accelerations reconstructed in time-domain are exactly matched with the standard PSDs,by which it can be proved that the proposed method in this paper can accurately reconstruct the excitation input spectral in time-domain.
In order to obtain the excitation inputs for vibration simulation and test of operator suspension seat,the vibration excitations in time-domain,such as acceleration,velocity and displacement,are reconstructed in this paper based on the inverse discrete Fourier transform( IDFT) and frequency domain integration methods,according to the excitation input spectral specified in national standards. Compared with the power spectral densities( PSDs) in national standards,the PSDs of the accelerations reconstructed in time-domain are exactly matched with the standard PSDs,by which it can be proved that the proposed method in this paper can accurately reconstruct the excitation input spectral in time-domain.
2013, 32(12): 1850-1854.
Abstract:
Aiming at the serious vibration problem of 2800 four-high reversible cold rolling mill,the vibration test study was made in this paper to master the rolling mill vibration law and determine the main vibration sources. The mill vertical system vibration characteristics were tested and researches were made with the performance status and process information of multi-physical processes collected from actual mill unit operation to make sure the vibration mechanism and vibration sources. A simplified spring-mass system model with 6 degrees of freedom was used to make simulation analysis of the inherent characteristics of the mill. Test and analysis results show that: the dominant vibration is self-excited vibration in the vertical mill system; the key vibration source is confirmed in the roll gap; and multiple variables of roll gap are considered to be the sensitive factors of the dynamic behavior of the rolling process,the concentrated band and core frequency for dynamic behavior of the work roll are obtained; and the influence of the main parameters on the vibration is analyzed and compared. Analysis and diagnosis conclusions are very important to develop a reasonable structural dynamics modification strategy and eliminate mill self-excited vibration.
Aiming at the serious vibration problem of 2800 four-high reversible cold rolling mill,the vibration test study was made in this paper to master the rolling mill vibration law and determine the main vibration sources. The mill vertical system vibration characteristics were tested and researches were made with the performance status and process information of multi-physical processes collected from actual mill unit operation to make sure the vibration mechanism and vibration sources. A simplified spring-mass system model with 6 degrees of freedom was used to make simulation analysis of the inherent characteristics of the mill. Test and analysis results show that: the dominant vibration is self-excited vibration in the vertical mill system; the key vibration source is confirmed in the roll gap; and multiple variables of roll gap are considered to be the sensitive factors of the dynamic behavior of the rolling process,the concentrated band and core frequency for dynamic behavior of the work roll are obtained; and the influence of the main parameters on the vibration is analyzed and compared. Analysis and diagnosis conclusions are very important to develop a reasonable structural dynamics modification strategy and eliminate mill self-excited vibration.
2013, 32(12): 1855-1858.
Abstract:
The hydraulic system fault diagnosis method based on fuzzy neural networks( FNN),fault tree analysis( FTA) and expertise knowledge is proposed to overcome the shortcomings of the traditional fault diagnosis methods because of the complexity coupling and uncertainty of hydraulic system fault. Taking lifting equipment's hydraulic system as study object,a fault tree model is set up,and the fault tree information and expertise knowledge are employed to establish the FNN structure and extract training data. The fuzzy membership functions,which are needed in fuzzy pre-processing,are confirmed by using the statistical parameter method. Finally,the trained FNN model is applied to examples; the application results show that the hydraulic system fault diagnosis method based on FTA and FNN is effective and practicable.
The hydraulic system fault diagnosis method based on fuzzy neural networks( FNN),fault tree analysis( FTA) and expertise knowledge is proposed to overcome the shortcomings of the traditional fault diagnosis methods because of the complexity coupling and uncertainty of hydraulic system fault. Taking lifting equipment's hydraulic system as study object,a fault tree model is set up,and the fault tree information and expertise knowledge are employed to establish the FNN structure and extract training data. The fuzzy membership functions,which are needed in fuzzy pre-processing,are confirmed by using the statistical parameter method. Finally,the trained FNN model is applied to examples; the application results show that the hydraulic system fault diagnosis method based on FTA and FNN is effective and practicable.
2013, 32(12): 1859-1863,1868.
Abstract:
There is not only permanent magnetic field but also electric magnetic field in permanent magnet biased magnetic bearing so that its mechanism and magnetic field distribution are always complex and a lot of parameters are involved. Taking a kind of permanent magnet biased radial magnetic bearing as an example; a parameter design method based on magnetic flux calculation is advanced in this paper after analyzing its operational principle and magnetic field distribution; and the designing flow and calculation illustrations are presented. Magnetic field simulation of the design result is operated by using the finite element analysis( FEA) software. The experimentation results testify that the permanent magnet biased radial magnetic bearing designed by this method has good levitation performance. The radial displacement and control current curves at 20 000 r/min are also presented.
There is not only permanent magnetic field but also electric magnetic field in permanent magnet biased magnetic bearing so that its mechanism and magnetic field distribution are always complex and a lot of parameters are involved. Taking a kind of permanent magnet biased radial magnetic bearing as an example; a parameter design method based on magnetic flux calculation is advanced in this paper after analyzing its operational principle and magnetic field distribution; and the designing flow and calculation illustrations are presented. Magnetic field simulation of the design result is operated by using the finite element analysis( FEA) software. The experimentation results testify that the permanent magnet biased radial magnetic bearing designed by this method has good levitation performance. The radial displacement and control current curves at 20 000 r/min are also presented.
2013, 32(12): 1864-1868.
Abstract:
A new type of metal rubber pressure regulation valve was introduced. The apparatus for testing the metal rubber pressure regulation valve was designed,and experiments on the flow resistance of the metal rubber pressure regulation valve were done. The experimental results show that: 1) the flow resistance of the metal rubber pressure regulation valve with same wire diameter and flux increases,whereas its porosity decreases but the pressure regulation range( ΔP = P2-P1) increases; 2) the flow resistance of the metal rubber pressure regulation valve with the same porosity and flux increases,whereas the wire diameter decreases but the pressure regulation range ΔP = P2-P1) increases. The metal rubber pressure regulation elements can restrain the vibration of fluid and keep it flowing stably.
A new type of metal rubber pressure regulation valve was introduced. The apparatus for testing the metal rubber pressure regulation valve was designed,and experiments on the flow resistance of the metal rubber pressure regulation valve were done. The experimental results show that: 1) the flow resistance of the metal rubber pressure regulation valve with same wire diameter and flux increases,whereas its porosity decreases but the pressure regulation range( ΔP = P2-P1) increases; 2) the flow resistance of the metal rubber pressure regulation valve with the same porosity and flux increases,whereas the wire diameter decreases but the pressure regulation range ΔP = P2-P1) increases. The metal rubber pressure regulation elements can restrain the vibration of fluid and keep it flowing stably.
2013, 32(12): 1869-1873,1878.
Abstract:
Due to the uncertainty of the structural optimization in a complex mechanical system,in this paper an accurate identifying method for the boundary conditions based on sub-structure techniques is studied,a successive approximation topological optimization design is proposed to make the structural topology gradually achieve optimal structure. In addition,aiming at solving the problem of complexity to do CAE analysis for enterprise,an automatic system for automobile seat components based on the HyperWorks is constructed by using TCL language and other secondary development techniques. FEA analysis,simulation analysis and topology optimization design are realized. A component named the right side panel of an automobile seat skeleton is selected as a typical example to demonstrate the suggested design process and the detail functions of the developed automatic system. The result shows that the present methods are effective and the developed system has practical and efficient advantages during the CAE analysis process.
Due to the uncertainty of the structural optimization in a complex mechanical system,in this paper an accurate identifying method for the boundary conditions based on sub-structure techniques is studied,a successive approximation topological optimization design is proposed to make the structural topology gradually achieve optimal structure. In addition,aiming at solving the problem of complexity to do CAE analysis for enterprise,an automatic system for automobile seat components based on the HyperWorks is constructed by using TCL language and other secondary development techniques. FEA analysis,simulation analysis and topology optimization design are realized. A component named the right side panel of an automobile seat skeleton is selected as a typical example to demonstrate the suggested design process and the detail functions of the developed automatic system. The result shows that the present methods are effective and the developed system has practical and efficient advantages during the CAE analysis process.
2013, 32(12): 1874-1878.
Abstract:
To plan the trajectory of a single robot working in a coordinated system,a time-optimal trajectory planning method based on velocity-path phase plane was presented. According to the path parameterization,the motion of the single robot with multiple joints was converted to the ultimate motion with only one DOF,which was constrained by geometrical path. By introducing the constraints of joint input torques,the admissible region of trajectory planning was studied. The dynamic search method was used in the velocity-path phase plane to plan the timeoptimal trajectory at the feasible maximum acceleration or deceleration. To compare with the existing time-minimal trajectory planning method,our time-optimal trajectory planning method was verified by simulating the MotomanUP6 robot; the simulation results show that our method can obtain the exact time-minimal solution and reduce the times of switching between acceleration and deceleration,thus improving the operating stability of the single robot
To plan the trajectory of a single robot working in a coordinated system,a time-optimal trajectory planning method based on velocity-path phase plane was presented. According to the path parameterization,the motion of the single robot with multiple joints was converted to the ultimate motion with only one DOF,which was constrained by geometrical path. By introducing the constraints of joint input torques,the admissible region of trajectory planning was studied. The dynamic search method was used in the velocity-path phase plane to plan the timeoptimal trajectory at the feasible maximum acceleration or deceleration. To compare with the existing time-minimal trajectory planning method,our time-optimal trajectory planning method was verified by simulating the MotomanUP6 robot; the simulation results show that our method can obtain the exact time-minimal solution and reduce the times of switching between acceleration and deceleration,thus improving the operating stability of the single robot
