Author Center
Editor Work
Peer Review
Editorial Entry
Email Alert
RSS2013 Vol. 32, No. 8
Display Method:
2013, 32(8): 1093-1097.
PDF 1343KB
Abstract:
The high speed turning superalloy GH4169 orthogonal test using the PVD-TiAlN carbide tool was pro-cessed to study the effect of cutting parameters on the surface integrity characteristics. The empirical formula for surface roughness, surface residual stress and microhardness was built and the machined surface morphology was observed. The prediction model between the surface integrity and cutting parameters was also established. The re-sults indicated that the surface roughness decreases with the increasing of cutting speed, while increases with the in-creasing of feed rate and cutting depth. Furthermore, the feed rate is the key factor affecting the surface roughness. With the increasing of feed rate, the surface morphology becomes worse and with the decreasing of feed rate and cutting speed the surface residual stress can be decreased. It is also observed that the feed rate has the most signifi-cant influence on compressive residual stress in cutting direction, while the cutting depth has the most significant influence on tensile residual stress in feed direction; the microhardness increases with the increasing of cutting speed , and cutting speed is the key factor affecting microhardness.
The high speed turning superalloy GH4169 orthogonal test using the PVD-TiAlN carbide tool was pro-cessed to study the effect of cutting parameters on the surface integrity characteristics. The empirical formula for surface roughness, surface residual stress and microhardness was built and the machined surface morphology was observed. The prediction model between the surface integrity and cutting parameters was also established. The re-sults indicated that the surface roughness decreases with the increasing of cutting speed, while increases with the in-creasing of feed rate and cutting depth. Furthermore, the feed rate is the key factor affecting the surface roughness. With the increasing of feed rate, the surface morphology becomes worse and with the decreasing of feed rate and cutting speed the surface residual stress can be decreased. It is also observed that the feed rate has the most signifi-cant influence on compressive residual stress in cutting direction, while the cutting depth has the most significant influence on tensile residual stress in feed direction; the microhardness increases with the increasing of cutting speed , and cutting speed is the key factor affecting microhardness.
2013, 32(8): 1098-1102.
Abstract:
The paper uses the quasicontinuum numerical method to study the nanometric cutting mechanism of single-crystal copper so as to improve its precision and expand its simulation size, avoiding the disadvantages of the molecular dynamics method, such as inefficiency, small simulation size and low-accuracy computation. The paper simulates the effects of the rake angle and cutting thickness of the nanometric cutting mechanism on the dislocation propagation, cutting force and residual stress of single-crystal copper. The simulation results show that: when the nanometric cutting mechanism uses the same tool, its specific cutting energy decreases gradually, whereas its depth of dislocation and residual stress increase accordingly. However, when the cutting thickness is the same, the fluctu-ation range of cutting force is maximum with the negative rake angle.
The paper uses the quasicontinuum numerical method to study the nanometric cutting mechanism of single-crystal copper so as to improve its precision and expand its simulation size, avoiding the disadvantages of the molecular dynamics method, such as inefficiency, small simulation size and low-accuracy computation. The paper simulates the effects of the rake angle and cutting thickness of the nanometric cutting mechanism on the dislocation propagation, cutting force and residual stress of single-crystal copper. The simulation results show that: when the nanometric cutting mechanism uses the same tool, its specific cutting energy decreases gradually, whereas its depth of dislocation and residual stress increase accordingly. However, when the cutting thickness is the same, the fluctu-ation range of cutting force is maximum with the negative rake angle.
2013, 32(8): 1103-1107.
Abstract:
To improve the stability of vehicle after tire blow-out, a flat tire model is established by using UA-Tire model and a mechanical model of the rim touched ground is also simulated by changing parameters in UA-Tire mod-el. Then, by importing the two models to CarSim, a whole vehicle model after tire burst is built. Furthermore, based on traditional analysis of vehicle stability, a fuzzy controller is designed to control the yaw moment of the ve-hicle. The two models and the controller are tested by co-simulation of CarSim and Simulink under three working conditions-straight and curve driving at 100 km/h when tire blows out, and steering sharply after tire deflated. The results indicate that the model of rim touched ground can qualitatively describe mechanical properties of the wheel. The lateral displacement、 yaw rate and roll angle can be efficiently controlled by the designed controller, so that the situation of rim touching ground can be prevented.
To improve the stability of vehicle after tire blow-out, a flat tire model is established by using UA-Tire model and a mechanical model of the rim touched ground is also simulated by changing parameters in UA-Tire mod-el. Then, by importing the two models to CarSim, a whole vehicle model after tire burst is built. Furthermore, based on traditional analysis of vehicle stability, a fuzzy controller is designed to control the yaw moment of the ve-hicle. The two models and the controller are tested by co-simulation of CarSim and Simulink under three working conditions-straight and curve driving at 100 km/h when tire blows out, and steering sharply after tire deflated. The results indicate that the model of rim touched ground can qualitatively describe mechanical properties of the wheel. The lateral displacement、 yaw rate and roll angle can be efficiently controlled by the designed controller, so that the situation of rim touching ground can be prevented.
2013, 32(8): 1108-1112.
Abstract:
The output power of loader hydraulic cylinder was one of important parameters to analyze the energy distri-bution rule, calculate the efficiency of hydraulic system and evaluate the matching reasonability of hydraulic compo-nents. In this paper, the determination method of the output power change characteristic of loader lifting arm cylinder was studied. Based on the analysis and establishment of the output power mathematical models of lifting arm cylinder, the sensors and data acquisition instrument for testing the working parameters of lifting arm cylinder were selected, and the hydraulic pressure of rodless chamber, rod chamber and piston displacement were actually tested when loader shovelling small stone, after analyzing and processing the measured hydraulic pressure and displacement with the soft-wares of Vib'SYS and nSoft, the change courses of the hydraulic pressure of rodless chamber, rod chamber and piston displacement of single typical operating cycle were obtained. In the paper, MATLAB soft was applied to fit the hy-draulic pressure and piston displacement at different operating segments of the obtained single typical operating cycle, and by the programming process, the power waveforms of different operating segments of lifting arm cylinder were ob-tained, after the power waveform of each work segment was merged according to the operating time order, the output power change characteristic curve of lifting arm cylinder when loader shovelling small stone was acquired. The analy-sis result showed that the provided determination method of lifting arm cylinder output power was feasible.
The output power of loader hydraulic cylinder was one of important parameters to analyze the energy distri-bution rule, calculate the efficiency of hydraulic system and evaluate the matching reasonability of hydraulic compo-nents. In this paper, the determination method of the output power change characteristic of loader lifting arm cylinder was studied. Based on the analysis and establishment of the output power mathematical models of lifting arm cylinder, the sensors and data acquisition instrument for testing the working parameters of lifting arm cylinder were selected, and the hydraulic pressure of rodless chamber, rod chamber and piston displacement were actually tested when loader shovelling small stone, after analyzing and processing the measured hydraulic pressure and displacement with the soft-wares of Vib'SYS and nSoft, the change courses of the hydraulic pressure of rodless chamber, rod chamber and piston displacement of single typical operating cycle were obtained. In the paper, MATLAB soft was applied to fit the hy-draulic pressure and piston displacement at different operating segments of the obtained single typical operating cycle, and by the programming process, the power waveforms of different operating segments of lifting arm cylinder were ob-tained, after the power waveform of each work segment was merged according to the operating time order, the output power change characteristic curve of lifting arm cylinder when loader shovelling small stone was acquired. The analy-sis result showed that the provided determination method of lifting arm cylinder output power was feasible.
2013, 32(8): 1113-1117.
Abstract:
A vibration isolation system was designed to isolate vibration for inertial navigation platform based on the vibration sources and theory of vibration isolation. The parameters of a rubber isolator such as stiffness and damping coefficient were obtained through experiment according to the theory of complex stiffness. The finite element model of the vibration isolation system was established with the help of ANSYS software. The first 12 order natural fre-quencies and the displacement response in case of excitation by engine idle speed and gyro dithering were obtained by modal analysis and harmonic response analysis, respectively. The calculated results indicate that natural fre-quencies of the designed system are far away from the frequency of engine idle speed and gyro dithering, and the displacement response amplitude is low. It is an effective vibration isolation system.
A vibration isolation system was designed to isolate vibration for inertial navigation platform based on the vibration sources and theory of vibration isolation. The parameters of a rubber isolator such as stiffness and damping coefficient were obtained through experiment according to the theory of complex stiffness. The finite element model of the vibration isolation system was established with the help of ANSYS software. The first 12 order natural fre-quencies and the displacement response in case of excitation by engine idle speed and gyro dithering were obtained by modal analysis and harmonic response analysis, respectively. The calculated results indicate that natural fre-quencies of the designed system are far away from the frequency of engine idle speed and gyro dithering, and the displacement response amplitude is low. It is an effective vibration isolation system.
2013, 32(8): 1118-1123.
Abstract:
Grinding wheel vibration has big influence on optical lens manufacturing. It not only reduces the effi-ciency of the following polishing procedure but also results in mid-frequency error on the surface. All the work in this paper expanded on the forced vibration of grinding wheel in parallel grinding of flat surface. The interference between wheel and workpiece is studied under different processing parameters. The research results show that wave-ness on the workpiece surface is decided by processing parameters; once the value of them is out of the critical points, the amplitude of the waveness on the workpiece surface will be lower than that of the wheel vibration. Therefore, reasonable choice of processing parameters is helpful to the improvement of the smoothness of the grind-ing surface.
Grinding wheel vibration has big influence on optical lens manufacturing. It not only reduces the effi-ciency of the following polishing procedure but also results in mid-frequency error on the surface. All the work in this paper expanded on the forced vibration of grinding wheel in parallel grinding of flat surface. The interference between wheel and workpiece is studied under different processing parameters. The research results show that wave-ness on the workpiece surface is decided by processing parameters; once the value of them is out of the critical points, the amplitude of the waveness on the workpiece surface will be lower than that of the wheel vibration. Therefore, reasonable choice of processing parameters is helpful to the improvement of the smoothness of the grind-ing surface.
2013, 32(8): 1124-1129.
Abstract:
This paper uses the SoftMotion and SolidWorks to build the virtual prototyping of a ring parts assembly system. After designing the parts assembly system with the Solidworks software, the control program was written and integrated into the LabVIEW, and the program execution method named the Boolean control of"attribute-value" node was proposed. The program execution method can accomplish repetitive tasks serially within one simulation. Taking the ring parts assembly as an example, the paper studies the NI virtual prototyping technology and achieves the control of the ring parts assembly system. The real parts assembly system was set up by combining mechanical design and control simulation, thus accelerating the development of the optimized physical prototype, shortening the design cycle of the parts assembly system and reducing design risks.
This paper uses the SoftMotion and SolidWorks to build the virtual prototyping of a ring parts assembly system. After designing the parts assembly system with the Solidworks software, the control program was written and integrated into the LabVIEW, and the program execution method named the Boolean control of"attribute-value" node was proposed. The program execution method can accomplish repetitive tasks serially within one simulation. Taking the ring parts assembly as an example, the paper studies the NI virtual prototyping technology and achieves the control of the ring parts assembly system. The real parts assembly system was set up by combining mechanical design and control simulation, thus accelerating the development of the optimized physical prototype, shortening the design cycle of the parts assembly system and reducing design risks.
2013, 32(8): 1130-1133.
Abstract:
Considering the complexity and poor universality of the existing numerical methods for generating non-circular gear teeth profiles, a simple and efficient method is proposed in this paper. When the pitch line of non-circular gears is given, each of the single tooth profile of the non-circular gear can be enveloped by a slotting cutter with only one gear tooth. A new numerical algorithm generating non-circular gear teeth profiles based on the above method is built, in this algorithm all of the teeth profiles are closed to the required profile gradually and achieved to non-circular gear teeth profiles at last. A computer program of the numerical algorithm generating non-circular gear teeth profiles is developed with MATLAB, the feasibility and accuracy of this algorithm is confirmed by numeriacal examples.
Considering the complexity and poor universality of the existing numerical methods for generating non-circular gear teeth profiles, a simple and efficient method is proposed in this paper. When the pitch line of non-circular gears is given, each of the single tooth profile of the non-circular gear can be enveloped by a slotting cutter with only one gear tooth. A new numerical algorithm generating non-circular gear teeth profiles based on the above method is built, in this algorithm all of the teeth profiles are closed to the required profile gradually and achieved to non-circular gear teeth profiles at last. A computer program of the numerical algorithm generating non-circular gear teeth profiles is developed with MATLAB, the feasibility and accuracy of this algorithm is confirmed by numeriacal examples.
2013, 32(8): 1134-1138.
Abstract:
In order to improve the internal fuel flow conditions in the nozzle 291 DLLA150 FC PV01 of the diesel engine D6114 and make fuel sprayed into the cylinder to obtain good atomization quality, nine schemes were de-signed based on the nozzle structure parameters: length-diameter ratio, the round angle-radius of nozzle inlet and orifices angle. Three-dimensional model of the internal nozzle flow field was established, and simulated using the CFD (Computational Fluid Dynamics) software. The influence of spray nozzle structure parameters on hole internal cavitation degree, turbulent kinetic energy and flow velocity was analyzed. The results show that with the decreasing of length-diameter ratio (L/D), the cavitation degree of fuel in the orifice and the velocity will increase, but the turbulent kinetic energy will decrease; with the increasing of round angle-radius to diameter ratio (r/D), the cavi-tation degree of fuel in the orifice and the velocity will also increase while the turbulent kinetic energy will de-screase; with the increasing of orifices angle (θ), the cavitation degree of fuel in the orifice will increase, and the turbulent kinetic energy will decrease.
In order to improve the internal fuel flow conditions in the nozzle 291 DLLA150 FC PV01 of the diesel engine D6114 and make fuel sprayed into the cylinder to obtain good atomization quality, nine schemes were de-signed based on the nozzle structure parameters: length-diameter ratio, the round angle-radius of nozzle inlet and orifices angle. Three-dimensional model of the internal nozzle flow field was established, and simulated using the CFD (Computational Fluid Dynamics) software. The influence of spray nozzle structure parameters on hole internal cavitation degree, turbulent kinetic energy and flow velocity was analyzed. The results show that with the decreasing of length-diameter ratio (L/D), the cavitation degree of fuel in the orifice and the velocity will increase, but the turbulent kinetic energy will decrease; with the increasing of round angle-radius to diameter ratio (r/D), the cavi-tation degree of fuel in the orifice and the velocity will also increase while the turbulent kinetic energy will de-screase; with the increasing of orifices angle (θ), the cavitation degree of fuel in the orifice will increase, and the turbulent kinetic energy will decrease.
2013, 32(8): 1139-1143.
Abstract:
To solve the problem that the traditional control methods have strong robustness and pole assignment com-plexity, we propose the optimal fuzzy multi-model switched control method based on the T-S optimal fuzzy model we have designed. First, we design the linear quadratic optimal controller for each linear subsystem of the T-S fuzzy model and combine it with the multi-model switched control method. Then, each controller is multiplied by its weight to obtain the global linear quadratic optimal controller. We obtain the state feedback matrix of the linear quadratic op-timal controller when the index of the linear quadratic performance is the smallest, thus improving its robustness and avoiding the pole assignment complexity. In case of the same number of fuzzy rules, our optimal fuzzy multi-model switched control method decreases the fuzzy domain and thus enhances the linear approximation accuracy. The effec-tiveness of our control method is verified with simulation results.
To solve the problem that the traditional control methods have strong robustness and pole assignment com-plexity, we propose the optimal fuzzy multi-model switched control method based on the T-S optimal fuzzy model we have designed. First, we design the linear quadratic optimal controller for each linear subsystem of the T-S fuzzy model and combine it with the multi-model switched control method. Then, each controller is multiplied by its weight to obtain the global linear quadratic optimal controller. We obtain the state feedback matrix of the linear quadratic op-timal controller when the index of the linear quadratic performance is the smallest, thus improving its robustness and avoiding the pole assignment complexity. In case of the same number of fuzzy rules, our optimal fuzzy multi-model switched control method decreases the fuzzy domain and thus enhances the linear approximation accuracy. The effec-tiveness of our control method is verified with simulation results.
2013, 32(8): 1144-1148.
Abstract:
We use modern control and mechanical dynamics to study a double mass-spring damping system. We es-tablish the state space model and the simulation structure of the damping system in accordance with its physical laws because they reflect approximately the relationships among and changes in state variables and reveal its internal characteristics. The state space model can recognize the internal characteristics of the damping system and therefore is applied to determining its controllability and observability. Besides, we use the modal superposition method to study quantitatively the dynamic performance of the damping system. Then we give the lower natural frequency, mode of vibration and displacement response of the damping system under harmonic excitation.
We use modern control and mechanical dynamics to study a double mass-spring damping system. We es-tablish the state space model and the simulation structure of the damping system in accordance with its physical laws because they reflect approximately the relationships among and changes in state variables and reveal its internal characteristics. The state space model can recognize the internal characteristics of the damping system and therefore is applied to determining its controllability and observability. Besides, we use the modal superposition method to study quantitatively the dynamic performance of the damping system. Then we give the lower natural frequency, mode of vibration and displacement response of the damping system under harmonic excitation.
2013, 32(8): 1149-1152.
Abstract:
To monitor the conditions of an electric power drive system, diagnose its fault and save energy, we use the Hall sensor and LabVIEW to develop a three-phase electrical signal real-time monitoring system. We use the signal acquisition circuit together with the industrial personal computer NI-PXI to gather the real-time electrical sig-nal. We use the one-cycle Fourier algorithm to detect the signal acquisition program and the fundamental compo-nents with the LabVIEW in an industrial personal computer, thus solving the real-time signal acquisition and detec-tion problems. The experimental results show that our signal monitoring system has a wide measurement range, good isolation effect and high accuracy and can quickly, accurately and stably acquire the three-phase electric signal of the electric power drive system.
To monitor the conditions of an electric power drive system, diagnose its fault and save energy, we use the Hall sensor and LabVIEW to develop a three-phase electrical signal real-time monitoring system. We use the signal acquisition circuit together with the industrial personal computer NI-PXI to gather the real-time electrical sig-nal. We use the one-cycle Fourier algorithm to detect the signal acquisition program and the fundamental compo-nents with the LabVIEW in an industrial personal computer, thus solving the real-time signal acquisition and detec-tion problems. The experimental results show that our signal monitoring system has a wide measurement range, good isolation effect and high accuracy and can quickly, accurately and stably acquire the three-phase electric signal of the electric power drive system.
2013, 32(8): 1153-1158.
Abstract:
In order to improve the reliability and intelligence of the hydraulic system for shield machine, one kind of fault feature extraction method, VW-AR X (variable-weighted-autoregressive exogenous) was described based on international standard of condition maintenance. For AR X algorithm made each variable have the same weight, which had bad identification effect, so VW algorithm was introduced to improve traditional AR X and give mathemat-ical deduction formula. Making erector hydraulic system as simulation object, on the whole, the input & output var-iables was set. Finally, for given four fault samples, the results of simulation shown that VW-AR X was better than AR X algorithm.
In order to improve the reliability and intelligence of the hydraulic system for shield machine, one kind of fault feature extraction method, VW-AR X (variable-weighted-autoregressive exogenous) was described based on international standard of condition maintenance. For AR X algorithm made each variable have the same weight, which had bad identification effect, so VW algorithm was introduced to improve traditional AR X and give mathemat-ical deduction formula. Making erector hydraulic system as simulation object, on the whole, the input & output var-iables was set. Finally, for given four fault samples, the results of simulation shown that VW-AR X was better than AR X algorithm.
2013, 32(8): 1159-1162.
Abstract:
The dynamic imbalance of coupling rotor in tufting carpet knitting machine is a key factor which has a negative impact on the work quality. To reduce the vibration of the shafting and improve the work quality of the loom, this paper selects loom spindle model as research object, and carries out dynamic balance correction for cou-pling spindle of the tufting carpet knitting machine with influence coefficient method. Firstly, coupling rotor model is established by three-dimensional modeling software, and then the model is dealt by finite element software, final-ly its vibration is simulated and analyzed by dynamic simulation software combining with the influence coefficient method. Comparing the spindle vibration curve and the axis orbit diagram before and after the correction, it draws the conclusion that the influence coefficient method can decrease the vibration of the spindle obviously.
The dynamic imbalance of coupling rotor in tufting carpet knitting machine is a key factor which has a negative impact on the work quality. To reduce the vibration of the shafting and improve the work quality of the loom, this paper selects loom spindle model as research object, and carries out dynamic balance correction for cou-pling spindle of the tufting carpet knitting machine with influence coefficient method. Firstly, coupling rotor model is established by three-dimensional modeling software, and then the model is dealt by finite element software, final-ly its vibration is simulated and analyzed by dynamic simulation software combining with the influence coefficient method. Comparing the spindle vibration curve and the axis orbit diagram before and after the correction, it draws the conclusion that the influence coefficient method can decrease the vibration of the spindle obviously.
2013, 32(8): 1163-1168.
Abstract:
A new nonlinear PID attitude controller was designed to control the attitude of a small quad-rotor air-craft. Combined with the simplified mathematical model of small quad-rotor aircraft, an attitude control method was proposed by using the new nonlinear PID attitude controller. Two tracking differentiators and a nonlinear state error feedback are used to overcome the deficiency of the traditional PID controller. The simulation results indicate that our attitude controller achieves strong robustness, anti-disturbance and high filtering performances, having high-dy-namic and steady-state performances.
A new nonlinear PID attitude controller was designed to control the attitude of a small quad-rotor air-craft. Combined with the simplified mathematical model of small quad-rotor aircraft, an attitude control method was proposed by using the new nonlinear PID attitude controller. Two tracking differentiators and a nonlinear state error feedback are used to overcome the deficiency of the traditional PID controller. The simulation results indicate that our attitude controller achieves strong robustness, anti-disturbance and high filtering performances, having high-dy-namic and steady-state performances.
2013, 32(8): 1167-1171.
Abstract:
In order to solve the problem of failing to generate the NC tool path caused by the poor quality of turbine blade surface, this paper presented a whole fairing and approximation algorithm of cubic Non-Uniform B-Spline curve to realize the fairing and fitting of blade surface's section line. The algorithm constructed an objective function com-posed of least square, sum of curvature and sum of curvature varieties on data points, obtained a series of the best control points by using the Gaussian elimination method. Besides, this algorithm can reduce the sum of curvature on data points as well as make the curvature varieties on data points more equable within the given approximation errors. In the end, this algorithm program was embedded in the UG5.0 secondary development program to develop automatic fairing and fitting module, and was proven to be more effective than existing algorithm by experiments.
In order to solve the problem of failing to generate the NC tool path caused by the poor quality of turbine blade surface, this paper presented a whole fairing and approximation algorithm of cubic Non-Uniform B-Spline curve to realize the fairing and fitting of blade surface's section line. The algorithm constructed an objective function com-posed of least square, sum of curvature and sum of curvature varieties on data points, obtained a series of the best control points by using the Gaussian elimination method. Besides, this algorithm can reduce the sum of curvature on data points as well as make the curvature varieties on data points more equable within the given approximation errors. In the end, this algorithm program was embedded in the UG5.0 secondary development program to develop automatic fairing and fitting module, and was proven to be more effective than existing algorithm by experiments.
2013, 32(8): 1172-1175.
Abstract:
We employ the Burton-Miller formula to overcome the non-unique problem of the conventional boundary element method for exterior acoustic scattering problems. We apply the effective singularity subtraction algorithm to implementing the hypersingular integral involved in the Burton-Miller formula, thus obtaining the improved weak form of the hypersingular integral, whose evaluation is no longer difficult. Furthermore, our algorithm adopts the ef-fective block diagonal pre-conditioner and the iterative solver to solve the matrix equation, thus improving its overall computational efficiency. Several numerical examples demonstrate the accuracy, efficiency and potential engineer-ing application of our algorithm.
We employ the Burton-Miller formula to overcome the non-unique problem of the conventional boundary element method for exterior acoustic scattering problems. We apply the effective singularity subtraction algorithm to implementing the hypersingular integral involved in the Burton-Miller formula, thus obtaining the improved weak form of the hypersingular integral, whose evaluation is no longer difficult. Furthermore, our algorithm adopts the ef-fective block diagonal pre-conditioner and the iterative solver to solve the matrix equation, thus improving its overall computational efficiency. Several numerical examples demonstrate the accuracy, efficiency and potential engineer-ing application of our algorithm.
2013, 32(8): 1176-1181.
Abstract:
The constrained independent component analysis (cICA) is derived from ICA, a method that can be ap-plied to extracting interesting independent components by relying on some prior information, thus overcoming the uncertainty of classic ICA. The use of cICA for diagnosing the faults of a rolling bearing can extract the interesting components of the vibration signal of the faulty bearing according to the prior information on the frequencies of fault features of the bearing. The incorporate order tracking and envelope analysis of cICA are used to effectively extract the fault features of incipient rolling element bearing during speed variation in its angle domain. The fault feature extraction method first obtains envelopes in the resonant frequency band, then applies the even-angle increment re-sampling to convert the envelopes from time domain to angle domain and finally constructs the reference signal for cICA in its angle domain. Both the simulation results and test results show that the method has good performance in extracting the incipient fault features of the bearing of a rotational machine during its speed increase and decrease.
The constrained independent component analysis (cICA) is derived from ICA, a method that can be ap-plied to extracting interesting independent components by relying on some prior information, thus overcoming the uncertainty of classic ICA. The use of cICA for diagnosing the faults of a rolling bearing can extract the interesting components of the vibration signal of the faulty bearing according to the prior information on the frequencies of fault features of the bearing. The incorporate order tracking and envelope analysis of cICA are used to effectively extract the fault features of incipient rolling element bearing during speed variation in its angle domain. The fault feature extraction method first obtains envelopes in the resonant frequency band, then applies the even-angle increment re-sampling to convert the envelopes from time domain to angle domain and finally constructs the reference signal for cICA in its angle domain. Both the simulation results and test results show that the method has good performance in extracting the incipient fault features of the bearing of a rotational machine during its speed increase and decrease.
2013, 32(8): 1182-1185.
Abstract:
We design a PGZX-1 pipe climbing robot whose climbing depends on caterpillar and can climb a verti-cally straight stove pipe. The climbing robot is used to detect a furnace pipe and the small gap of a slender pipe. We make a special effort to study the running gear of the caterpillar. To do so, we establish the model of the climb-ing robot by using SolidWorks and simulate it by using ADAMS. We make use of macros to increase restriction and loading and simulate the press, velocity and acceleration of the track pad of the climbing robot with belt wheel and pipe. We analyze the caterpillar climbing carefully and decide the load-carrying capability and motion state of the caterpillar.
We design a PGZX-1 pipe climbing robot whose climbing depends on caterpillar and can climb a verti-cally straight stove pipe. The climbing robot is used to detect a furnace pipe and the small gap of a slender pipe. We make a special effort to study the running gear of the caterpillar. To do so, we establish the model of the climb-ing robot by using SolidWorks and simulate it by using ADAMS. We make use of macros to increase restriction and loading and simulate the press, velocity and acceleration of the track pad of the climbing robot with belt wheel and pipe. We analyze the caterpillar climbing carefully and decide the load-carrying capability and motion state of the caterpillar.
2013, 32(8): 1186-1189.
Abstract:
It is difficult to realize the longitudinal-torsional compound vibration during the ultrasonic machining, we study the conical composite horn under single excitation. We derive the longitudinal vibration frequency equation and the torsional vibration frequency equation of the conical composite horn by using the theory of longitudinal vi-bration and torsional vibration of a one-dimensional variable cross-section bar, thus obtaining the vibration charac-teristics parameters. We explain the mechanisms of longitudinal-torsional compound vibration with the conical com-posite horn under single excitation and verify them with a practical application. The results of theoretical calcula-tion, numerical study and experimental tests show that the longitudinal-torsional compound vibration can be realized with the conical composite horn when the appropriate geometrical parameters are chosen.
It is difficult to realize the longitudinal-torsional compound vibration during the ultrasonic machining, we study the conical composite horn under single excitation. We derive the longitudinal vibration frequency equation and the torsional vibration frequency equation of the conical composite horn by using the theory of longitudinal vi-bration and torsional vibration of a one-dimensional variable cross-section bar, thus obtaining the vibration charac-teristics parameters. We explain the mechanisms of longitudinal-torsional compound vibration with the conical com-posite horn under single excitation and verify them with a practical application. The results of theoretical calcula-tion, numerical study and experimental tests show that the longitudinal-torsional compound vibration can be realized with the conical composite horn when the appropriate geometrical parameters are chosen.
2013, 32(8): 1190-1194.
Abstract:
A multi-objective topology optimization method for continuum structures, satisfying trade-off method was proposed in this paper, in which both the compliance and eigenvalue were regarded as static and dynamic optimiza-tion objectives. Based on the interpolation model of the solid isotropic material with penalization(SIMP), satisfying trade-off method was used to transform the multi-objective question as the simple target question. This method over-comes the shortcoming of single-objective topology optimization, which can not meet the performance requirements of automotive structures. At the same time, some transformation methods were employed to avoid equality constraint condition of the Satisfying trade-off method. Taking the engine's hood as the example, the multi-objective topology optimization by the OptiStruct software was carried out, and the numerical calculation results verified the feasibility of the optimization program compared with the hood＇s mature model.
A multi-objective topology optimization method for continuum structures, satisfying trade-off method was proposed in this paper, in which both the compliance and eigenvalue were regarded as static and dynamic optimiza-tion objectives. Based on the interpolation model of the solid isotropic material with penalization(SIMP), satisfying trade-off method was used to transform the multi-objective question as the simple target question. This method over-comes the shortcoming of single-objective topology optimization, which can not meet the performance requirements of automotive structures. At the same time, some transformation methods were employed to avoid equality constraint condition of the Satisfying trade-off method. Taking the engine's hood as the example, the multi-objective topology optimization by the OptiStruct software was carried out, and the numerical calculation results verified the feasibility of the optimization program compared with the hood＇s mature model.
2013, 32(8): 1195-1199.
Abstract:
A virtual prototype model of wine bottle packing mechanism is established by using ADAMS platform, and the structure is optimized using the minimum acceleration as the objective function. Considering the effect of clearance and flexibility, the wine bottle packing mechanism is reconstructed based on space vector model. Based on the nonlinear contact force model, the relationship of contact force and displacement is established, the influ-ence rule of clearance and flexibility on the mechanism kinematic and kinetic characteristics is obtained. The re-sults show the flexible link has a buffer effect on the impact forces and reduce adverse effects to the target motion characteristics to a certain extent.
A virtual prototype model of wine bottle packing mechanism is established by using ADAMS platform, and the structure is optimized using the minimum acceleration as the objective function. Considering the effect of clearance and flexibility, the wine bottle packing mechanism is reconstructed based on space vector model. Based on the nonlinear contact force model, the relationship of contact force and displacement is established, the influ-ence rule of clearance and flexibility on the mechanism kinematic and kinetic characteristics is obtained. The re-sults show the flexible link has a buffer effect on the impact forces and reduce adverse effects to the target motion characteristics to a certain extent.
2013, 32(8): 1200-1206.
Abstract:
This paper presents a new method to solve some key problems in the autofrettage of the thick wall cylin-der shell based on the unified strength theory and concludes the unified solutions of the un-autofrettage thick wall cylinder shell under the elastic and plastic limit loads. The paper also concludes the radius of the boundary when the equivalent load is minimum in the elastic and the plastic zone. In the case of the materials with different tension pressure strength and considering the medium principal stress on material, the ratio of the external radius to internal radius for avoiding the reverse yield is obtained. Besides, the result in autofrettage of the thick wall cylinder shell based on Yu's unified strength theory is compared with the different results of present strength theories. These re-sults have academic and practical significance in making full use of the properties of the materials and changing structural parameters of the design.
This paper presents a new method to solve some key problems in the autofrettage of the thick wall cylin-der shell based on the unified strength theory and concludes the unified solutions of the un-autofrettage thick wall cylinder shell under the elastic and plastic limit loads. The paper also concludes the radius of the boundary when the equivalent load is minimum in the elastic and the plastic zone. In the case of the materials with different tension pressure strength and considering the medium principal stress on material, the ratio of the external radius to internal radius for avoiding the reverse yield is obtained. Besides, the result in autofrettage of the thick wall cylinder shell based on Yu's unified strength theory is compared with the different results of present strength theories. These re-sults have academic and practical significance in making full use of the properties of the materials and changing structural parameters of the design.
2013, 32(8): 1207-1210.
Abstract:
In this paper, the ISIGHT software is used to decouple and optimize the power-train mounting system (PMS) of a big mini passenger car, and a six-degrees of freedom (DOF) rigid body model of the PMS is established. The robust optimization model of the PMS is presented aiming at maximizing the decoupling ratios of the PMS, and the stiffness and the position parameters of each mount are selected as design variables. The statistic properties of the optimization objective and constraints are calculated using the first order Taylor series expansion. The robust optimiza-tion model is solved by combining the modified feasible direction and mixed integer optimization algorithms. Monte Carlo simulation is conducted to perform robustness analysis of the PMS by regarding the optimal variables as normal distribution random ones. The simulation results verify the robustness of the optimization results.
In this paper, the ISIGHT software is used to decouple and optimize the power-train mounting system (PMS) of a big mini passenger car, and a six-degrees of freedom (DOF) rigid body model of the PMS is established. The robust optimization model of the PMS is presented aiming at maximizing the decoupling ratios of the PMS, and the stiffness and the position parameters of each mount are selected as design variables. The statistic properties of the optimization objective and constraints are calculated using the first order Taylor series expansion. The robust optimiza-tion model is solved by combining the modified feasible direction and mixed integer optimization algorithms. Monte Carlo simulation is conducted to perform robustness analysis of the PMS by regarding the optimal variables as normal distribution random ones. The simulation results verify the robustness of the optimization results.
2013, 32(8): 1211-1214.
Abstract:
Currently, experiment plays the prime method in soldering reflow profile forecasting. The prime difficul-ty in reflow processing is input parameters setting. According to the nonlinear relationship between the multi input and output, an improved genetic algorithm (GA)-based input parameters setting method is proposed. R eal-coding form expressed each gene's significances directly. Usage of improved genetic operators and chromosome restart mechanism avoids the premature phenomenon and possibility of fell into a local optimum, and improves search ac-curacy as well. The genetic operation combined with neural network prediction program built the complete parame-ter settings and production forecasting model. MAPE(mean absolute percentage error) assessment is carried to compare GA prediction and the production data of a company. R esult shows that predicted error meets the required precision. In conclusion, BP neural network is effective and efficient in reflow profile prediction.
Currently, experiment plays the prime method in soldering reflow profile forecasting. The prime difficul-ty in reflow processing is input parameters setting. According to the nonlinear relationship between the multi input and output, an improved genetic algorithm (GA)-based input parameters setting method is proposed. R eal-coding form expressed each gene's significances directly. Usage of improved genetic operators and chromosome restart mechanism avoids the premature phenomenon and possibility of fell into a local optimum, and improves search ac-curacy as well. The genetic operation combined with neural network prediction program built the complete parame-ter settings and production forecasting model. MAPE(mean absolute percentage error) assessment is carried to compare GA prediction and the production data of a company. R esult shows that predicted error meets the required precision. In conclusion, BP neural network is effective and efficient in reflow profile prediction.
2013, 32(8): 1215-1220,1214.
Abstract:
In order to study the effect of the stress and galvanic factors on the corrosion behavior of 2E12-T3 alumi-num alloy, the stress corrosion experiment, galvanic corrosion experiment, electrochemical impedance techniques, metallography techniques and scanning electron microscope (SEM) were used to study the mechanism. The results show that: in NaCl-H2 O2 solution, the corrosion resistance of 2E12-T3 is low and the aluminum alloy has high stress corrosion sensitivity. When the aluminum alloy is not coupled to stainless steel, with increase of the tensile stress, the surface impedance of aluminum alloy is slightly reduced, and the resistance to corrosion fell. The tensile stress increases the corrosion degree of aluminum alloy. When coupled to stainless steel, at the same stress condi-tions, the impedance of the aluminum alloy is lower than that not coupled to stainless steel. After coupled to stain-less steel, the aluminum alloy's fracture time is shorten 1/3. The galvanic factors play a significant role. Under the condition of stress and galvanic, the corrosion sensitivity of aluminum alloy is very high.
In order to study the effect of the stress and galvanic factors on the corrosion behavior of 2E12-T3 alumi-num alloy, the stress corrosion experiment, galvanic corrosion experiment, electrochemical impedance techniques, metallography techniques and scanning electron microscope (SEM) were used to study the mechanism. The results show that: in NaCl-H2 O2 solution, the corrosion resistance of 2E12-T3 is low and the aluminum alloy has high stress corrosion sensitivity. When the aluminum alloy is not coupled to stainless steel, with increase of the tensile stress, the surface impedance of aluminum alloy is slightly reduced, and the resistance to corrosion fell. The tensile stress increases the corrosion degree of aluminum alloy. When coupled to stainless steel, at the same stress condi-tions, the impedance of the aluminum alloy is lower than that not coupled to stainless steel. After coupled to stain-less steel, the aluminum alloy's fracture time is shorten 1/3. The galvanic factors play a significant role. Under the condition of stress and galvanic, the corrosion sensitivity of aluminum alloy is very high.
2013, 32(8): 1221-1224.
Abstract:
The sensitivity analysis is very significant in structural optimization design and reliability analysis. To overcome the shortcomings of the analytical eigenvalue sensitivity method in the finite element analysis, a semi-analytical adjoint variable method is proposed, in which the finite difference method has been adopted instead of the analytical derivative. In addition, a new method is developed to store the sparse derivative matrix, which is applied to the proposed adjoint variable method to save the computational memory. Finally, a comparison is made between a general analytical method and the proposed semi-analytical adjoint variable method, it is found that the accuracy and computational efficiency has been improved greatly, and also the proposed method is suitable for large-scale structural sensitivity analysis.
The sensitivity analysis is very significant in structural optimization design and reliability analysis. To overcome the shortcomings of the analytical eigenvalue sensitivity method in the finite element analysis, a semi-analytical adjoint variable method is proposed, in which the finite difference method has been adopted instead of the analytical derivative. In addition, a new method is developed to store the sparse derivative matrix, which is applied to the proposed adjoint variable method to save the computational memory. Finally, a comparison is made between a general analytical method and the proposed semi-analytical adjoint variable method, it is found that the accuracy and computational efficiency has been improved greatly, and also the proposed method is suitable for large-scale structural sensitivity analysis.
2013, 32(8): 1225-1229,1224.
Abstract:
The virtual prototype model is established for the wheel-legged lunar rover based on double-half-revolution mechanism, and its mechanical data of wheel-leg planetary mechanism shafts are obtained by dynamic simulation under some typical road conditions. On this basis, its finite element analysis model is established, and the stress of the wheel-leg planetary mechanism shafts is analyzed by using ANSYS software. Based on ANSYS parametric design language (APDL), the optimization design for the above shafts are done combined with the least-square approxima-tion optimization method. The results show that the optimized shafts not only meet the strength requirement, but also their weights are about 30% lower than the original design, which will provide a new and effective way for optimizing the whole wheel-leg structure of lunar rover.
The virtual prototype model is established for the wheel-legged lunar rover based on double-half-revolution mechanism, and its mechanical data of wheel-leg planetary mechanism shafts are obtained by dynamic simulation under some typical road conditions. On this basis, its finite element analysis model is established, and the stress of the wheel-leg planetary mechanism shafts is analyzed by using ANSYS software. Based on ANSYS parametric design language (APDL), the optimization design for the above shafts are done combined with the least-square approxima-tion optimization method. The results show that the optimized shafts not only meet the strength requirement, but also their weights are about 30% lower than the original design, which will provide a new and effective way for optimizing the whole wheel-leg structure of lunar rover.
2013, 32(8): 1230-1234,1238.
Abstract:
In order to solve the problem of lower forming accuracy and distribution insufficient of the channel finish-ing margin of blisk channel, the method of radial feeding in electrochemical machining is proposed, and a mathe-matical model of machining gap is established to study the influence rule of side gap on channel forming process, then the process parameters such as bare end of electrode, characteristics of electrolyte, pulse processing parame-ters, and tool feed rate are studied and optimized. With optimized parameters, the high accuracy channels of Ni-based superalloy are machined with good stability, and the result reveals that the minimum finishing margin of the concave and convex airfoil surface can be increased to 2. 43 mm and 2. 41 mm at the corresponding area of the blade sampling point, in contrast to 1. 82 mm and 1. 56 mm with unoptimized parameters. The process environment of blade finishing is hence improved.
In order to solve the problem of lower forming accuracy and distribution insufficient of the channel finish-ing margin of blisk channel, the method of radial feeding in electrochemical machining is proposed, and a mathe-matical model of machining gap is established to study the influence rule of side gap on channel forming process, then the process parameters such as bare end of electrode, characteristics of electrolyte, pulse processing parame-ters, and tool feed rate are studied and optimized. With optimized parameters, the high accuracy channels of Ni-based superalloy are machined with good stability, and the result reveals that the minimum finishing margin of the concave and convex airfoil surface can be increased to 2. 43 mm and 2. 41 mm at the corresponding area of the blade sampling point, in contrast to 1. 82 mm and 1. 56 mm with unoptimized parameters. The process environment of blade finishing is hence improved.
2013, 32(8): 1235-1238.
Abstract:
The microminiature element plays an important role in various kinds of fields, and its processing is par-ticularly important. Based on high speed micro milling experiment, this paper studies the tool wear mechanism of the micro milling process, and verifies that the change of the cutting speed, one of the three elements of cutting consumption, affects on the tool wear. Results of analysis and experiment draw the conclusion: in the high speed micro milling process, not changing the other conditions and in a certain cutting speed range, the effect of the cut-ting speed on tool wear is corresponded with the traditional milling processing law, that is, the greater the cutting speed, the more serious the tool wear and the shorter the life of the tool; however, the tool wear is quite serious if the cutting speed exceed the upper limit value.
The microminiature element plays an important role in various kinds of fields, and its processing is par-ticularly important. Based on high speed micro milling experiment, this paper studies the tool wear mechanism of the micro milling process, and verifies that the change of the cutting speed, one of the three elements of cutting consumption, affects on the tool wear. Results of analysis and experiment draw the conclusion: in the high speed micro milling process, not changing the other conditions and in a certain cutting speed range, the effect of the cut-ting speed on tool wear is corresponded with the traditional milling processing law, that is, the greater the cutting speed, the more serious the tool wear and the shorter the life of the tool; however, the tool wear is quite serious if the cutting speed exceed the upper limit value.
2013, 32(8): 1239-1242.
Abstract:
The assembly quality of the scroll compressor mainly depends on the scroll plate assembly space. The existing assembly methods can not meet the axial and radial clearance requirements, so that the assembly rate is low and assembly quality is not good. To solve this problem, non-dominated sorting genetic algorithm-Ⅱ was used in scroll plate selective assembly. According to the assembly requirements, several objective functions were estab-lished. Matching algorithm was designed, which can realize the multi-objective optimization. A number of uniform distributed Pareto optimal solutions can be obtained using this algorithm. Decision makers can choose the best one according to actual needs. It was proved that the various assembly targets were all satisfied. This method can opti-mize both axial and radial clearance, and minimize the surplus components at the same time.
The assembly quality of the scroll compressor mainly depends on the scroll plate assembly space. The existing assembly methods can not meet the axial and radial clearance requirements, so that the assembly rate is low and assembly quality is not good. To solve this problem, non-dominated sorting genetic algorithm-Ⅱ was used in scroll plate selective assembly. According to the assembly requirements, several objective functions were estab-lished. Matching algorithm was designed, which can realize the multi-objective optimization. A number of uniform distributed Pareto optimal solutions can be obtained using this algorithm. Decision makers can choose the best one according to actual needs. It was proved that the various assembly targets were all satisfied. This method can opti-mize both axial and radial clearance, and minimize the surplus components at the same time.
2013, 32(8): 1243-1248.
Abstract:
In order to predict the performance of a big end bearing more accurately, then improve its reliability and life. We use the elastohydrodynamic lubrication theory to build the elastohydrodynamic lubrication model of the big end bearing of the connecting rod of a two-cylinder diesel engine. We apply the orthogonal experiment design method and use the indices such as peak oil film pressure, minimum oil film thickness and average total friction power loss to study the influence of the structural design parameters of the big end bearing such as clearance, width, oil hole posi-tion angle and oil hole diameter on its lubrication performance. The exploration results show that, in comparison of the optimal scheme with the original one, the minimum oil film thickness of the optimal scheme increases by 44. 86%; its peak oil film pressure is reduced by 1.00%, and its average total friction power loss increases by 4.84%.
In order to predict the performance of a big end bearing more accurately, then improve its reliability and life. We use the elastohydrodynamic lubrication theory to build the elastohydrodynamic lubrication model of the big end bearing of the connecting rod of a two-cylinder diesel engine. We apply the orthogonal experiment design method and use the indices such as peak oil film pressure, minimum oil film thickness and average total friction power loss to study the influence of the structural design parameters of the big end bearing such as clearance, width, oil hole posi-tion angle and oil hole diameter on its lubrication performance. The exploration results show that, in comparison of the optimal scheme with the original one, the minimum oil film thickness of the optimal scheme increases by 44. 86%; its peak oil film pressure is reduced by 1.00%, and its average total friction power loss increases by 4.84%.
