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RSS2017 Vol. 36, No. 3
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2017, 36(3): 329-334.
doi: 10.13433/j.cnki.1003-8728.2017.0301
PDF 1017KB
Abstract:
With the application of Euler model, RNG κ-ε(Renormalization-group κ-ε) turbulence model and SIMPLEC algorithm, the numerical analysis of solid-liquid two phase flow of impeller and diffuser in slurry pump was carried on to investigate the internal characteristics of flow field and performance on the influence of rotational speed in slurry pump for deep-sea mining. The effects of absolute velocity distribution of impeller blades and guide vanes and performance of slurry pump were researched. The results show that: when the rotational speed increases,the boundary layer separates more easily in the impeller flow region, and the flow capacity weakens; At the outlet of impeller, the stronger the jet-wake structure is, the more serious hydraulic loss is; The more violent the impact of space guide vane inlet is, the more confused the flow of the region is, and there is a large scale two flow in the inlet of the guide vane pressure. However, with the increase of the rotational speed,the flow separation of the mixed fluid at the inlet of the guide vane suction surface is suppressed, which increases the flow capacity and reduces the hydraulic loss.
With the application of Euler model, RNG κ-ε(Renormalization-group κ-ε) turbulence model and SIMPLEC algorithm, the numerical analysis of solid-liquid two phase flow of impeller and diffuser in slurry pump was carried on to investigate the internal characteristics of flow field and performance on the influence of rotational speed in slurry pump for deep-sea mining. The effects of absolute velocity distribution of impeller blades and guide vanes and performance of slurry pump were researched. The results show that: when the rotational speed increases,the boundary layer separates more easily in the impeller flow region, and the flow capacity weakens; At the outlet of impeller, the stronger the jet-wake structure is, the more serious hydraulic loss is; The more violent the impact of space guide vane inlet is, the more confused the flow of the region is, and there is a large scale two flow in the inlet of the guide vane pressure. However, with the increase of the rotational speed,the flow separation of the mixed fluid at the inlet of the guide vane suction surface is suppressed, which increases the flow capacity and reduces the hydraulic loss.
2017, 36(3): 335-340.
doi: 10.13433/j.cnki.1003-8728.2017.0302
Abstract:
In order to explore the influence of the elastic deformation of connecting rod on engine block surface vibration, multi-body dynamics analysis is used in this paper. First, a model of an in-line 6-cylinder diesel engine is built by AVL EXCITE Designer, including the finite element model and simulation model of cylinder block, crankshaft and connecting rod. Then, modal analysis and experimental verification are carried out to ensure the accuracy of the simulation model. Through the vibration acceleration of different locations selected in the model, engine block surface vibration is evaluated respectively for using rigid connecting rod and flexible connecting rod. According to the simulation results, the acceleration of each analysis point on the body has a certain decline, and fluctuations in the peak are also significantly reduced when considering the flexible connecting rod. Results also show that using flexible body makes main bearing stress decrease at piston movement direction, and the minimum film thickness at the peaks becomes smaller. A much satisfactory agreement of simulation and measurement results can be achieved when considering flexible connecting rod.
In order to explore the influence of the elastic deformation of connecting rod on engine block surface vibration, multi-body dynamics analysis is used in this paper. First, a model of an in-line 6-cylinder diesel engine is built by AVL EXCITE Designer, including the finite element model and simulation model of cylinder block, crankshaft and connecting rod. Then, modal analysis and experimental verification are carried out to ensure the accuracy of the simulation model. Through the vibration acceleration of different locations selected in the model, engine block surface vibration is evaluated respectively for using rigid connecting rod and flexible connecting rod. According to the simulation results, the acceleration of each analysis point on the body has a certain decline, and fluctuations in the peak are also significantly reduced when considering the flexible connecting rod. Results also show that using flexible body makes main bearing stress decrease at piston movement direction, and the minimum film thickness at the peaks becomes smaller. A much satisfactory agreement of simulation and measurement results can be achieved when considering flexible connecting rod.
2017, 36(3): 341-346.
doi: 10.13433/j.cnki.1003-8728.2017.0303
Abstract:
At present, radioactive seeds implantation is an effective method for cranio-maxillofacial tumors therapy, but it has the problems of low accuracy, long operation time and the manually inserted radiation acceptance by doctors. According to the characteristics and requirements of the surgery, an radioactive seeds implantation surgery robot for cranio-maxillofacial tumors is designed, to realize automatic implanted radioactive seeds for robot-assisted cranio-maxillofacial tumors therapy. The mechanical structure design of the robot and the device of seeds storage and automatic propulsion are completed, kinematics equation and kinematics solution formulas of the joints are established. Finally, the control system is designed in the operation mode of continuous automatic implanted seeds, and the space registration based on marker points is completed, the robot automatically implanted seeds is realized. Experiment shows that the robot has high position accuracy and can automatic implant the seeds safely and effectively, which meets the requirements of cranio-maxillofacial tumors surgery.
At present, radioactive seeds implantation is an effective method for cranio-maxillofacial tumors therapy, but it has the problems of low accuracy, long operation time and the manually inserted radiation acceptance by doctors. According to the characteristics and requirements of the surgery, an radioactive seeds implantation surgery robot for cranio-maxillofacial tumors is designed, to realize automatic implanted radioactive seeds for robot-assisted cranio-maxillofacial tumors therapy. The mechanical structure design of the robot and the device of seeds storage and automatic propulsion are completed, kinematics equation and kinematics solution formulas of the joints are established. Finally, the control system is designed in the operation mode of continuous automatic implanted seeds, and the space registration based on marker points is completed, the robot automatically implanted seeds is realized. Experiment shows that the robot has high position accuracy and can automatic implant the seeds safely and effectively, which meets the requirements of cranio-maxillofacial tumors surgery.
2017, 36(3): 347-353.
doi: 10.13433/j.cnki.1003-8728.2017.0304
Abstract:
A hybrid drill bit combines the structural features and working principles of PDC drill bit and cone drill bit, being able to drill hard formation more efficiently. But its research and development is blind and its promotion is limited due to lack of knowledge about its rock breaking mechanisms. Based on elastoplastic mechanics and rock breaking theory, 3D non-linear dynamic simulation models of dynamic rock breaking with full-gauge hybrid drill bit and PDC bit are established with the finite element method. The constitutive relation of rock is described by Drucker-Prager criteria and the plastic strain is used as the criterion for describing the rock breaking. The failure mechanisms for rock breaking in hard formation with the hybrid drill bit are studied. The dynamic rock breaking with hybrid drill bit in hard formation are compared with that of PDC drill bit. The comparison results show that the well drilled by hybrid drill bit can satisfy the borehole wall stability requirements but that the sidewall rock may fall off. This partly explains the reasons why the use of hybrid drill bit significantly enhances the penetration rate in hard formation and why the rock is broken mainly by tensile stress. The torsional vibration of hybrid drill bit is lower than that of PDC drill bit and the rock breaking efficiency is higher in hard formation. The impact of hybrid drill bit on rock is greater than that of PDC drill bit due to the polygon effect of cone drill bit during scrolling; therefore the hybrid drill bit can drill rock faster than PDC drill bit in hard formation.
A hybrid drill bit combines the structural features and working principles of PDC drill bit and cone drill bit, being able to drill hard formation more efficiently. But its research and development is blind and its promotion is limited due to lack of knowledge about its rock breaking mechanisms. Based on elastoplastic mechanics and rock breaking theory, 3D non-linear dynamic simulation models of dynamic rock breaking with full-gauge hybrid drill bit and PDC bit are established with the finite element method. The constitutive relation of rock is described by Drucker-Prager criteria and the plastic strain is used as the criterion for describing the rock breaking. The failure mechanisms for rock breaking in hard formation with the hybrid drill bit are studied. The dynamic rock breaking with hybrid drill bit in hard formation are compared with that of PDC drill bit. The comparison results show that the well drilled by hybrid drill bit can satisfy the borehole wall stability requirements but that the sidewall rock may fall off. This partly explains the reasons why the use of hybrid drill bit significantly enhances the penetration rate in hard formation and why the rock is broken mainly by tensile stress. The torsional vibration of hybrid drill bit is lower than that of PDC drill bit and the rock breaking efficiency is higher in hard formation. The impact of hybrid drill bit on rock is greater than that of PDC drill bit due to the polygon effect of cone drill bit during scrolling; therefore the hybrid drill bit can drill rock faster than PDC drill bit in hard formation.
2017, 36(3): 354-358.
doi: 10.13433/j.cnki.1003-8728.2017.0305
Abstract:
Based on Assur group theory, the structural features of planar single DOF multi-loop mechanism are analyzed. According to topological relationship between Assur group and input/output links of the mechanism, the general description method of planar single DOF multi-loop mechanism is given. Based on this, the transmission of Assur group is defined with the concept'virtual coefficient' in screw theory. The transmission index of single DOF multi-loop planar mechanism is given accord to the connection relationship of Assur group. Finally, one cam-linkage mechanism is proposed as an example for the transmission analysis compared with the traditional methods. The result proves that the proposed method is closely related to the actual working state of the mechanism and verifies the effectiveness of the transmission index.
Based on Assur group theory, the structural features of planar single DOF multi-loop mechanism are analyzed. According to topological relationship between Assur group and input/output links of the mechanism, the general description method of planar single DOF multi-loop mechanism is given. Based on this, the transmission of Assur group is defined with the concept'virtual coefficient' in screw theory. The transmission index of single DOF multi-loop planar mechanism is given accord to the connection relationship of Assur group. Finally, one cam-linkage mechanism is proposed as an example for the transmission analysis compared with the traditional methods. The result proves that the proposed method is closely related to the actual working state of the mechanism and verifies the effectiveness of the transmission index.
2017, 36(3): 359-364.
doi: 10.13433/j.cnki.1003-8728.2017.0306
Abstract:
In order to investigate the fault characteristic of planetary gear train, nonlinear dimensionless dynamical equations of planetary gear train with the chipping and wear fault of planetary gear are established respectively and solved by using numerical method. The bifurcation properties and fault properties of planetary gear train with chipping fault and wear fault are analyzed by using bifurcation diagram, phase contrail and Poincaré section with an excitation frequency increase. The influence of the damping coefficient and external excitation on the system is analyzed. The result shows the moving rules of planetary gear with chipping fault, the effect of the whole tooth wear fault of planetary gear on the bifurcation characteristics, and the influence of the damping coefficient and external excitation on the chaotic characteristic.
In order to investigate the fault characteristic of planetary gear train, nonlinear dimensionless dynamical equations of planetary gear train with the chipping and wear fault of planetary gear are established respectively and solved by using numerical method. The bifurcation properties and fault properties of planetary gear train with chipping fault and wear fault are analyzed by using bifurcation diagram, phase contrail and Poincaré section with an excitation frequency increase. The influence of the damping coefficient and external excitation on the system is analyzed. The result shows the moving rules of planetary gear with chipping fault, the effect of the whole tooth wear fault of planetary gear on the bifurcation characteristics, and the influence of the damping coefficient and external excitation on the chaotic characteristic.
2017, 36(3): 365-371.
doi: 10.13433/j.cnki.1003-8728.2017.0307
Abstract:
A three degrees of freedom (DOFs) parallel mechanism with limbs of embedding structures is a new type of parallel mechanism whose moving platform can continuously rotate for 360°, so this mechanism has a larger workspace. Comparing with the traditional mechanisms, the biggest difference among them is to share joint axes for each limb, which makes the structure more compact. However, this special mechanism leads to non-unique limb division method. Based on the above method, a method of reasonably dividing limbs is proposed. This method takes the degenerate-rank spatial parallel mechanism input selection theory as the basis of judgment. According to this theory, not all the limb division methods are correct. In judging, the first is to correctly calculate the freedom by using the existing three limb division method, the second is to calculate the structure constraint reciprocal screw and the rigid constraint reciprocal screw, finally the maximum linear independence group of the structure constraint reciprocal screw and the rigid constraint reciprocal screw is counted. So the input selection reasonableness of the limb division method can be verified, and the one which meets the input selection theory is the reasonable limb division method.
A three degrees of freedom (DOFs) parallel mechanism with limbs of embedding structures is a new type of parallel mechanism whose moving platform can continuously rotate for 360°, so this mechanism has a larger workspace. Comparing with the traditional mechanisms, the biggest difference among them is to share joint axes for each limb, which makes the structure more compact. However, this special mechanism leads to non-unique limb division method. Based on the above method, a method of reasonably dividing limbs is proposed. This method takes the degenerate-rank spatial parallel mechanism input selection theory as the basis of judgment. According to this theory, not all the limb division methods are correct. In judging, the first is to correctly calculate the freedom by using the existing three limb division method, the second is to calculate the structure constraint reciprocal screw and the rigid constraint reciprocal screw, finally the maximum linear independence group of the structure constraint reciprocal screw and the rigid constraint reciprocal screw is counted. So the input selection reasonableness of the limb division method can be verified, and the one which meets the input selection theory is the reasonable limb division method.
2017, 36(3): 372-377.
doi: 10.13433/j.cnki.1003-8728.2017.0308
Abstract:
In order to achieve the trajectory tracking control of a joint robot, because an uncertain joint robot's structural parameters cause a dynamic model's modeling errors and interfere with the working environment and the uncertain joint robot's resonant mode, the joint robot's dynamic model was divided into nominal model and error model. The error model was compensated by the RBF neural network, thus obtaining its estimation information. The neural network's output weights were adjusted adaptively according to the Lyapunov stability theory. The joint robot's adaptive neural network controller was used to solve the problems for the uncertain joint robot's dynamic system. Besides, the controller can gradually and stably track the desired trajectory though defining the Lyapunov function, being used to control a three-joint robot's torque. All the three joints can track the desired trajectory in 4 s. Tracking errors can gradually approach 0. Simulation and experimental results show that the RBF neural network can favorably approach modeling errors caused by uncertainties.
In order to achieve the trajectory tracking control of a joint robot, because an uncertain joint robot's structural parameters cause a dynamic model's modeling errors and interfere with the working environment and the uncertain joint robot's resonant mode, the joint robot's dynamic model was divided into nominal model and error model. The error model was compensated by the RBF neural network, thus obtaining its estimation information. The neural network's output weights were adjusted adaptively according to the Lyapunov stability theory. The joint robot's adaptive neural network controller was used to solve the problems for the uncertain joint robot's dynamic system. Besides, the controller can gradually and stably track the desired trajectory though defining the Lyapunov function, being used to control a three-joint robot's torque. All the three joints can track the desired trajectory in 4 s. Tracking errors can gradually approach 0. Simulation and experimental results show that the RBF neural network can favorably approach modeling errors caused by uncertainties.
2017, 36(3): 378-385.
doi: 10.13433/j.cnki.1003-8728.2017.0309
Abstract:
The industrial robot error models and the existing methods of position and orientation compensation are investigated. The compensation method based on spatial interpolation is studied, and it is found that the high correlation between the robot end pose error and the robot end position is a necessary factor for this method. The geometric error model derived by differential method is obtained, and the high linear dependency between the pose error of two points and the correspondent distance is achieved when the orientation of robot is fixed; Finally, a position and orientation compensation method is proposed based on uniform grid and algorithm of space IDSW (Inverse distance squared weighting) interpolation, and comparative experiments are design and tested to verify the effectiveness of the proposed method.
The industrial robot error models and the existing methods of position and orientation compensation are investigated. The compensation method based on spatial interpolation is studied, and it is found that the high correlation between the robot end pose error and the robot end position is a necessary factor for this method. The geometric error model derived by differential method is obtained, and the high linear dependency between the pose error of two points and the correspondent distance is achieved when the orientation of robot is fixed; Finally, a position and orientation compensation method is proposed based on uniform grid and algorithm of space IDSW (Inverse distance squared weighting) interpolation, and comparative experiments are design and tested to verify the effectiveness of the proposed method.
2017, 36(3): 386-390.
doi: 10.13433/j.cnki.1003-8728.2017.0310
Abstract:
To simultaneously achieve a higher material removal rate and a better surface integrity, the highly nonlinear relationship between the process parameters and the machining performance was investigated. A Taguchi experiment was designed with water pressure (WP), pulse-on time (Ton), pulse-off time (Toff), wire tension (WT), wire speed (WS) and servo voltage (SV) as the main optimization parameters, surface roughness (Ra) and material removal rate (MRR) as the optimization targets. It is innovative to apply the support vector machines regression (SVMR) and particle swarm algorithm (PSO) to acquire the optimized parameters combination by establishing a multi-objective model. The verification experiment showed that the multi-objective optimization model is efficient for increasing MRR and reducing Ra.
To simultaneously achieve a higher material removal rate and a better surface integrity, the highly nonlinear relationship between the process parameters and the machining performance was investigated. A Taguchi experiment was designed with water pressure (WP), pulse-on time (Ton), pulse-off time (Toff), wire tension (WT), wire speed (WS) and servo voltage (SV) as the main optimization parameters, surface roughness (Ra) and material removal rate (MRR) as the optimization targets. It is innovative to apply the support vector machines regression (SVMR) and particle swarm algorithm (PSO) to acquire the optimized parameters combination by establishing a multi-objective model. The verification experiment showed that the multi-objective optimization model is efficient for increasing MRR and reducing Ra.
2017, 36(3): 391-396.
doi: 10.13433/j.cnki.1003-8728.2017.0311
Abstract:
In the light of complexity of BTA drill cutter body structure, processing of drilling not only need to be subjected to massive cutting load, it also demands sufficiently large space for chip removal, so the key to resolve the conflicts between strength and chip removal capacity is to achieve optimization design of BTA drill. Finite element analysis and experiments are applied to study the cutter body strength and stress-strain distribution of the BTA drill, which is for the tube sheets of nuclear power plants under torsion load. And the results show that the root of external insert and transverse reinforcement between the two chip of center cutter body and removal channels, which have a severe stress concentration issue, are its weakness to the existing BTA drill, and torque generated in the experiment parts and simulation results are consistent with each other. So the present results provide the basis for improving design for BTA drill. By optimizing the weak links of the cutter body with shape optimization and topology optimization, cutter body strength and chip removal capacity are optimized, processing efficiency of BTA drill on tube sheets of nuclear power plants are enhanced.
In the light of complexity of BTA drill cutter body structure, processing of drilling not only need to be subjected to massive cutting load, it also demands sufficiently large space for chip removal, so the key to resolve the conflicts between strength and chip removal capacity is to achieve optimization design of BTA drill. Finite element analysis and experiments are applied to study the cutter body strength and stress-strain distribution of the BTA drill, which is for the tube sheets of nuclear power plants under torsion load. And the results show that the root of external insert and transverse reinforcement between the two chip of center cutter body and removal channels, which have a severe stress concentration issue, are its weakness to the existing BTA drill, and torque generated in the experiment parts and simulation results are consistent with each other. So the present results provide the basis for improving design for BTA drill. By optimizing the weak links of the cutter body with shape optimization and topology optimization, cutter body strength and chip removal capacity are optimized, processing efficiency of BTA drill on tube sheets of nuclear power plants are enhanced.
2017, 36(3): 397-401.
doi: 10.13433/j.cnki.1003-8728.2017.0312
Abstract:
We propose a novel measurement method for hub bearing raceway based on the Hough transform curve fitting, which can solve the problem but whose results are easily affected by abnormal points using the traditional measurement methods. First, the arc parameters are calculated using the least squares fitting method, and then, the parameter values are used to determine the scope of search for the Hough transform, thus improving the calculation of the Hough transform. The results obtained with the Hough transform can be used to filter the abnormal points, whose influence on measurement accuracy can thus be eliminated when the least squares fitting method is applied to data processing. Both simulation and experimental results prove the validity of the measurement method. Compared with the traditional least squares fitting methods, our measurement method has the advantages of high precision and good robustness.
We propose a novel measurement method for hub bearing raceway based on the Hough transform curve fitting, which can solve the problem but whose results are easily affected by abnormal points using the traditional measurement methods. First, the arc parameters are calculated using the least squares fitting method, and then, the parameter values are used to determine the scope of search for the Hough transform, thus improving the calculation of the Hough transform. The results obtained with the Hough transform can be used to filter the abnormal points, whose influence on measurement accuracy can thus be eliminated when the least squares fitting method is applied to data processing. Both simulation and experimental results prove the validity of the measurement method. Compared with the traditional least squares fitting methods, our measurement method has the advantages of high precision and good robustness.
2017, 36(3): 402-408.
doi: 10.13433/j.cnki.1003-8728.2017.0313
Abstract:
In order to solve the problem of linear and circular interpolation, the relevant principles of five-axis machining of NURBS interpolation computation was studied by using cubic spline Non-Uniform Rational B-Splines parameterization; tip point and tool axis vector parameterization were made based on the UG pre-output cutter location data points so as to calculate its control points by using inverse calculation achieved NURBS interpolation. Then It can insert with feed rate control interpolation error through the calculation of the interpolation points of the curvature derived relationship interpolation error and feed rate. By using CNC system of HEIDENHAIN iTNC530 and IMSpost, the postprocessor of NURBS interpolation function was conducted so as to achieve the output NC program. The impeller' NURBS interpolation was conducted via MATLAB so as to achieve processing requirements.
In order to solve the problem of linear and circular interpolation, the relevant principles of five-axis machining of NURBS interpolation computation was studied by using cubic spline Non-Uniform Rational B-Splines parameterization; tip point and tool axis vector parameterization were made based on the UG pre-output cutter location data points so as to calculate its control points by using inverse calculation achieved NURBS interpolation. Then It can insert with feed rate control interpolation error through the calculation of the interpolation points of the curvature derived relationship interpolation error and feed rate. By using CNC system of HEIDENHAIN iTNC530 and IMSpost, the postprocessor of NURBS interpolation function was conducted so as to achieve the output NC program. The impeller' NURBS interpolation was conducted via MATLAB so as to achieve processing requirements.
2017, 36(3): 409-416.
doi: 10.13433/j.cnki.1003-8728.2017.0314
Abstract:
The poor forming quality is still one of the biggest challenge for the development and commercialization of single point incremental forming, the forming quality include surface quality and geometric error. In this paper, the cone shape is taken as the research object, Box-Behnken design for cone parts forming have been performed, where four factors and three levels were considered as the experiment scheme. The effects of the four input parameters (tool diameter, step down, sheet thickness and wall angle) on the two outputs including surface roughness and geometric error had been investigated, each of them are predicted by using quadratic equations, then the independent and simultaneous optimization has been used for the present models. It can be concluded that the step down presented the most significant liner effects on surface roughness, while sheet thickness to geometric error. With the target of minimal synchronization of surface roughness and geometric error, which are 0.97 μm, 1.939 mm, four processing parameters were optimized with tool diameter as 16 mm, step down as 0.5 mm, sheet thickness as 0.57 mm and wall angle as 65° respectively, under such circumstances.
The poor forming quality is still one of the biggest challenge for the development and commercialization of single point incremental forming, the forming quality include surface quality and geometric error. In this paper, the cone shape is taken as the research object, Box-Behnken design for cone parts forming have been performed, where four factors and three levels were considered as the experiment scheme. The effects of the four input parameters (tool diameter, step down, sheet thickness and wall angle) on the two outputs including surface roughness and geometric error had been investigated, each of them are predicted by using quadratic equations, then the independent and simultaneous optimization has been used for the present models. It can be concluded that the step down presented the most significant liner effects on surface roughness, while sheet thickness to geometric error. With the target of minimal synchronization of surface roughness and geometric error, which are 0.97 μm, 1.939 mm, four processing parameters were optimized with tool diameter as 16 mm, step down as 0.5 mm, sheet thickness as 0.57 mm and wall angle as 65° respectively, under such circumstances.
2017, 36(3): 417-421.
doi: 10.13433/j.cnki.1003-8728.2017.0315
Abstract:
Reflection line method is now widely applied to the field of surface interrogation. Considering the low efficiency of existing algorithm, the distortion of reflection lines and strong correlation of reference light source, this paper constructed the distance surface basing on the distance between the reference light line and the intersection point of each incident light and light source plane by optimizing the distance function model. Then the reflection points were worked out by classified tracing algorithm of grid surfaces based on the contour algorithm. The reflection lines were generated with high computational efficiency by computer programming. Finally, the advantages of the new algorithms were verified by several analysis cases of surface interrogation, and it also verified that the proposed optimization algorithm of reflection line is an effective tool for analyzing the surface quality.
Reflection line method is now widely applied to the field of surface interrogation. Considering the low efficiency of existing algorithm, the distortion of reflection lines and strong correlation of reference light source, this paper constructed the distance surface basing on the distance between the reference light line and the intersection point of each incident light and light source plane by optimizing the distance function model. Then the reflection points were worked out by classified tracing algorithm of grid surfaces based on the contour algorithm. The reflection lines were generated with high computational efficiency by computer programming. Finally, the advantages of the new algorithms were verified by several analysis cases of surface interrogation, and it also verified that the proposed optimization algorithm of reflection line is an effective tool for analyzing the surface quality.
2017, 36(3): 422-425.
doi: 10.13433/j.cnki.1003-8728.2017.0316
Abstract:
The reliability design and experimental verification for brittle fracture bolt which was used in shape memory alloy fracture mechanism under a certain load was conducted. The distribution of tensile strength and brittle characteristics was obtained via tension. The reliability design for brittle fracture bolt has been done using FOSM, and the stress-concentration-factor was taken into consideration. The reliability design was confirmed by using Monte Carlo method and function tests. An approximate normal-distribution curve has been found to suit the tensile strength of brittle steel. The material was characterized by using quasi-brittle property. Stress-concentration-factor and roughness on surface had a great impact on separation load in reliability design. The reliability experiment proved that the reliability design method of brittle fracture bolt was correct.
The reliability design and experimental verification for brittle fracture bolt which was used in shape memory alloy fracture mechanism under a certain load was conducted. The distribution of tensile strength and brittle characteristics was obtained via tension. The reliability design for brittle fracture bolt has been done using FOSM, and the stress-concentration-factor was taken into consideration. The reliability design was confirmed by using Monte Carlo method and function tests. An approximate normal-distribution curve has been found to suit the tensile strength of brittle steel. The material was characterized by using quasi-brittle property. Stress-concentration-factor and roughness on surface had a great impact on separation load in reliability design. The reliability experiment proved that the reliability design method of brittle fracture bolt was correct.
2017, 36(3): 426-435.
doi: 10.13433/j.cnki.1003-8728.2017.0317
Abstract:
The integration of process planning with process scheduling is important for the development of a manufacturing system. However, the integrated process planning and scheduling (IPPS) problem for batch manufacturing is not solved. Therefore, the batch splitting problem is integrated into IPPS problem. The equal splitting strategy may lead to the unbalance between production capacity and machine loading. To solve this problem, the flexible batch splitting strategy was adopted. The setup time and processing time were considered simultaneously. Makespan was the main optimization target. The model of the IPPS problem was established, and the problem was solved with the particle swarm optimization (PSO) algorithm. Finally, the model and the solution were proved through an application instance.
The integration of process planning with process scheduling is important for the development of a manufacturing system. However, the integrated process planning and scheduling (IPPS) problem for batch manufacturing is not solved. Therefore, the batch splitting problem is integrated into IPPS problem. The equal splitting strategy may lead to the unbalance between production capacity and machine loading. To solve this problem, the flexible batch splitting strategy was adopted. The setup time and processing time were considered simultaneously. Makespan was the main optimization target. The model of the IPPS problem was established, and the problem was solved with the particle swarm optimization (PSO) algorithm. Finally, the model and the solution were proved through an application instance.
2017, 36(3): 436-441.
doi: 10.13433/j.cnki.1003-8728.2017.0318
Abstract:
According to the reliability life of typical mining and metallurgy parts that is difficult to predict accurately in unfavorable working condition, a new method is established for predicting the reliability life of typical mining and metallurgy parts by using an improved Weibull distribution. Firstly, combining the feature of mining and metallurgy equipment typical components with the traditional mean rank method shortcomings in calculating empirical distribution function, prediction model is built for typical mining and metallurgy parts based on two parameters Weibull distribution. And then improved mean rank order method and least squares estimation are used to estimate the shape parameter and size parameter of the model. To use new improved method predicts reliability life of typical parts. Taking the crankshaft failure and censored data of a specific type jaw crushing machine as an example, the result achieves fine result and proves that forecasting precision of present method is more effective than the conventional.
According to the reliability life of typical mining and metallurgy parts that is difficult to predict accurately in unfavorable working condition, a new method is established for predicting the reliability life of typical mining and metallurgy parts by using an improved Weibull distribution. Firstly, combining the feature of mining and metallurgy equipment typical components with the traditional mean rank method shortcomings in calculating empirical distribution function, prediction model is built for typical mining and metallurgy parts based on two parameters Weibull distribution. And then improved mean rank order method and least squares estimation are used to estimate the shape parameter and size parameter of the model. To use new improved method predicts reliability life of typical parts. Taking the crankshaft failure and censored data of a specific type jaw crushing machine as an example, the result achieves fine result and proves that forecasting precision of present method is more effective than the conventional.
2017, 36(3): 442-447.
doi: 10.13433/j.cnki.1003-8728.2017.0319
Abstract:
To investigate the effects of sinusoidal surface roughness on power-law fluids electroosmotic flow (EOF) flow characteristics in microchannels, the Poisson-Nernst-Planck (PNP) mathematical model of power-law fluid EOF in two-dimensional parallel-plate rough microchannels was established. The Poisson equation for electric double layers (EDL) potential, the Nernst-Planck equation for the ion concentration, the Cauchy momentum equation and the constitutive equation for flows of power-law fluid electrolyte solution were solved using the finite element method. After the PNP model of power-law fluid EOF is verified, the effects of sinusoidal surface roughness relative height and frequency on the EDL potential and EOF flow of power-law fluid were investigated. The computer simulation results show that the sinusoidal surface roughness greatly affects the distribution of externally applied electric potential, the EDL potential and velocity vectors of EOF near the roughness surface. The EDL potential at the wave trough area increases with the roughness relative height and frequency, while an opposite trend occurs at the wave crest region. The flow of power-law fluid decreases with the increase of the roughness relative height only, but with the increase of the roughness frequency, it first decreases to the lowest value, where the roughness frequency equals to 2.2 and then increases. Particularly, with the decrease of power-law index, the effects of sinusoidal surface roughness on the fluid increase.
To investigate the effects of sinusoidal surface roughness on power-law fluids electroosmotic flow (EOF) flow characteristics in microchannels, the Poisson-Nernst-Planck (PNP) mathematical model of power-law fluid EOF in two-dimensional parallel-plate rough microchannels was established. The Poisson equation for electric double layers (EDL) potential, the Nernst-Planck equation for the ion concentration, the Cauchy momentum equation and the constitutive equation for flows of power-law fluid electrolyte solution were solved using the finite element method. After the PNP model of power-law fluid EOF is verified, the effects of sinusoidal surface roughness relative height and frequency on the EDL potential and EOF flow of power-law fluid were investigated. The computer simulation results show that the sinusoidal surface roughness greatly affects the distribution of externally applied electric potential, the EDL potential and velocity vectors of EOF near the roughness surface. The EDL potential at the wave trough area increases with the roughness relative height and frequency, while an opposite trend occurs at the wave crest region. The flow of power-law fluid decreases with the increase of the roughness relative height only, but with the increase of the roughness frequency, it first decreases to the lowest value, where the roughness frequency equals to 2.2 and then increases. Particularly, with the decrease of power-law index, the effects of sinusoidal surface roughness on the fluid increase.
2017, 36(3): 448-454.
doi: 10.13433/j.cnki.1003-8728.2017.0320
Abstract:
To obtain a wide range of highly accurate actual pose data for identifying the accurate parameters of manipulator model, a measurement method of serial manipulator-end based on spherical numbered targets is presented. The standard target ball rigidly connected to the end flange is tracked by binocular vision, the marked-targets set on the sphere surface are distinguished and numbered by the particular arrangement and distribution. The coordinates and orientations of ball center are calculated by at least four marked-targets captured and the known space geometry position relation according to Cramer's rule. Manipulator is moved in the working space at will for pose measurement. The pose error model is built and accurate manipulator model geometric parameters are gained by using least squares method achieving the manipulator error calibration. The experiments show that the results are accurate and the proposed method can solve the problem of narrow vision field of the binocular camera when traditional vision system is tracking and it reduces the cost of position and orientation measurements of manipulator-en. The present method is simple and reliable, and it effectively improves the positioning accuracy of manipulator.
To obtain a wide range of highly accurate actual pose data for identifying the accurate parameters of manipulator model, a measurement method of serial manipulator-end based on spherical numbered targets is presented. The standard target ball rigidly connected to the end flange is tracked by binocular vision, the marked-targets set on the sphere surface are distinguished and numbered by the particular arrangement and distribution. The coordinates and orientations of ball center are calculated by at least four marked-targets captured and the known space geometry position relation according to Cramer's rule. Manipulator is moved in the working space at will for pose measurement. The pose error model is built and accurate manipulator model geometric parameters are gained by using least squares method achieving the manipulator error calibration. The experiments show that the results are accurate and the proposed method can solve the problem of narrow vision field of the binocular camera when traditional vision system is tracking and it reduces the cost of position and orientation measurements of manipulator-en. The present method is simple and reliable, and it effectively improves the positioning accuracy of manipulator.
2017, 36(3): 455-461.
doi: 10.13433/j.cnki.1003-8728.2017.0321
Abstract:
FE-SEA (Finite element-statistical energy analysis) hybrid model of a passenger car was established, and verified the reliability of the model by comparing simulation results with experiment results. Taking each layer sound packages' material types and thickness of the firewall and floor as design variables, and selecting the sound pressure level (SPL) at driver's right ear, the total weight and total price of sound packages as optimization targets, the grey relational analysis (GRA) was coupled with orthogonal experiment methods to determine the optimal level of material types and thickness in each layer. Using thickness of each layer as design variables for the further study, the method of optimal Latin hypercube design was adopted to generate 75 sample points, and their response values were acquired through simulations, choose 67 sample points discretionarily to establish a Kring approximate model, and the remaining 8 sample points was used to verify the reliability of the approximate model. Finally, multi-objective optimization was performed based on this approximation model, compared with original sound packages, the SPL at driver's right ear decreases by 0.4 dB(A), the total weight and total price of sound packages decreases by 33.21% and 14% respectively.
FE-SEA (Finite element-statistical energy analysis) hybrid model of a passenger car was established, and verified the reliability of the model by comparing simulation results with experiment results. Taking each layer sound packages' material types and thickness of the firewall and floor as design variables, and selecting the sound pressure level (SPL) at driver's right ear, the total weight and total price of sound packages as optimization targets, the grey relational analysis (GRA) was coupled with orthogonal experiment methods to determine the optimal level of material types and thickness in each layer. Using thickness of each layer as design variables for the further study, the method of optimal Latin hypercube design was adopted to generate 75 sample points, and their response values were acquired through simulations, choose 67 sample points discretionarily to establish a Kring approximate model, and the remaining 8 sample points was used to verify the reliability of the approximate model. Finally, multi-objective optimization was performed based on this approximation model, compared with original sound packages, the SPL at driver's right ear decreases by 0.4 dB(A), the total weight and total price of sound packages decreases by 33.21% and 14% respectively.
2017, 36(3): 462-468.
doi: 10.13433/j.cnki.1003-8728.2017.0322
Abstract:
In the traditional design method of the suspension system, controller and structural parameters were designed separately, and the global optimum performances of suspension can not be achieved. In this paper, an integrated optimization method of structural and controller parameters is presented for the electronically controlled air suspension (ECAS). Firstly, a model of an ECAS with air spring with auxiliary chamber and solenoid valve damper is built, and the accuracy of the model is checked with bench tests. LQR controller is designed to control the damping force of the shock absorber. Selecting the orifice size of air spring with auxiliary chamber as structural optimization parameter and the acceleration weighting coefficient as the controller optimization parameter, controller parameter optimization and structural parameter optimization are done respectively with multiple population genetic algorithms. Optimization results demonstrate that the suspension system performance is further enhanced after parameters optimization.
In the traditional design method of the suspension system, controller and structural parameters were designed separately, and the global optimum performances of suspension can not be achieved. In this paper, an integrated optimization method of structural and controller parameters is presented for the electronically controlled air suspension (ECAS). Firstly, a model of an ECAS with air spring with auxiliary chamber and solenoid valve damper is built, and the accuracy of the model is checked with bench tests. LQR controller is designed to control the damping force of the shock absorber. Selecting the orifice size of air spring with auxiliary chamber as structural optimization parameter and the acceleration weighting coefficient as the controller optimization parameter, controller parameter optimization and structural parameter optimization are done respectively with multiple population genetic algorithms. Optimization results demonstrate that the suspension system performance is further enhanced after parameters optimization.
2017, 36(3): 469-474.
doi: 10.13433/j.cnki.1003-8728.2017.0323
Abstract:
As an advanced measuring technology, nano-indentation technology has been widely used in small volumes, especially for the measurement of material properties at microscopic and smaller scale to identify material parameters. Therefore,it is necessary to systematically and intensively review current achievements.Firstly, the principle of nano-indentation technology is analyzed. Then, the research progress both at domestic and abroad is summarized. Lastly, the research difficulties and the main problems in current research of nano-indentation technology are pointed out. The development trends of nano-indentation technology are proposed.
As an advanced measuring technology, nano-indentation technology has been widely used in small volumes, especially for the measurement of material properties at microscopic and smaller scale to identify material parameters. Therefore,it is necessary to systematically and intensively review current achievements.Firstly, the principle of nano-indentation technology is analyzed. Then, the research progress both at domestic and abroad is summarized. Lastly, the research difficulties and the main problems in current research of nano-indentation technology are pointed out. The development trends of nano-indentation technology are proposed.
2017, 36(3): 475-480.
doi: 10.13433/j.cnki.1003-8728.2017.0324
Abstract:
Carbon nanotube film loudspeaker is a new kind of speaker constituted by the superaligned carbon nanotubes based on thermoacoustic effect in recent years. For the purpose of probing the feasibility of carbon nanotube film loudspeaker as secondary sound source, the main factors which affect the far-field sound pressure of carbon nanotube film are analyzed. According to the characteristics, a simple and adjustable carbon nanotube film loudspeaker is designed to facilitate the practical application. The application of carbon nanotube film loudspeaker in active noise control has been proposed for the first time in this paper and the model of active noise control is constructed with the film as secondary source. For the target of the least total sound power of primary and secondary source, the optimal control voltage of the film is sovled. Five different carbon nanotube film loudspeakers are designed to control monopole acoustic radiation as the secondary source respectively. The active control effect is calculated and the main factors are analyzed.
Carbon nanotube film loudspeaker is a new kind of speaker constituted by the superaligned carbon nanotubes based on thermoacoustic effect in recent years. For the purpose of probing the feasibility of carbon nanotube film loudspeaker as secondary sound source, the main factors which affect the far-field sound pressure of carbon nanotube film are analyzed. According to the characteristics, a simple and adjustable carbon nanotube film loudspeaker is designed to facilitate the practical application. The application of carbon nanotube film loudspeaker in active noise control has been proposed for the first time in this paper and the model of active noise control is constructed with the film as secondary source. For the target of the least total sound power of primary and secondary source, the optimal control voltage of the film is sovled. Five different carbon nanotube film loudspeakers are designed to control monopole acoustic radiation as the secondary source respectively. The active control effect is calculated and the main factors are analyzed.
2017, 36(3): 481-486.
doi: 10.13433/j.cnki.1003-8728.2017.0325
Abstract:
The active heat transfer performance of light-weight sandwich panel with lattice-frame material(LFM) is analyzed based on the fin method, and Nusselt number of LFM under two different heat transfer boundary conditions, constant heat flux and constant temperature applied to the heat sink under steady state conditions, are derived respectively. The predicted results via the present models are compared with the experimental data. Furthermore, the influence factors which impact the active heat transfer performance are discussed, and the active heat transfer performance of Tetrahedral truss, Pyramidal truss and Kagome truss LFMs are investigated under the same porosity. The results reveal that the truss length and the number of cells along flow direction are more important, and the Kagome truss LFM is significantly better than the others.
The active heat transfer performance of light-weight sandwich panel with lattice-frame material(LFM) is analyzed based on the fin method, and Nusselt number of LFM under two different heat transfer boundary conditions, constant heat flux and constant temperature applied to the heat sink under steady state conditions, are derived respectively. The predicted results via the present models are compared with the experimental data. Furthermore, the influence factors which impact the active heat transfer performance are discussed, and the active heat transfer performance of Tetrahedral truss, Pyramidal truss and Kagome truss LFMs are investigated under the same porosity. The results reveal that the truss length and the number of cells along flow direction are more important, and the Kagome truss LFM is significantly better than the others.
2017, 36(3): 487-492.
doi: 10.13433/j.cnki.1003-8728.2017.0326
Abstract:
A less DOF experiment platform of flight simulator was studied, which is composed of a moving platform, a static platform and three PRS active branch chains between them. The active branch chains had 120° between each other. Based on scale parameter plane, a multiple-evaluation-indexes dimensional synthesis approach was proposed in this paper. It was taken the simulation performance, stiffness, operating performance and maximum angle of hinge as evaluation indexes. The influence laws of scale parameters to evaluation indexes were studied and discussed. In the scale parameter plane, the contour of evaluation indexes was drawn. According to the influence laws and the contour, the scale parameter region was confirmed and the region was satisfied the range of evaluation indexes. Then the scale parameter was determined in the region. Finally, the effectiveness of the method was proved by the example.
A less DOF experiment platform of flight simulator was studied, which is composed of a moving platform, a static platform and three PRS active branch chains between them. The active branch chains had 120° between each other. Based on scale parameter plane, a multiple-evaluation-indexes dimensional synthesis approach was proposed in this paper. It was taken the simulation performance, stiffness, operating performance and maximum angle of hinge as evaluation indexes. The influence laws of scale parameters to evaluation indexes were studied and discussed. In the scale parameter plane, the contour of evaluation indexes was drawn. According to the influence laws and the contour, the scale parameter region was confirmed and the region was satisfied the range of evaluation indexes. Then the scale parameter was determined in the region. Finally, the effectiveness of the method was proved by the example.
