Table of Content

10 September 2019, Volume 30 Issue 17

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Research on Grinding Force Model of Plane Grinding for Unidirectional C/SiC Composites

WANG Tao;WANG Sheng;QIAO Weilin;ZHANG Lifeng;ZHEN Tingting

2019, 30(17):  2017-2021. 

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In order to explore the grinding force model of woven ceramic matrix composites and find out the material removal mechanism, a unidirectional C/SiC composite was designed and fabricated. The special surface grinding experiments were used to grind along the typical direction of the fibers, and a multi-exponential fitting method was proposed to establish the grinding force model. The research results show that the grinding parameters have a significant influence on the grinding forces, and the grinding forces decrease with the increasing of the grinding wheel speeds, and increase with the increasing of the grinding depths and the feed rates. When grinding in three typical directions, the grinding forces from large to small in order are as: normal, longitudinal, transverse. The model goodness analysis was used to verify the reliability of the model for predicting the grinding forces of unidirectional C/SiC composites.

Equidistant & Radial-moving Modifications of Cycloidal Gear Tooth Profiles Used in RV Reducer Based on Optimized Carrying Capacity

LU Longsheng;ZHANG Feixiang;TANG Heng;WAN Zhenping;TANG Yong

2019, 30(17):  2022-2029. 

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Combined the traditional equidistant modification method and radial-moving modification method, a new composite modification method of equidistant & radial-moving（ERM） for cycloidal teeth was proposed based on optimized carrying capacity. Taking the cycloidal pin of a RV-40E reducer in industrial robots as an example, the mechanics analysis of the transmission was carried out, aiming at optimal carrying capacity, the mathematical model of the cycloidal profile modifications was established as well as optimized by the grid method. Finally, the ERM modification tooth profiles of cycloidal gears were obtained by using numerical solution. The processing technology of cycloidal gears was designed. A cycloidal gear optimized by ERM modifications and a cycloidal gear designed by traditional fitting angle(TFA) modifications used as a comparison were manufactured respectively, and their corresponding RV reducers were assembled to conduct performance tests respectively. The testing results show that the transmission efficiency of the new RV reducer made from the cycloidal gears modified by ERM method is as high as 85%. Compared with the RV reducer made from the cycloidal gears modified by TFA method, the noise and temperature rise of the new RV reducers are evidently reduced under the heavy load conditions. Overall, the carrying capacity of the new RV reducers is improved significantly.

AE Signal Characteristics of High-speed Milling Hardened Steels with Coated Tools

XIE Yingxing;WANG Chengyong;ZHENG Lijuan;SUI Jianbo

2019, 30(17):  2030-2039. 

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By measuring the AE signals and chip morphologies of different coated tool high-speed milling hardened steels with different hardness values, the voltage-time AE signals and the relationships between RMS values of AE signals and cutting parameters were obtained. The research results show that the AE signals are related to the hardness of the hardened steels, the tool coating types and the cutting parameter values. The AE signals may be used to evaluate the hardness changes of hardened steels, with the increasing of the hardness of hardened steels, the voltage values of AE signals increase gradually. The shear band lengths of sawtooth chips produced by the TiAlN coating are the shortest, the chips are easy to break so that the RMS values of AE are small during the cutting processes. With the increasing of cutting speeds and feed rates, the AE signals of TiSiN, TiAlN, AlCrN and CrSiN coated tools increase rapidly. However, as the axial and radial cutting depths increase, the AE signals of four coated tools do not change significantly. Under the same cutting parameter conditions, the cutting performances of the coated tools may be evaluated indirectly based on the chip deformation characteristic changes of the hardened steels. According to the peak values of AE signal oscillogram, the generating states of sawtooth chips may be well reflected, and then may be used to monitor the cutting stability of hardened steels during the working processes.

An Efficient Reduced Basis Optimization Method for Structures with Ellipsoidal Convex Parameter Domains

ZHANG Zheng;BI Rengui;YAN Can

2019, 30(17):  2039-2043. 

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An efficient optimization method for the structures with ellipsoidal convex parameter domain structures was presented based on the reduced basis method. The ellipsoidal convex parameter domains were processed by changing basis and the rectangular convex boundaries were found for packaging the processed ellipsoidal convex parameter domains, by which the standard rectangular parameter domains and the reduced basis spaces of low dimension were formed. The fast simulation and calculation were conducted on the ellipsoidal convex parameter domains, and the reduced basis equation was used to replace the finite element equation in the structure optimization model, which would change the structure optimization model into an optimization model with reduced basis. The research results show that due to the actual reductions and transformations of the conventional optimization model, the proposed method may obtain higher solution efficiency without changing the general optimization algorithm. The analysis of the structure example herein verifies the engineering effectiveness of the proposed method.

Research on Surface Integrity of GH4169 Nickel-based Superalloys by Robotic Belt Grinding

DUAN Lian1,2;HUANG Yun1,2;ZOU Lai1,2

2019, 30(17):  2044-2050. 

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The belt grinding tests of GH4169 nickel-based superalloys were carried out by robot. The test equipment was designed and analyzed to ensure the stability of grinding pressures. The grinding depths of GH4169 were obtained by orthogonal tests during the belt grinding processes. Single factor tests were used to determine the effects of belt linear speeds and grinding pressures on the surface integrity of GH4169.The testing results show that when GH4169 is machined with ceramic abrasive belt with particle size of 80, the surface roughnesses are as 0.6~0.7 μm, and decrease with the increasing of belt linear speeds, and increase with the increasing of grinding pressures. The surface hardness values are as 430~485HV, and the surface residual stresses are all residual compressive stresses, and the values are as -410~ -60 MPa.

Improved Kriging Response Surface Reliability Calculation Method Based on Two-point Addition Strategy

LI Yonghua1;LIANG Xiaojia1,2;GONG Qi1

2019, 30(17):  2051-2057,2065. 

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Aiming at the problems that the polynomial model in the classical response surface method was insufficient in fitting the highly nonlinear structural performance functions, the Kriging model was used to replace the real structural performance functions and an improved Kriging response surface reliability calculation method was proposed based on two-point addition strategy. According to the two-point adding strategy, the best sample points selected according to the interpolation formula and the evaluation function, as well as the checking points generated by first-order second-moment method were added to the sample library together to update the Kriging model . The important parameters of Kriging model were optimized by genetic algorithm, and the optimized model was used to fit the structural performance functions, then the reliability calculation results were corrected with the important sampling method. The results of numerical examples show that the proposed method may  take into account both of the calculation accuracy and the calculation efficiency, which verifies the applicability and efficiency of  proposed method.

Dynamic Mechanics Properties of SUS301L-HT Stainless Steel Used in Carbodies of Trains and Effects on Energy Absorption Characteristics of Structures

CHEN Shujian1;CHENG Di2;XIAO Shoune1;ZHU Tao1;YANG Guangwu1;YANG Bing1;FENG Yue1

2019, 30(17):  2058-2065. 

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The quasi-static tension tests and dynamic impact tension tests of SUS301L-HT stainless steels were carried out respectively to obtain the material constitutive relations under different strain rates. The tabular interpolation method was adopted to accurately describe the dynamic mechanics properties of SUS301L-HT stainless steels, and the reliability of this method was verified by the comparisons of finite element solutions and test data. Taking the typical thin-walled structures as the carriers, the influences of the material dynamic mechanics properties on energy absorption characteristics were investigated by using two kinds of material parameters. The research results show that the SUS301L-HT stainless steel exhibits obvious strain rate hardening effectiveness, with the increasing of strain rates, the plasticity hardening ability of the material decreases, which presents distinct temperature softening effectiveness. The dynamic mechanics properties of SUS301L-HT stainless steel may be described more accurately by the tabular interpolation method than by the dynamic constitutive models, and the results obtained by tabular interpolation method are in good agreement with the test and numerical results. The strain rates of train collisions belong to the range of low-middle strain rates. For the energy absorption structures made of the SUS301L-HT stainless steel, the practical absorbed energy of the structures considering the strain rate effectiveness is higher than that of the same structures without considering the strain rate effectiveness, but the initial peak force is relatively high.

Research on Anti-rollover Hierarchical Control of Counterbalanced Forklifts

XIA Guang1,3;ZHANG Yang1,3;TANG Xiwen2;XIE Hai1,3;YANG Meng1,3;GAO Jun1,3

2019, 30(17):  2066-2075. 

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Based on the analysis of forklift structures and rollover mechanism, an anti-roll hydraulic cylinder was designed as the actuator for anti-rollover control to provide lateral support forces. An anti-rollover hierarchical control method was proposed based on T-S fuzzy neural network. The forklift anti-rollover was controlled hierarchically: the T-S fuzzy neural network was used by the upper identification layer to judge the real-time motion states of the forklifts and as the basis of the lower layer control, the middle control layer selected the corresponding strategies according to the divisions of the motion states，the lower execution layer controlled the outputs of the model by the action forms of the actuators under different strategies. The simulation and real vehicle test results show that the proposed method may divide the safety domains of the forklifts under the emergency conditions and achieve the purpose of improving the safety of the forklifts.

Effects of Perforation on Edgewise Compression Performances of Honeycomb Sandwich Structures with Plain Woven Panels

WANG Xuan1;LIU Wushuai1;YU Fen1;DENG Yunfei1;ZHOU Chunping2

2019, 30(17):  2076-2083. 

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A progressive damage model of honeycomb sandwich structures with plain woven panels was established to study the edgewise compressive performances of honeycomb sandwich structures with no-damage panels and with perforation damages on single side panels respectively, and the results were compared with the testing results to verify the correctness of the model. Considering the high material nonlinearity of the model, ABAQUS/Explicit solver was used to simulate the quasi-static edgewise compressive performances of honeycomb sandwich structures. By compiling VUMAT subroutine, failure criteria and stiffness degradation model of the panels and cores were set up respectively. Cohesive model was used to simulate the adhesive and progressive damage analyses of honeycomb sandwich structures subjected to edgewise compression were simulated. The research results show that the edgewise compressive strengths of honeycomb sandwich structures with no-damage panels are controlled by the buckling behaviors of the panels, and the edgewise compressive strengths of honeycomb sandwich structures with perforation damages on single side panels are controlled by the compression resistances of the panel matrixes with perforation, as well as the perforation damages may seriously reduce the edgewise compressive strengths of honeycomb sandwich structures.

Rotor Redesign Method for Suppressing Torque Ripples of Permanent Magnet Synchronous Motors

SONG Shouxu;LI Nuonan;DU Yi;LIU Tao

2019, 30(17):  2084-2090,2134. 

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In order to suppress the torque ripples of remanufactured permanent magnet synchronous motors, a progressive redesign method of single inner pole eccentric groove, combined eccentric groove and magnetic bridge optimization was proposed. Taking JEEMC01003B permanent magnet synchronous motors for vehicles as the research objects, the influences of single inner pole eccentric groove and combined eccentric groove on cogging torques and harmonic torques were analyzed. Based on these, the magnetic bridge redesign was carried out and the torque ripples were comprehensively optimized. The research results show that compared with the original motor, the torque ripples of the remanufactured motors are decreased by 3%, the average torques are increased by 0.2 N·m, the cogging torques are decreased by 6%, the iron losses are reduced by 4.7 W/kg, the magnetic density distortion rates are reduced by 5.6%, and the efficiency is improved to 97.60%, the motor performance is improved significantly.

Modeling and Improved SFLA for Disassembly Line Balancing under Resource Constraints

CAI Ning;ZHANG Zeqiang;ZHANG Ying;ZHU Lixia

2019, 30(17):  2091-2099. 

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Aiming at the resource constraints and the hazardous parts involved in the actual disassembly lines, a mathematical model of multi-objective resource constraint disassembly line balancing problem was constructed considering the total number of resources, the number of stations and the hazard as index three objective functions to be optimized. Based on the AND/OR relation, the descriptions of the OR relation were added to the priority relation matrix, which solved the problems that the initial solution only took into account the AND relation. An improved SFLA incorporating the Pareto's idea was proposed. An improved ranking grouping strategy was adopted based on satisfaction to solve the multi-objective optimization population grouping problems for the proposed algorithm. A new cross-mutation method was proposed to implement the local search to improve the convergence. The crowded distance mechanism was used to evaluate the non-inferior solution sets and effectively maintain the size of the external file. And Taguchi experiment and statistical analysis method were used to determine the optimal combinations of algorithm parameters. The multi-index was used to compare and analyze the results of the testing instances obtained by the SFLA before and after the improvement as well as the NSGA-Ⅱ. The research results show that the improved SFLA has a good comprehensive solution. Finally, the algorithm was applied to a refrigerator disassembly line, which provided a better solution scheme for decision makers.

Evaluation of Product Process Planning Schemes for Green Manufacturing

LI Lianhui1;XU Guanying2;GAO Yang1;MAO Chunlei3;WANG Hongguang4

2019, 30(17):  2100-2107. 

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In view of the uncertainty and incompatibility in the product process planning scheme evaluation under the background of green manufacturing, an evaluation method of product process planning scheme was proposed based on extension analysis and D-S theory. According to the extension analysis theory, the classical domain matter element matrix, the joint domain matter element matrix and the matter element matrix to be evaluated of product process planning scheme evaluation problem were established, and the correlation function matrix of the matter element matrix to be evaluated was obtained. The identification framework of D-S theory was established after conversion processing and the correlation function matrix in extension analysis was extended to the basic probability assignment(BPA) function matrix in D-S theory. The CRITIC method, which combined the contrast strength and conflict, was used to calculate the importance degree of each feature. The evidences were fused considering the feature importance degree. According to the BPA function values after fusion, the process planning schemes were analyzed and compared. Finally, the classification results of multiple process planning schemes and the ranking relations of the same level schemes were obtained. The effectiveness of the proposed method was verified by an example of an automobile rear door frame process planning scheme evaluation.

Microstructure and Mechanics Properties of Interfaces between Laser Cladded Inconel718 Coating and Substrate

FANG Jinxiang1;WANG Yujiang2;DONG Shiyun2;XU Binshi2;YAN Shixing2;SONG Chaoqun2,3;SHU Fengyuan3;HE Peng3

2019, 30(17):  2108-2113. 

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An Inconel718 coating was fabricated on the surfaces of Inconel 718 alloy by laser cladding, and the microstructure and mechanics properties in the zones of bonding interfaces were investigated. The results demonstrate that the hardness and strength decrease in the HAZ due to the dissolution of the strengthening phase. Under typical processing conditions, the HAZ decrease with the increasing scanning speeds. There is no planar crystal structures at the bottoms of cladding layers. Furthermore, the structures in the fusion zones were densified and presented smooth transition, the chemical components are consistent with those of the substrate. In the cladding layers, the microstructure consists of an dendritic structure and lots of  intergranular Laves phases. The hardness in the cladding layers is higher compared to the HAZ. After the aging heat treatment, the strength in both of HAZs and cladding layers are improved, and are close to that of the substrate materials, and a smooth mechanics properties transition are obtained in the interface zones between the coatings and substrates.

Applications of Nonlinear Geometric Frame Model in Forward Design for Electric Vehicle Bodies

GUO Wei1，2;CHEN Jiqing1，2;HUANG Jianan1，2;LAN Fengchong1，2

2019, 30(17):  2114-2121. 

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In view of the low precision of the concept simplified model in the forward design processes for traditional vehicle bodies, which might not reflect the complex and practical problems of the beam section elements in the detailed design stages. In order to improve the accuracy of vehicle forward design and explore the development processes of the forward design for electric vehicle bodies, a new method of establishing conceptual simplified model was proposed, which adopted nonlinear geometric frames and complex beam section elements to approximate vehicle body modeling. The proposed method was applied to the forward design of electric vehicle bodies, further the concept design, analysis and prediction, detailed design and analysis as well as the tests and analyses of sample vehicle test stages, and a rationality evaluation basis of the conceptual simplified model was put forward. The research results show that the static and dynamic performance index errors of the conceptual simplified model are less than 25%. The proposed method of establishing conceptual simplified model may be well applied in the forward design for electric vehicle bodies, and may reasonably predict the later detailed design and the overall performances of the prototype.

Preventive Maintenance Method of CNC Machine Tools Based on Performance Degradation Prediction

DAI Bochao;ZHANG Yingjie;LI Yangfan;CHEN Bo

2019, 30(17):  2122-2128. 

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In order to solve the disadvantages of “under maintenance” or “over maintenance” in traditional maintenance methods of CNC machine tools, a preventive maintenance method was proposed based on the prediction of system performance degradation. The SPC technology was used to analyze the product quality data and realize the prediction of the working states for the machine tools. The Wiener degradation model of a key component was established to predict the life distribution, so that the optimal preventive maintenance strategy might be determined by residual life and revenues. Taking the abnormal data of CNC machine tools in an automobile piston production line as an example, the validity of proposed method was verified.

Influences of Corrosion Environments on Fatigue Life and Crack Propagation of Aircraft Beam Structure Connectors

ZHENG Jie1;LIU Yang1,2;TONG Mingbo1

2019, 30(17):  2129-2134. 

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The coastal aircraft's parking-flight-parking processes were modeled by the alternating effects of the corrosion environment spectrum and the fatigue load spectrum, taking the lower wall panels of the aircraft beam structure connectors as the main research object. The propagation of the cracks was monitored by the marked load method and the detailed visual inspection method, and the fracture morphology was observed with a GE5 microscope. The influences of the corrosion environments on the fatigue life and crack propagation of the aircraft beam structure connectors were analyzed. The testing results show that the specimens are protected by the protective paints on the surfaces and the sealant at the joints during the initial formation stages of the penetrated cracks, the corrosion environments have no obvious effects on the fatigue life of the beam structure connectors during this stage. Compared with the non-corrosion tests, the life of this period is reduced by 5.5%. The corrosion environment accelerates the propagation processes of penetrated cracks during the propagation stages of penetration cracks. Meanwhile, the dispersion of the crack propagation processes was exacerbated. Compared with the non-corrosion tests, the propagation life of penetrated cracks is reduced by 23.1%.

Mechanics Properties of Negative Poisson's Ratio Honeycomb Structures with Variable Arc Angle Curved Concave Sides

SHEN Jianbang;XIAO Junhua

2019, 30(17):  2135-2141. 

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A variable arc angle curved concave honeycomb structure with negative Poisson's ratio effect was proposed based on the circular honeycomb structure.The bending internal forces of the rigid frame structures were analyzed and the analytical formulas of the transverse/longitudinal equivalent elastic modulus and the equivalent Poisson's ratio were obtained by using the energy method. The proposed curved concave honeycomb structure might be degenerated into the existing circular honeycomb structure when the arc angle is as 180°. The present analytical solutions were in agreement with the existing theoretical solutions and finite element results, which showed the validity of the present method. Based on the obtained analytical solutions, the effects of the microstructure geometric parameters on the equivalent elastic modulus and the equivalent Poisson's ratio were discussed.The research results show that the equivalent elastic modulus is significantly affected by the arc angles. The equivalent Poisson's ratio is also obviously affected by the arc angles, the lengths of vertical walls and the widths between two vertical walls, while the influences of the connected part lengths are not obvious.