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Cross-domain Fault Diagnosis of Bearings Based on Joint Subdomain Contrast Alignment YANG Kang1, CHEN Xuejun1, 2, ZHANG Lei3, LIU Feng3 China Mechanical Engineering    2025, 36 (05): 1065-1073.   DOI: 10.3969/j.issn.1004-132X.2025.05.018 Abstract （1753）      PDF（pc） （5744KB）（35）       Knowledge map    Save The fault data of bearings exhibited significant distribution discrepancies under varying operating conditions， relatively low diagnostic accuracy was resulted in practical fault detection models. Additionally， most existing research on cross-domain bearing fault diagnosis primarily emphasized inter-domain alignment and intra-class comparison， while neglecting the influences of interactions between subdomains. Therefore， a cross-domain fault diagnosis method of bearings was proposed based on joint subdomain contrast alignment. In order to highlight the fault features， the bearing vibration signals were transformed into time-frequency graph by short-time Fourier transform， and the fault features were obtained by inputting them into the feature extraction module. Domain adaptation methods achieved cross-domain recognition by transferring knowledge learned from the source domain to the target domain. During the domain adaptation processes， a joint subdomain contrast alignment strategy was used to bring samples from the same subdomain closer together while separating samples from different subdomains， which aligned the subdomain distributions of the same class samples among the source and target domains， thereby enhancing the models generalization ability in the target domain. Resnet34 was used as the feature extraction network on the model architecture， and the maximum mean difference was used at the output of the network to align the global distribution of the source domain and the target domain. Compared with the classical domain adaptation methods， the experimental results on the bearing fault data set of Case Western Reserve University shows that the cross-domain fault diagnosis method of bearings based on joint subdomain contrast alignment has better feature transfer ability.  Reference | Related Articles | Metrics | Comments（0）

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Influences of Loading Angle on Fatigue Characteristics and Failure Modes of Self-piercing Riveted Joints in Aluminum Alloy 6082 LEI Fuyu1, XU Xiaoxu2, ZHAO Yaming2, LUO Jun1, MA Chao1, XU Congchang1, LI Luoxing13 China Mechanical Engineering    2025, 36 (01): 141-151.   DOI: 10.3969/j.issn.1004-132X.2025.01.015 Abstract （1727）      PDF（pc） （41395KB）（58）       Knowledge map    Save Taking the self-piercing riveting of 6082 aluminum alloy as the research object, the fatigue crack propagation mechanism and fretting wear behavior of the joints were studied by tensile tests, fatigue tests and scanning electron microscopy. The results show that compared to the 0° and 45°, the joint has the best static mechanics properties under the loading angle of 90°. Under the same load level, the fatigue life of the joints increases with the increase of the loading angles. Under high-cycle fatigue, the joints fail by cracking of the lower plate, while under low-cycle fatigue, the joints fail by cracking of the upper plate and rivet fracture. Fretting wear affects the location and propagation path of the fatigue crack initiation in the joints, and the loading angles of the joints affect the fretting wear in different areas of the joints. Under the loading angle of 90°, the fretting wear in the contact areas between rivet head and upper plate is the most serious. Under the loading angle of 0°, the fretting wear in the contact areas between lower plate and surface of the rivet leg is the most serious. Reference | Related Articles | Metrics | Comments（0）

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Bearing Fault Data Generation Method Based on WLT-ACGAN JIAO Huachao, SUN Wenlei, WANG Hongwei China Mechanical Engineering    2025, 36 (03): 546-557.   DOI: 10.3969/j.issn.1004-132X.2025.03.018 Abstract （1695）      PDF（pc） （7836KB）（59）       Knowledge map    Save Using data generation method to generate high-quality data which made time-domain and frequency-domain features consistent with the real signals of bearing faults, and constructing balanced dataset, were of great significance for the establishment of an efficient diagnostic model of bearing faults in the case of data imbalance. In order to address the limitations of the existing data generation methods, which focused on a single feature in time or frequency domains, WLT-ACGAN was proposed herein. Firstly, a WLT network was constructed with a multi-layer neural network based on the principle of wavelet transform. The wavelet transform and inverse transform were simulated, and the mapping relationship between time-domain signal and frequency-domain signal was established. Secondly, the WLT network was embedded into ACGAN model as the primary component of model generator. Finally, two discriminators were constructed with different functions, enabling the improved ACGAN to learn time-domain and frequency-domain feature information of authentic bearing vibration signals concurrently. Experimental results show that the bearing vibration signals generated by WLT-ACGAN model exhibit consistent time-domain and frequency-domain features with those of the actual bearing vibration signals. Furthermore, the fault diagnostic model constructed with the balanced dataset augmented by the generated signals exhibits a high degree of accuracy when the data are imbalanced. Reference | Related Articles | Metrics | Comments（0）

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Research Progresses for Machining Characteristics and Field-assisted Techniques of γ-TiAl Alloys FAN Tao1, 2, YAO Changfeng1, 2, TAN Liang1, 2, SHAN Chenwei１, ２, XIA Ziwen1, 2 China Mechanical Engineering    2025, 36 (04): 636-645.   DOI: 10.3969/j.issn.1004-132X.2025.04.001 Abstract （1686）      PDF（pc） （25364KB）（164）       Knowledge map    Save γ-TiAl alloys, due to their low density, high specific strength and excellent high-temperature oxidation resistance had broad application potentials in the aerospace fields. However, due to their high brittleness and low room-temperature plasticity, they were considered typical difficult-to-machine materials, with challenges such as high cutting forces, rapid tool wear and surface defects during the machining processes. In recent years, field-assisted machining technologies provided new solutions to these issues. The material properties, machining characteristics, and surface integrity of γ-TiAl alloys were systematically analyzed, with a focus on the research progresses of field-assisted machining technologies, including their applications in reducing cutting forces, extending tool life and improving surface quality. Additionally, the current research limitations and future development trends were sorted out, aiming to provide theoretical and technical references for the efficient machining of γ-TiAl alloys.  Reference | Related Articles | Metrics | Comments（0）

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Influence Law and Mechanism of Geometric Parameters on Wrinkling Characteristics of Hollow Aluminum Profiles in Stretch-Bending#br# LIU Zhiwen1, 2, LEI Chong1, SUN Kaibo1, OUYANG Basheng1, LI Luoxing2, LIU Xiao3, LI Fazhi1 China Mechanical Engineering    2025, 36 (05): 1083-1093.   DOI: 10.3969/j.issn.1004-132X.2025.05.020 Abstract （1630）      PDF（pc） （8620KB）（30）       Knowledge map    Save Based on the plate and shell theory， the expression of wrinkling energy and external force work functions of hollow aluminum profiles in stretch-bending were derived. Combined with the energy criterion， the theoretical prediction model of wrinkling was established for hollow profiles in stretch-bending and the accuracy of model was verified by bending experiments. The formation mechanism of wrinkling defects in stretch-bending of hollow profiles was revealed and the influences of geometric parameters on wrinkling limit and morphology were quantitatively studied. The results show that the theoretical predictions of the number and height of wrinkling under three different bending radii are in good agreement with those of the experimental ones. The maximum differences are as 1.2 and 0.55 mm， respectively， with relative errors of 16.93% and 11.28%， respectively. The growth rate of external force work in the bending stages is greater than that of wrinkling energy. With the increase of bending time， the external force work is greater than the wrinkling energy， resulting in the appearance of wrinkling instability. With the increase of thickness-to-height ratio and thickness-to-width ratio of the profiles， the wrinkle ratio and wrinkling number decrease， while the wrinkling limit and wrinkling height increase. With the increase of the aspect ratio， the wrinkle ratio and wrinkle height increase， while the wrinkling limit and wrinkling number decrease. The wrinkling limit might be increased by adding inner reinforcement rib in the profile cavities， while the wrinkling number increases and the wrinkling height decreases.  Reference | Related Articles | Metrics | Comments（0）

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Effects of Forced Positioning&Clamping on Geometric and Physical Assembly Performances for Composite Structures and Collaborative Guarantee Strategies GUO Feiyan1, ZHANG Yongliang2, LIU Jialiang1, ZHANG Hui2 China Mechanical Engineering    2025, 36 (04): 655-670.   DOI: 10.3969/j.issn.1004-132X.2025.04.002 Abstract （1565）      PDF（pc） （7015KB）（115）       Knowledge map    Save The large-size & thin-walled aviation composite structures had low forming accuracy and huge in-plane warping deformation. The accumulation of assembly errors, unexpected geometric gaps and shape deviations were prone to occur at the joining areas. In engineering, passive reduction actions, such as applying local clamping forces was usually applied, but uneven internal stress distribution and even internal damages would be occurred, which affected the mechanical performances of the structures in service directly. Firstly, the principle of forced positioning clamping was explained, and the affection on geometric accuracy and mechanical properties of weak rigid composite parts was analyzed. Secondly, starting from the analysis of two main aspects, i.e. optimization on forced clamping process parameters before assembly, and flexible positioning force&position adjustment of fixtures during assembly, five key technologies were solved with detailed technical solutions, i.e. setting forced assembly force limits, reduction of geometric gaps, prediction of stress/damage evolution, reverse optimization of forced clamping process parameters, and precise measurement of assembly stress&damage. Then the active control of shape&force coupling and macro & micro collaborative guarantee in the clamping processes for assembly performance, could be achieved. Finally, for the composite assembly structures, from the perspective of practical engineering applications, the future working focus towards high assembly quality and efficient, and low-cost assembly goals were proposed. Reference | Related Articles | Metrics | Comments（0）

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Study on Lubricating Performances and Mechanism of Nano-carbon Balls Cutting Fluids SUN Hao1, LAN Qixin2, YAO Bin2, LU Jingjing1, ZHANG Jinhui2, PAN Zhirong2, ZHAO Kexin2 China Mechanical Engineering    2025, 36 (04): 715-723.   DOI: 10.3969/j.issn.1004-132X.2025.04.008 Abstract （1522）      PDF（pc） （8056KB）（55）       Knowledge map    Save Nano-carbon balls cutting fluid was applied to the cutting processes of difficult-to-machine aerospace gear steels(15Cr14Co12Mo5Ni2W), and the lubrication enhancement effects of nano-carbon particles on the cutting fluid were investigated. Firstly, a cutting force model for metal cutting was established to analyze the relationship between cutting lubrication and cutting forces. Furthermore, through combined friction-wear tests and milling experiments, the lubrication performance of nano-carbon balls cutting fluid was evaluated in terms of friction coefficient, wear volume, friction surface quality, and cutting forces. Compared with the base cutting fluid, when the mass fraction of nano-carbon is reached 0.02%, the milling forces for the gear steels are decreased by over 10%, and surface roughness is reduced by more than 15%. Experimental observations reveal that nano-carbon particles on the friction contact surfaces preferentially are adsorbed onto micro-peak regions with higher surface free energy, forming a nano-carbon adsorption film. Lubrication mechanism analysis indicates that this adsorption film may exert a friction-reducing “micro-bearing” effects. Reference | Related Articles | Metrics | Comments（0）

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Fault Diagnosis of Rotating Machinery Bearings Based on Multi-source Wavelet Transform Neural Network GUO Haiyu1, ZOU Shenggong1, ZHANG Xiaoguang2, 3, 4, LU Fanfan2CHEN Yang2, WANG Han2, XU Xinzhi2 China Mechanical Engineering    2024, 35 (11): 2026-2034.   DOI: 10.3969/j.issn.1004-132X.2024.11.014 Abstract （1503）      PDF（pc） （5837KB）（84）       Knowledge map    Save  A multi-source wavelet time-frequency transform convolutional neural network was proposed to address the issues of limited fault samples in rotating machinery bearing fault diagnosis, along with the vulnerability to overfitting and the poor generalization ability of traditional models when dealing with small datasets. Initially, for high-frequency data obtained from a single vibration sensor, a wavelet transform-based time-frequency convolutional layer was formulated to integrate both the real and imaginary components of wavelet coefficients. Here, the real component represented the amplitude information of vibration signals, while the imaginary component depicted phase information. Compared with a convolution layer that only considering real part, this convolutional layer may extract comprehensive time-frequency features. Subsequently, the time-frequency convolutional layer was employed to independently extract features from high-frequency data acquired by multi-sensors on a single device, and these features were then concatenated. Lastly, a dense module utilizing lightweight depth-separable convolution was developed to conduct further feature extraction from the concatenated features, facilitating fault classification. The effectiveness of the model was confirmed through experimentation using Case Western Reserve University rolling bearing dataset, achieving an accuracy of 98.5%.Additionally, the model was deployed for fault diagnosis in rotary kilns, belt conveyors, and grate coolers, demonstrating an average accuracy of 97.19%. Reference | Related Articles | Metrics | Comments（0）

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Rolling Bearing Fault Diagnosis of Wind Turbines Based on Frequency Domain Group Sparse Model with Graph Regularization Constraints LI Jimeng, WANG Ze, SHI Qingxin, MENG Zong China Mechanical Engineering    2024, 35 (11): 1909-1919.   DOI: 10.3969/j.issn.1004-132X.2024.11.002 Abstract （1350）      PDF（pc） （11269KB）（136）       Knowledge map    Save Due to effects of the non-stationary operations, noisy working environment and strong electromagnetic interference for the wind turbines, the fault impulses of rolling bearings were submerged by strong noise, and the weak features were difficult to accurately identify. To solve the above problems, a frequency domain group sparse model with graph regularization constraints was proposed, which might effectively extract fault features of rolling bearings without periodic prior knowledge. Firstly, vibration signals were converted into graph signals to construct the graph regularization constraints, and the structured information was utilized to guide the penalty strength to improve the accuracy of sparse reconstruction. Secondly, the frequency domain group sparse model with graph regularization constraints was constructed, the method was given to determine the shrinkage threshold of the in-group components, and the objective function was simplified with the proximal mapping to optimize the solution. Finally, the parameters of the model were optimized by using the constructed comprehensive index and the moth flame optimization algorithm, and rolling bearing faults were identified by the envelope spectrum analysis of the reconstructed signals in the time domain. Numerical simulation and experimental results demonstrate that the proposed method has good anti-noise performance and may effectively extract weak fault features of rolling bearings under strong noise interference. Reference | Related Articles | Metrics | Comments（0）

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Spiral Machining Trajectory Planning Method Based on Discrete Point Cloud Construction of Radial Lines WU Jiangsheng, CHAI Xingliang, BO Qile, LIU Haibo, WANG Yongqing China Mechanical Engineering    2025, 36 (04): 697-702,714.   DOI: 10.3969/j.issn.1004-132X.2025.04.006 Abstract （1283）      PDF（pc） （7105KB）（58）       Knowledge map    Save Aiming at the problems that it was difficult to directly generate efficient and accurate continuous smooth tool path trajectories based on discrete point clouds, a method to directly construct radial lines on point cloud and generate spiral machining trajectories through radial line interpolation was proposed herein. For the construction of radial lines, a boundary recognition method was proposed based on feature descriptors to extract boundary points as two end points of the radial lines. Taking the optimal discrete geodesics between two end points on the point cloud as the radial point set, the curvature minimization problems of discrete geodesics were proposed and solved by Newton iteration method. The B-spline curves were used to fit and resampling according to the residual height based on the radial point sets. The radial line interpolation algorithm was proposed to generate the spiral machining trajectory with equal residual height. Finally, an example was given to demonstrate the spiral machining trajectories directly generated by the point cloud data, which fully verified the effectiveness of the proposed method. Reference | Related Articles | Metrics | Comments（0）

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Tensile-shear Property of Composite Secondary Bonding Joints with Resistance Heating Technology WANG Xuan1, YAO Kaifei1, YUAN Weiqiang1, WANG Kuikui2, YU Jixuan2, ZHANG Yi3 China Mechanical Engineering    2025, 36 (01): 152-159.   DOI: 10.3969/j.issn.1004-132X.2025.01.016 Abstract （1279）      PDF（pc） （16272KB）（36）       Knowledge map    Save The impacts of 5 embeddings on tensile-shear properties of the secondary bonding joints were analyzed. The experimental results indicate that to improve the quality of the joints, the embedded metal mesh might undergo surface treatment. Tensile-shear strength of the joints by resistance heating technology is better than that by autoclave technology. The additions of embedded material enhanced the tensile shear properties of the joints, and the joints with prepreg embedding demonstrate the best tensile-shear strength. Nickel mesh embeddings exhibit higher densities, and have better bonding quality than that of copper mesh. End regions of the overlap joint experience severe stress concentration. Metal mesh embeddings enhance joint tensile stiffness. The joints with embeddings exhibit cohesive failure, adhesive failure, fiber tearing fracture of bonded parts and embedding failure, and the peeling stress is a major factor in failure. The more irregular distribution of failure modes is in the failure section, the poorer bonding quality is. Reference | Related Articles | Metrics | Comments（0）

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Study on In-plane Shear Behavior and Interaction Mechanism of Flexible Elastic Composite Lattice Structures NIU Guofa1, JI Xiaogang1, 2, WANG Wei1, WANG Guangyang1 China Mechanical Engineering    2025, 36 (05): 1103-1110.   DOI: 10.3969/j.issn.1004-132X.2025.05.022 Abstract （1279）      PDF（pc） （8492KB）（25）       Knowledge map    Save The shear behavior and interaction mechanism of composite lattice structures were studied under in-plane shear loads by tests and numerical simulations. The damage failure courses and failure modes of matrix body centered cube(BCC) structures were analyzed experimentally. Using BCC cell structure as matrix, the influences of the diameter of chimeric structures on shear strength and shear modulus of composite structures were investigated by means of chimeric structure. Finally, the reliability of finite element analysis was verified by face centered cubic(FCC) structure tests, and the interaction mechanism of FCC-BCC structures was explored under in-plane shear loads. The testing results show that the mosaicism amang structures enhances the bearing capacity of the composite lattice structures, and influences the strains of the composite structures. The ultimate shear strength of FCC-BCC and simple cube-body centered cube(SC-BCC) are as 159% and 80% higher than that of the matrix respectively when the diameter size of the structural rods are both 0.45 mm. Reference | Related Articles | Metrics | Comments（0）

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Effects of Glass Fiber Mass Fraction on W-PACIM Pipes of Long Glass Fiber Reinforced Polypropylene LIAO Qiansheng1, 3, LIU Hesheng2, KUANG Tangqing2, LIU Jiahao2, ZHANG Wei2 China Mechanical Engineering    2025, 36 (06): 1329-1337.   DOI: 10.3969/j.issn.1004-132X.2025.06.020 Abstract （1242）      PDF（pc） （6799KB）（18）       Knowledge map    Save To study the effects of glass fiber mass fraction on W-PACIM pipes with long glass fiber reinforced polypropylene as the outer material and pure polypropylene as the inner material, the influences of glass fiber mass fraction on the residual wall thickness, the orientation distribution of glass fibers and the pressure resistance of the pipes were analyzed by experimental methods. The results show that with the increases of glass fiber mass fraction, the total residual wall thickness of the pipes decreases first and then increases. The outer layer of the pipes may be divided into near the mold wall layer, the middle layer and the near interface layer according to the distribution characteristics of the glass fiber orientations, the orientation of the glass fiber along the melt flow direction increases gradually from the outside to the inside, the uniformity of the distribution of the outer glass fiber decreases with the increase of glass fiber mass fraction. The pressure resistance of pipes increases first and then decreases, when the glass fiber mass fraction is 20%, the pressure resistance of pipes is the best. Reference | Related Articles | Metrics | Comments（0）

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Design of Jig and Fixture for Machining Precision Forged Blade Tenons of Aeroengine ZHANG Shen1, LIANG Jiawei2, WU Dongbo3, WANG Hui4, ZHAO Bing1, XU Lijun5, ZHOU Fen5 China Mechanical Engineering    2025, 36 (04): 703-714.   DOI: 10.3969/j.issn.1004-132X.2025.04.007 Abstract （1173）      PDF（pc） （9510KB）（100）       Knowledge map    Save Precision forged blades of aeroengine were a typical thin-walled parts with complex curved surface. When milling the blade tenons, it was difficult to locate and easy to produce deformations and vibrations. Aiming at the above problems, a design method of multi-point clamping fixture for precision forged blades was proposed, and a low stress hard clamping fixture was designed. Static analysis was used to optimize the clamping position, select the coping element materials and optimize the clamping method. The effectiveness of the fixture was tested by modal tests and vibration tests. The results show that the low-band amplitude of the system is reduced by 50%, the high-band amplitude by 75%, the first-order resonance frequency is increased from 210 Hz to 402 Hz, the damping ratio under the peak value is increased from 17.4% to 25.9%, the effective value of vibration displacement signals is reduced by 35%, and the machining error margin is reduced by 59%. Reference | Related Articles | Metrics | Comments（0）

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Depth of Cut Control for Thin-walled Parts in Robotic Milling Based on FLADRC SHI Long, ZHOU Hexiang, LI Zhoulong China Mechanical Engineering    2025, 36 (04): 671-680.   DOI: 10.3969/j.issn.1004-132X.2025.04.003 Abstract （1116）      PDF（pc） （8675KB）（112）       Knowledge map    Save Weakly rigid large thin-walled parts had large deformations and vibrations during robotic thinning machining, which led to a degradation of the surface quality of the workpieces and difficulties in ensuring the accuracy of the remaining wall thickness. To this end, a VCM-driven follower support head was used for vibration and deformation suppression, and a FLADRC based control strategy was proposed for depth of cut of robotic milling thin-walled parts. In order to verify the effectiveness of the control strategy, the system control models were firstly established based on the MATLAB/Simulink simulation and experimental platform, and the simulation analysis was carried out, then experimental verification was carried out on the thin-walled parts robotic milling experiment platform. Both of the simulation and experimental results show that the depth-of-cut control strategy based on the follower support head may significantly suppress the vibrations and deformations during the machining processes of thin-walled parts and effectively ensure the accuracy of the remaining wall thickness. In addition, compared with the traditional fuzzy PID control, the FLADRC has a better control effectiveness and exhibits higher robustness in the presence of external disturbances. Reference | Related Articles | Metrics | Comments（0）

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Generation Method of Milling Paths of Open Blisk Channels Based on Parameter Mapping HAN Jiang1, 2, ZHANG Wenqiang1, 2, TIAN Xiaoqing1, 2, XIA Lian1, 2 China Mechanical Engineering    2025, 36 (04): 688-696.   DOI: 10.3969/j.issn.1004-132X.2025.04.005 Abstract （1018）      PDF（pc） （9035KB）（48）       Knowledge map    Save A machining strategy for variable layer thickness with layered surfaces was proposed to address the rough machining issues of the channels across the entire blisk components. Considering the characteristics of the variation in the width of the channels across the entire blisk components, the geodesic offset was used to determine the toolpath boundaries on both sides of the channels, and the step size and the number of paths were determined. A planning method for the longitudinal milling path along the channels was proposed, and then the tool axis vector of the channel boundaries is calculated, and the tool axis vector of the middle cutter positions of the channel boundaries is calculated by quaternion interpolation. The calculation results show that, compared with the conventional uniform layering method using the blisk hub rotary surface offset or the blisk covering rotary surface offset, the variable layer thickness surface delamination may better adapt to the surface changes from the covered rotary surface to the hub rotary surface, the surface quality of the blades is ensured, with the advantage of a uniform machined blade surface allowance, and the feasibility of the algorithm was verified through machining examples.  Reference | Related Articles | Metrics | Comments（0）

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Instantaneous Milling Force Modeling and Coefficient Calibration Method of Variable Helical Circular-arc End Mills with Unequal Rake Angle QI Shutao, LI Jiaqi, ZHENG Shucai, XU Jinting, SUN Yuwen China Mechanical Engineering    2025, 36 (04): 681-687,696.   DOI: 10.3969/j.issn.1004-132X.2025.04.004 Abstract （994）      PDF（pc） （5531KB）（41）       Knowledge map    Save Variable helical end mills with unequal rake angle maight effectively suppress milling chatters, which significantly improved the machined surface quality and simultaneously reduced the risk of tool breakages, however, due to the unequal geometric parameters of each cutting edge, the existing models had difficulty to accurately predict the cutting forces, hence, a new instantaneous milling force modeling and coefficient calibration method were proposed. Firstly, the geometry and position relational expression of the cutting edges for variable helical circular-arc end mills were given, then considering the tool runout and variation of geometrical parameters of cutting edges, an instantaneous uncut chip thickness calculation and element cutting force prediction model was established; Subsequently, a nonlinear optimization method to simultaneously calibrate the cutting force coefficients and tool runout parameters was proposed, and an efficient algorithm for solving the model parameter initial values was also given based on linear least squares and oblique cutting theory. The experimental results show that the amplitude and waveform of predicted cutting forces are consistent with the measured ones with errors of less than 15%, verifying the effectiveness of the proposed model. Reference | Related Articles | Metrics | Comments（0）

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C-warping Mechanism and Treatment Strategies in Leveling Processes of Strip Steels YANG Yonghui1, ZHANG Ji1, TAN Hailong1, NIU Baicao1, BAI Zhenhua1, 2, 3 China Mechanical Engineering    2025, 36 (06): 1345-1351.   DOI: 10.3969/j.issn.1004-132X.2025.06.022 Abstract （991）      PDF（pc） （1401KB）（14）       Knowledge map    Save  In order to solve the problems of C-warping defects in strip steels in the leveling processes, the processing parameters in the strip leveling processes were optimized, and a set of C-warping prediction and treatment strategies for strip steels were developed. The formation mechanism of C-warping was analyzed from three aspects: rolling, processing lubrication systems and the influences of anti-wrinkle rollers and anti-trembling rollers on the forces of strip steels. The stress distribution of the horizontal direction of the outlet strips in the thickness was obtained, based on the stress analysis of the strips under the assumption of half-plane infinite body， the maximum and minimum transverse elongation in the thickness direction of the strips were obtained, and the height of the C warp of the strips was obtained through the geometric relationship. A set of optimal height settings of anti-wrinkle rollers and anti-trembling rollers were sought to minimize the objective function of the comprehensive control, and the elongation in the direction of strip thickness was controlled, so as to reduce C-warp. The model and treatment strategies were applied to a leveling unit in China, and the prediction errors of C warping height are controlled within 10%, and the maximum warpage ranges of the unit are reduced from 1.4~6.5 mm to 0.9~4.5 mm. The results show that the C warpage prediction and treatment strategy meet the production demands, and the warpage values are significantly reduced, which reduces the repair rate caused by warpages. Reference | Related Articles | Metrics | Comments（0）

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Study on Thickness Distribution of Single Point Incremental Hydroforming of Complex Shaped Parts SHANG Miao, LI Yan, SHAN Shunkun, YANG Mingshun China Mechanical Engineering    2025, 36 (06): 1338-1344.   DOI: 10.3969/j.issn.1004-132X.2025.06.021 Abstract （985）      PDF（pc） （10225KB）（23）       Knowledge map    Save To analyze and enhance the performances of single point incremental forming for complex shaped parts, a new process combining SPIF and hydroforming was presented for manufacturing multi-featured parts with spire structures. The forming processes of the target parts were designed, the theoretical prediction model of thickness was established, and the effects of different hydraulic parameters on the thickness distribution of the target parts in different forming stages were analyzed. The experimental results show that complex shaped parts may be formed using the new processes and appropriate hydraulic pressures; the geometric errors between the experimental and theoretical profiles may be reduced from 11.44% to 5.18% with assistance compared to SPIF without hydraulic assistance; the thickness distribution patterns are related to the assisted pressure, forming heights, forming shape, etc., and the established theoretical model may be used to predict the thickness distribution of complex shaped parts. Reference | Related Articles | Metrics | Comments（0）

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Influences of Differential Lubrication on Forming Quality for 5A02 Aluminum Alloy T-shape Tubes XU Yong1, 2, 3, ZHANG Chi1, XIE Wenlong2, 3, XIA Liangliang4, YANG Baocheng2, 3, ZHANG Shihong2, 3, HUANG Xinyue5, WANG Shengcheng5 China Mechanical Engineering    2025, 36 (05): 1094-1102,1131.   DOI: 10.3969/j.issn.1004-132X.2025.05.021 Abstract （945）      PDF（pc） （12824KB）（26）       Knowledge map    Save  In order to improve the forming quality of T-shape tubes, a method of differential lubrication was proposed by using hydroforming. The advantages of differential lubrication were verified by finite element simulation compared with traditional lubrication. Based on the fluidity of materials, the tensile stress and compressive stress of axial and circumferential elements of T-shape tubes were extracted during deformation. The influences of the area of the differential lubrication zones on the forming quality were analyzed. The results show that compared with the traditional lubrication method, the differential lubrication may effectively reduce the wall thickness thinning rate of the sides and tops of the T-shape tubes. Differential lubrication also may reduce the amount of side feed to reduce the risk of wrinkling. With the increasing of lubrication area in the bulging zones, the axial tensile stress of the arm element is gradually reduced, and the thinning rate of the arm sides of the T-shape tubes is reduced. With the increasing of the artificial roughing areas in the non-bulging zones, the axial compressive stress of the T-shape tubes sidewall element decreases, but the circumferential  tensile stress  increases gradually, and the material is more likely to flow to the transition zone of T-shape tubes, avoiding material accumulation in the middle of the tubes, thus reducing the risk of wrinkling. The research may provide technical support and theoretical reference for the forming of T-shape tubes. Reference | Related Articles | Metrics | Comments（0）

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Establishment and Influences of Critical Wrinkling Criterion of Sheet Metals Considering Thickness Stress DU Bing1, 2, LI Yang1, 2, LIU Fenghua1, 2, DONG Mingxin1, 2, WAN Yufan1, 2, ZHONG Qingshuai1, 2 China Mechanical Engineering    2025, 36 (05): 1074-1082.   DOI: 10.3969/j.issn.1004-132X.2025.05.019 Abstract （910）      PDF（pc） （9174KB）（40）       Knowledge map    Save Wrinkling instability was one of the main technical challenges affecting the precise plastic forming of thin-walled parts. The stress state in the thick direction had a great influence on the forming limit of the sheet metals during the sheet forming processes. In view of the above problems， the wrinkling instability of sheet metals in plastic forming processes was studied under different thickness stress conditions. The Buckle-Dynamic algorithm in ABAQUS software was combined with solid element modeling to establish a numerical analysis model of liquid-filled compression of fan-shaped parts， and the accuracy of the simulation algorithm was verified by tests. According to the wrinkling bifurcation theory and numerical analysis results， a method was adopted for defining the critical wrinkling time of the plates considering the thickness stress， and the critical wrinkling limit curve was established under the compression conditions of the plates. The influences of thickness stress on the compression wrinkling behaviors， wrinkle resistances and the positions of critical wrinkling limit curve in space of fan-shaped parts were discussed. The results show that the applications of thick stress may improve the wrinkle resistances of the sheets and improve the forming quality， which provides useful reference and experimental basis for the selection of sheet metal forming parameters and the trial production of typical parts.  Reference | Related Articles | Metrics | Comments（0）

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Research Progresses on Incremental EMF Technology for Thin-walled Components CHENG Xiao1, LI Rui2, ZOU Guisheng2, LIN Junfeng1, 3, YU Haiping1, 3 China Mechanical Engineering    2024, 35 (12): 2092-2105.   DOI: 10.3969/j.issn.1004-132X.2024.12.001 Abstract （815）      PDF（pc） （12617KB）（145）       Knowledge map    Save With the development of Chinas high-end manufacturing industries, the demands for thin-walled components in many industrial fields such as aerospace were increased dramatically. The high-speed forming characteristics, traditional EMF was successfully applied to the production of thin-walled components of some key lightweight materials. However, due to the limitations of forming coil and discharge equipment, it was difficult to process large-scale and complex structure parts. In the past decade, incremental EMF technology was developed and gradually applied to the large thin-wall components processing, where a large number of research results were emerged. On the basis of briefly describing the principle and characteristics of EMF technology, the existing incremental EMF technology was divided into two categories according to the processing form: incremental electromagnetic composite forming and incremental electromagnetic direct forming. The research status of each processes was expounded from the aspects of basic principle, technical scheme and application results. Thus the main problems existing in the incremental EMF technology were analyzed, then the future development prospects and research direction of the incremental EMF technology were prospected. Reference | Related Articles | Metrics | Comments（0）

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Research on Station Optimization of Aircraft Assembly Laser Trackers Based on Digital Twins LI Hao1, JIAO Yanchao1, ZHANG Yuyan1, ZHANG Hao1, XING Hongwen2, WEN Xiaoyu1, WANG Haoqi1, YE Guoyong1, GUAN Xiao2 China Mechanical Engineering    2024, 35 (11): 1986-1994.   DOI: 10.3969/j.issn.1004-132X.2024.11.010 Abstract （748）      PDF（pc） （4789KB）（113）       Knowledge map    Save  Due to the large size of aircraft parts and the complex distribution of tooling on the assembly site, the laser tracker had poor visibility. During the guided assembly or off-rack inspection, it was necessary to adjust the laser tracker station repeatedly, which seriously affected the measurement stability and efficiency. To solve this problem, a method was proposed for optimizing the station of a laser tracker in aircraft assembly based on digital twins. A measurement constrained model of laser trackers for aircraft assembly was established. The digital twin environment was established based on an accurate simulation of aircraft assembly site elements. Then, the optimization of laser tracker station placement was completed. Finally, a measurement simulation of the laser trackers in the digital twin environment was conducted to verify the feasibility of the genetic algorithm in solving the optimal station of the laser trackers. The results show that the coverage rate of the optimized laser tracker to the measuring points is increased by 110%, and the coincidence rate of the measuring points is increased from 11.7% to 55.5%, both the coverage rate and the coincidence rate of the measuring points of the laser trackers are significantly improved. Reference | Related Articles | Metrics | Comments（0）

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Influences of Strain Rate on Plastic Deformations and Martensitic Transformation Behaviors of 304 Stainless Steels ZHAN Lihua1, 2, ZHAO Shuai1, YANG Youliang1, 2, CHANG Zhilong3 China Mechanical Engineering    2024, 35 (12): 2132-2138，2168.   DOI: 10.3969/j.issn.1004-132X.2024.12.005 Abstract （552）      PDF（pc） （5871KB）（143）       Knowledge map    Save To investigate the plastic deformation behaviors and martensitic transformation rules of 0.5 mm thick 304 stainless steels at room temperature, uniaxial tensile tests were conducted at five different strain rates of 0.000 67 s-1, 0.002 s-1, 0.01 s-1, 0.1 s-1 and 1.0 s-1, with subsequent X-ray diffraction(XRD) analysis for phase analysis. The results reveal a notable increase in yield strength with rising strain rate, indicating strain rate strengthening effects. Additionally, due to plastic work converting into heat during tensile processes, martensitic transformation was inhibited, resulting in a slight tensile strength reduction. Below a true strain of 0.27, work hardening rates decrease under varying strain rates. However, beyond this threshold true strain, significant secondary hardening occurs under low strain rates, which is attributed to the internal martensitic transformation.To address this phenomenon, the Olson-Cohen equation was integrated into the traditional Johnson-Cook model to characterize secondary hardening during tensile processes across different strain rates. The improved Johnson-Cook model achieves high accuracy in predicting rheological stress changes, with deviations of 3.23%, 3.42%, 4.13%, 4.09%, and 5.14% respectively compared to experimental values, effectively capturing the secondary hardening stage at various strain rates. Reference | Related Articles | Metrics | Comments（0）

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Research on Compound Wave Propulsion Performance Improvement for Bionic Fish Robots LUO Zirong1, XIA Minghai1, YIN Qian2, LU Zhongyue1, JIANG Tao1, ZHU Yiming1 China Mechanical Engineering    2024, 35 (11): 1901-1908.   DOI: 10.3969/j.issn.1004-132X.2024.11.001 Abstract （478）      PDF（pc） （8473KB）（196）       Knowledge map    Save Motivated by the profound impacts of longitudinal and transverse waves of earthquake, a novel underwater bionic propeller that utilized longitudinal and transverse compound wave patterns was proposed and designed. A kinematic model incorporating the composite waves was theoretically established, alongside the development of a physical prototype and testing platform. The propulsion performances of the propeller were systematically compared and analyzed through CFD simulations as well as prototype tests under varying amplitudes of longitudinal wave superposition. Simulation results show that both the thrust and velocity generated by the undulating fin may be significantly enhanced, with mean thrust increasing by 27.6% and peak thrust exceeding 200%. Experimental results reveal that under a frequency of 2 Hz with a longitudinal-wave amplitude of 20°, the steady-state average velocity achieved by the propeller reaches 0.761 m/s, which is approximately 14.7% greater than that of without longitudinal wave. This paper demonstrates that composite wave bionic fins exhibit superior thrust and velocity performance compared to single sinusoidal wave configurations, thereby offering an innovative propulsion mechanism for advancing high-performance bionic fish robots. Reference | Related Articles | Metrics | Comments（0）

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State-of-the-art and Trend of High Loading Capacity Plastic Gear Drives LIU Huaiju, LU Zehua, ZHU Caichao China Mechanical Engineering    2025, 36 (01): 2-17.   DOI: 10.3969/j.issn.1004-132X.2025.01.001 Abstract （459）      PDF（pc） （15004KB）（170）       Knowledge map    Save Focusing on the loading capacity and applications in power transmission of plastic gears, the failure modes and loading capacity under the current materials and technology levels were introduced. The strengthening measures for improving loading capacity of plastic gears were elaborated from the application of new materials, lubrication improvement, collaborative design, and so on. The applications and potential of plastic gears scenarios in power transmissions such as automobile engines, vehicle reducers, and aeroengine accessory gearboxes were introduced, which has important reference significance for promoting the development of high load plastic gear technology and applications. Reference | Related Articles | Metrics | Comments（0）

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Ultrasonic Vibration Softening Johnson-Cook Modeling and Validation of Thin Tube Curling Experiments SONG Pengfei1, 2, CAO Miaoyan1, 2, FU Min1, 2, CUI Yashuo1, 2, LI Yunfeng1, 2, LIU Zheng1, 2 China Mechanical Engineering    2024, 35 (12): 2106-2113，2121.   DOI: 10.3969/j.issn.1004-132X.2024.12.002 Abstract （451）      PDF（pc） （6974KB）（119）       Knowledge map    Save In order to accurately describe the deformation behaviors of lightweight thin-walled components during ultrasonic vibration-assisted forming, ultrasonic vibration normal excitation-assisted uniaxial tensile experiments were carried out with TU1 oxygen-free copper and 316L stainless steel. Considering the ultrasonic vibration softening effects, an ultrasonic vibration Johnson-Cook model was developed by introducing a new ultrasonic softening function. A subroutine was developed and embedded into finite elements for simulation, and was validated by comparison with unidirectional tensile and curling experiments. The results show that the numerical model may effectively capture the ultrasonic vibrational softening behaviors of the materials with an average absolute percentage error as low as 0.97%. Although different materials have different sensitivities to ultrasonic vibration, the ultrasonic softening rates all follow an Allometricl functional relationship with the ultrasonic energy field density. Reference | Related Articles | Metrics | Comments（0）

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Development and Applications of Aero-engine Accessory Gearbox Gear Transmission Design and Analysis Softwares LIU Guiyuan1, WANG Zeng2, YANG Ziyi2, HU Mingzhu1, LIU Huaiju1 China Mechanical Engineering    2024, 35 (11): 1938-1947.   DOI: 10.3969/j.issn.1004-132X.2024.11.005 Abstract （439）      PDF（pc） （12715KB）（112）       Knowledge map    Save The accessory gearbox gear transmissions were pivotal components for power transmission of the aero-engine accessories. The configuration and structure design of the accessory gearbox transmissions for aero-engines were complex, involving many parameters of components and system. Traditional design methods based on empirical formulas and scattered software programs could not meet the more efficient design requirements of advanced aviation equipment for high load capacity, long service life, lightweight, high performance transmission systems. Therefore, a “configuration design—component design—system analysis—system optimization” method for aero-engine gear transmission design was established, and the aero-engine accessory gearbox gear transmission design and analysis softwares were developed based on the C++/Python. According to the design requirements, four configuration schemes were generated applying the software, and a coaxial multiple-output non-symmetric power split configuration scheme was selected by comparison. A multi-objective optimization model for the transmission system was developed based on the NSGA-Ⅱ algorithm. With lightweight and high load capacity as the optimization goals, a reduction of 15.81% in gear transmission weight and an improvement of 2.98% in weak gear transmission safety are achieved. This provides theoretical methods and software tools to the research of gear transmissions for new generations of advanced aviation equipment. Reference | Related Articles | Metrics | Comments（0）

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Machine Learning and Finite Element Simulation and Experimentation for Springback Prediction of Al-Li Alloys HUI Shengmeng1, MAO Xiaobo4, ZHAN Lihua1, 2, 3 China Mechanical Engineering    2024, 35 (12): 2114-2121.   DOI: 10.3969/j.issn.1004-132X.2024.12.003 Abstract （433）      PDF（pc） （4522KB）（130）       Knowledge map    Save Creep aging tests were conducted on the 2195 Al-Li alloys under various stress conditions at temperatures of 180 ℃, 190 ℃, and 200 ℃ respectively. Constitutive equations were derived using MATLAB software and incorporated into the nonlinear finite element software MSC.Marc to build a finite element model for the creep aging forming of 2195 Al-Li alloy spade segments. The model utilized time, stress, and temperature as input parameters, with the springback radius being the critical output parameter. To enhance the accuracy and efficiency of predictions, a comparative analysis of various machine learning regression models was conducted, leading to the selection of the ridge regression model as the predictive tool, which facilitated the rapid and precise prediction of the springback radius under diverse processing conditions. The high predictive accuracy and practical utility of the model were validated through 1∶1 experimental verification, demonstrating a relative error of 0.9% between the experimental components springback profile and the target profile.  Reference | Related Articles | Metrics | Comments（0）

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Research Progresses on Reliability Analysis and Optimal Design of Automobile Structures ZHANG Lei1, 2, 3, SUN Xuetao1, 2, CHEN Jie1, 2, SUN Yuanbo3, GUO Jiajia1, 2, ZHENG Jie1, 2 China Mechanical Engineering    2024, 35 (11): 1948-1962，1970.   DOI: 10.3969/j.issn.1004-132X.2024.11.006 Abstract （427）      PDF（pc） （2504KB）（161）       Knowledge map    Save In order to study the reliability of automobile structures, the uncertainty of mechanical structure analysis and design was summarized, and the uncertainty of design variables and parameters of automobile structures was analyzed from three aspects: structural parameter uncertainty, material performance parameter uncertainty and load uncertainty. The research progresses of probabilistic reliability analysis and non-probabilistic reliability analysis methods were reviewed and summarized. The applications of reliability analysis method in automobile structures were listed. The mathematical model and algorithm of reliability were sorted out, and the applications of reliability optimization design in lightweight and crashworthiness of automobiles were studied, and the development trends of reliability analysis and optimization design of automobile structures were presented.  Reference | Related Articles | Metrics | Comments（0）

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Active Order Noise Control of Hybrid Electric Vehicles Based on Variable Order Notch Filter Algorithm ZHOU Xuelian1, HE Yansong1, SU Hongjian2, LIN Weixiong2, GUO Lin2, FU Xiaoyu1 China Mechanical Engineering    2024, 35 (11): 2082-2089.   DOI: 10.3969/j.issn.1004-132X.2024.11.020 Abstract （415）      PDF（pc） （5720KB）（62）       Knowledge map    Save  For the issues of decreased effectiveness in active noise reduction under acceleration conditions with rich and varying orders in the working speeds of hybrid electric vehicle engines, a variable order notch filter-x least mean square(VOFxLMS) algorithm was proposed, and a corresponding multi-channel active engine noise control system was established. In MATLAB/Simulink, the multi-channel active engine noise control simulation model was constructed for a seven-seat hybrid multi-purpose vehicle(MPV), by utilizing the actual vehicle acoustic path, in-cabin noise, and engine speed signals, two algorithms were employed for noise reduction simulation and comparison. Simulation results indicate that the proposed VOFxLMS algorithm may effectively reduce noise for specific orders at various charging speed points. Compared to the traditional notch FxLMS algorithm, the proposed VOFxLMS algorithms overall noise reductions at the left and right ears of the drivers seat and the third-row left seat are increased by 28.5%, 60%, 50% and 50%, respectively. The noise reduction effectiveness of the active engine noise control system employing the VOFxLMS algorithm was verified through on-road tests during acceleration conditions at speeds ranging from 70 to 100 km/h, and the system demonstrates effective suppression across various engine orders, including 2nd, 5th, 5.5th, 6th, 6.5th, 7th, and 8th orders. Reference | Related Articles | Metrics | Comments（0）

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Deep Reinforcement Learning Method for Flexible Job Shop Scheduling ZHU Zhengyu1, GUO Jutao2, LYU Youlong3, ZUO Liling1, ZHANG Jie3 China Mechanical Engineering    2024, 35 (11): 2007-2014，2034.   DOI: 10.3969/j.issn.1004-132X.2024.11.012 Abstract （413）      PDF（pc） （4565KB）（95）       Knowledge map    Save Aiming at the flexible job shop scheduling problems under the mode of multi variety and small batch production, an intelligent scheduling method was proposed to minimize the total tardiness of orders based on combination rules and reinforcement learning. Transforming the flexible job shop production scheduling problem into a Markov decision process, according to the characteristics and optimization objectives of the problems, seven features were used to represent the workshop states, and six combination rules were designed as an action library. The problem was solved by using the improved DQN algorithm. Taking the aerospace structural parts machining workshop as a case study, the feasibility and effectiveness of the proposed method in shortening task delivery time are verified by comparing with other common rule-based methods in five different scale calculation examples. Reference | Related Articles | Metrics | Comments（0）

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Effects of Instantaneous Currents and Subsequent Aging Processes on Mechanics Properties and Microstructure of 7075 Aluminum Alloys CUI Xiaohui1, 2, YU Zhuoxing1, XIAO Ang3, YAN Ziqin4, YANG Guang1, WANG Hanpeng1, LI Rui1 China Mechanical Engineering    2024, 35 (12): 2139-2148.   DOI: 10.3969/j.issn.1004-132X.2024.12.006 Abstract （411）      PDF（pc） （31804KB）（56）       Knowledge map    Save  The ultrafast solution with pulsed instantaneous currents and subsequent aging strengthening of aluminum alloys were proposed and the mechanics properties and microstructure evolution of aluminum alloys were analyzed by means of macro and micro experiments. The results show that the yield strength of 7075 aluminum alloys decreases gradually with the increase of discharge voltages, but the elongation of 7075 aluminum alloys shows a trend of “small increase-decrease-large increase”. When the peak pulse currents exceed 86 kA(corresponding to a discharge voltage of more than 9 kV), the mechanics tensile curve of the material appears the Portevine Le Chatelier(PLC) effects. When the peak pulse currents exceed 96 kA(corresponding discharge voltage exceeds 10 kV), the elongation of the samples increases by more than 508.09%. It is found that the dislocation density in the materials decreases at 10 kV voltage, η′ phase dissolves back into the aluminum matrix and forms susaturated solid solution, which significantly improves the plasticity of the materials. The results show that ultrafast(<1 ms) solution of 7075 aluminum alloys may be achieved by pulsed instantaneous currents. The strength of 7075 aluminum alloys reaches the peak after 21 hrs of artificial aging, and the hardness after peak aging reaches 98.69% of that of conventional solution quenching. Reference | Related Articles | Metrics | Comments（0）

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Tool Wear Prediction Method Based on ISABO-IBiLSTM Model ZENG Hao, CAO Huajun, DONG Jianxiong China Mechanical Engineering    2024, 35 (11): 1995-2006.   DOI: 10.3969/j.issn.1004-132X.2024.11.011 Abstract （409）      PDF（pc） （8106KB）（81）       Knowledge map    Save Aiming at the existing tool wear prediction methods which caused the problems of poor prediction accuracy due to lack optimization algorithms and inadequate network structure. A tool wear prediction model with the combination of improved SABO(ISABO) and improved BiLSTM(IBiLSTM) network(ISABO-IBiLSTM model) was proposed. Firstly, the acceleration vibration signal and force signal data were preprocessed by truncation method, Hampel filtering method, and improved complete ensemble empirical mode decomposition with adaptive noise(ICEEMDAN)-improved wavelet thresholding noise reduction method. Then, the time-domain, frequency-domain, and time-frequency-domain features of the preprocessed signal data were extracted, and the features are screened by Spearman and maximum mutual information correlation coefficient to construct the inputs of the model. Finally, the ISABO algorithm was used to perform parameter optimization of the IBiLSTM network, and based on the obtained optimized parameters, the network was trained to achieve wear prediction. The experimental data analysis results show that the proposed ISABO-IBiLSTM model has a prediction accuracy of 98.49% to 98.83% for tool wear, which is significantly improved compared to BiLSTM, IBiLSTM, and improved convolutional neural networks(ICNN)-BiLSTM models. Reference | Related Articles | Metrics | Comments（0）

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Hybrid Optimization for Housing Structure Stiffener and Support Location LI Jian1, DING Xiaohong1, ZHANG Yijie2, XIONG Min1, WANG Han1, ZHANG Heng1 China Mechanical Engineering    2025, 36 (01): 69-77.   DOI: 10.3969/j.issn.1004-132X.2025.01.007 Abstract （409）      PDF（pc） （9519KB）（76）       Knowledge map    Save The internal stiffener layout and support location of housing structure played an important role in improving of structural performance and lightweight. A design method for hybrid distribution optimization of stiffener and support locations of housing structures was proposed. Independent support elements and stiffener base structures were introduced to establish a mathematical model for the hybrid optimization of stiffener distribution and support location of the housing structure. The optimal design for stiffener distribution of the housing structure was performed by an adaptive growth method. The support location was optimized based on the bi-directional evolutionary structural optimization method. The results show that the support locations and distribution of stiffeners obtained from the hybrid optimization have better mechanics properties than the optimized results of the housing structure with known support locations. Reference | Related Articles | Metrics | Comments（0）

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Study on Absolute Linear Time-grid Displacement Sensors with  Multi-frequency Magnetic Field Coupling YANG Jisen1, 2, 3, YUAN Junsong1, 3, XIU Fu1, 3, LIU Jiacheng1, 3, ZHANG Xiaolong1, 3 China Mechanical Engineering    2025, 36 (05): 889-897.   DOI: 10.3969/j.issn.1004-132X.2025.05.001 Abstract （404）      PDF（pc） （8864KB）（146）       Knowledge map    Save Aiming at the problems of mutual crosstalk among magnetic fields affecting the measurement accuracy of the sensors and reducing the signal-to-noise ratio when the excitation frequency of two code channels of a dual-row planar magnetic field sensor was the same， a multi-frequency magnetic field coupled absolute linear time-grid displacement sensor design scheme was proposed， which achieved the solution to the problems of eliminating the crosstalk of the magnetic fields among the code channels while solving the absolute displacement. The sensor was divided into fixed scale and dynamic scale， both using double-layer alternating structure， fixed scale using two columns of incremental code channel combination， divided into fine and coarse machines， the pairs of poles of two rows of excitation coils were two integers of the reciprocal relation， the absolute displacement measurement was realized by using the pairs of poles within the displacement difference. Precision machine measurement channel and rough machine measurement channel were input  different frequencies of the excitation current signals at the same time，  the precision machine was input the 1 MHz high-frequency current signals， the high-frequency excitation current signals might effectively enhance the inductive signals， improve the signal-to-noise ratio of the electrical processing system. Through the method of outlier frequency reduction， the sensor resolution was improved， which effectively solved the problems that it were difficult to reconcile the signal-to-noise ratio enhancement of the signals by increasing the frequency of the excitation signals and the high resolution of the sensors. Theoretical validation and error analysis of the sensors were carried out through electromagnetic simulation analysis. Finally， the experimental platform was built to carry out prototype experiments， and the experimental results show that the absolute sensor structure with multi-frequency magnetic field coupling effectively eliminates the magnetic field crosstalk between the fine and coarse machines， and the signal-to-noise ratio of the sensors is improved， with measurement errors are less than ±17.34 μm in the measurement range of 140 mm.  Reference | Related Articles | Metrics | Comments（0）

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Construction of Assembly Information Model Based on Assembly Feature Automatic Extraction for STEP Models JIA Kang1, 2, TANG Jing1, 2, REN Dongxu1, 2, WANG Hao1, 2, ZHAO Qiangqiang1, 2, HONG Jun1, 2 China Mechanical Engineering    2025, 36 (01): 123-132.   DOI: 10.3969/j.issn.1004-132X.2025.01.013 Abstract （394）      PDF（pc） （8528KB）（81）       Knowledge map    Save Assembly information modeling was the foundation of digital assembly and intelligent assembly. However, the manual interactive modeling was inefficient and prone to errors in assembly feature recognition and assembly feature fitting, which was difficult to meet the precise modeling needs of complex mechanical systems. Based on the assembly process information implied by a 3D assembly model, this paper used STEP model files as inputs to study the algorithms for automatic extraction of assembly features and recognition of fitting relationships focused on geometric information. Furthermore, an information reasoning algorithm was proposed for constructing an integrated assembly information model from the perspectives of assembly accuracy modeling and assembly sequence planning. Finally, the effectiveness of the proposed algorithms was demonstrated through the construction of assembly instance information models based on the developed system. Reference | Related Articles | Metrics | Comments（0）

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Simulation Analysis and Process Study of Scribing Processes for GaAs Cleavage Processing ZHANG Qingzheng1, JIANG Chen1, GAO Rui2, JIANG Jinxin1 China Mechanical Engineering    2024, 35 (12): 2203-2210.   DOI: 10.3969/j.issn.1004-132X.2024.12.013 Abstract （361）      PDF（pc） （13141KB）（64）       Knowledge map    Save In order to effectively improve the quality of GaAs-based semiconductor laser cavity mirrors, a new type of scribing method was proposed and carried out in simulation analysis and processing experiments. A finite element simulation model of the scribing processes of GaAs materials was established to optimize the existing processing methods and to investigate the distribution of scribing loads and stresses under different processes. A cleavage processing validation experiment was carried out to analyze the morphological characteristics of the cleavage surfaces. It is found that the optimized processing method, which involves scribing from the inside out, can effectively reduce the degree of material surface damages in the scribing processes and reduce the brittle fracture phenomenon. The experimental results were in high consistency with the simulation ones. Reference | Related Articles | Metrics | Comments（0）

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Optimal Design of Face-hobbed Hypoid Gear Meshing Efficiency in Drive Axles WANG Qin1, HE Di1, XUE Jianhua2, PENG Jin3, FAN Zijie1 China Mechanical Engineering    2024, 35 (11): 1920-1927，1937.   DOI: 10.3969/j.issn.1004-132X.2024.11.003 Abstract （361）      PDF（pc） （5325KB）（114）       Knowledge map    Save Based on the gear friction loaded tooth contact analysis(FLTCA) method, an optimal design method was proposed for the meshing efficiency of face-hobbed hypoid gears. Firstly, a method was employed to preset the peak-to-peak values of unloaded transmission errors and the positions of the contact zones, facilitating the modification design of the positive and negative tooth surfaces of face-hobbed hypoid gears. Then, building upon the modified tooth surface design, an optimization objective was set to maximize gear meshing efficiency under driving conditions. And the optimization analysis model was established by comprehensively considering factors such as the peak-to-peak values of gear pair loaded transmission errors, distribution of full-load contact pattern on both sides of the tooth surfaces and the maximum contact stresses. To enhance the solution speed of the optimization model, the Kriging surrogate model was employed in conjunction with a multi-island genetic algorithm to address and solve the optimization model. Finally, a case design and test validation were conducted on a commercial drive axle with a face-hobbed hypoid gear pair. The effectivenesses of the optimization method proposed were verified through unloaded contact pattern tests and whole-axle transmission efficiency tests. Reference | Related Articles | Metrics | Comments（0）

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Soft Sensor Modeling and Uncertainty Analysis Approach of Tool Wear Based on Semi-supervised Bayesian Transformer LI Yue1, 2, XIE Heng1, ZHOU Gongbo1, 2, ZHOU Ping1, 2, LI Menggang1, 2 China Mechanical Engineering    2024, 35 (11): 2015-2025.   DOI: 10.3969/j.issn.1004-132X.2024.11.013 Abstract （357）      PDF（pc） （8872KB）（74）       Knowledge map    Save Due to limitations inherent in offline tool wear measurement methods, the availability of wear samples was restricted, and measurement noise was often unavoidable, which complicated the reliability of tool wear monitoring. To address these challenges, a soft sensor modeling and uncertainty analysis approach of tool wear was proposed based on semi-supervised Bayesian Transformer by integrating a semi-supervised Transformer model, Dropout and Monte Carlo(MC) simulation methods. Firstly, a soft sensor model was constructed based on the semi-supervised Transformer network architecture, the network training methods of unsupervised feature extraction and supervised fine-tuning were used to guide the construction of the tool wear soft sensor model under small samples. Then, in order to quantify the impacts of noise on tool wear, a noise network channel was designed for uncertainty analysis. Finally, using approximate Bayesian computation based MC-Dropout, the random uncertainty caused by noise and the cognitive uncertainty resulting from model modeling errors were quantified, aiming at providing more comprehensive information for tool wear assessment. The results show that the proposed soft sensor model and the uncertainty analysis framework may provide a powerful tool for tool health management. Reference | Related Articles | Metrics | Comments（0）