2023年, 第36卷, 第1期　
刊出日期：2023-02-16

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Intelligent Manufacturing Technology
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  Denoising Fault-Aware Wavelet Network: A Signal Processing Informed Neural Network for Fault Diagnosis

  Zuogang Shang, Zhibin Zhao, Ruqiang Yan

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 9-9. https://doi.org/10.1186/s10033-023-00838-0

  摘要 ( 72 ) PDF全文 ( 52 )   可视化   收藏

  Deep learning (DL) is progressively popular as a viable alternative to traditional signal processing (SP) based methods for fault diagnosis. However, the lack of explainability makes DL-based fault diagnosis methods difficult to be trusted and understood by industrial users. In addition, the extraction of weak fault features from signals with heavy noise is imperative in industrial applications. To address these limitations, inspired by the Filterbank-Feature-Decision methodology, we propose a new Signal Processing Informed Neural Network (SPINN) framework by embedding SP knowledge into the DL model. As one of the practical implementations for SPINN, a denoising fault-aware wavelet network (DFAWNet) is developed, which consists of fused wavelet convolution (FWConv), dynamic hard thresholding (DHT), index-based soft filtering (ISF), and a classifier. Taking advantage of wavelet transform, FWConv extracts multiscale features while learning wavelet scales and selecting important wavelet bases automatically; DHT dynamically eliminates noise-related components via point-wise hard thresholding; inspired by index-based filtering, ISF optimizes and selects optimal filters for diagnostic feature extraction. It's worth noting that SPINN may be readily applied to different deep learning networks by simply adding filterbank and feature modules in front. Experiments results demonstrate a significant diagnostic performance improvement over other explainable or denoising deep learning networks. The corresponding code is available at https://github.com/albertszg/DFAWnet.
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  Product Specification Analysis for Modular Product Design Using Big Sales Data

  Jian Zhang, Bingbing Li, Qingjin Peng, Peihua Gu

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 17-17. https://doi.org/10.1186/s10033-023-00841-5

  摘要 ( 60 ) PDF全文 ( 27 )   可视化   收藏

  Big data on product sales are an emerging resource for supporting modular product design to meet diversified customers' requirements of product specification combinations. To better facilitate decision-making of modular product design, correlations among specifications and components originated from customers' conscious and subconscious preferences can be investigated by using big data on product sales. This study proposes a framework and the associated methods for supporting modular product design decisions based on correlation analysis of product specifications and components using big sales data. The correlations of the product specifications are determined by analyzing the collected product sales data. By building the relations between the product components and specifications, a matrix for measuring the correlation among product components is formed for component clustering. Six rules for supporting the decision making of modular product design are proposed based on the frequency analysis of the specification values per component cluster. A case study of electric vehicles illustrates the application of the proposed method.
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  Condition-based Maintenance Optimization for Gamma Deteriorating Systems under Performance-based Contracting

  Xi Zhu, Liang Wen, Juan Li, Mingchang Song, Qiwei Hu

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 18-18. https://doi.org/10.1186/s10033-023-00849-x

  摘要 ( 80 ) PDF全文 ( 27 )   可视化   收藏

  With the further development of service-oriented, performance-based contracting (PBC) has been widely adopted in industry and manufacturing. However, maintenance optimization problems under PBC have not received enough attention. To further extend the scope of PBC's application in the field of maintenance optimization, we investigate the condition-based maintenance (CBM) optimization for gamma deteriorating systems under PBC. Considering the repairable single-component system subject to the gamma degradation process, this paper proposes a CBM optimization model to maximize the profit and improve system performance at a relatively low cost under PBC. In the proposed CBM model, the first inspection interval has been considered in order to reduce the inspection frequency and the cost rate. Then, a particle swarm algorithm (PSO) and related solution procedure are presented to solve the multiple decision variables in our proposed model. In the end, a numerical example is provided so as to demonstrate the superiority of the presented model. By comparing the proposed policy with the conventional ones, the superiority of our proposed policy is proved, which can bring more profits to providers and improve performance. Sensitivity analysis is conducted in order to research the effect of corrective maintenance cost and time required for corrective maintenance on optimization policy. A comparative study is given to illustrate the necessity of distinguishing the first inspection interval or not.
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  Multi-Objective Optimization of Fused Deposition Modeling for Mechanical Properties of Biopolymer Parts Using the Grey-Taguchi Method

  Kapil Kumar, Hari Singh

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 30-30. https://doi.org/10.1186/s10033-023-00847-z

  摘要 ( 48 ) PDF全文 ( 26 )   可视化   收藏

  The urgent need to develop customized functional products only possible by 3D printing had realized when faced with the unavailability of medical devices like surgical instruments during the coronavirus-19 disease and the on-demand necessity to perform surgery during space missions. Biopolymers have recently been the most appropriate option for fabricating surgical instruments via 3D printing in terms of cheaper and faster processing. Among all 3D printing techniques, fused deposition modelling (FDM) is a low-cost and more rapid printing technique. This article proposes the fabrication of surgical instruments, namely, forceps and hemostat using the fused deposition modeling (FDM) process. Excellent mechanical properties are the only indicator to judge the quality of the functional parts. The mechanical properties of FDM-processed parts depend on various process parameters. These parameters are layer height, infill pattern, top/bottom pattern, number of top/bottom layers, infill density, flow, number of shells, printing temperature, build plate temperature, printing speed, and fan speed. Tensile strength and modulus of elasticity are chosen as evaluation indexes to ascertain the mechanical properties of polylactic acid (PLA) parts printed by FDM. The experiments have performed through Taguchi's L₂₇ orthogonal array (OA). Variance analysis (ANOVA) ascertains the significance of the process parameters and their percent contributions to the evaluation indexes. Finally, as a multi-objective optimization technique, grey relational analysis (GRA) obtains an optimal set of FDM process parameters to fabricate the best parts with comprehensive mechanical properties. Scanning electron microscopy (SEM) examines the types of defects and strong bonding between rasters. The proposed research ensures the successful fabrication of functional surgical tools with substantial ultimate tensile strength (42.6 MPa) and modulus of elasticity (3274 MPa).
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  Surface Integrity of Inconel 738LC Parts Manufactured by Selective Laser Melting Followed by High-speed Milling

  Guanhui Ren, Sai Guo, Bi Zhang

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 5-5. https://doi.org/10.1186/s10033-022-00827-9

  摘要 ( 49 ) PDF全文 ( 19 )   可视化   收藏

  This study is concerned with the surface integrity of Inconel 738LC parts manufactured by selective laser melting (SLM) followed by high-speed milling (HSM). In the investigation process of surface integrity, the study employs ultradepth three-dimensional microscopy, laser scanning confocal microscopy, scanning electron microscopy, electron backscatter diffractometry, and energy dispersive spectroscopy to characterize the evolution of material microstructure, work hardening, residual stress coupling, and anisotropic effect of the building direction on surface integrity of the samples. The results show that SLM/HSM hybrid manufacturing can be an effective method to obtain better surface quality with a thinner machining metamorphic layer. High-speed machining is adopted to reduce cutting force and suppress machining heat, which is an effective way to produce better surface mechanical properties during the SLM/HSM hybrid manufacturing process. In general, high-speed milling of the SLM-built Inconel 738LC samples offers better surface integrity, compared to simplex additive manufacturing or casting.
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  Stress-Induced Deformation of Thin Copper Substrate in Double-Sided Lapping

  Jiang Guo, Zengxu He, Bo Pan, Bin Wang, Qian Bai, Jinxing Kong, Renke Kang

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 15-15. https://doi.org/10.1186/s10033-022-00824-y

  摘要 ( 62 ) PDF全文 ( 34 )   可视化   收藏

  Double-sided lapping is an precision machining method capable of obtaining high-precision surface. However, during the lapping process of thin pure copper substrate, the workpiece will be warped due to the influence of residual stress, including the machining stress and initial residual stress, which will deteriorate the flatness of the workpiece and ultimately affect the performance of components. In this study, finite element method (FEM) was adopted to study the effect of residual stress-related on the deformation of pure copper substrate during double-sided lapping. Considering the initial residual stress of the workpiece, the stress caused by the lapping and their distribution characteristics, a prediction model was proposed for simulating workpiece machining deformation in lapping process by measuring the material removal rate of the upper and lower surfaces of the workpiece under the corresponding parameters. The results showed that the primary cause of the warping deformation of the workpiece in the double-sided lapping is the redistribution of initial residual stress caused by uneven material removal on the both surfaces. The finite element simulation results were in good agreement with the experimental results.
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  Evaluation of Surface Roughness of Aluminum Alloy in Burnishing Process Based on Chaos Theory

  Zhipeng Yuan, Zhenyu Zhou, Zhiguo Jiang, Zeyu Zhao, Cong Ding, Zhongyu Piao

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 2-2. https://doi.org/10.1186/s10033-022-00828-8

  摘要 ( 65 ) PDF全文 ( 25 )   可视化   收藏

  Burnishing experiments with different burnishing parameters were performed on a computer numerical control milling machine to characterize the surface roughness of an aluminum alloy during burnishing. The chaos theory was employed to investigate the nonlinear features of the burnishing system. The experimental results show that the power spectrum is broadband and continuous, and the Lyapunov exponent λ is positive, proving that burnishing has chaotic characteristics. The chaotic characteristic parameter, the correlation dimension D, is sensitive to the time behavior of the system and is used to establish the corresponding relationship with the surface roughness. The correlation dimension was the largest, when the surface roughness was the smallest. Furthermore, when the correlation dimension curve decreases, the roughness curve increases. The correlation dimension and surface roughness exhibit opposite variation trends. The higher the correlation dimension, the lower the surface roughness. The surface roughness of the aluminum alloy can be characterized online by calculating the correlation dimension during burnishing.
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  Local Buckling-Induced Forming Method to Produce Metal Bellows

  Tianyin Zhang, Dongqing Li, Tianjiao Xu, Yongfeng Sui, Xianhong Han

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 16-16. https://doi.org/10.1186/s10033-023-00852-2

  摘要 ( 49 ) PDF全文 ( 21 )   可视化   收藏

  A novel buckling-induced forming method is proposed to produce metal bellows. The tube billet is firstly treated by local heating and cooling, and the axial loading is applied on both ends of the tube, then the buckling occurs at the designated position and forms a convolution. In this paper, a forming apparatus is designed and developed to produce both discontinuous and continuous bellows of 304 stainless steel, and their characteristics are discussed respectively. Furthermore, the influences of process parameters and geometric parameters on the final convolution profile are deeply studied based on FEM analysis. The results suggest that the steel bellows fabricated by the presented buckling-induced forming method have a uniform shape and no obvious reduction of wall thickness. Meanwhile, the forming force required in the process is quite small.
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  Experimental Research on the Surface Quality of Milling Contour Bevel Gears

  Mingyang Wu, Jianyu Zhang, Chunjie Ma, Yali Zhang, Yaonan Cheng

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 4-4. https://doi.org/10.1186/s10033-022-00825-x

  摘要 ( 44 ) PDF全文 ( 29 )   可视化   收藏

  Contour bevel gears have the advantages of high coincidence, low noise and large bearing capacity, which are widely used in automobile manufacturing, shipbuilding and construction machinery. However, when the surface quality is poor, the effective contact area between the gear mating surfaces decreases, affecting the stability of the fit and thus the transmission accuracy, so it is of great significance to optimize the surface quality of the contour bevel gear. This paper firstly analyzes the formation process of machined surface roughness of contour bevel gears on the basis of generating machining method, and dry milling experiments of contour bevel gears are conducted to analyze the effects of cutting speed and feed rate on the machined surface roughness and surface topography of the workpiece. Then, the surface defects on the machined surface of the workpiece are studied by SEM, and the causes of the surface defects are analyzed by EDS. After that, XRD is used to compare the microscopic grains of the machined surface and the substrate material for diffraction peak analysis, and the effect of cutting parameters on the microhardness of the workpiece machined surface is investigated by work hardening experiment. The research results are of great significance for improving the machining accuracy of contour bevel gears, reducing friction losses and improving transmission efficiency.
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  Progressive Failure Analysis of Composite/Aluminum Riveted Joints Subjected to Pull-Through Loading

  Yuxing Yang, Yongjie Bao, Xueshu Liu, Jinlong Wang, Fengming Du

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 10-10. https://doi.org/10.1186/s10033-023-00839-z

  摘要 ( 52 ) PDF全文 ( 105 )   可视化   收藏

  Out-of-plane mechanical properties of the riveted joints restrict the performance of the wing box assembly of airplane. It is necessary to investigate the pull-through performance of the composite/metal riveted joints in order to guide the riveting design and ensure the safety of the wing box assembly. The progressive failure mechanism of composite/aluminum riveted joint subjected to pull-through loading was investigated by experiments and finite element method. A progressive damage model based on the Hashin-type criteria and zero-thickness cohesive zone method was developed by VUMAT subroutine, which was validated by both open-hole tensile test and three-point bending test. Predicted load-displacement response, failure modes and damage propagation were analysed and compared with the results of the pull-through tests. There are 4 obvious characteristic stages on the load-displacement curve of the pull-through test and that of the finite element model: first load take-up stage, damage stage, second load take-up stage and failure stage. Relative error of stiffness, first load peak and second load peak between finite element method and experiments were 8.1%, - 3.3% and 10.6%, respectively. It was found that the specimen was mainly broken by rivet-penetration fracture and delamination of plies of the composite laminate. And the material within the scope of the rivet head is more dangerous with more serious tensile damages than other regions, especially for 90° plies. This study proposes a numerical method for damage prediction and reveals the progressive failure mechanism of the hybrid material riveted joints subjected to the pull-through loading.
Research article
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  Simulation Analysis of Torsion Beam Hydroforming Based on the Fluid-Solid Coupling Method

  Yu Huang, Jian Li, Jiachun Yang, Yongdong Peng, Weixuan Zhang

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 3-3. https://doi.org/10.1186/s10033-022-00819-9

  摘要 ( 63 ) PDF全文 ( 24 )   可视化   收藏

  Hydroformed parts are widely used in industrial automotive parts because of their higher stiffness and fatigue strength and reduced weight relative to their corresponding cast and welded parts. This paper reports a hydraulic-forming experimental platform for rectangular tube fittings that was constructed to conduct an experiment on the hydraulic forming of rectangular tube fittings. A finite element model was established on the basis of the fluid–solid coupling method and simulation analysis. The correctness of the simulation analysis and the feasibility of the fluid–solid coupling method for hydraulic forming simulation analysis were verified by comparing the experimental results with the simulation results. On the basis of the simulation analysis of the hydraulic process of the torsion beam using the fluid–solid coupling method, a sliding mold suitable for the hydroforming of torsion beams was designed for its structural characteristics. The effects of fluid characteristics, shaping pressure, axial feed rate, and friction coefficient on the wall thicknesses of torsions beams during formation were investigated. Fluid movement speed was related to tube deformation. Shaping pressure had a significant effect on rounded corners and straight edges. The axial feed speed was increased, and the uneven distribution of wall thicknesses was effectively improved. Although the friction coefficient had a nonsignificant effect on the wall thickness of the ladder-shaped region, it had a significant influence on a large deformation of wall thickness in the V-shaped area. In this paper, a method of fluid-solid coupling simulation analysis and sliding die is proposed to study the high pressure forming law in torsion beam.
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  A Multi-mode Electronic Load Sensing Control Scheme with Power Limitation and Pressure Cut-off for Mobile Machinery

  Min Cheng, Bolin Sun, Ruqi Ding, Bing Xu

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 29-29. https://doi.org/10.1186/s10033-023-00861-1

  摘要 ( 61 ) PDF全文 ( 28 )   可视化   收藏

  In mobile machinery, hydro-mechanical pumps are increasingly replaced by electronically controlled pumps to improve the automation level, but diversified control functions (e.g., power limitation and pressure cut-off) are integrated into the electronic controller only from the pump level, leading to the potential instability of the overall system. To solve this problem, a multi-mode electrohydraulic load sensing (MELS) control scheme is proposed especially considering the switching stability from the system level, which includes four working modes of flow control, load sensing, power limitation, and pressure control. Depending on the actual working requirements, the switching rules for the different modes and the switching direction (i.e., the modes can be switched bilaterally or unilaterally) are defined. The priority of different modes is also defined, from high to low: pressure control, power limitation, load sensing, and flow control. When multiple switching rules are satisfied at the same time, the system switches to the control mode with the highest priority. In addition, the switching stability between flow control and pressure control modes is analyzed, and the controller parameters that guarantee the switching stability are obtained. A comparative study is carried out based on a test rig with a 2-ton hydraulic excavator. The results show that the MELS controller can achieve the control functions of proper flow supplement, power limitation, and pressure cut-off, which has good stability performance when switching between different control modes. This research proposes the MELS control method that realizes the stability of multi-mode switching of the hydraulic system of mobile machinery under different working conditions.
Intelligent Manufacturing Technology
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  Influence of Cavitation on Unsteady Vortical Flows in a Side Channel Pump

  Yefang Wang, Fan Zhang, Shouqi Yuan, Ke Chen, Feng Hong, Desmond Appiah

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 25-25. https://doi.org/10.1186/s10033-023-00842-4

  摘要 ( 44 ) PDF全文 ( 26 )   可视化   收藏

  Previous investigation on side channel pump mainly concentrates on parameter optimization and internal unsteady vortical flows. However, cavitation is prone to occur in a side channel pump, which is a challenging issue in promoting performance. In the present study, the cavitating flow is investigated numerically by the turbulence model of SAS combined with the Zwart cavitation model. The vapors inside the side channel pump firstly occur in the impeller passage near the inlet and then spread gradually to the downstream passages with the decrease of NPSHa. Moreover, a strong adverse pressure gradient is presented at the end of the cavity closure region, which leads to cavity shedding from the wall. The small scaled vortices in each passage reduce significantly and gather into larger vortices due to the cavitation. Comparing the three terms of vorticity transport equation with the vapor volume fraction and vorticity distributions, it is found that the stretching term is dominant and responsible for the vorticity production and evolution in cavitating flows. In addition, the magnitudes of the stretching term decrease once the cavitation occurs, while the values of dilatation are high in the cavity region and increase with the decreasing NPSHa. Even though the magnitude of the baroclinic torque term is smaller than vortex stretching and dilatation terms, it is important for the vorticity production along the cavity surface and near the cavity closure region. The pressure fluctuations in the impeller and side channel tend to be stronger due to the cavitation. The primary frequency of monitor points in the impeller is 24.94 Hz and in the side channel is 598.05 Hz. They are quite corresponding to the shaft frequency of 25 Hz (f_shaft = 1/n = 25 Hz) and the blade frequency of 600 Hz (f_blade = Z/n =600 Hz) respectively. This study complements the investigation on cavitation in the side channel pump, which could provide the theoretical foundation for further optimization of performance.
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  Terahertz Spectroscopic Characterization and Thickness Evaluation of Internal Delamination Defects in GFRP Composites

  Walter Nsengiyumva, Shuncong Zhong, Manting Luo, Bing Wang

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 6-6. https://doi.org/10.1186/s10033-022-00829-7

  摘要 ( 49 ) PDF全文 ( 25 )   可视化   收藏

  The use of terahertz time-domain spectroscopy (THz-TDS) for the nondestructive testing and evaluation (NDT & E) of materials and structural systems has attracted significant attention over the past two decades due to its superior spatial resolution and capabilities of detecting and characterizing defects and structural damage in non-conducting materials. In this study, the THz-TDS system is used to detect, localize and evaluate hidden multi-delamination defects (i.e., a three-level multi-delamination system) in multilayered GFRP composite laminates. To obtain accurate results, a wavelet shrinkage de-noising algorithm is used to remove the noise from the measured time-of-flight (TOF) signals. The thickness and location of each delamination defect in the z-direction (i.e., through-the-thickness direction) are calculated from the de-noised TOF signals considering the interaction between the pulsed THz waves and the different interfaces in the GFRP composite laminates. A comparison between the actual and the measured thickness values of the delamination defects before and after the wavelet shrinkage denoising process indicates that the latter provides better results with less than 3.712% relative error, while the relative error of the non-de-noised signals reaches 16.388%. Also, the power and absorbance levels of the THz waves at every interface with different refractive indices in the GFRP composite laminates are evaluated based on analytical and experimental approaches. The present study provides an adequate theoretical analysis that could help NDT & E specialists to estimate the maximum thickness of GFRP composite materials and/or structures with different interfaces that can be evaluated by the THz-TDS. Also, the accuracy of the obtained results highlights the capabilities of the THz-TDS for the NDT & E of multilayered GFRP composite laminates.
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  Application of Nonlinear Lamb Wave Mixing Method for Residual Stress Measurement in Metal Plate

  Jingpin Jiao, Li Li, Xiang Gao, Quan Cheng, Cunfu He, Bin Wu

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 12-12. https://doi.org/10.1186/s10033-023-00832-6

  摘要 ( 33 ) PDF全文 ( 38 )   可视化   收藏

  Harmonic nonlinear ultrasound can offer high sensitivity for residual stress measurements; however, it cannot be used for local stress measurements at a point in space and exhibits nonlinear distortions in the experimental system. This paper presents a feasibility study on the measurement of residual stress in a metal plate using a nonlinear Lamb wave-mixing technique. The resonant conditions for two Lamb waves to generate a mixing frequency wave are obtained via theoretical analysis. Finite element simulations are performed to investigate the nonlinear interactions between the two Lamb waves. Results show that two incident A0 waves interact in regions of material nonlinearity and generate a rightward S0 wave at the sum frequency. Residual stress measurement experiments are conducted on steel plate specimens using the collinear Lamb wave-mixing technique. By setting different delays for two transmitters, the generated sum-frequency component at different spatial locations is measured. Experimental results show that the spatial distribution of the amplitude of the sum-frequency component agrees well with the spatial distribution of the residual stress measured using X-rays. The proposed collinear Lamb wave-mixing method is effective for measuring the distribution of residual stress in metal plates.
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  Micro-Sized Pinhole Inspection with Segmented Time Reversal and High-Order Modes Cluster Lamb Waves Based on EMATs

  Jinjie Zhou, Yang Hu, Xiang Li, Yang Zheng, Sanhu Yang, Yao Liu

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 27-27. https://doi.org/10.1186/s10033-023-00853-1

  摘要 ( 49 ) PDF全文 ( 19 )   可视化   收藏

  Pinhole corrosion is difficult to discover through conventional ultrasonic guided waves inspection, particularly for micro-sized pinholes less than 1 mm in diameter. This study proposes a new micro-sized pinhole inspection method based on segmented time reversal (STR) and high-order modes cluster (HOMC) Lamb waves. First, the principle of defect echo enhancement using STR is introduced. Conventional and STR inspection experiments were conducted on aluminum plates with a thickness of 3 mm and defects with different diameters and depths. The parameters of the segment window are discussed in detail. The results indicate that the proposed method had an amplitude four times larger than of conventional ultrasonic guided waves inspection method for pinhole defect detection and could detect micro-sized pinhole defects as small as 0.5 mm in diameter and 0.5 mm in depth. Moreover, the segment window location and width (5-10 times width of the conventional excitation signal) did not affect the detection sensitivity. The combination of low-power and STR is more conducive to detection in different environments, indicating the robustness of the proposed method. Compared with conventional ultrasonic guided wave inspection methods, the proposed method can detect much smaller defect echoes usually obscured by noise that are difficult to detect with a lower excitation power and thus this study would be a good reference for pinhole defect detection.
Mechanism and Robotics
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  Power Consumption Characteristics Research on Mobile System of Electrically Driven Large-Load-Ratio Six-Legged Robot

  Hongchao Zhuang, Ning Wang, Haibo Gao, Zongquan Deng

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 26-26. https://doi.org/10.1186/s10033-023-00848-y

  摘要 ( 46 ) PDF全文 ( 23 )   可视化   收藏

  The electrically driven large-load-ratio six-legged robot with engineering capability can be widely used in outdoor and planetary exploration. However, due to the particularity of its parallel structure, the effective utilization rate of energy is not high, which has become an important obstacle to its practical application. To research the power consumption characteristics of robot mobile system is beneficial to speed up it toward practicability. Based on the configuration and walking modes of robot, the mathematical model of the power consumption of mobile system is set up. In view of the tripod gait is often selected for the six-legged robots, the simplified power consumption model of mobile system under the tripod gait is established by means of reducing the dimension of the robot's statically indeterminate problem and constructing the equal force distribution. Then, the power consumption of robot mobile system is solved under different working conditions. The variable tendencies of the power consumption of robot mobile system are respectively obtained with changes in the rotational angles of hip joint and knee joint, body height, and span. The articulated rotational zones and the ranges of body height and span are determined under the lowest power consumption. According to the walking experiments of prototype, the variable tendencies of the average power consumption of robot mobile system are respectively acquired with changes in duty ratio, body height, and span. Then, the feasibility and correctness of theory analysis are verified in the power consumption of robot mobile system. The proposed analysis method in this paper can provide a reference on the lower power research of the large-load-ratio multi-legged robots.
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  Inverted Modelling: An Effective Way to Support Motion Planning of Legged Mobile Robots

  Chenyao Zhao, Weizhong Guo

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 19-19. https://doi.org/10.1186/s10033-023-00851-3

  摘要 ( 57 ) PDF全文 ( 37 )   可视化   收藏

  This paper presents an effective way to support motion planning of legged mobile robots—Inverted Modelling, based on the equivalent metamorphic mechanism concept. The difference from the previous research is that we herein invert the equivalent parallel mechanism. Assuming the leg mechanisms are hybrid links, the body of robot being considered as fixed platform, and ground as moving platform. The motion performance is transformed and measured in the body frame. Terrain and joint limits are used as input parameters to the model, resulting in the representation which is independent of terrains and particular poses in Inverted Modelling. Hence, it can universally be applied to any kind of legged robots as global motion performance framework. Several performance measurements using Inverted Modelling are presented and used in motion performance evaluation. According to the requirements of actual work like motion continuity and stability, motion planning of legged robot can be achieved using different measurements on different terrains. Two cases studies present the simulations of quadruped and hexapod robots walking on rugged roads. The results verify the correctness and effectiveness of the proposed method.
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  Ultralong Stretchable Soft Actuator (US²A): Design, Modeling and Application

  Wenbiao Wang, Yunfei Zhu, Shibo Cai, Guanjun Bao

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 13-13. https://doi.org/10.1186/s10033-023-00835-3

  摘要 ( 32 ) PDF全文 ( 25 )   可视化   收藏

  Actuator plays a significant role in soft robotics. This paper proposed an ultralong stretchable soft actuator (US²A) with a variable and sizeable maximum elongation. The US²A is composed of a silicone rubber tube and a bellows woven sleeve. The maximal extension can be conveniently regulated by just adjusting the wrinkles' initial angle of the bellows woven sleeve. The kinematics of US²A could be obtained by geometrically analyzing the structure of the bellows woven sleeve when the silicone rubber tube is inflated. Based on the principle of virtual work, the actuating models have been established: the pressure-elongation model and the pressure-force model. These models reflect the influence of the silicone tube's shell thickness and material properties on the pneumatic muscle's performance, which facilitates the optimal design of US²A for various working conditions. The experimental results showed that the maximum elongation of the US²A prototype is 257%, and the effective elongation could be variably regulated in the range of 0 and 257%. The proposed models were also verified by pressure-elongation and pressure-force experiments, with an average error of 5% and 2.5%, respectively. Finally, based on the US²A, we designed a pneumatic rehabilitation glove, soft arm robot, and rigid-soft coupling continuous robot, which further verified the feasibility of US²A as a soft driving component.
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  Force Analysis of the Overconstrained Mechanisms Based on Equivalent Stiffness Considering Limb Axial Deformation

  Jinwei Guo, Yongsheng Zhao, Bo Chen, Guoxing Zhang, Yundou Xu, Jiantao Yao

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 23-23. https://doi.org/10.1186/s10033-023-00845-1

  摘要 ( 40 ) PDF全文 ( 25 )   可视化   收藏

  Overconstrained mechanism has the advantages of large bearing capacity and high motion reliability, but its force analysis is complex and difficult because the mechanism system contains overconstraints. Considering the limb axial deformation, taking typical 2SS+P and 7-SS passive overconstrained mechanisms, 2SPS+P and 7-SPS active overconstrained mechanisms, and 2SPS+P and 7-SPS passive-input overconstrained mechanisms as examples, a new force analysis method based on the idea of equivalent stiffness is proposed. The equivalent stiffness matrix of passive overconstrained mechanism is derived by combining the force balance and deformation compatibility equations with consideration of axial elastic limb deformations. The relationship between the constraint wrench magnitudes and the external force, limb stiffness is established. The equivalent stiffness matrix of active overconstrained mechanism is derived by combining the force balance and displacement compatibility equations. Here, the relationship between the magnitudes of the actuated wrenches and the external force, limb stiffness is investigated. Combining with the equivalent stiffness of the passive overconstrained mechanism, an analytical relationship between the actuated forces of passive-input overconstrained mechanism and the output displacement, limb stiffness is explored. Finally, adaptability of the equivalent stiffness to overconstrained mechanisms is discussed, and the effect of the limb stiffness on overconstrained mechanisms force distribution is revealed. The research results provide a theoretical reference for the design, research and practical application of overconstrained mechanism.
Advanced Transportation Equipment
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  Online Identification of Lithium-ion Battery Model Parameters with Initial Value Uncertainty and Measurement Noise

  Xinghao Du, Jinhao Meng, Kailong Liu, Yingmin Zhang, Shunli Wang, Jichang Peng, Tianqi Liu

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 7-7. https://doi.org/10.1186/s10033-023-00846-0

  摘要 ( 35 ) PDF全文 ( 27 )   可视化   收藏

  Online parameter identification is essential for the accuracy of the battery equivalent circuit model (ECM). The traditional recursive least squares (RLS) method is easily biased with the noise disturbances from sensors, which degrades the modeling accuracy in practice. Meanwhile, the recursive total least squares (RTLS) method can deal with the noise interferences, but the parameter slowly converges to the reference with initial value uncertainty. To alleviate the above issues, this paper proposes a co-estimation framework utilizing the advantages of RLS and RTLS for a higher parameter identification performance of the battery ECM. RLS converges quickly by updating the parameters along the gradient of the cost function. RTLS is applied to attenuate the noise effect once the parameters have converged. Both simulation and experimental results prove that the proposed method has good accuracy, a fast convergence rate, and also robustness against noise corruption.
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  A Compensation Algorithm for Large Element Characterizing the Damage Evolution Process and Its Application to Structure Collisions

  Wen Liu, Lele Zhang, Yifan Ru, Geng Chen, Weiyuan Dou

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 8-8. https://doi.org/10.1186/s10033-023-00837-1

  摘要 ( 59 ) PDF全文 ( 29 )   可视化   收藏

  When simulating the process from elastic–plastic deformation, damage to failure in a metal structure collision, it is necessary to use the large shell element due to the calculation efficiency, but this would affect the accuracy of damage evolution simulation. The compensation algorithm adjusting failure strain according to element size is usually used in the damage model to deal with the problem. In this paper, a new nonlinear compensation algorithm between failure strain and element size was proposed, which was incorporated in the damage model GISSMO (Generalized incremental stress state dependent damage model) to characterize ductile fracture. And associated material parameters were calibrated based on tensile experiments of aluminum alloy specimens with notches. Simulation and experimental results show that the new compensation algorithm significantly reduces the dependence of element size compared with the constant failure strain model and the damage model with the linear compensation algorithm. During the axial splitting process of a circular tubular structure, the new compensation algorithm keeps the failure prediction errors low over the stress states ranging from shear to biaxial tension, and achieves the objective prediction of the damage evolution process. This study demonstrates how the compensation algorithm resolves the contradiction between large element size and fracture prediction accuracy, and this facilitates the use of the damage model in ductile fracture prediction for engineering structures.
Smart Material
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  Parameters Calibration of the GISSMO Failure Model for SUS301L-MT

  Tao Zhu, Haoxu Ding, Chao Wang, Yuxin Liu, Shoune Xiao, Guangwu Yang, Bing Yang

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 20-20. https://doi.org/10.1186/s10033-023-00844-2

  摘要 ( 46 ) PDF全文 ( 32 )   可视化   收藏

  With the development of the rail transit industry, more attention has been paid to the passive safety of rail vehicles. Structural damage is one of the main failure behaviors in a rail vehicle collision, but it has been paid little attention to in past research. In this paper, the quasi-static fracture experiments of SUS301L-MT under different stress states were carried out. The mechanical fracture properties of this material were studied, and the corresponding finite element simulation accuracy was improved to guide the design of vehicle crashworthiness. Through the tests, the fracture behavior of materials with wide stress triaxiality was obtained, and each specimen's fracture locations and fracture strains were determined. Parameters of a generalized incremental stress state dependent damage model (GISSMO) of the material were calibrated, and the model's accuracy was verified with test results from a 45° shear specimen. The GISSMO failure model accurately reflected the fracture characteristics of the material. The mesh dependency of this model was modified and discussed. The results show that the simulation agrees well with experimental data for the force-displacement curve after correction, but the strain distribution needs to be further studied and improved.
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  Fatigue Life Prediction for SiC/Al Materials Based on Path Planning Algorithm Considering Residual Stress

  Wenqian Shang, Xintian Liu, Xu Wang, Xiaolan Wang

  Chinese Journal of Mechanical Engineering. 2023, 36(1): 24-24. https://doi.org/10.1186/s10033-023-00843-3

  摘要 ( 59 ) PDF全文 ( 25 )   可视化   收藏

  To explore the influence of path deflection on crack propagation, a path planning algorithm is presented to calculate the crack growth length. The fatigue crack growth life of metal matrix composites (MMCs) is estimated based on an improved Paris formula. Considering the different expansion coefficient of different materials, the unequal shrinkage will lead to residual stress when the composite is molded and cooled. The crack growth model is improved by the modified stress ratio based on residual stress. The Dijkstra algorithm is introduced to avoid the cracks passing through the strengthening base and the characteristics of crack steps. This model can be extended to predict crack growth length for other similarly-structured composite materials. The shortest path of crack growth is simulated by using path planning algorithm, and the fatigue life of composites is calculated based on the shortest path and improved model. And the residual stress caused by temperature change is considered to improve the fatigue crack growth model in the material. The improved model can well predict the fatigue life curve of composites. By analyzing the fatigue life of composites, it is found that there is a certain regularity based on metal materials, and the new fatigue prediction model can also reflect this regularity.