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  • Brief Notes
    JIN Minghu, BIAN Zhentao, LIU Jingjing, HOU Xue, WANG Zhuo, QI Baiyu
    Physical Testing and Chemical Analysis Part B:Chemical Analgsis. 2023, 59(4): 444-447. https://doi.org/10.11973/lhjy-hx202304013
    In view of some disadvantages of HJ 1082-2019 for the determination of hexavalent chromium in agricultural soil with high organic matter, the method of this standard was improved. The main improvement measures mainly included the following five aspects. Firstly, ethanol was added into the alkaline extract, and the co-solvent effect of ethanol was used to make the extract fully contact with the organic matter and minerals in the soil in homogeneous phase. Secondly, sodium carbonate-sodium bicarbonate instead of phosphate as buffer solution was used to avoid the inclusion of hexavalent chromium by the associative precipitation with phosphate and ions of calcium and magnesium leached from soil. Thirdly, magnesium chloride was added, and the strong ion exchange ability of magnesium ion was used to exchange with hexavalent chromium in soil. Fourthly, double frequency orthogonal ultrasonic instead of stirring was used to fully decompose and degrade organic matter, especially humic acid. Fifthly, the use of conical bottle and reflux pipe instead of polyethylene film sealing was used to reduce the loss of hexvalent chromium through reflux. It was shown that when the weighing sample was 3.000 0 g, the addition amount of extract was 40 mL, the addition amount of magnesium chloride was 0.4 g, and the addition of sodium bicarbonate-sodium bicarbonate buffer solution was 0.6 mL, the extraction effect was better. The linear range of the standard curve of hexavalent chromium was within 5.00 mg·L-1, with detection limit (3.143s) of the improved method of 0.09 mg·kg-1, RSDs (n=7) of the determined values for the actual samples less than 0.30%, and the recoveries in the range of 94.0%-100%. By comparing the improved method with HJ 1082-2019, the determined values of hexavalent chromium obtained by the improved method were higher than those obtained by HJ 1082-2019, and the recoveries of the improved method were better, indicating that the improved method was accurate and feasible.
  • Quality Control and Failure Analysis
    LYU Yuan
    Physical Testing and Chemical Analysis Part A:Physical Testing. 2023, 59(4): 4-7. https://doi.org/10.11973/lhjy-wl202304002
    The reasons for the fracture of the metal hose were analyzed by means of macroscopic observation, chemical composition analysis, scanning electron microscopy and energy spectrum analysis, metallographic examination. The results show that the corrosive medium in the environment infiltrated into the inner layer of the metal hose. Under the combined action of corrosive medium and external force, intergranular stress corrosion cracking occurred in the inner layer, resulting in the fracture of the metal woven mesh and the thinning of the bellows, and finally fracture occured under the action of external force.
  • Quality Control and Failure Analysis
    HUA Yanxia, LI Youbin
    Physical Testing and Chemical Analysis Part A:Physical Testing. 2023, 59(4): 54-56. https://doi.org/10.11973/lhjy-wl202304014
    The bending cracking reason of Q235B steel plate of moderate thickness was analyzed by means of macroscopic observation, chemical composition analysis, metallographic examination and scanning electron microscopy and energy spectrum analysis. The results showed that there were bubbles on the near surface of the cracked Q235B steel plate of moderate thickness, and there were serious segregation and sulfide segregation at the crack propagation and extension. Under the action of stress during cold bending, the crack source was first formed at the near surface bubble position of Q235B steel plate of moderate thickness, and the crack propagated along the segregation band and sulfide extension direction, which eventually led to bending cracking.
  • Innovative Design
    DING Yang, ZHANG Minglu, JIAO Xin, LI Manhong
    Journal of Engineering Design. 2023, 30(2): 154-163. https://doi.org/10.3785/j.issn.1006-754X.2023.00.022
    The existing hexapod robots have shortcomings in single foot structure design, body layout and compliant motion control, resulting in weak terrain adaptability and low motion compliant performance. Therefore, observation experiment was conducted on a typical hexapod organism-ant.Based on the analysis of the physiological structure characteristic and driving mode of ant, basic principles applicable to the structure design of hexapod robot were proposed; based on the design of a low inertia single foot structure, an overall biomimetic structure of a hexapod robot driven by joint motors was proposed by optimizing the body layout of the robot; based on the gait of the straight and turning movements of the hexapod robot, a foot end trajectory combining trigonometric function curve and straight line was planned, and a compliant motion control method for the hexapod robot based on hierarchical control was proposed. The prototype experimental results showed that the hexapod robot had a reasonable structure design and could achieve relatively compliant straight and turning movements. The research results can provide important references for the design of robot biomimetic structure and compliant motion control.
  • Test Technique and Method
    CEN Feng, HU Xianjun, GU Ye, ZHANG Hongyu
    Physical Testing and Chemical Analysis Part A:Physical Testing. 2023, 59(4): 1-3. https://doi.org/10.11973/lhjy-wl202304001
    Aiming at the problem that the sample of thermal simulation compression test was small and the tensile test could not be carried out directly, the tensile test of small sample was carried out by using the self-made small sample fixture. Through small sample tensile test and hardness test on 8 kinds of samples with different strength levels, the correlation between them was analyzed. The analysis results of small specimens and standard tensile specimens were compared. The results show that the tensile test results of small specimens and standard tensile specimens were basically the same, and the standard deviation of tensile strength was less than 3. 00. The tensile strength of materials could be accurately determined by small specimens.
  • Quality Control and Failure Analysis
    WEI Caili, ZHANG Shenjie, DU Gangfeng, LI Peizhe
    Physical Testing and Chemical Analysis Part A:Physical Testing. 2023, 59(4): 29-30,61. https://doi.org/10.11973/lhjy-wl202304008
    The drive axle of a certain type of tractor fractured in the straightening process after induction quenching. The fracture cause was analyzed by means of macroscopic observation, metallographic examination and hot acid etching test. The results show that the local overburning of the drive axle during the forging process led to a significant reduction in the strength and plasticity of the material. When the external force was too large, the part broke.
  • Quality Control and Failure Analysis
    JIA Shijun, SUN Mingzheng
    Physical Testing and Chemical Analysis Part A:Physical Testing. 2023, 59(4): 57-61. https://doi.org/10.11973/lhjy-wl202304015
    The polyurethane pipe of a robot equipment cracked. The cracking reason was analyzed by macroscopic observation, infrared spectrum analysis, mechanical property test, scanning electron microscope and energy spectrum analysis. The results showed that the polyurethane pipe did not undergo thermal oxidative aging and ultraviolet aging. The fine aluminum particles in the environment caused wear on the surface of the pipe, and the damage became a stress concentration point and cracks were initiated. The cracks further expanded and penetrated the wall, eventually led to internal medium leakage.
  • Quality Control and Failure Analysis
    PENG Shuang, SUN Zhijun, JIN Yi, TENG Yuefei, CAO Wei
    Physical Testing and Chemical Analysis Part A:Physical Testing. 2023, 59(4): 31-37. https://doi.org/10.11973/lhjy-wl202304009
    The fatigue properties of TC17 titanium alloy circular perforated plate specimens were different. The reason for the differences was analyzed by scanning electron microscopy and energy spectrum analysis, metallographic examination, residual stress test and roughness test. The results show that for the plate-shaped circular hole fatigue specimen with Kt=2.52 and short life, the fatigue crack originated from the processing damage at the rounding of the hole edge or the processing damage of the inner wall of the hole, and the fatigue cracks of the longer life specimen originated from the inner wall of the hole. For the plate-shaped hole fatigue specimen with Kt=2.1 and short life, the fatigue crack originated from the machining damage of the inner wall of the hole or the rounding damage of the hole edge, while the fatigue cracks of the long-life specimen mostly originated from the surface machining defects or the subsurface of the inner wall of the hole. The fatigue properties of the samples were greatly different due to the processing damage of the samples, the large residual compressive stress on the inner wall of the hole and the dispersion of the residual stress.
  • Quality Control and Failure Analysis
    CHEN Dongjun, LI Guangyang, LIU Gang
    Physical Testing and Chemical Analysis Part A:Physical Testing. 2023, 59(4): 46-48,56. https://doi.org/10.11973/lhjy-wl202304012
    The fracture reason of GCr15 steel bushing was analyzed by means of macroscopic observation, chemical composition analysis, scanning electron microscope and energy spectrum analysis, metallographic examination, and microhardness test. The results show that the fracture of the bushing was characterized by brittle fracture, and there were early cracks at the starting position of the fracture. Due to improper grinding process, grinding burn occured on the end face of the bushing, and the surface hardness of the bushing decreased.
  • Modeling, Simulation, Analysis and Decision
    LI Yangbo, CAI Gaipin, RUAN Liao
    Journal of Engineering Design. 2023, 30(2): 212-225. https://doi.org/10.3785/j.issn.1006-754X.2023.00.012
    Aiming at the complexity of rock crushing process and the limitations of traditional simulation models, which reflects the little information about the replacement particle groups and can not locate a particle in the replacement particle groups, resulting in the simulated particles can not be broken continuously and the simulation accuracy is low, an improved crushing model developed by the discrete element application program interface is proposed, which is the bonded particle model(BPM)with multiple replacements. This method realizes the multiple continuous replacements of particles during the crushing process, which is closer to the actual crushing process and can improve the simulation accuracy. Based on the three-dimensional model of dual-roller crusher and the W-ore particle groups after parameter calibration, the visual simulation analysis of laminated crushing of W-ore particle groups in crusher was carried out, and the laminated crushing characteristics of the dual-roller crusher were studied through indoor tests to verify the effectiveness of numerical simulation. The results showed that: the relationship between the force on W-ore particles and the crushing rate obtained through simulation indicated that the dual-roller crusher could achieve laminated crushing; the error of particle size distribution after crushing was 0.889-1.940 mm, and the particle size distribution after crushing met the normal distribution, which verified the simulation analysis was accurate and effective. The laminating crushing test results of W-ore with different particle size ratios showed that the influence of particle interaction on crushing efficiency was greater than that of particle low porosity. The research results provide a basis for improving the production efficiency of dual-roller crusher, and the proposed improved crushing model also provides a new method for the study of material crushing.
  • ZHANG Long, HU Yanqing, ZHAO Lijuan, ZHANG Hao
    China Mechanical Engineering. 2023, 34(8): 966-975. https://doi.org/10.3969/j.issn.1004-132X.2023.08.011
    To address the problems of inadequate information on the characteristics of single channel signals, a rotating machinery fault diagnosis method of multichannel information fusion and deep transfer learning approach was proposed. Firstly, the one-dimensional signals collected by multi-sensors were used to generate separate time-frequency maps by wavelet transforms. Then, the information of the maps was fused into multi-channel images. Finally, the pre-trained deep residual network, as a transfer model, was used for fault diagnosis of the rotating machinery. The identification accuracy of the tests on the cylindrical roller bearing, locomotive bearing, and gearbox datasets of a bureau of locomotive section is as 99.23%, 99.78%, and 99.50% respectively; and the identification accuracy of the cross-service transfer tests on the Case Western Reserve University bearing dataset is as 93.12%, which indicates the superiority and scalability of the proposed method.
  • Quality Control and Failure Analysis
    LI Tianfu, ZHONG Yunfei, QU Shen, DONG Chen, ZHANG Zhefeng
    Physical Testing and Chemical Analysis Part A:Physical Testing. 2023, 59(4): 49-53. https://doi.org/10.11973/lhjy-wl202304013
    The main shaft bearing of a digital controlled lathe was damaged. The causes of bearing damage were analyzed by macroscopic observation, chemical composition analysis, scanning electron microscopy and energy spectrum analysis, metallographic examination and hardness test. The results show that early contact fatigue occured in both main shaft bearings, but the damage degree was slight. There were damage pits and furrows formed by abrasive wear on the surface of one of the bearing raceways. The abrasive particles were hard aluminum debris produced by lathe machining. The debris entered the bearing, formed extrusion pits on the contact surface and moved with the rolling body. The furrows were formed on the surface of the raceway, which increased the roughness of the contact area and eventually led to poor rotation of the bearing and abnormal noise.
  • Quality Control and Failure Analysis
    HOU Xinghui, WANG Xiaolan, JI Cannan, LU Xuxia
    Physical Testing and Chemical Analysis Part A:Physical Testing. 2023, 59(4): 15-18,56. https://doi.org/10.11973/lhjy-wl202304005
    The causes of fatigue fracture of 55SiCrA steel spring were analyzed by means of macroscopic observation, chemical composition analysis, microhardness test, metallographic examination and scanning electron microscope analysis. The results show that the inner and outer surface defects of the spring were potential crack sources, which were easy to form stress concentration and produce cracks, and the cracks continued to expand, eventually led to spring fracture.
  • Laboratory Management
    WANG Bin, ZHENG Shaofeng, WANG Liping, LI Weicai, ZHONG Kanghua, FANG Cheng, SONG Wuyuan, LAN Lili
    Physical Testing and Chemical Analysis Part B:Chemical Analgsis. 2023, 59(5): 537-539. https://doi.org/10.11973/lhjy-hx202305008
  • TIAN Zongrui, ZHI Pengpeng, YUN Guoli, GUO Xinkai, GUAN Yi
    China Mechanical Engineering. 2023, 34(8): 931-940. https://doi.org/10.3969/j.issn.1004-132X.2023.08.007
    A multi-objective robust optimization design method of adaptive incremental Kriging model was proposed. Firstly, according to the structural characteristics and optimization objectives, the incremental Kriging surrogate model was constructed, and a hybrid sampling strategy was proposed to improve the adaptability of the incremental Kriging surrogate model. Secondly, the Cauchy mutation MOPSO(CMMOPSO) algorithm was proposed. By improving the inertia weight factor, individual learning factor and social learning factor, and introducing the Cauchy mutation strategy, the efficiency and precision of the optimization model were improved. Finally, an optimization model was constructed with the structural parameters as the design variables, the standard deviation of the performance indicators as the objective, and the 3σ variable reduction interval as the constraint. The optimal solutions of multi-objective robust optimization were obtained combining CMMOPSO and grey correlation analysis. Analysis results of the example show that the proposed method may obtain a high-precision structural optimization model with fewer performance function calls, and the optimization results have faster convergence rate and better robustness than that of traditional methods.
  • YANG Shuangjuan, DONG Guixia, GUAN Ruohan, WU Di
    Powder Metallurgy Technology. 2023, 41(2): 167-174,186. https://doi.org/10.19591/j.cnki.cn11-1974/tf.2020080010
    Positive temperature coefficient (PTC) thermal ceramics are a kind of key electronic functional ceramics, which are widely used in heating elements, sensors, circuit protectors, temperature controllers, and electrical demagnetization, because of the excellent characteristics. The positive temperature coefficient thermistor (PTCR) prepared by using BaTiO3 as the host materials is a type of PTC elements with a large amount at present, showing the important research significance. The classification and advantages-disadvantages of the PTC heat-sensitive materials were elaborated in the article, the PTC effect, heat-sensitive mechanism, and semiconductivity principle of the BaTiO3-based PTC materials were introduced, and the research status of the BaTiO3-based PTC heat-sensitive ceramics was summarized at home and abroad. The effects of peak shifting agent, donor doping, acceptor doping, and sintering process on the BaTiO3-based PTC thermal ceramics were analyzed. The application principle and application of the PTC thermal components were summarized in the related fields, and the lead-free PTC thermal ceramics were looked forward.
  • XI Yi, LI Baoren, WAN buyan, XU Jingwei
    China Mechanical Engineering. 2023, 34(8): 948-954. https://doi.org/10.3969/j.issn.1004-132X.2023.08.009
    Aiming at the problems for low accuracy of the calculation method for pulsation suppression performance and unclear pulsation suppression mechanism of in-lined bladder style pressure pulsation attenuator(bladder attenuator), an improved acoustic-solid coupling finite element method was proposed to calculate the pulsation suppression characteristics of bladder attenuator, which was based on the acoustic impedance calculation of micro-perforated plates by micro-perforation theory. The effect laws of system operating pressure, inflation pressure, main structural parameters, and bladder material on the pressure pulsation suppression characteristics were studied. The correctness of the proposed calculation method and theoretical analysis results were verified by experiments.
  • Basic Parts Design
    DUAN Weijie, QIN Huibin, LIU Rong, LI Zhongyi, BAI Shaoping
    Journal of Engineering Design. 2023, 30(2): 262-270. https://doi.org/10.3785/j.issn.1006-754X.2023.00.028
    Compliant actuators can achieve safe interaction between robots and humans due to their inherent flexibility, and have strong environmental adaptability. To meet the requirements of exoskeleton robots for joint flexibility and variable stiffness characteristics, a reconfigurable variable stiffness compliant actuator was designed, which could achieve reconstruction by changing the geometric parameters, materials and quantity of elastic components, and achieve variable stiffness within an adjustable range by adjusting the radial preload. Firstly, based on the transmission principle of a zerolength frame four-bar mechanism, a stiffness mathematical model of the variable stiffness compliant actuator was established, and the influence of the number of flexible branches and the stiffness and preload of elastic components on the output torque and stiffness of the actuator was analyzed. Then, an ADAMS virtual prototype model of the actuator was established, and the statics performance simulation analysis was carried out to verify the correctness of the stiffness mathematical model. Finally, the dynamics model of the actuator was established and the transfer function of the dynamics system was obtained through Laplace transform. The frequency characteristics analysis results indicated that the stability of the compliant actuator was good. The designed compliant actuator had a small volume and small mass, which could be applied in the driving mechanism of wearable exoskeleton robots. The research results provide theoretical and technical references for the design of compliant driving joints in robots.
  • Basic Theory and Method of Design
    DING Yuqi, YANG Chaoliang, LU Ye, YANG Ming, ZHANG Jiahe, LIU Kai, LU Hong
    Journal of Engineering Design. 2023, 30(2): 144-153. https://doi.org/10.3785/j.issn.1006-754X.2023.00.025
    Storage tanks are prone to structural failure under occasional explosive loads, resulting in the outflow of liquid inside the tank and causing huge economic losses. However, storage tanks designed with weak roofs can reduce losses in such accidents. Therefore, taking the vertical vault storage tank as the research object, taking into account factors such as internal pressure, stress and crack propagation during the tank failure process, a method for evaluating the implosion weak roof performance of storage tank based on multiple discriminant conditions was established. Meanwhile, by means of numerical simulation, a three-dimensional finite element model of storage tank implosion was established using the CEL(coupled Euler-Lagrange) fluid-structure coupling algorithm. The failure process of storage tank under implosion load and the weak roof performance of storage tank under different influencing factors were studied. The calculation results showed that in the evaluation of weak roof performance based on pressure and stress, the peak pressure ratios of the storage tank at positions of 90°, 135° and 180° were greater than 1, meeting the requirements of weak roof; in the evaluation of weak roof performance based on structural fracture, due to the extension of cracks below the liquid level, two cracks passed through the liquid level of 1.99 m and 5.21 m, respectively, and the storage tank did not have weak roof performance. As the volume and liquid level of the storage tank increased, the weak roof performance of storage tank increased. Based on the calculated results, the method of setting a protective ring above the liquid level was adopted to optimize the storage tank, so that the non-weak roof storage tank met the design requirements of the weak roof structure. The established evaluation conditions for the weak roof performance of storage tanks can provide reference for the design and analysis of the weak roof of storage tanks.
  • Optimization Design
    YANG Ganhua, CENG Qingjun, HAN Chunwei, HUANG Xin, DAI Xiaoqiang
    Journal of Engineering Design. 2023, 30(2): 164-171. https://doi.org/10.3785/j.issn.1006-754X.2023.00.027
    Aiming at the requirements of teleoperation robots grasping soft or fragile objects in unknown environments such as the deep sea, a master-slave soft hand position tracking method for humancomputer interactive teleoperation robot was proposed. Firstly, the structure and working principle of the master-slave soft hand control system were introduced. The system mainly included the master control loop, acommunication link and slave control loop, which was used to control the grasping action of the soft hand. Then, the modeling process and controller design of the soft finger were described. The hypothetical modal method was used to model the soft finger, and the model predictive control algorithm was introduced into the position tracking control of the soft finger to solve the problem of poor performance of the soft slave hand tracking soft master hand. Finally, the soft master hand, soft slave hand and their control systems were designed and developed, in which the soft slave hand was made of silicone and embedded with solid materials to increase the stiffness. Meanwhile, the experiment of soft slave hand tracking soft master hand to grasp the target object was conducted. The simulation results showed that the designed model predictive controller could effectively solve the problem of control accuracy degradation caused by model mismatch for soft fingers; the experimental results showed that the developed soft slave hand could effectively track the soft master hand to grasp the target objects, and the entire control system ran well. The research results provide a reference for the tracking control application of soft hands of human-computer interactive teleoperation robot.
  • Design for Quality
    SUN Guangming, ZHANG Dawei, SUN Mingze, XU Pengfei, CHEN Faze, LI Zhijun
    Journal of Engineering Design. 2023, 30(2): 200-211. https://doi.org/10.3785/j.issn.1006-754X.2023.00.023
    The phenomenon of error averaging in the linear feed system of precision machine tools is a key concern in machine tool accuracy design. Taking a typical linear feed system with double guide rails and four sliders in precision horizontal machining center as the research object, the averaging mechanism between the geometric error of rolling guide rail pair and the motion error of workbench was emphatically studied. Firstly, the equivalent stiffness method based on transfer function was used to establish the mapping relationship between the geometric error of guide rail and the motion error of workbench, and the error averaging mechanism was revealed by taking the normal straightness error as an example. Then, the finite element model of the linear feed system with double guide rails and four sliders was established, and the averaging coefficients of the geometric error of guide rail and the motion error of workbench were analyzed. Finally, an error averaging mechanism analysis experiment was conducted to verify the correctness of the theoretical analysis and simulation analysis by measuring the geometric error of guide rail and the motion error of workbench and calculating the error averaging coefficient. The research results provide a theoretical basis for the accuracy design of machine tools.
  • Quality Control and Failure Analysis
    XIE Jinhong
    Physical Testing and Chemical Analysis Part A:Physical Testing. 2023, 59(4): 8-11. https://doi.org/10.11973/lhjy-wl202304003
    The fan blades of a Q235A steel cracked after running for about 180-500 h. The reason of cracking was analyzed by means of macroscopic observation, chemical composition analysis, scanning electron microscopy and energy spectrum analysis, metallographic examination and hardness test. The results show that the crack originated from the heat affected zone at the weld edge on both sides of the blade root. Under the action of alternating stress and welding stress generated by the rotation of the fan and the overall vibration of the generator, the crack initiated and propagated, which eventually led to the crack of the blade.
  • Brief Notes
    LI Shaofei, JIANG Lili
    Physical Testing and Chemical Analysis Part B:Chemical Analgsis. 2023, 59(5): 517-522. https://doi.org/10.11973/lhjy-hx202305004
    In order to solve the problems of false positive results and difficult separation of m-xylene and p-xylene in the determination of benzene series in indoor air after home decoration by gas chromatography with a single chromatographic column and single detector, the title method was proposed. Both ends of the activated carbon adsorption tube were connected to the sampler, and indoor air sample after home decoration was collected for 30 min at flow rate of 1 L·min-1. After collecting 30 L of gas, the activated carbon adsorption tube was removed and sealed with the polytetrafluoroethylene cap. The activated carbon was taken out from the activated carbon adsorption tube, and 1.00 mL of carbon disulfide was added for desorption at room temperature for 30 min. The resulting gas was introduced into the gas chromatograph at column flow rate of 1.5 mL · min-1 and split ratio of 1∶5. Eight common benzene series, such as benzene, toluene, ethylbenzene, o-xylene, m-xylene, p-xylene, styrene, and 4-tert-butyl toluene, were passed through a CP-Wax strong polar capillary column (30 m×0.32 mm, 0.25 μm) and a DB-5 weak polar capillary column (30 m×0.25 mm, 0.25 μm) for separation, and detected by dual hydrogen flame ionization detectors. It was shown that the mass concentrations of the 8 benzene series were in a linear relationship with the corresponding peak areas in the range of 0.1-20.0 mg·L-1, with detection limits (3.143s) in the range of 0.000 3-0.000 5 mg·m-3. The spiked recovery test was conducted on negative samples at 3 concentration levels, giving recoveries in the range of 96.0%-102%, and RSDs (n=6) of the determined values ranged from 0.30% to 4.9%.
  • Testing & Research
    YU Qingping, ZHANG Guangsheng, XIA Liansen, FANG Huimin
    Materials For Mechanical Engineering. 2023, 47(4): 18-22,32. https://doi.org/10.11973/jxgccl202304004
    Fe-2%Cu-0.4%C iron-based powder metallurgy material was boronized at 950 ℃ for 5 h by solid powder boronizing method with a boronizing agent containing CeO2. The effects of CeO2 addition (0,2%, 4%, mass fraction) on the microstructure and friction and wear properties of the boronizing layer were studied. The results show that the boronizing layer with different addition amounts of CeO2 had a single Fe2B phase. With the increase of CeO2 addition, the surface roughness of the boronizing layer increased, and the thickness, hardness and wear resistance increased first and then decreased. When the mass fraction of CeO2 was 2%, the thickness and hardness of the boronizing layer were the largest, about 144 μm and 58.0 HRC, respectively. At this time, the surface integrity of the boronizing layer was relatively good, the amount of wear was the smallest, about 0.008 g, and the wear resistance was the best.
  • WANG Jianzhong, AO Qingbo, MA Jun, LI Aijun
    Powder Metallurgy Technology. 2023, 41(2): 125-130. https://doi.org/10.19591/j.cnki.cn11-1974/tf.2021080005
    To reduce the cost of Ti and Ti alloy products, the Ti chips (cutting fibers) from the surface of Ti ingots were used as the raw materials to prepare the Ti alloy fiber porous materials by cleaning, cutting, pressing, and high temperature confined sintering. The microstructures were observed, the influence of pressing pressure on porosity was analyzed, and the effects of sintering temperature, fiber width, and porosity on the compressive properties of the Ti alloy fiber porous materials were systemically studied. The results show that, the interior of Ti alloy fiber porous materials is the through-pore. As the increase of the pressing pressure, the porosity of the Ti alloy fiber porous materials decreases. The compressive platform stress of the Ti alloy fiber porous materials sintered at 1200 ℃ is up to 17.34 MPa with the fiber width of 2 mm and the porosity of 56.0%. The titanium alloy fiber porous materials are prepared at zero cost for the raw materials in this paper, which can be applied in the fields of damping, vibration reduction, and impact protection.
  • Test Research
    CHENG Shuyun, LU Minghui, LIU Yuanyu, LIU Xunfeng, ZHU Ying
    Nondestructive Testing. 2023, 45(4): 33-38,81. https://doi.org/10.11973/wsjc202304007
    Some noise signals are often carried in ultrasonic detection signals, and the most of them are the scattering noise at material grain boundary and system noise. In view of the limitations or shortcomings of some traditional methods of ultrasonic signal noise reduction, this paper introduces the singular spectrum analysis (SSA) algorithm to the noise reduction of ultrasonic signals. The method originates from principal component analysis (PCA). The main component of signal was extracted according to the difference of singular value between the main component and noise component in singular spectrum, and then several extracted signal principal components were reconstructed to realize the purpose of noise reduction. The noise reduction effect of SSA algorithm is compared with traditional methods such as wavelet threshold denoising, EMD filtering and sparse decomposition reconstruction. The experimental results show that SSA algorithm has better noise reduction effect on different SNR signals, which was significantly better than other traditional noise reduction methods, and no more prior information was needed.
  • Brief Notes
    LI Dengshan, LI Lina, ZHANG Rencheng
    Physical Testing and Chemical Analysis Part B:Chemical Analgsis. 2023, 59(4): 405-408. https://doi.org/10.11973/lhjy-hx202304006
    In order to reduce the effect of different cuvettes on the measurement results of near infrared spectroscopy, as well as improve the prediction accuracy of quantitative analysis model for the acidity of water, the removel effect of orthogonal signal correction (OSC) on the spectral background interference from different curvettes was discussed. Two cuvettes from the same batch were used to load 32 water samples with different pH values, and near infrared spectral data were collected, and OSC was used to preprocess the original spectra. The difference between the two groups of spectra before and after OSC preprocessing was compared, and the partial least squares (PLS) quantitative analysis models were established to analyze the effect of spectral difference on the prediction accuracy of the models. As shown by the results, after OSC preprocessing, the average difference value between the two groups of spectra decreased from 0.004 2 to 0.001 3, and the spectral correction rate reached 90%. Compared with the PLS models established by the original spectra, the prediction accuracy of the PLS models established by the spectra after the OSC preprocessing was significantly improved, and the difference values of predicted root-mean-square error decreased from 0.912 to 0.205, and that of correlation coefficient decreased from 0.364 to 7.00×10-3, and both of them reduced by 78% and 98%, respectively.
  • Basic Theory and Method of Design
    WANG Jiadong, HU Ming, YAN Wei, LI Haoran
    Journal of Engineering Design. 2023, 30(2): 136-143. https://doi.org/10.3785/j.issn.1006-754X.2023.00.026
    Fatigue failure of metal components is a common form of failure in industry. In order to improve the prediction accuracy of fatigue life of components, aiming at the influence of average strain on fatigue life under low cycle fatigue load, a low cycle fatigue life prediction model considering average strain was established based on the continuum damage mechanics and its irreversible thermodynamic framework, by introducing the Ramberg-Osgood cyclic constitutive model and using equivalent intrinsic damage dissipation work as an equal life condition. In order to compare and verify the effectiveness and progressiveness of the new model, the new model, modified Ohji model, Sandor model and Wei-Wong model were used to predict the low cycle fatigue life of 45 steel and 2124-T851 aluminum alloy with superimposed average strain, and compared with the corresponding test results.The results showed that the prediction results of the new model were in good agreement with the experimental results, and its prediction effect was better than the existing models. The fatigue life prediction method based on the intrinsic damage dissipation theory provides a new idea for the fatigue life prediction of metal materials.
  • Design for Quality
    ZHANG Chunyan, JIANG Yiwen, YANG Jie, JIANG Xinxing
    Journal of Engineering Design. 2023, 30(2): 189-199. https://doi.org/10.3785/j.issn.1006-754X.2023.00.029
    In order to improve the ability of parallel robots to adapt to multiple complex terrain environments, a variable-direction multi-terrain mobile full R pair parallel robot was proposed by combining the advantages of reconfigurable parallel robots and multi-motion mode mobile robots.Based on the spatial axis relation of adjacent kinematic pairs, a closed chain mechanism with threedirection rotation ability was constructed by taking the planar single-ring 4R mechanism as the body.Based on the orthogonal spatial geometric relation, two closed chains with full R pairs were formed into an omni-directional mobile parallel mechanism which could realize multiple rolling modes through geometric deformation and self-reconstruction. Then, the degree of freedom analysis and verification,gait planning simulation and motion control design for the designed parallel robot were carried out.Finally, the robot prototype was made to verify the feasibility of the robot design scheme and its motion mode through experiments. The results showed that using geometric deformation and self-reconstruction could improve the ability of parallel robots to adapt to multiple complex terrain environments. The research results can provide a new idea for the design of multi-mode parallel mobile robots.
  • China Mechanical Engineering. 2023, 34(8): 1007-1007.
  • Material Properties & Application
    LI Pengfei, ZHAO Zhimeng, QING Zhouchang, WANG Shanlin
    Materials For Mechanical Engineering. 2023, 47(4): 74-82. https://doi.org/10.11973/jxgccl202304014
    N80 steel sheet was polished and then modified by fluorination with 1H,1H,2H, 2H-perfluorodecyltriethoxysilane, and the effect of fluorination modification on the corrosion resistance of the test steel in 3.5wt% NaCl solution and anti-scaling performance in simulated seawater was studied. The results show that after immersion in NaCl solution for 7 d, the surface corrosion of the fluorination modified specimen was the lightest, and the low frequency (0.01 Hz) impedance modulus was 450 Ω·cm2, which was much larger than that of the unpolished and polished specimens. After seven-time rapid evaporation scaling tests, the scaling amount of the fluorination modified specimen was reduced by about 42.55% and 37.00% those of the unpolished and polished specimens, respectively. After 35-day of multi-field coupling scaling test, there was no obvious scaling phenomenon in the fluorination modified specimen, and the scaling amount was close to 0. Fluorination modification could improve the corrosion resistance and anti-scaling performance of N80 steel.
  • Special Reports (Analysis of Emerging Contaminants by Chromatography-Mass Spectrometry)
    HOU Dekun, SONG Yeping, LIU Cuizhen, LONG Rongke
    Physical Testing and Chemical Analysis Part B:Chemical Analgsis. 2023, 59(5): 578-582. https://doi.org/10.11973/lhjy-hx202305016
    The tile grout sample was incubated, frozen overnight, and ground into particles with particle size of not more than 1 mm. An aliquot (2.0 g) of the sample was taken, and 50 mL of n-hexane was added. The mixture was extracted under 400 W ultrasound power in 40 ℃ water bath for 1 h. The extract was dried by anhydrous sodium sulfate, and evaporated to 1 mL by rotating at 35 ℃, all of which passed through the HLB solid phase extraction column. Elution was carried out by 5 mL of acetone, 5 mL of mixed solution composed of acetone and n-hexane at volume ratio of 1∶1 and 5 mL of n-hexane, and all the eluate was collected, blown to near dryness by nitrogen, and diluted to 1 mL by n-hexane. The resulting solution was analyzed by gas chromatograph-mass spectrometer. Nonylphenol was separated on the HP-5MS chromatographic column as the stationary phase, ionized by electron impact ion source, and quantified by external standard method. As found by the results, the retention time of 12 nonylphenol isomers was found in the range of 7.8-8.6 min, and linear relationship between values of the mass concentration of nonylphenol and the sum of peak areas of quantitative ions (m/z 107, 121, 135, 149, 163) was kept in the range of 0.3-5.0 mg·L-1, with detection limit (3S/N) of 0.05 mg·kg-1. Test for recovery was made by standard addition method, giving recoveries in the range of 88.4%-98.6%, and RSDs (n=6) of the determined values ranged from 2.7% to 11%. The proposed method was applied to the analysis of 8 tile grout samples from the market, nonylphenol was detected in 1 sample, with detection amount of 0.21 mg·kg-1.
  • Test Research
    LIU Zhenghao, XI Qing, ZHANG Wei, DENG Jun, CHANG Dingyue, YU Tuoxia
    Nondestructive Testing. 2023, 45(4): 1-6,57. https://doi.org/10.11973/wsjc202304001
    The electromagnetic field in eddy current detection decays rapidly in space, and the sensor size is an important factor affecting the sensitivity of eddy current detection. A large flux-gate magnetometer was used to achieve the detection of 304 stainless steel at a depth of 20 mm and aluminum alloy at a depth of 16 mm. At the same time, the numerical simulation of the test process was carried out, and it was found that the actual results of Bx signal maximum variation were 33%~44% lower than the numerical simulation results. However qualitatively both of those two results were in good agreement. Numerical simulation shows that the sensitivity of small size and high sensitivity magnetic sensor in eddy current detection was much better than that of induction coil eddy current detector. Small size of the sensor could make up for the disadvantage of magnetic sensitivity. At the same time, the sensitivity demand curve could be drawn according to the sensor size and sensitivity to compare the eddy current detection sensitivity of different sensors. The results were helpful to optimize the design of new eddy current sensors.
  • Test Research
    LUAN Chuanbin, LÜ Jian, HUANG Yeling, LI Qi, ZOU Yongning
    Nondestructive Testing. 2023, 45(4): 7-12,52. https://doi.org/10.11973/wsjc202304002
    Due to the unstable dose of micro focus CT ray source, detection and acquisition noise and multi-energy spectrum ray, the CT image of aeroengine precision parts inevitably contain noise and artifacts. Therefore, image enhancement processing is of great significance. The beam hardening effect causes cup artifacts in the reconstructed images, in order to eliminate this effect, a simple and practical correction method was proposed. Firstly, the logarithm of the collected data was taken, and then the difference with the air lograithm value was made to obtain the integral of the multi-color beam attenuation coefficient. Secondly, the parameters of power function transformation curve was set and hardening correction was carried out. Finally, convolution back projection reconstruction was carried out. In order to further reduce the noise in the image, the anisotropic diffusion filtering model was used to denoise the image. Experimental results show that the proposed method can significantly improve the CT image quality and reduce image artifacts and noise.
  • Test Research
    ZHAO Min, DING Ning, YUAN Xiaoqiang, FU Xueqi, ZHENG Zhenliang
    Nondestructive Testing. 2023, 45(4): 17-21. https://doi.org/10.11973/wsjc202304004
    In this paper, an defect detection method in steel plates was proposed based on abnormal geomagnetic imaging. First of all, the spatial geomagnetic information of the defect specimen area made on the steel plate was collected, the component information of the three directions of the geomagnetic field is obtained, and the abnormal geomagnetic image was finally formed. Through the analysis and processing of the images of different directions of geomagnetism, the defect dectection in steel plate was achieved and the effectiveness and reliability of the abnormal geomagnetic imaging method for the defect detection of steel plate defects were verified.
  • Optimization Design
    FAN Junliang, XIAO Li, LUO Yueting, CHEN Gang, JU Xiaolin, TANG Yi, GONG Hengxiang
    Journal of Engineering Design. 2023, 30(2): 182-188. https://doi.org/10.3785/j.issn.1006-754X.2023.00.018
    In order to realize the customization,reusability and economy of atomization assisted CVD(chemical vapor deposition) cavity,and meet the actual requirements of high-quality single crystal Ga2O3 thin film preparation,a new atomization assisted CVD cavity was designed and developed.The cavity was mainly composed of reaction chamber module,cooling module and buffer chamber module.Ga2O3 thin films were prepared by using a new cavity and a conventional cavity,and then the X-ray diffraction(XRD) patterns analysis and its surface morphology observation by atomic force microscope (AFM)were carried out.The experimental results showed that the new cavity could produce better performanceα-Ga2O3 and β-Ga2O3 thin film;the half-peak widths of (006) crystal plane of the α-Ga2O3 thin films prepared by the new cavity and the conventional cavity were 0.172°and 0.272°,respectively,and the surface roughness was 25.6 nm and 26.8 nm,respectively.It could be seen that the α-Ga2O3 thin film made with the new cavity had better crystallinity,surface smoothness and density.Through the design of the new cavity,a stable environment conducive to the growth of single crystal Ga2O3 thin film was constructed,which provided a reliable path for the optimization of the preparation process of Ga2O3 thin film.The research results provide a reference for the preparation of high-quality metal oxide semiconductor films.
  • Test Research
    ZHU Xiusen, GAO Hongbo, HU Maochun, LÜ Chengshu, ZHANG Shijing, WANG Zhan, HU Tanneng
    Nondestructive Testing. 2023, 45(4): 27-32,86. https://doi.org/10.11973/wsjc202304006
    In order to improve the detection and identification of underexposed small-diameter pipe girth weld defects, digital radiography (DR) was used to complete the safety monitoring of pressure vessels in nuclear power plants. Guided filtering and dark channel demisting theory were combined to enhance the DR Image of small-diameter pipe girth weld at low dose. The image quality was evaluated through objective evaluation indicators, and compared with adaptive histogram equalization (AHE) and contrast limited adaptive histogram equalization (CLAHE) image enhancement methods. The results show that the dark channel image enhancement technology has a better impact on image quality improvement, the image contrast-to-noise ratio was increased by 31. 5% and signal-to-noise ratio was increased by about 1. 5 times, and the defect contour was clearer.
  • Test Research
    LIANG Xiangyu
    Nondestructive Testing. 2023, 45(4): 48-52. https://doi.org/10.11973/wsjc202304010
    In order to solve the problem of near-surface blind area of TOFD technology, creeping wave was used to supplement the detection of the near-surface blind area. The near-surface blind area test block was used to calibrate the creeping wave detection system. The block with grooves and the simulated blocks containing near-surface opening defects were inspected. The experimental results show that the creeping wave could cover the near-surface blind area when the interested regions were within the detectable range of creeping wave, and it was an effective method to inspect the near-surface blind area.
  • FU Xiang, WANG Yuxin, LIU Daoyuan, WANG Jijie
    China Mechanical Engineering. 2023, 34(8): 955-965. https://doi.org/10.3969/j.issn.1004-132X.2023.08.010
    According to the shortcomings of the existing condition recognition strategy in identifying undulating terrain and variable adhesion road surfaces, based on the LuGre tire model, observation space equations were constructed to quickly identify the transient changes of adhesion conditions. The real-time working conditions were mapped with 6 typical working conditions based on fuzzy control algorithm, and a closed-loop control strategy was designed to adaptively adjust the real-time output torque of hub motors based on the working condition identification results. Simulation test and real vehicle verification show that the drive force control strategy based on the off-road condition identification may quickly track the transient changes of each wheel adhesion limit and grounding state, and adaptively adjust the real-time driving power of the vehicle to achieve comprehensive optimization of vehicle power performance and stability.
  • Whole Machine and System Design
    XU Zhe, SUN Shufeng, ZHANG Xingbo, WANG Qian, ZHANG Fengyun, WANG Pingping, XIE Zhangwei, ZHANG Yu, LIU Jixin, SUN Weili, CAO Aixia
    Journal of Engineering Design. 2023, 30(2): 254-261. https://doi.org/10.3785/j.issn.1006-754X.2023.00.024
    In order to solve the problems of inconvenience in experimental operation, difficulty in monitoring equipment operation status and poor interactivity caused by concealed installation position and difficulty in installing auxiliary devices on the self-built laser parallel processing experimental platform, taking a single optical displacement stage in the experimental platform as an example, an interactive control system based on digital twin technology was designed by using Unity engine. This interactive control system used MQTT(message queuing telemetry transport) communication protocol protocol to complete the cross-software information interaction by using the server to transfer data. The Kinesis control software of optical displacement stage and the virtual control panel in Unity engine served as clients in MQTT communication, acting as subscribers and publishers. The digital twin model of the optical displacement stage performed real-time mapping of the motion state of its physical entity based on data information. Users completed synchronous interactive control of the physical entity and the digital twin model through the Kinesis control software or virtual control panel. The secondary development of Kinesis control software was carried out by referencing.dll file, and the motion control class of Kinesis control software was called to complete the motion control of the optical displacement stage. The motion data variables were set to high-precision float type and decimal type to ensure that the data precision was not lost. Ten groups of actual processing data were selected to test the operation latency and synchronization of the interactive control system. The results showed that the data publishing time on the Kinesis control software and the data subscription time on the Unity engine were controlled within 20 ms and 10 ms, respectively. The designed system can better ensure the consistency of synchronous control and real-time action mapping between the digital twin model and the physical entity, which achieves the visual monitoring function of the motion state of the optical displacement stage. In addition, the motion data type can meet the micron level information transmission, ensuring the accuracy requirements of the optical displacement stage. At the same time, the functions of virtual control panel run normally, which improves the convenience of the optical displacement stage control.