Table of Content

25 August 2023, Volume 34 Issue 16

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Study on Contact Fatigue Crack Modeling and Propagation Law of Rolling Bearings

GUO Wei, CAO Hongrui, ZI Yanyang, WEI Xunkai

2023, 34(16):  1891-1899.  DOI: 10.3969/j.issn.1004-132X.2023.16.001

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Aiming at the damage evolution problems of rolling bearings, fatigue crack propagation mechanism was studied via XFEM. The reliability of the XFEM was verified by an example. An XFEM model of rolling contact fatigue with subsurface initial crack was proposed through fracture mechanics theory. The influencing mechanism of initial crack angle, depth and length on the propagation life and growth path of cracks in subsurfaces were analysed. Crack propagation mechanism was studied through analyzed the variation of stress intensity factors. Results show that sliding mode is the main growth mode of initial cracks in subsurface. The crack angle has a great influence on the fatigue crack growth path. The initial cracks with angle in the 15~45 degree range are easy to change the grow direction to surface which lead to fatigue spall. The crack size and depth have little effects on the morphology of the crack propagation path, but will affect the difficulty of crack propagation.

Design Techniques of Soft Robot Arms Based on Mechanics Metamaterials

CHENG Jibin, DAI Ning, GUO Pei, XIONG Jiyuan, YE Shiwei, CHENG Xiaosheng

2023, 34(16):  1900-1906.  DOI: 10.3969/j.issn.1004-132X.2023.16.002

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Based on mechanics metamaterials, the soft robot arm might realize multiple bending motions through the deployment design of mechanics metamaterials. In order to investigate the deformation characteristics of this kind of soft robot arms, based on the analysis of the structure of the soft robot arms and the driving principle, a mathematical model of voxels deformation was established through the piecewise constant curvature hypothesis. At the same time, according to the bending characteristics of soft robot arm units, single-section and multi-section soft robot arm deformation prediction model were proposed. Finally, the effectiveness of the deformation prediction model was verified by the physical experiments, and the bending of more than ±90° was completed， the environment around the end was explored, which might be applied to the inspection of complex and narrow spaces.

A Method for Estimating Damage Degree of Wheel Flat Scars Based on Time-frequency Energy Spectrum and VGG16

LI Dazhu, NIU Jiang, LIANG Shuling, CHI Maoru

2023, 34(16):  1907-1914.  DOI: 10.3969/j.issn.1004-132X.2023.16.003

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In order to accurate monitoring of the damage degree of wheel flat scars of vehicles in operation， a method for estimating the damage degree of wheel flat scars was proposed based on the combination of time-frequency energy spectrum and VGG16 convolutional neural network. This method might quantitatively estimate the damage degree of wheel flat scars in real time by analyzing and processing the vibration acceleration signals of axle box during vehicle operation. The dynamics models of rigid flexible coupling system of vehicle tracks and the mathematical models of wheel flat scars were established to simulate the vibration response of the vehicle axle box under different flat scar damage conditions. Using morphological filter and CEEMDAN-WVD time-frequency analysis method， the vibration acceleration signals of the axle box were filtered and reduced， and then expressed in the time-frequency energy spectrum. The VGG16 convolutional neural network models were constructed， and the training sets were constructed by using the time-frequency energy spectrum of a large number of wheel flat scar fault data to train the VGG16 models. Several wheel flat scar conditions were randomly simulated and the VGG16 models were tested and verified. The simulation tests show that the method combining time-frequency energy spectrum with VGG16 models may accurately estimate the damage degree of wheel flat scars of vehicles in operation， and the estimation errors are within 1.6 mm. 

Pipeline Defect Edge Recognition Model Based on MGD Optimized Magnetic Gradient Tensor Combination Invariant Algorithm

XING Haiyan, YI Ming, DUAN Chengkai, WANG Xuezeng, LIU Weinan, LIU Chuan

2023, 34(16):  1915-1920.  DOI: 10.3969/j.issn.1004-132X.2023.16.004

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 Aiming at the problems that the magnetic memory detection of oil and gas pipelines was greatly affected by the direction and the accurate identification of defect edges was difficult, a magnetic gradient tensor combination invariant algorithm was proposed for accurate identification of pipeline defect edges based on MGD optimization. Taking L245N pipeline steel as the test material, the circular hole defects with different depths and diameters were prefabricated, and the magnetic gradient tensor measurement system was designed. Combined with TSC-5M-32 magnetic memory instrument, the magnetic gradient tensor matrix of pipeline was obtained. In order to overcome the influences of the detection direction on the magnetic memory signals, the second invariant I1 and the third invariant I2 of the magnetic gradient tensor were extracted respectively. Further considering that these two invariants were easy to present ambiguity at the edges of the defects, the two invariants were improved according to the Cardano formula, and the weights a and b were set separately for superposition to obtain the combined invariant I. The fractional derivative improved gradient descent algorithm was used to determine the optimal weight, and the magnetic memory representation model of the pipeline defect edges was established. The verification results show that the average relative error of the model for defect edge recognition is as 3.59%, and the maximum relative error is as 6%, which provides a feasible method for accurate identification of pipeline defect edges in practical engineering.

Influences of Irregular-shaped Feedback Slots on Proportional Throttle Valve Characteristics

ZHOU Xingwei, FENG Kewen, ZHAO Xingyu, GE Lei, YANG Jing, QUAN Long

2023, 34(16):  1921-1928.  DOI: 10.3969/j.issn.1004-132X.2023.16.005

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 The flow characteristics of Valvistor proportional throttle valves under different feedback slot shapes were studied to provide reference for realizing multi-stage flow control of actuators. The mathematical models and multi-discipline co-simulation models of the proportional throttle valves were established， and the accuracy of the models was verified by the test data. Then， the influences of different feedback slot shapes and parameters on the dynamic and static characteristics of the valves were analyzed. The results show that the proportional throttle valves have different flow characteristics under different feedback slot shapes. When the shape of the feedback slot is inverted trapezoidal， the initial flow gain of the valves is low， which is good for the smooth starting of the actuators. When the shape of the feedback slot is a dual-rectangle combination， the valves possess good micro-motion control performance. Meanwhile， the valve response speed will be increased along with the increase of the area gain in the feedback slots. However， the larger area gain and smaller pre-opening of the feedback slots may reduce valve stability. 

Simulation and Investigation on a Synthetic Jet Piezoelectric Fan with Multiple Jet Holes

WANG Jiantao, GAO Mingze, ZHU Jian, WANG Qizhi, LI Hao

2023, 34(16):  1929-1935.  DOI: 10.3969/j.issn.1004-132X.2023.16.006

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In order to improve the gas driving ability of piezoelectric gas drivers, a piezoelectric fan with multiple jet holes was proposed, which used piezoelectric transducer to excite gas particle oscillation and to form the gas jet. Working characteristics were studied on the aspects of simulation and investigation. The gas driving law of piezoelectric fans with different density of jet holes was obtained through FLUENT simulation analysis. Multiple jet holes may improve the energy utilization efficiency of piezoelectric transducer, and further improve the gas driving performance of piezoelectric fans. Experimental results on the prototypes show that the piezoelectric fan with single jet hole which is set in the center has better gas driving performance; the energy utilization efficiency of piezoelectric transducer may be improved by using multiple jet holes, and there is an optimal jet hole density; when the driving voltage Vpp is 90 V, the gas velocity of piezoelectric fan with 89 jet holes reaches 4.7 m/s.

Study on Stability of Surface Turning Finishing Processes of Titanium Alloy Wires Based on Process Damping

SHI Lichen, ZHANG Qian, LIU Tengfei, LIU Yaxiong, LU Zhuqing

2023, 34(16):  1936-1945.  DOI: 10.3969/j.issn.1004-132X.2023.16.007

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In view of the slender structural characteristics of titanium alloy wire coil as raw materials for aviation fasteners and the machining difficulties, a centerless lathe was used to finish the surfaces of titanium alloy wire coil. Considering the requirements of high precision surface quality after turning, in order to improve the machining stability of centerless lathe, a multi-degree-of-freedom coupled flutter vibration mechanics model was established considering process damping effect. By solving the model and drawing the stability lobe diagram of the cutter head cutting system of centerless lathe for stability analysis, the stable machinable parameter group was obained. Further analysis of the influences of tool structure parameters shows that when the radius of the tool nose is as 0.1~0.3 mm, the rake angle of the tool is as 1°~2°, and the clearance angle of the tool is as 2°~5°, the stable machinable parameter set with the highest design safety may be obtained. The experimental platform was set up to verify the theoretical analysis results, and the obtained tool structure parameter selection domain and stable machinable parameter set may provide a reference for surface finishing of titanium alloy wire coils.

Universal Surface Texture Modeling Method for Five-axis Surface Milling

ZHU Sipei, FU Guoqiang, ZHENG Yue, LI Zhengtang, YANG Jixiang

2023, 34(16):  1946-1957.  DOI: 10.3969/j.issn.1004-132X.2023.16.008

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To further improve the universality of five-axis milling surface texture simulation modeling method, and to provide reference for surface texture quality assessment considering tool attitude angle and classification， a kind of five-axis milling surface texture topography simulation method was proposed with general tool parameters and general curved tool contact coordinates. The tool cutting edge expression suitable for the surface texture process of five-axis milling of different tools and surfaces was established with the tool poses defined by the tool inclination angle  and rotation angle θ of the generality of annular milling cutter. Then, a surface texture simulation model was established with searching the grid points of the workpiece in the instantaneous swept quadrilateral through geometric relationship based on the idea of discretization and the expression of cutting edge points. Under different tool attitude angles, the surface texture simulation models of two traditional surfaces with different geometric characteristics plane, spherical surfaces and different types of freeform surfaces were established, according to the simulation results, the plane simulation morphology was divided into  = 0° and  ≠ 0°, and the efficiency of the simulation method was verified by comparing the plane simulation time. Finally, the plane cutting experiments were carried out. The results show that the actual cutting workpiece texture is basically consistent with the simulation texture morphology under the combination of θ = -40°,  = 20° and θ = 15°,  = 60°. At the same time, the actual cutting surface texture morphology characteristics are consistent with the classification results of the simulated workpiece surface texture morphology, which further verifies the correctness of the surface texture morphology modeling and simulation methods.

Path Planning Method of Aviation Cables Based on Improved A* Algorithm

SUN Hao, YUAN Ye, ZHANG Qi, ZHANG Xiaobei

2023, 34(16):  1958-1964,1974.  DOI: 10.3969/j.issn.1004-132X.2023.16.009

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To solve the complex constraints of automatic routing in aviation EWIS, a path planning method was proposed based on improved A* algorithm. Constraints were incorporated into the grid point weights of the grid map including avoiding obstacles, sticking to the structure surfaces, isolating electromagnetism, protecting against heat, isolating crosstalk and merging compatible cables. And the weights were applied for calculating the evaluation function of the improved A* algorithm. Moreover, the bending factor and rigidity factor were introduced to reduce cable bending damage. Finally, curve fitting was performed on the planned cable paths to adapt to the circular fuselage outline of the aircraft. Experimental simulations show that the sticking proportion of the cable path planned by the proposed method is increased by 48.40% on average compared with the one realized by the traditional A* algorithm, the number of bends is reduced by 6.50, and the isolation requirements are all satisfied, which may help EWIS automation and intelligent design upgrade.

Dimensioning Completeness Checking Algorithm for 3D Models

YAN Zhe, DONG Yude, HE Jinxin, GUI Xingfeng, TAO Gaozhou

2023, 34(16):  1967-1974.  DOI: 10.3969/j.issn.1004-132X.2023.16.010

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Aiming at the problems of incomplete redundancy judgment and low efficiency of complex model checking in the completeness tests of 3D dimensioning, the concepts of equivalent dimension sets and equivalent nodes were proposed, and a 3D dimensioning completeness test algorithm was realized based on equivalent size. The equivalent dimension sets were created in the dimensioning processes, the redundancy judgment of equivalent dimension was realized based on the equivalent dimension sets, and the redundancy tests of dimension chain were carried out based on the undirected graph composed of equivalent nodes. After the dimensioning was completed, the dimension missing check was converted into surface feature constraint judgment. In the three-dimensional labeling system designed in CREO software, several models with different characteristics were tested. The results show that the algorithm may accurately judge the equivalent dimension redundancy, dimension chain redundancy and dimension missing, and effectively improve the overall efficiency of labeling.

Study on Properties of Ultrasonic-assisted Injection Molding of Carbon Fiber-reinforced Polypropylene Parts

LIU Ying, CHEN Yue, ZHAO Xueli, YU Tongmin, ZHU Tieli,

2023, 34(16):  1975-1981.  DOI: 10.3969/j.issn.1004-132X.2023.16.011

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Reinforced polypropylene parts with carbon fiber content of 20% were fabricated by the self-developed ultrasonic-assisted injection molding system. The effects of ultrasonic power, mold temperature, polymer-melt temperature and injection pressure on the molecular condensed state structure and mechanics properties of the polypropylene parts were studied by means of X-ray diffraction, scanning electron microscopy and tensile test. The results show that under the condition of higher mold temperature, lower polymer-melt temperature and lower injection pressure, ultrasonic vibration with power of 600 W may envidently increase the polymer-melt flow shear rate, leading to enhanced orientation of polymer molecular chains and carbon fibers. As a result, nucleation and crystal growth will be promoted, and tensile strength of the polymer parts will be significantly improved.

Theoretical Wrinkling Modeling and Critical Forming Radius Analysis of Aviation Tube Bending Forming Considering Circumferential Waveform Characteristics

LIU Heng, WANG Zhineng, BIN Guangfu, LIN Weiming, LIN Yaochen, MA Yanxiang

2023, 34(16):  1982-1990.  DOI: 10.3969/j.issn.1004-132X.2023.16.012

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The variation characteristics of the circumferential waveform of tubes were ignored by the traditional theoretical models of bending wrinkling, resulting in low prediction accuracy. Aiming at such a problem, the circumferential waveform functions of tube wrinkling wave were established based on parameter fitting method and theoretical derivation, the mechanism models of tube bending wrinkling were established in combination with the tube bending stress models. The correctness of the theoretical models were verified through the finite element simulations and experiments. The results show that the prediction accuracy of the new theoretical models for tube wrinkling reaches 94. 5%, which is 12% higher than that of the traditional models and solves the problem of low accuracy of the traditional prediction models. In addition, the smaller the bending radius is, the easier it is for the tube to wrinkle. To avoid wrinkling, the critical bending forming radius should not be less than 1.89 times of the pipe diameter. 

Forming Mechanism of Axial Wrinkle Defects in Inner Walls of Radial Precision Forged Gun Barrel with Integrated Forming Chamber and Rifling

YANG Yuzhao, YANG Chen, XU Cheng, FAN Lixia

2023, 34(16):  1991-2000,2008.  DOI: 10.3969/j.issn.1004-132X.2023.16.013

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 Integrated radial precision forging forming the chamber and rifling of the gun barrels was efficient， and the radial forged gun barrels had high coaxiality. However， the inner walls of the barrels formed by this processes would generate axial wrinkles. The wrinkles might evolve into a fissure which significantly affected the safety of the gun barrels. To investigate the forming mechanism of wrinkle defects， a three-dimensional radial precision forging finite element model was established， and multiple sets of processing parameters such as feed speed， rotational speed， hammer angle， and clamping pressure were simulated. The simulation results show that the axial wrinkle defects in the inner walls are formed in the sinking zones of the forging processes. The gaps among the four hammerheads cause uneven radial deformation of the workpieces at the same cross-section during each forging， resulting in a difference in radial displacements. After multiple forging accumulations， the radial displacement difference between adjacent nodes on the inner walls forms the axial wrinkles. The paper also shows that the larger the hammer angle， the smaller the blank thickness， and the smaller the internal diameter of the blank， the later the wrinkle formation occurres. A wrinkle-forming criterion was established based on the radius reduction in the sinking zones， and the correctness of the criterion was verified through radial precision forging experiments. 

In-situ Particle Size Detection Method of Fine Particles Based on Features of Light Scattering Pattern Images

SUN Yi, LI Changyang, MAO Yalang, YE Weiwei,

2023, 34(16):  2001-2008.  DOI: 10.3969/j.issn.1004-132X.2023.16.014

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It was difficult to on-line detect the sizes of fine particles that were prepared from industrial production processes. An on-line detection method was developed based on light scattering extinction to measure particle sizes. The law of image pixel value data of different sample particle concentrations under on-line detection was analyzed and discussed using image analysis and data feature analysis methods. Under the conditions of the in-situ experiments of the ball mill, the scattered light spot images were collected, which determined sample particle mass concentration within a certain particle size range. The difference of brightness of the light spot images was analyzed, and the distribution law of the minimum value of the pixel value was statistically obtained. The standard control parameter models were established for different particle size ranges and different sample concentrations. The models were verified by the sample particle liquid with known parameters, and the similarity matching degree is more than 0.95. The models were applied to in-situ measure fine particles sizes which were prepared by ball mill showing that the method may be used for the primary detection of in-situ particle sizes.

Design and Experimental Study of an Ultrasonic Bonding Pressure Adaptive Balancing Device

ZHOU Lijie, HAO Ruilin, CAI Guoqing, LIU Hui, SU Shijie

2023, 34(16):  2009-2015.  DOI: 10.3969/j.issn.1004-132X.2023.16.015

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In order to meet the requirements of high bonding uniformity and high bonding precision in the ultrasonic bonding processes for POCT chips, an ultrasonic bonding pressure adaptive balancing device was designed by using the characteristics of air with low frictional resistance and elastic compressibility, and the principle of bonding pressure adaptive balancing was analyzed. To verify the bonding effects of the devices, several pressure distribution uniformity experiments, bonding experiments, and comparison tests of resonance frequency and impedance for ultrasonic vibrators were carried out. The results show that the devices may control the peak-to-peak value of micro-channel height within 1.3 μm and the peak-to-peak value of fusion line width within 23.3 μm for chips with the size of 69 mm×15 mm. Compared with the control group, the devices may reduce the pressure distribution uniformity coefficient by about 50%~72%, reduce the peak-to-peak value of micro-channel height by 96.2% and the standard deviation by 96.8%, reduce the peak-to-peak value of fusion line width by 96.8% and the standard deviation by 96.3%. The devices have good adaptability to the chips with a length in range of 19~69 mm, and the peak-to-peak value of micro-channel height may be controlled within 1.9 μm. The devices do not have a large impact on the ultrasonic vibrator systems of the original bonding equipment. And at the same bonding pressure compared to the stainless steel fixture, the maximum difference in resonant frequency and anti-resonant frequency is as 2 Hz, and the difference in minimum and maximum impedance values do not exceed 3.5%. The ultrasonic bonding pressure adaptive balancing devices have good pressure adaptive balancing capability, which may effectively improve bond uniformity and bonding accuracy to meet the requirements of POCT chips for high bond uniformity and high bonding accuracy.