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2022 Vol. 41, No. 3
Published: 2022-02-15
 
1 Test method for interior ballistic mechanical characteristics of series launched projectile
HANG Yu, KONG Deren, SHANG Fei
Guide::null
Aiming at measuring the projectile’s interior ballistic mechanical properties of small caliber series launch weapon, a simultaneous measurement method based on the storage testing technology was proposed for the bottom pressure and front pressure of the projectile. Simulated projectiles and small Polyvinylidene Difluoride（PVDF） piezoelectric force sensors were designed. Two force sensors were used as the simulated projectile’s bottom screw and head screw component to withstand and measure the projectile’s bottom pressure and front pressure. The system’s measurement equation under high-overload ballistic environment was derived according to the mechanical analysis of the force sensor. The influence of the mass and the thickness of the force transmission block, the thickness and the area of the PVDF film on the dynamic characteristics and temperature rise of the sensor were analyzed. The sensitivity of the force sensor was analyzed and the calibration experiment was carried out. The results shown that the greater the preload of the PVDF film, the lower the sensor’s sensitivity. The calibration results were consistent with the theoretical analysis. A series launch test was carried out based on two simulated projectiles, and the measured interior ballistic mechanical properties of the projectiles were in accordance with the numerical simulation results.
2022 Vol. 41 (3): 1-7 [Abstract] ( 298 ) HTML (1 KB)  PDF (2205 KB)  ( 225 )
8 Design and simulation analysis for multilayer stacked permanent magnet dynamic vibration absorber cutter bar
WANG Min1,2, LIU Baozhong1, QIN Peng1, SUN Tiewei1
Aiming at the problems of rubber fatigue aging, easy leakage of damping fluid, and difficulty in precise design of stiffness and damping of traditional dynamic vibration absorber in large aspect ratio cutter bar, a multi-stacked permanent dynamic vibration absorber with magnetic stiffness and eddy current damping to provide stiffness and damping was designed, this design can tune the stiffness and damping of proposed cutter bar efficiently and independently. The unique stacked structure can provide more magnetic stiffness and eddy current damping at the same space, which ensures that the permanent dynamic vibration absorber can achieve a better optimal vibration reduction condition. The theoretical calculation models of magnetic stiffness and eddy current damping in multi-stacked permanent dynamic vibration absorber were established respectively, and the relationships between magnetic stiffness and eddy current damping and the size parameters of each part of permanent dynamic vibration absorber were explored with MATLAB software and Maxwell electromagnetic simulation software respectively. Finally, MATLAB software was used to simulate and analyze the cutter bar installed with the permanent magnet dynamic vibration absorber and the original cutter bar with the same size, the results show that the maximum amplitude of frequency response function of the utter tip decreased by over 90% with the use of permanent dynamic vibration absorber.
2022 Vol. 41 (3): 8-17 [Abstract] ( 232 ) HTML (1 KB)  PDF (1286 KB)  ( 146 )
18 Fluid-structure coupled vibration mechanism of wave conical cylinder
ZOU Lin, QIN Ao, YANG Yaozong, LIE Yujun, XU Jinli
In order to enhance and control the energy collection efficiency of the bladeless wind energy capture structure, this paper introduces the slope parameter of the surface structure into the wave-shaped cylinder, and develops a new type of wave-cone-shaped cylinder. Numerical and experimental research on the response characteristics of wave-cone cylindrical vortex-induced vibration with different wavelength ratio, wave amplitude ratio and slope parameters under Reynolds number Re=3900. The study found that at different reduced flow rates, the cone cylinders with slope k=0.05 and the wavy cone cylinder with wavelength ratio λ/Dm =1.75, wave amplitude ratio α/Dm =0.10, slope k=0.05 have the maximum amplitude ratio increased, compared with the straight cylinder, the maximum amplitude increases by 26.4% and 12.6% respectively, and their frequency lock range can be expanded. When the reduced flow velocity is in the locked frequency range, “2S” and “2P” vortex detachment modes are observed in the wake of the wave-conical cylindrical flow, and the “2P” vortex detachment mode tends to change to “2C” mode as it develops downstream. This research can provide theoretical support for the vortex-induced vibration of bladeless wind energy capture structures and the improvement of power generation efficiency.
2022 Vol. 41 (3): 18-26 [Abstract] ( 161 ) HTML (1 KB)  PDF (3535 KB)  ( 132 )
27 Transient pressure and train wind during high-speed train entering a  tunnel under crosswind
WANG Lei1,2,3, LUO Jianjun1,2,3, LI Feilong1,2,3
For the general case of high-speed trains passing a tunnel under crosswinds, considering the unsteady compressible turbulence characteristics of the flow, a 3D numerical model including train-tunnel-crosswind was established to and study the aerodynamic pressure change laws and slipstream characteristics under the conditions of crosswinds and without crosswinds comparatively. The accuracy of the numerical method was validated by the full-scale experiment. The main conclusions can be summarized as follow: Compared with the condition of without crosswind, the transient pressure and slipstream near the tunnel entrance change significantly when the train enters under crosswind. Before the full entry of the tail car, the influence of crosswind on the aerodynamic pressure at the leeward side is greater than that on the windward side, and the influence of the head car on the aerodynamic pressure at the tunnel entrance is the most significant. The influence of crosswind on aerodynamic pressure and gust in tunnel is limited. When the crosswind speed is 24.4 m / s, the distance affected in the tunnel is 50 m. When the head car enters, the crosswind has a great influence on the train wind on the leeward side of the train, while the influence of crosswind on the windward side of the train is more serious when the tail car enters completely. The crosswind effect is the fundamental reason for the large fluctuation of aerodynamic pressure and air velocity.
2022 Vol. 41 (3): 27-36 [Abstract] ( 216 ) HTML (1 KB)  PDF (4741 KB)  ( 98 )
37 Tests for crack diffraction enhancement based on phased array laser ultrasound
GAO Feng1, ZHOU Hong1, HUANG Chao2
Aiming at the problems of poor detection accuracy, low reliability of area detection and low signal-to-noise ratio of ultrasonic diffraction time difference method, a phased array laser ultrasonic crack detection method based on fiber picosecond laser and high-speed rotating mirror is proposed. The finite element method is used to simulate the thermoelastic mechanism, and a two-dimensional transient laser ultrasonic thermo-solid coupling model is established to generate S-waves and P-waves to diffract at the defect. The influence of different singularities of crack tip, different center frequency of acoustic wave and different position of phased array excitation source on acoustic diffraction is analyzed and verified by experiment. The results show that the numerical simulation results are in good agreement with the experimental results. Compared with the traditional single beam laser source, the phased array laser source has an obvious enhancement effect on the diffraction signal amplitude and signal-to-noise ratio, and the P-wave diffraction signal is ideal. The amplitude of the diffraction signal increases with the increase of the defect singularities and the decrease of the acoustic wave frequency. The signal-to-noise ratio increases with the increase of the tip singularity, and has no obvious change with the increase of the center frequency in a certain range. With the increase of the laser source distance, the signal-to-noise ratio first increases and then decreases, and the error between quantitative analysis of crack length and actual crack is less than 6.8%.
2022 Vol. 41 (3): 37-44 [Abstract] ( 119 ) HTML (1 KB)  PDF (3164 KB)  ( 106 )
45 A deep adaptive network for cross-domain bearing fault diagnosis
XIA Yi1,2, XU Wenxue1
The vibration data of bearings are often distributed differently in different working conditions, leading to low fault diagnosis accuracy. To this end, a novel deep adaptation network was proposed for bearing fault diagnosis under cross-domain conditions. First, Fourier transform is used to transform the original vibration signals in the time domain into corresponding signals in the frequency domain. After that, the classification features are extracted by deep feature extractor. Second, Maximize Mean Discrepancy (MMD) is used for aligning marginal distribution of a deep characteristics. Finally, Wasserstein metric network is used to match the category structure of labeled data of the source domain with that of unlabeled data of the target domain, that is, to align the category condition distribution of different domains. By this way, the distribution of data feature can be best aligned in different domains resulting in better diagnosis accuracy of the trained model in the unlabeled target domain. In the experiment, the model migrations under two kinds of cross-domain conditions are designed and tested by using the faulty bearing dataset published by Case Western Reserve University, and it was verified that the network had high diagnosis accuracy in different migration scenarios and was superior to other deep adaptation networks.
2022 Vol. 41 (3): 45-53 [Abstract] ( 231 ) HTML (1 KB)  PDF (2296 KB)  ( 96 )
54 Load identification method of track driving system based on genetic neural network
ZHANG Zhihong, ZHANG Hong, CHEN You, LI Zhi, LI Guohua, FU Zheng
In view of the practical engineering problem that the load cannot be obtained directly and effectively due to the adverse working conditions of the crawler travel system of coal mining robot, a method of vibration signal load identification based on genetic neural network is proposed. A genetic algorithm optimized BP(back propagation) neural network load identification model was constructed. The road test method was used to collect 5 sets of vibration acceleration data and a single set of stress load data of the crawler travel system. Discussed the influence of road roughness frequency and driving wheel meshing frequency on the vibration and stress load of crawler travel system. Used fast Fourier transform to denoise the original stress load data. According to the ride comfort index of the crawler travel system, the sym8 wavelet function was used to extract the five-layer feature of the vibration acceleration signal to improve the accuracy of load identification. Then 5 groups of wavelet transform decomposed acceleration data and filtered stress load data were used as the input and output of the GA-BP neural network for training and verification, revealing the relationship between vibration and stress load in the moving process of the crawler travel system. The results show that road roughness frequency, meshing frequency, and rotating frequency are the main frequency components of crawler vibration, the vibration frequency caused by road roughness is 13.765 Hz, the meshing frequency of the driving wheel is 68.25 Hz, and the rotating frequency is 3.25 Hz. After many tests, the best hidden layer neurons number of BP neural network is 63. The stress load identified by the GA-BP neural network is highly consistent with the expected stress load, and the relative error is 4.5%, which verifies the effectiveness of the method. It provides a good theoretical basis for the reliability research of the crawler travel system of coal mine machinery.
2022 Vol. 41 (3): 54-61 [Abstract] ( 154 ) HTML (1 KB)  PDF (2597 KB)  ( 274 )
62 Test of a new vertical eddy current magnetic hybrid damping device
ZHU Qiankun, MA Qifei, ZHANG Qiong, DU Yongfeng
A new type of vertical eddy current magnetic hybrid damper is developed for the vibration reduction of long-span lightweight structures. Firstly, the vibration reduction principle and vibration equation of the hybrid damper are introduced; then, the design and manufacture process of three different magnetic circuits are introduced; then, the prototype is tested to measure its dynamic parameters and vibration reduction performance. The results show that the geometric stiffness of the damper can be changed by installing magnets behind the copper plate and above the bottom plate; the specific magnetic circuit design reduces the eddy current damping coefficient, and increases the equivalent magnetic damping coefficient and negative stiffness. Among them, the vibration reduction rate of the eddy current damper on the structural model can reach 89.9%, and the vibration reduction rate of the three kinds of eddy current magnetic dampers can reach 92.5%, 94.8% and 95.9%, respectively. When the excitation amplitude increases, the control effect of eddy current magnetic damper is stronger than that of eddy current damper. This study has reference significance for the application and development of magnetic vibration reduction in civil engineering.
2022 Vol. 41 (3): 62-72 [Abstract] ( 107 ) HTML (1 KB)  PDF (3575 KB)  ( 101 )
73 Eigenvalue topology optimization of periodic cellular structures
FU Junjian1,2, ZHANG Yue2, DU Yixian1,2, GAO Liang3
To realize the vibration isolation performance optimization of scale-related periodic cellular structures, this paper proposed an eigenvalue topology optimization method of periodic cellular structures. The stiffness matrix and mass matrix of the cellular structures are reduced based on the substructural dynamic condensation method. Local level set functions are applied to implicitly describe the geometry of the cellular structures. The topology optimization model of periodic cellular structures is established to maximize the first 6 eigenvalues with volume fraction as the constraint. The topology optimization model is then solved by the optimality criteria method. The scale effect of the topology optimization of cellular structures is also investigated. Research shows that the proposed method can effectively realize the topology optimization of scale-related 2D and 3D periodic cellular structures. The computational efficiency of the eigenvalue topology optimization is also improved intensively.
2022 Vol. 41 (3): 73-81 [Abstract] ( 194 ) HTML (1 KB)  PDF (2489 KB)  ( 143 )
82 Ultimate seismic capacity loss of high arch dam based on mainshock-aftershock sequences
JIN Aiyun, WANG Jinting, PAN Jianwen
In the current practice of dam engineering, only the mainshock is considered in the seismic design of high arch dams, and the multiple aftershocks which may occur in an earthquake event are ignored. In this paper, the mainshock-ETA aftershock sequences which based on endurance time analysis (ETA) method are constructed and the loss of ultimate seismic capacity (USC) is defined. As a case study, the seismic behavior of the Dagangshan arch dam using the nonlinear analysis model of dam-reservoir-foundation systems, which considers the opening of contraction joints, the nonlinearity of dam concrete, and the radiation damping effect of semi-unbounded foundation. The analysis results show that the structure response resulted from ETA is comparable with that of incremental dynamic analysis (IDA). Mainshocks may results in the loss of the USC of high arch dams, which will increase with increasing in the mainshock intensity. Finally, the USC curve of the Dagangshan arch dam is generated. According the USC curve, the Dagangshan arch dam has a certain safety margin under design earthquakes.
2022 Vol. 41 (3): 82-89 [Abstract] ( 129 ) HTML (1 KB)  PDF (2296 KB)  ( 127 )
90 Dynamic characteristics of reinforced gravelly soil under semi-sinusoidal cyclic traffic dynamic load
WANG Jiaquan1,2, HOU Senlei1,2, LIN Zhinan1,2, HUANG Shibin1,2
In order to study the dynamic characteristics of reinforced gravel soil under traffic load with different reinforcement form, which included non-reinforcing, horizontal reinforcing, circular vertical reinforcing and circular 3-dimensional (3D) combination reinforcing with geogrid as the reinforcement material, a series of dynamic triaxial tests under multi-stage and long-term half sinusoidal cyclic load were carried out. And the formula of soil damping ratio under half sinusoidal cyclic load is deduced. Furthermore, the effects of the number of reinforced layers and confining pressure on the dynamic characteristics of circular 3D combination reinforced gravel soil were studied, such as the damping ratio and shaft curve. The test results show that under multi-stage cyclic loading, the damping ratio of gravelly soil samples increases in the early stage and then decreases. The damping ratio reaches its peak when the dynamic strain reaches about 1%, and the reinforcement can reduce the damping ratio of the samples. Hardin-Drnevich model was found it is applicable to describe the backbone curve of reinforced gravel soils. The parameters A and B have a linear and exponential relationships between confining pressure and reinforcement layers, respectively. Finally, the backbone curve equation of the circular 3D combination reinforced gravel soil under different confining pressures and reinforced layers is presented, which based on Hardin-Drnevich model.
2022 Vol. 41 (3): 90-98 [Abstract] ( 115 ) HTML (1 KB)  PDF (1335 KB)  ( 64 )
99 Noise suppression of landing gear cabin based on deformable cavity
ZHAI Qingbo1, NING Fangli1, DING Hui1, LIU Zhe1, WEI Juan2， LI Baoqing3
A landing gear cabin structure based on the deformable cavity is proposed. The tilt angles of the cabin floor and rear wall are adjusted by mechanical devices without additional cabin volume. The acoustic finite element method is adopted to investigate the noise suppression effect of the proposed structure at low Mach numbers. It is found that with the increase of the rear wall tilt angle, the noise inside and outside the cabin is significantly reduced. Meanwhile, the modal frequencies gradually increase, which is beneficial to avoid the occurrence of cabin structure. A small rear wall tilt angle can effectively improve the internal sound reflection environment, thereby suppressing the high-frequency modal noise and the overall sound pressure level inside the cabin. When the rear wall tilt angle is greater than a certain critical value, further increasing the tilt angle has no obvious effect on the suppression of high-frequency modal noise and the overall sound pressure level. Under the current simulation conditions, the optimal range of the rear wall tilt angle is from 10 degrees to 16 degrees.
2022 Vol. 41 (3): 99-106 [Abstract] ( 127 ) HTML (1 KB)  PDF (2538 KB)  ( 30 )
107 Dynamic response of Q460 high strength steel column under near explosion load
ZHANG Xiuhua1, ZHANG Weijia1, ZHANG Yu2
The finite element models of steel column were established by ANSYS/LS-DYNA.The dynamic responses of Q460 high strength steel columns under explosion load were simulated by fluid-solid coupling method. On the basis,a piecewise equivalent triangular wave calculation method is proposed to apply explosive load to the structure/member, and the major influencing factors were numerically analyzed.The results show that the piecewise equivalent triangular wave calculation method is in good agreement with the fluid-solid coupling method, and the feasibility of that is verified. The blast wave with high velocity, high peak load and short duration has strong destructive force on the steel column. The greater the steel strength grade, the stronger the steel column's ability to resist deformation. The lower the explosive position,the easier the shear failure of the column foot. The flange, as the blasting surface, is more resistant to explosion shock. Properly reducing the width to thickness ratio of flange and web can enhance the ability of steel column to resist dynamic load.The piecewise equivalent triangular wave calculation method can provide further reference for the study of explosion resistance.
2022 Vol. 41 (3): 107-114 [Abstract] ( 149 ) HTML (1 KB)  PDF (2567 KB)  ( 234 )
115 Calculation method for contact stiffness of contact surface based on multi-scale plastic index model
ZHAO Yongsheng1,2, NIU Nana1,2, YANG Congbin1,2, LIU Zhifeng1,3, JIANG Kai1,3, MENG Lingjun1,3
The contact characteristics of the joint surface of the bolt connection is the key to affect the dynamic and static characteristics of the mechanical system. When the joint surface is in the vibration fatigue state, it will lead to an increase in damping and a decrease in resonance frequency. Therefore, it is very important to establish an accurate prediction model of bolted joint surface for studying the dynamic characteristics of the entire machine tool. This paper combines the plastic exponential expression, statistical roughness parameter and fractal parameter given by Greenwood and Williamson, and establishes a plastic exponential model related to the frequency order of microconvex body, so as to obtain the elasticity-elasticity-plasticity of microconvex body according to the plastic index.  The critical frequency ordinal of plastic deformation, and based on the Hertz contact theory, the contact load and contact stiffness of the entire joint surface are obtained by integrating the micro-convex bodies in different frequency intervals.  Finally, the combination of finite element simulation and experiment verifies the correctness of the theoretical model, and proves that the above theoretical model has strong engineering application value.
2022 Vol. 41 (3): 115-122 [Abstract] ( 164 ) HTML (1 KB)  PDF (1550 KB)  ( 208 )
123 Experimental test for power generation performance of I-L composite piezoelectric beam energy harvester with magnetic nonlinear coupling
WANG Man1,2, HOU Chengwei1, MENG Jinpeng1, YANG Xiaohui1, SONG Rujun1
Here, aiming at problems of narrower energy capture frequency band and lower output of linear piezoelectric vibration energy harvester, an I-L composite piezoelectric beam energy harvester with magnetic nonlinear coupling was proposed. The energy harvester was composed of I-shaped piezoelectric beam with permanent magnet and L-shaped one. Different nonlinear magnetic coupling effects could be obtained by adjusting horizontal distance between the two permanent magnets. The test results showed that there is an optimal resistance to maximize output power of the piezoelectric energy harvesting(PEH) system; compared with the non-magnetic system, the resonance frequency of the proposed energy harvester has an obvious shift with I-type piezoelectric beam shifting to the left and L-type one shifting to the right to widen the energy capture frequency band of the system; when the excitation acceleration is 0.2g, the horizontal distance is 20 mm and the excitation frequency is 18.4 Hz, the proposed energy harvester can obtain the maximum output power of 1.2 mW.
2022 Vol. 41 (3): 123-128 [Abstract] ( 136 ) HTML (1 KB)  PDF (1834 KB)  ( 140 )
129 Nonlinear vibration calculation method for cable-stayed bridge based on finite element & vector form finite element method
WANG Tao1, HU Yupeng2, ZHANG Xingbiao1, LIU Degui1
Vector form finite element method in essence is an explicit dynamic time-history integration method by considering geometric nonlinearity. The basic principle of vector finite element was described. The similarities and differences between the vector form finite element method and the nonlinear finite element method dynamic calculation based on co-rotational formulation element coordinate system are compared. A program for calculating the unified algorithm framework of finite element and vector form finite element using link and beam elements was developed. It makes up for the shortcomings of the two calculation methods. The calculation model of the long-span cable-stayed bridge was established by using the program. Firstly, the nonlinear finite element method was used to calculate the static state and dynamic characteristics of the cable-stayed bridge, and the vibration of the bridge under the coupled dynamic action of train and bridge was calculated. Then, the nonlinear vibration characteristics of cable-stayed bridge under the condition of sudden cable fracture are calculated by using vector form finite element method. Finally, the vibration state of the bridge and the train when the cable breaking under train-bridge coupled dynamic effect was calculated. The results show that, the nonlinear vibration of cable-stayed bridges under failure can be simulated directly and reliably by using vector form finite element method. When the train runs near the mid-span, if the longest cable breaks suddenly in the mid-span of a cable-stayed bridge, the safety of other cables is not affected much, and the further away from the broken cables, the less affected the cables are. The sudden fracture of the cable can pose a threat to the safety of the moving train. This paper provides a new technical scheme for nonlinear vibration analysis of long-span cable-stayed Bridges under failure condition.
2022 Vol. 41 (3): 129-138 [Abstract] ( 152 ) HTML (1 KB)  PDF (3224 KB)  ( 252 )
139 A new blind deconvolution method based on signal subspace
ZHOU Tao1,2, ZHAO Ming1, GUO Dong2, OU Shudong1
The deconvolution methods have been widely applied to extract the fault impulse from the vibration signal. However, due to the complex and changeable operating conditions of the equipment, the difficulty in accurately predicting the fault feature period and the interference of random impulse, the current deconvolution method is difficult to meet the requirements of the enhanced fault impulse in the complex environment of the industrial site. To solve the above problem, a blind deconvolution method based on signal subspace was proposed. The method decomposed the test signal space and separated each subspace by singular value decomposition (SVD), restrained subspace noise by sparse code shrinkage. Then effective subspace was screened based on impulse sparse index. Finally fault impulse was extracted by iteration. The experimental results of bearing simulation signals in variable speed and train bearing show that proposed method can effectively eliminate the interference of random impulse and noise, avoid the influence of energy on subspace screening, and accurately extract fault impulse without the precise fault feature period.
2022 Vol. 41 (3): 139-147 [Abstract] ( 141 ) HTML (1 KB)  PDF (2707 KB)  ( 309 )
148 Real time hybrid test method for cable-damper system based on energy consistent integration
YANG Ge1,2, SUN Hongshuo1, WU Bin1, PAN Tianlin3, WANG Zhen1
Real-time hybrid simulation is a seismic test method which is capable of investigating the dynamic performance of velocity dependent specimens and can be applied to study the mechanical behavior of cable-damper system. Due to the strong geometric nonlinearity of the cable, the traditional integration algorithm with linear unconditional stability cannot guarantee the stability of calculation in the dynamic analysis of cable-damper system. The energy-consistent integration algorithm can achieve unconditional stability for nonlinear system, but when applied to real-time hybrid simulations, the loading speed of actuator will fluctuate greatly due to iteration. In order to apply the energy-consistent integration algorithm to real-time hybrid simulations, fixed iterative steps were adopted and the iterative displacements were interpolated to achieve smooth loading, then the measured restoring forces of the experimental substructure were modified to ensure consistency of the system energy. At last, a real-time hybrid simulation of a cable-damper system under first-order modal vibration was carried out to verify the feasibility of the proposed method.
2022 Vol. 41 (3): 148-153 [Abstract] ( 162 ) HTML (1 KB)  PDF (1094 KB)  ( 53 )
154 Fast fault diagnosis algorithm for rolling bearing based on transfer learning and deep residual network
LIU Fei1, CHEN Renwen1, XING Kailing2, DING Shanshan1, ZHANG Maiyi1
Aiming at the shortcomings of the existing deep learning-based rolling bearing fault diagnosis algorithms that the training parameters are large, the training time is long, and a large number of training samples are required, a fast fault diagnosis algorithm (TL-ResNet) based on Transfer Learning (TL) and Deep Residual Network (ResNet) is proposed. First developed a method of converting vibration signals into three-channel image data by combining short-time Fourier transform (STFT) with pseudo-color processing; then the ResNet18 model trained on the ImageNet dataset is used as a pre-training model, and applied to the field of rolling bearing fault diagnosis through the method of transfer learning; finally, the method of small sample transfer is proposed for the fault diagnosis of rolling bearing under different working conditions. Experiments were performed on the Case Western Reserve University（CWRU）and Universität Paderborn（PU） datasets. The diagnosis accuracy of TL-ResNet is 99.8% and 95.2%, respectively, and the training time of TL-ResNet on the CWRU dataset is only 1.5s, which shows that this algorithm is superior to other deep learning-based fault diagnosis algorithms and classic algorithms, it can be used for rapid fault diagnosis in actual industrial environments.
2022 Vol. 41 (3): 154-164 [Abstract] ( 490 ) HTML (1 KB)  PDF (3545 KB)  ( 216 )
165 Vibration fault identification method of hydropower unit based on EEMD-SDCCⅠ-HMM
HU Xiao1, XIAO Zhihuai1,2, LIU Dong3, ZHAO Wenli4, WANG Hai4, JIANG Wenjun1
In order to solve the problem of fault diagnosis of hydropower units, a fault identification method based on ensemble empirical mode decomposition (EEMD), curve code (CC) and hidden Markov model (HMM) was proposed. Firstly, EEMD was used to process the vibration signal of the unit to obtain a series of intrinsic mode functions (IMFs) , and the corresponding Standard Deviations (SDs) were calculated. Then, the curve plotted by the SDs was coded into a digital sequence called CC as a fault feature. Finally, the feature vectors were input as learning samples into the HMM to train and obtain the parameters of the HMM of each state. Through comparing the log-probabilities output of various models, the state of the test sample could be judged. The test results showed that the method can effectively extract the fault characteristics from vibration signal of the unit and identify the fault type. At the same time, compared with conventional fault identification methods, it has a higher accuracy.
2022 Vol. 41 (3): 165-175 [Abstract] ( 146 ) HTML (1 KB)  PDF (4385 KB)  ( 108 )
176 Tests and robustness analysis for asymmetric NES
WANG Jingjing1,2, ZHANG Chao3, LIU Zhibin1, LI Haobo4
To address current issues existing in tuned mass dampers (TMDs) and nonlinear energy sinks (NESs), a new type of mass damper, asymmetric nonlinear energy sink (Asym NES) is proposed. Asym NES is configured based on type I NES in which a linear force is introduced at a new force equilibrium position to compensate the nonlinear force, the restoring force of asymmetric NES is, therefore, a combination of linearity and nonlinearity. The Asym NES is experimentally tested on a small-scale three-story steel frame structure under impulsive excitations. The proposed device shows excellent control capacities on different structures. Using the validated numerical model, an Asym, a TMD, and an NES are numerically compared on a six-story primary structure. Structural response comparisons show that Asym NES exhibits effective control capacity in cases of various input energy and decreased structural frequency, demonstrating strong frequency-robustness and energy-robustness.
2022 Vol. 41 (3): 176-182 [Abstract] ( 180 ) HTML (1 KB)  PDF (2395 KB)  ( 79 )
183 Tendon damage identification of 10 MW floating wind turbine based on CMS-CNN
XU Zifei1,2, YANG Yang2,3, LI Chun1,4, MIAO Weipao1, ZHANG Wanfu1, JIN Jiangtao1, WANG Xinyu1
A novel end-to-end Diagnosis model named Continuous-Multi-Scale Convolutional Neural Network (CMS-CNN) has been proposed to improve the rate of identification of structural damage on the damaged tendons in the float wind turbine platform. The effectiveness of the proposed CMS-CNN is examined by a 10MW float wind turbine model. The damaged locations and damaged degrees of the tendons in the 10MW float wind turbine are diagnosed by the proposed method. The results show that: The model considered more information by the continuous multi-scale coarse-grained procedure has better performance than the traditional multi-scale based model. The CMS-CNN model, using sway acceleration as the inputs, is more reliable than the model using the other accredited information. The CMS-CNN model can locate the damaged positions in the initial stages of damage evolution and diagnose both the locations and degrees of recessive damage of the tendons.
2022 Vol. 41 (3): 183-189 [Abstract] ( 130 ) HTML (1 KB)  PDF (3446 KB)  ( 55 )
190 Semi analytical solution to hydro-elastic slamming of wedge with constant velocity and free-falling body
FENG Song1, GAO Jian2, CHEN Yuzhen3, SUN Zhe1, ZHANG Guiyong1,4
A semi-analytical solution based which couples Wagner theory and modal superposition method is proposed to investigate hydroelastic slamming of two-dimensional flexible wedges. The velocity potential on the wetted surface is solved based on Wagner theory and the hydroelasticity effect is considered. Slamming load is obtained through Bernoulli equation and the velocity square term is considered to improve the accuracy. The averaged elastic velocity is used to account the effect of hydroelasticity and forming the fluid added mass and damping matrix. The coupling equation is established by incorporating the fluid added mass and damping in the solid dynamic equation and solved by the implicitly Newmark-β scheme. Two types of wedge motion are simulated i.e. vertical impact with constant velocity and freefall motion. The proposed algorithm is proven to be reliable by comparison with semi-analytical method, numerical solutions and experimental results in the published studies.
2022 Vol. 41 (3): 190-198 [Abstract] ( 168 ) HTML (1 KB)  PDF (2120 KB)  ( 30 )
199 Nonlinear vibration characteristics of integral blade disc coated with strain-dependent hard coating
GAO Feng1,2, LIU Xiuting1,3, HUA Guoxiang1
In order to improve the operating life and working reliability of the blisk, a damped vibration reduction method by the strain-dependent hard coating was proposed, and the nonlinear vibration characteristics of the hard-coating blisk were studied in this paper. Firstly, using the experimental discrete values and the high-order polynomials, the continuous mechanical parameters of the strain-dependent hard coating were characterized well; and then, the nonlinear vibration model of the hard-coating blisk considering the strain-dependent manner was established by the energy-based finite element method consisting of the improved complex modulus and composite Mindlin plate theory; next, an iterative solution procedure employing the Newton-Raphson method was developed to solve its nonlinear resonant frequencies and responses. Finally, an academic blisk deposited NiCoCrAlY+YSZ hard coating on blades was chosen to conduct vibration calculations and experiment, and the influence of strain-dependent manner on the the blisk were investigated emphatically. The comparative results show that by damping hard coating can suppress the vibration responses of the blisk effectively, and the strain-dependent manner can further enhance the performance of vibration reduction on the blisk effectively.
2022 Vol. 41 (3): 199-208 [Abstract] ( 136 ) HTML (1 KB)  PDF (2552 KB)  ( 65 )
209 Evaluation method of bearing performance degradation based on EMD multi-scale Weibull distribution and HMM
WANG Ran1, ZHOU Yanxiang1, HU Xiong1, CHEN Jin2
As an important part of rotating machinery, bearing’s performance degradation assessment is an important prerequisite for predictive maintenance. In view of the lack of robustness and sensitivity of the existing performance degradation indicators, a bearing performance degradation assessment method based on multi-scale Weibull distribution of empirical mode decomposition (EMD) and hidden Markov model (HMM) is proposed. Firstly, the bearing vibration signal is decomposed by EMD, and the bearing vibration data are decomposed into several intrinsic mode components of different scales. Then, the IMF components with obvious fault characteristic information are selected by kurtosis index, and each intrinsic mode function（IMF）component is fitted by sliding window Weibull distribution. The multi-scale Weibull shape parameters are extracted as performance degradation features. Finally, the degradation characteristic parameters of the bearing in the normal state are input into HMM for training, and then the established performance degradation assessment model is utilized to realize bearing performance degradation assessment . Experimental results show that the proposed method can effectively reflect the bearing’s performance degradation trend. Meanwhile, compared with other related methods, the proposed method can identify the early fault of the bearing in time with strong stability.
2022 Vol. 41 (3): 209-215 [Abstract] ( 161 ) HTML (1 KB)  PDF (2008 KB)  ( 199 )
216 Fault recognition of rolling bearing based on improved 1D convolutional neural network
WANG Qi, DENG Linfeng, ZHAO Rongzhen
Fault recognition of rolling bearings is largely significant to prevent the deterioration of the rotating machinery system and to guarantee its safe operation. Aiming at the problem that the used intelligent diagnosis models usually have too many parameters and low recognition efficiency, a rolling bearing fault recognition method based on improved one-dimensional convolutional neural network(FRICNN–1D) is proposed in this paper. For one thing, the 1×1 convolution kernel is introduced to enhance the nonlinear expression ability of the one-dimensional convolutional neural network model; for another, the global average pooling layer is used to replace the fully connection layer in the traditional convolution neural network, so as to reduce the model parameters and the amount of calculation and prevent over fitting phenomenon. The experimental results show that the proposed method can accurately recognize different fault status of a real rolling bearing and has particular potential in engineering application.
2022 Vol. 41 (3): 216-223 [Abstract] ( 251 ) HTML (1 KB)  PDF (2880 KB)  ( 261 )
224 Modal parallel algorithm based on Shenwei heterogeneous multi-core processor architecture
YU Gaoyuan1,2, MA Zhiqiang1,2,3, LI Junjie1,2, JIN Xianlong1,2
According to the architecture characteristics of domestic heterogeneous multi-core processor, a hierarchical communication parallel computing algorithm for structural modal finite element analysis is proposed, which has important significance to improve the parallel efficiency of the system modal analysis on the entire large structure under the domestic heterogeneous multi-core and distributed memory parallel computers. Based on hierarchical communication and accelerating subspace iteration, a parallel computing system for a large-scale modal analysis was established, which can not only significantly improve communication rate through the hierarchical computing and communication, but also improve data access and storage rate through the distributed storage of a large amount of data. As a typical application, it was used to get solutions to the main structure of a certain brake system on ultra-deep drilling rig and the over-river tunnel, a parallel modal analysis with over ten-million-DOF was performed and ten thousands of core processors were applied. Then, the correctness and efficiency of the proposed method were validated. The results showed that the proposed parallel solving system can significantly improve the parallel efficiency of the modal analysis on the major equipment system with the domestic heterogeneous multi-core and distributed memory parallel computers.
2022 Vol. 41 (3): 224-230 [Abstract] ( 171 ) HTML (1 KB)  PDF (2602 KB)  ( 237 )
231 Numerical calculation method and laws for nozzle damping of solid rocket motor
ZHAO Tianquan1, ZHANG Xiangyu1, GAN Xiaosong2
From the perspective of acoustics, referring to the steady-state wave attenuation method, comprehensively considering the nozzle radiation loss and convection loss, the acoustic energy resonance numerical calculation method for solid rocket motor nozzle damping is established, and the simulation method is verified by comparing with the test results measuring by impedance tube method. The influence of nozzle throat diameter, monitoring point location, sound source intensity and average pressure on nozzle damping is explored. The results show that the numerical results are in good agreement with the experimental results, which shows that the simulation method established in this paper is effective; The damping of nozzle increases with the increase of throat diameter, which reduces the pressure amplitude when the steady standing wave is formed in the cavity. The analysis results of the sound transmission characteristics show that the nozzle throat diameter increases, the sound power transmission coefficient increases, and the nozzle damping increases; The position of the monitoring point and the intensity of the sound source have no effect on the nozzle damping, but affect the pressure amplitude; Both damping and pressure amplitude have nothing to do with the average pressure.
2022 Vol. 41 (3): 231-237 [Abstract] ( 139 ) HTML (1 KB)  PDF (2902 KB)  ( 182 )
238 Chaotic characteristics analysis of tunnel blasting vibration signals
XIE Quanmin1,2， JIA Yongsheng1,2， DING Kai3， ZHANG Jie4， LING Zhendong4， LIU Dingshen5
Based on the chaos theory, the phase space reconstruction of the vibration response time series of the existing tunnel under the action of the blasting of the adjacent tunnel and the blasting of the upper span tunnel was carried out by using the attractor and Lyapunov The core parameters, such as index and correlation dimension, were calculated to analyze the chaotic characteristics of tunnel blasting vibration response signal. After calculation, the phase space reconstruction of the vibration response signal of the existing tunnel under the blasting action of the adjacent tunnel has strange attractor, and the Lyapunov index is greater than 0. It can be judged that it has chaotic characteristics. The Lyapunov index of the vibration response signal of the existing tunnel under the blasting action of the upper span tunnel is greater than 0. It shows that it also has chaotic characteristics. The research shows that the blasting vibration signal of the tunnel has chaotic characteristics. As the blasting distance between the drilling and blasting working face and the existing tunnel decreases, the value becomes larger, the chaotic characteristic of the tunnel blasting vibration response increases, and the rational optimization of blasting parameters and blasting should be strengthened. Vibration real-time monitoring to ensure construction quality and blasting safety.
2022 Vol. 41 (3): 238-244 [Abstract] ( 218 ) HTML (1 KB)  PDF (2047 KB)  ( 177 )
245 Vibration characteristics analysis of rail squats and harm of rail in heavy haul railway
LIU Guangpeng, XIAO Hong, WANG Hongge, JIN Feng, YANG Songlin
Rail squats are widely exist in heavy-haul railways, resulting in an increase in the dynamic response of the entire track-subgrade at the diseased location, which seriously affects the normal service status of the track-subgrade. In order to study the characteristics of the time-frequency domain effects of typical rail squats on the entire track-subgrade in heavy-haul railways, on-site static testing and cause of disease analysis were carried out, and the dynamic test comparison between the diseased section and the normal section was carried out. Experiments have obtained the time-frequency domain and vibration transmission characteristics of the diseased section. The results show that: the rail head of the diseased section has local collapse, shelling and multiple cracks. There will exist obvious crack propagation area on the surface of the rail head, which extend in a Y-shape and have a tendency to penetrate the entire rail head. The track-subgrade vibration of the diseased section is obviously larger than the normal section, and the average value of the vibration of the rail, sleeper, ballast and subgrade is 26, 23, 13 and 5 times than the normal section respectively. The track-subgrade spectrum peak of the diseased section has a periodic modulation frequency with the bogie and the adjacent wheelbase at a fundamental frequency of about 10 Hz. The serious pulverization of ballast under the sleeper on the damaged section results in almost no attenuation of vibration energy near 2000Hz, while the vibration energy of the normal section decreases sequentially from top to bottom around 2000 Hz. The increase of vehicle speed has the strongest impact on the vibration and impact of the diseased section rail, and the impact on the lower sleepers and subgrade gradually weakens in the interval of 45~75km/h.
2022 Vol. 41 (3): 245-252 [Abstract] ( 190 ) HTML (1 KB)  PDF (3282 KB)  ( 233 )
253 Anti-impact performance of marine medium voltage AC vacuum circuit breaker structure
HUANG Lei1, WANG Huamin1, TU Yu1, WANG Wei2, SHA Xinle1, XU Tingwei1
Anti-shock capability of marine electromechanical equipment is an important indicator for assessing the reliability in wartime. In this paper, the impact machine test and numerical simulation method were used to study the anti-shock capability of the breaker. The results show that the impact test has changed three-phase overtravel of breaker due to structural deformation. The high stress area of the model mainly exists in the bottom plate and supporting base, using numerical simulation method (frequency domain load) to improve the model structure, and the improved structure fulfil requirements.The transient response characteristics under the time domain load show that the vertical response is relatively sharp, the horizontal and vertical directions are relatively gentle, and the response has dramatic value in 0.015s, and tends to be stable at 0.15s. The model response results under the two loads are relatively close. The statistical results of the frequency domain load stress value are slightly larger than the time domain load. The frequency domain load simulation is more conservative. The research results are generally applicable to the anti-shock research of similar marine equipment.
2022 Vol. 41 (3): 253-261 [Abstract] ( 109 ) HTML (1 KB)  PDF (4281 KB)  ( 156 )
262 Explicit closed form solution to dynamic response of retaining wall under continuous action of soil
CHEN Qingsheng1, HU Yun1, KE Wenhai1, XU Changjie1,2, PENG Zewen1
The dynamic interaction between retaining wall and soil is the key factor affecting the seismic response of retaining wall. It is understood that, the continuum medium model is the main approach to analyze the dynamic interaction between retaining wall and soil. However, significant disadvantage exists in current continuum medium model considering that it cannot obtain the exact expression of parameters governing the dynamic interaction between retaining wall and soil, which could help to understand the seismic response mechanism of retaining wall. To address this issue, in current study, a simple and efficient continuous medium model is developed by introducing the least square response surface method to investigate the dynamic response of retaining wall under earthquake loading conditions. In the proposed method, the dynamic interaction between retaining wall and soil are governed by five components: wall bending, shear resistances of soil, Winkler modulus, inertia of wall and inertia of soil. The results show that the proposed model can provide simple and accurate estimation of the dynamic response of retaining wall. The translation factor and rotation factor are very sensitive to the frequency of the incident wave, and greatly affected by the relative flexibility coefficient of the retaining wall. Also, the internal force of the retaining wall is sensitive to the relative flexibility coefficient, rotation coefficient and incident wave frequency. In addition, the dynamic response of retaining wall is greatly influenced by the constraint conditions.
2022 Vol. 41 (3): 262-267 [Abstract] ( 117 ) HTML (1 KB)  PDF (1424 KB)  ( 30 )
268 Effects of elastic support model on structural vibration response during rocket launch
ZHAO Zhenjun1, ZANG Yuqing1, LI Qiang1, SHI Xiaojun2
The launch dynamics model including rocket, launch tube and elastic support is established by multibody dynamics to study the influence of elastic support model on structural vibration response during solid rocket launching from tube. Based on the analysis of rocket launching physical process, the finite element model of elastic support and rocket shell is established using ANSYS/LS-DYNA software to obtain the influence of the contact area between elastic support and rocket shell on support stiffness, based on which the improved elastic support model is proposed for multibody dynamic modeling of rocket launch. The structural vibration response and the reaction of the elastic support before and after the improvement of the elastic support model are solved to analysize the influence of the improved elastic support model. The results show that the proposed improved elastic support model can accurately describe the physical process of the contact area gradually changing to zero in separating the elastic support of the rocket tail, and the peak moment response decreases significantly compared with the original model. It is helpful to accurately calculate the structural response of the rocket launch process, and has engineering significance for refined design of rocket structure.
 
2022 Vol. 41 (3): 268-277 [Abstract] ( 170 ) HTML (1 KB)  PDF (3441 KB)  ( 69 )
278 Numerical simulation for flow-induced vibration of regular triangular column under different angles of attack
WEI Yuhan, JI Chunning, XU Dong, CHEN Weilin
The flow induced vibration of a equilateral triangular prism with different angles of attack is studied by using the immersed boundary method. The angles of attack is α=0°-60° (a vertex of the triangular prism faces the flow when α=60°), the Reynolds number is Re=100, the mass ratio is m*=5, and the reduced velocity is Ur=2-20. The transverse vibration amplitude, the vibration frequency, the hydrodynamic coefficients, the phase difference between the lift and displacement and the wake pattern are investigated with different angles of attack and reduced velocities. Results show that there are three different vibration modes: the combined vortex-induced vibration (VIV) and galloping in the range of α=0°-15°, the separated VIV and galloping at α=20°-22.5°, and VIV in the range of α=25°-60°. Three angles of attack of α=0°, 20° and 60° are selected in this paper to discuss the flow-induced vibration characteristics of the triangular prism. It is found that the lateral shift of the balanced position of the triangular prism is non-zero at some Ur when α=0°, and the occurrence of this phenomenon is related to the even harmonic component of the lift. Moreover, the α range of galloping is further investigated by using the quasi-steady theory. The results show good agreement with the numerical simulation, which indicates that the quasi-steady theory can accurately predict the α range of galloping of the triangular prism.
2022 Vol. 41 (3): 278-286 [Abstract] ( 148 ) HTML (1 KB)  PDF (2797 KB)  ( 246 )
287 Principal-internal joint resonance of an axially moving conductive beam between parallel conductors
LI Xiaojing1,2, HU Yuda1,2
The principle-internal resonance of an axially moving conductive beam in the magnetic field induced by parallel wires is investigated. Based on the theory of electromagnetic field and Hamilton principle, the nonlinear vibration equation of the beam under external excitation and magnetic field is derived. For a conductive beam with one side clamped and the other side hinged, the approximate analytical solution and the amplitude frequency response equations for the nonlinear equation are derived by the multiple-scale method, and the stability of the steady-state solutions are also analyzed. Through numerical examples, the corresponding amplitude curves of the first two order vibration modes varying with different frequency tuning parameters, external excitation force, axial velocity and current intensity are obtained. The results show that the first and the second-order response are both excited, and different multi-solution regions are found. The number of steady-state solutions of the first and second-order amplitudes changes simultaneously in the multi-solution regions, and the number depends on the external excitation force, moving velocity and current intensity value.
2022 Vol. 41 (3): 287-298 [Abstract] ( 115 ) HTML (1 KB)  PDF (3416 KB)  ( 215 )
299 Numerical code development and dynamic response of articulated offshore wind turbine
ZHANG Pei1,2,3, TANG Yougang1,2,3, YANG Shugeng1,2,3, LI Yan1,2,3, JING Xuejiao1,2,3, YIN Tianchang1,2,3
A new-type articulated offshore wind turbine (AOWT) is proposed for the water depth of 50 m, and an analytical model for the swing motion of AOWT was established. Through adopting the aerodynamic-hydrodynamic coupling analysis method and programing MATLAB code, the dynamic response of the structure under the action of different environmental loads such as wind, wave and flow was analyzed. Besides, the influence of the steady and turbulent wind models on the overall movement and load response of the structure was conducted. The results show that AOWT has great movement and load performance under the rated wind condition, the structure design meets the requirements of safe operation. Compared with the steady wind, the amplitude changes greatly under the action of the turbulent wind, but the mean value significantly decreases, and a large coupling resonance is induced in the low frequency range.
2022 Vol. 41 (3): 299-306 [Abstract] ( 160 ) HTML (1 KB)  PDF (2060 KB)  ( 217 )
307 Evolution prediction of tailings flow in dam break of tailings pond under model test and numerical simulation
LUO Changtai1,2, LI Dongwei1, YU Guoping3, ZHANG Chaochao1, XU Bin2
The tailing flow generated after dam failure will evolve into Geo-hazards like debris flows. Tailings flow is characterized by rapid development, strong destructiveness, wide range of influence and insufficient warning time. It is of great significance for disaster prevention and mitigation to study the evolution law of dam-break tailings flow and its influence range. In the study, we used RAMMS debris flow software to establish a numerical three-dimensional model for the numerical simulation of dam-break. We tested the evolution process and influence range of the dam-break tailings flow on the downstream by building a physical model (1:150), and compared the experimental data with the numerical calculation results to verify the reliability and effectiveness of the numerical simulation. The results showed that in the process of the tailings dam-break, the tailings flow began to impact downstream villages (0.7 km away from the tailings dam) within 9 minutes when we started timing from the over-topping water reaches the bottom of the dam. As the dam break continued, the dam-break silt deposits gradually deepened, and the water level continued to rise. Finally, it caused a full-scale flooding of the downstream within 18 minutes, with an impact area of 0.558 km2, and the total amount of tailings in the reservoir could reach 1.3×107m³. It is strongly recommended that the design, management and risk assessment of tailings dams should be combined with potential hazards to increase disaster prevention and mitigation measures.
2022 Vol. 41 (3): 307-315 [Abstract] ( 175 ) HTML (1 KB)  PDF (2690 KB)  ( 33 )
316 Nonlinear dynamic analysis of SWR under random load
GU Honglu， LI Xiaomin， GUO Haiyan， CUI Peng， LIU Zhen， LI Fuheng
Numerical investigation was conducted for the nonlinear dynamic analysis of steep wave riser (SWR) under random load. The numerical model of SWR with internal flow was established based on the slender rod model. The Newmark-β method was adopted to solve the dynamic behavior of SWR. A corresponding calculation process, DRSWR, was programmed with MATLAB. Calculation results were compared with those of OrcaFlex to verify the accuracy and reliability of DRSWR. Furthermore, the parametric sensitivity analysis of SWR stress under the combination excitation of random wave and top floater motion was obtained. The analysis results show that the buoyancy section of SWR has the highest global stress level and stress variation amplitude. The peak points of stress are located at the arc bend point and sag bend point. Random wave with large significant wave height and low period can cause a sharp increase in the global stress level. An increase in the mean offset leads to a decrease in stress extremes. Low frequency motion, with a large magnitude and high frequency, can significantly increase the stress of hang-off point. SWR shows high stress under high-density, high-flow velocity internal flow.
2022 Vol. 41 (3): 316-324 [Abstract] ( 142 ) HTML (1 KB)  PDF (2523 KB)  ( 339 )
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