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2024 Vol. 43, No. 8 Published: 2024-04-28 1 Research on crack propagation mechanism of rock impacted by particles under confining pressure LIU Yong1,2，LI Xing1,2，GUO Xinhui1,2，WEI Jianping1,2，SONG Dazhao3 In order to reveal the influence of the confining pressure on the formation and expansion mechanism of rock fissures under particle impact, particle impact rock-breaking experiments and micro-nano industrial CT scanning experiments were carried out, which clarified the influence of the confining pressure on the characteristics of the rock fissure expansion under the action of particle impact; and numerical simulations were carried out on the particle impact under the conditions of different confining pressures, to analyze the evolution process of the rock's stress and fissure fields, and to reveal the intrinsic mechanism of the confining pressure influencing the expansion of fissures. The results show that after the particles impact the rock, a fracture zone and intergranular main crack propagation zone are thus formed in the rock. The shear stress and tensile stress caused by compressive stress are the main reasons for the formation of the fracture zone, while the formation of the intergranular main crack propagation zone is mainly due to tangential derived tensile stress. The confining pressure induces prestress between rock particles such that the derived tensile stress needs to overcome the initial compressive stress between the particles to form tensile fractures. And the increase in the confining pressure leads to increases in the proportion of shear cracks and friction effects between rock particles, resulting in an increase in energy consumption for the same number of cracks，which inhibits the formation of the fracture zone and intergranular main crack propagation zone. 2024 Vol. 43 (8): 1-10 [Abstract] ( 203 ) HTML (1 KB)  PDF (3286 KB)  ( 76 ) 11 Vibration characteristics of misalignment-rubbing coupling fault foran axial-flow hydrogenerator unit ZHANG Leike1，YU Jianhui1，WANG Xueni2,1，ZHANG Jinjian3，MA Zhenyue3，DENG Xianyu4 Aiming at the vibration problem of the rub-impact rotor-runner system in axial-flow hydrogenerator set caused by misalignment of coupling Angle, based on the modified LuGre friction model,the expressions for the rub-impact forces of runner blades under the misalignment fault are derived in this paper. On this basis, the system dynamic model is established which comprehensively considers external excitations including unbalanced magnetic pull force. The influence of the misalignment angle on the vibration characteristics of the system is studied by numerical method, and the stability of the periodic solution of the system with the speed as the control variable is analyzed based on Floquet theory. The results show that the existence of misalignment significantly changes the dynamic characteristics and increases the possibility of system instability. In addition, the effect of the misalignment angle on the vibration response of the rotor and the runner is quite different. With the increase of the misalignment angle, the runner vibration varies obviously and the degree of rub-impact is worse. The research results in this paper can provide references for the safe operation and stability analysis of axial-flow hydrogenerator set. 2024 Vol. 43 (8): 11-18 [Abstract] ( 93 ) HTML (1 KB)  PDF (1833 KB)  ( 93 ) 19 Design and performance study of wireless metal corrosion probes using piezoelectric tube stack WANG Jianjun1，LIU Honghui2，CAO Yalei1，FU Xuanming3，LI Weijie3，LUO Mingzhang4，LAN Chengming2 A type of metal corrosion probes was proposed using piezoelectric tube stack and electro mechanical impedance (EMI) technique. The probe consists of a piezoelectric tube stack and a metal bar. The transfer matrix model of the multilayer structured probe in longitudinal vibration mode was established, and the electrical impedance was derived to solve the first resonance and anti-resonance frequencies. The theoretical results were validated by comparing them with those of the special cases in the published literature. In addition, the probe performance was studied systematically through theoretical analysis, artificial uniform corrosion experiments, temperature-sensitive experiments, accelerated corrosion tests, and wireless impedance measurement experiments. The results show that the first resonance and anti-resonance frequencies of the probe are increased with the decrease of the bar length, the increase of the corrosion days, and decreased with the increase of temperature. The measured impedance spectra of the wireless impedance measurement system are very consistent with the test results of the traditional impedance analyzer. The present study provides an important reference for developing the novel metal corrosion probes of wireless quantitative measurement. 2024 Vol. 43 (8): 19-33 [Abstract] ( 418 ) HTML (1 KB)  PDF (3223 KB)  ( 26 ) 34 Model updating and virtual verification for launch vehicle strap-on thermal mechanical structures HE Kui1，ZHANG Wei2，LI Changlong2，PEI Changhao2 Facing the lack of experiment data, a model updating and virtual verification method considering modelling uncertainty is proposed to obtain accurate thermal-mechanical coupling finite element model (FEM) for launch vehicle strap-on structures. The proposed method makes full use of the experiment data of previous model and enable the new developing model without any experiment data, through the virtual mapping, verification and calibration based on the generalized theoretical model of friction heat. Firstly, the FEM of previous model is established and calibrated through the Bayesian updating framework. And then, determine the undetermined coefficients in theoretical model to reduce the discrepancy between theoretical value and simulation result. Finally, verify and calibrate the FEM of new developing model based on the theoretical model. The proposed method is performed to solve digital modeling and verification problem of a novel developing strap-on structure without sufficient experiment data and the result shows the calibrated FEM has higher accuracy and reliability. 2024 Vol. 43 (8): 34-42 [Abstract] ( 52 ) HTML (1 KB)  PDF (2030 KB)  ( 19 ) 43 A study on flow-solid coupling distributed parameter model and utility of non-standard water tanks in nuclear power engineering LI Jianbo1,2，LIU Jia1,2，LI Zhiyuan3，LIN Gao1,2 In the realm of fluid-structure interaction dynamics, the traditional Housner model plays a pivotal role in engineering design. However, its theoretical derivation is limited to regular water tanks, employing a concentrated mass overall model to describe the global effect of liquid oscillations. This approach inadequately captures the finely detailed responses of irregularly shaped liquid storage structures, necessitating the development of a distributed additional mass model suitable for simulating oscillations in irregular water bodies.Through potential flow theory, a modal synthesis model is derived, achieving the decoupling of distributed mass and the vibrational acceleration of the liquid storage tank wall. This model effectively disentangles distributed impulse mass and convective mass. Moreover, the vibrational mode analysis of solid grids is applicable to the dynamic analysis of water bodies with arbitrary shapes. The model's accuracy and reliability are verified through comparisons with detailed Computational Fluid Dynamics (CFD) simulations.Finally, utilizing the proposed model, this study investigates the dynamic response patterns of safety tanks with irregular shapes in nuclear power plants at various water levels and sway grid distributions. The applicability of the model in engineering scenarios is demonstrated. 2024 Vol. 43 (8): 43-51 [Abstract] ( 53 ) HTML (1 KB)  PDF (2333 KB)  ( 33 ) 52 Fault warning method of a hydropower unit based on IMSGP-WEDI CAO Chaofan1，LI Mingliang2，JIANG Shuangyun1，ZHANG Guangtao3，LI Zhongliang1，LU Na1 The early warning of faults in hydropower units is greatly affected by the warning indicators. However, these indicators are mostly based on single sensor signal and information, and therefore limited in their abilities to comprehensively characterize the unit operating status. To address this issue, a method combining Integrated Multi-Sensor Genetic Programming (IMSGP) and Weighted Euclidean Distance Index (WEDI) is proposed. First, multiple sensor signals are preprocessed to eliminate interference. Next, multivariate features are extracted from the preprocessed signals to construct the original warning feature set. Then, the Composite Detection Index (CDI) is used for feature selection, and IMSGP is investigated for feature construction. Finally, Principal Component Analysis (PCA) and the Euclidean distance are used to construct WEDI for identifying abnormal states of the unit. Through analysis of hydropower unit data, the ability of the proposed method on detecting early faults and achieving effective fault warning were verified. 2024 Vol. 43 (8): 52-60 [Abstract] ( 75 ) HTML (1 KB)  PDF (2329 KB)  ( 70 ) 61 Numerical simulation of loosening law of bolted joints under lateral vibration ZHAO Weiping1，CHANG Haotan1，JI Chunlei2，GUO Xinsuo1，HE Yuxiang1 The bolted connection joints of transmission towers often experience loosening due to transverse cyclic loads, resulting in damage to the transmission towers. Currently, many single-bolt tests conducted on vibration test machines and finite element studies are not applicable to the actual working conditions of angle steel-bolt group joints due to bolt constraint issues. To address this problem, a refined bolt model considering thread incline is established in ABAQUS. The applicability of the finite element model is verified based on the results of fastener tests. The bolt model is then extended to complex single-limb, single-wrap, and double-wrap angle steel-bolt group joint models to analyze the loosening mechanism and pre-tension variation process of bolt group joints under transverse vibration loads. The analysis results show that under transverse cyclic loads, the pre-tension alternates between increasing and decreasing. The thread contact surface enters the slip state before the pressure surface of the bolt head. With an increase in the friction coefficient and pre-torque, the decreasing trend of pre-tension becomes smaller. With an increase in vibration amplitude, the decreasing trend of pre-tension becomes larger. The vibration frequency has a negligible impact on bolt loosening. The degree of bolt loosening in single-wrap and double-wrap joints gradually decreases from the outer side to the inner side. Applying preload will reduce the tendency of bolt loosening to some extent. The degree of loosening for double-limb single-packet joint bolts decreases by 16% to 23.24%, and for double-limb double-packet joint bolts, it decreases by 2.63% to 3.80%. Therefore, it is important to monitor the easily loosened bolt locations in actual engineering to ensure the load-bearing capacity of the joints. 2024 Vol. 43 (8): 61-69 [Abstract] ( 67 ) HTML (1 KB)  PDF (2872 KB)  ( 62 ) 70 Interval analysis for normal contact stiffness of mechanical joint surface based on the Legendre-scanning method LIU Yong1，QU Jie1，ZHANG Qing1，WANG Dawei1，YAN Fangchao2 An interval model was established to analyze the normal contact stiffness of a mechanical joint. The model takes into consideration the uncertain parameters such as asperity radius of curvature, distribution density, and asperity height variance. To address the limitations of traditional contact stiffness models in determining the reasonable range of normal contact stiffness, the KE elastic-plastic contact stiffness model and Legendre polynomials were utilized. The model was validated by comparing it with contact stiffness test data and traditional model solution results. The feasibility and accuracy of Legendre-scanning method were proved by the results. The results show that the rough surface topography parameters have a significant impact on normal contact stiffness, with the uncertainty of asperity height variance having the greatest influence. As the dimensionless contact distance decreases, the degree of influence increases. The establishment and analysis of the interval model for normal contact stiffness in mechanical joints can serve as a reference for further research on joints. 2024 Vol. 43 (8): 70-77 [Abstract] ( 47 ) HTML (1 KB)  PDF (1780 KB)  ( 30 ) 78 Sensitivity analysis of the coupling model of a hydro-turbine governing system and a shaft system to system parameters ZHANG Zhiping1，ZHANG Songxiao1，YANG Xiong1，QIN Cheng1，SUN Jie2，FENG Chen3，ZHANG Yuquan3 The frequent transient process of pumped storage power station has an important effect on shafting vibration, so it is very important to establish a coupling model between the regulation system and shafting which can reflect the transient response of hydropower units for the safe operation of pumped storage power station. In this paper, a transient coupling model between the regulation system and the shafting system considering multiple vibration factors is established based on the torque equation derived from the Lagrangian formula. The dynamic response process of the shafting under different load rejection is calculated, and the influence of the eccentric mass of the generator and the excitation current of the generator on the transient process of the shafting is analyzed. It is found that the more the load is rejected, the more severe the vibration of the shafting in the process of dynamic response. After 30 %, 60 % and 100 % load rejection, the amplitude of the generator rotor in the x direction is increased by 68.7 %, 109.3 % and 126.3 % respectively compared with that before load rejection. The larger the eccentric mass of the generator is, the higher the amplitude of the shaft system of the hydro-generator set in the dynamic response process is, and the more unstable the system is. The larger the excitation current is, the smaller the amplitude of the shaft system in the response process is, which is more conducive to the stable operation of the system. The purpose of this paper is to provide a method for the establishment of the transient coupling model of the regulating system and shafting system of hydro-generator set, discuss and evaluate the parameter sensitivity of the transient coupling model under load rejection, and ensure the safe and stable operation of the unit under the transient state. 2024 Vol. 43 (8): 78-88 [Abstract] ( 70 ) HTML (1 KB)  PDF (6657 KB)  ( 16 ) 89 The homotopy analysis for the nonlinear dynamics of a multi-mesh gear train XUN Chao，WU Haixuan，WANG Yunlong The nonlinearity in the multi-mesh gear train due to the periodically time-varying mesh stiffness, contact loss, and the couplings between the multi-mesh stiffnesses are considered. The nonlinear oscillation is investigated by the homotopy analysis method (HAM). And closed-form approximations for the primary resonance, sub-harmonic resonance, and super-harmonic resonance are obtained. In contrast to the method of multi-scale (MMS), the HAM is independent of the contact loss ratio. Results indicate that with large contact loss ratios over 30%, the amplitude-frequency curves obtained by HAM agree better with the numerical integration (NI) results than those obtained by the MMS. This study lays a higher accurate foundation for more complex nonlinear dynamic analysis of gear sets. 2024 Vol. 43 (8): 89-97 [Abstract] ( 46 ) HTML (1 KB)  PDF (1725 KB)  ( 14 ) 98 Seismic performance of the variable hysteresis performance damper and its application in RC bridge bents DONG Huihui，LI Yanling，HAN Qiang，DU Xiuli To achieve the purpose of multi-level protection of the main structure and reduce the residual deformation of conventional energy dissipation dampers under strong earthquakes, A novel variable hysteresis performance damper based on shape memory alloy (SMA-VHD) is proposed. This paper elucidates the damper's configuration, variable hysteresis performance, and working mechanism. A refined finite element model of the damper is formulated by leveraging the outcomes of plate specimen tests using SMA. The hysteresis performance study and parametric investigations are based on the verified finite element model. Finally, the multi-level seismic performance of a double-column RC bridge bents with additional variable hysteresis performance damper is studied by dynamic time-history analysis. The results indicate that SMA exhibits a distinctive stress-strain relationship resembling a flag, which shows good self-centering capability. The SMA-VHD actualizes variable hysteresis performance, with the hysteresis response transitioning from rectangular to flag-shaped as the damper deformation increases, accompanied by a prominent multi-level platform. Applying SMA-VHD to RC bridge bents imparts multi-level seismic performance and enhances the structure's seismic performance. 2024 Vol. 43 (8): 98-108 [Abstract] ( 65 ) HTML (1 KB)  PDF (2921 KB)  ( 127 ) 109 A robust CHIEF method for a coupling boundary element method and an equivalent source method BAO Yingchao1,2，XIANG Yu1,2，CHEN Jie1,2，SHI Ziyu3 Aiming at the problem of non-uniqueness of solution and singular integral in acoustic boundary element method, based on the idea of CHIEF method, the conventional boundary element equation and the equivalent source equation are combined, and the coupling equivalent relation between the coefficient matrix of the two equations is used to indirectly replace the singular coefficient matrix in the conventional boundary element method, and then a coupled CHIEF method with unique solution in full frequency domain, high computational accuracy and high stability is proposed. In this method, the equivalent source equation is used as the supplementary equation, which not only solves the failure of the interior point supplementary equation of the traditional CHIEF method, but also avoids the direct calculation of singular integrals by the indirect substitution of matrix, which significantly improves the computational efficiency and accuracy. Through typical examples of acoustic radiation and scattering, the results of the proposed method, conventional boundary element method, conventional Burton-Miller method and equivalent source method are compared. The results show that not only the unique solution can be obtained in the full wavenumber domain, but also the calculation accuracy and efficiency of the proposed method are better than those of the conventional boundary element method and the conventional Burton-Miller method, and the condition number of the coefficient matrix is much lower than that of the equivalent source method. 2024 Vol. 43 (8): 109-118 [Abstract] ( 163 ) HTML (1 KB)  PDF (2822 KB)  ( 31 ) 119 Analysis of wheel rail vibration response caused by wheel flat of heavy freight vehicles under braking conditions QI Yayun1,2，ZHANG Wenqian1，ZHANG Liangwei2，JIANG Ruijin2，LIU Fengwei2 With the development of heavy haul railway in China, the axle load of heavy haul freight vehicles is increasing, and the problem of wheel flat is also increasingly prominent, this problem lead to a dramatic increase in dynamic wheel rail loads. In this paper, a rigid-flexible coupling dynamic model of heavy haul freight vehicle-track is established, and the influence of wheel flat on vertical force and longitudinal creep between wheel and rail is investigated under different braking conditions of heavy haul freight vehicles, and the limit value is calculated. The results show that the P1 and P2 forces of the vehicle increase with the increase of the length and speed of the wheel flat, and the emergency braking condition is greater than the normal braking condition. The wheel/rail vertical force of the empty car is far less than that in the load car, but the wheel/rail vertical force fluctuation of the empty car will be greater under the effect of the flat. On the other hand, the braking of the vehicle will lead to changes in the longitudinal creepage and the longitudinal creep force. At the same time, the longitudinal creepage and the longitudinal creep force will fluctuate under the action of the wheel flat. The larger of the wheel flat, the greater the fluctuation. According to the wheel/rail vertical force and wheel load reduction rate specified by the state, the wheel flat limit value of the vehicle under different working conditions is calculated. Combining the empty and load vehicles as well as the braking conditions, the limit value of wheel flat of the heavy haul freight vehicle is obtained as 38mm.. The study will provide relevant guidance for the operation and maintenance of heavy haul freight vehicles. 2024 Vol. 43 (8): 119-126 [Abstract] ( 58 ) HTML (1 KB)  PDF (2239 KB)  ( 31 ) 127 Experiment and numerical simulation of a novel dual self-centering friction damper QU Juntong，BAI Yuxiang，ZHANG Chao，LI Yuheng，WANG Wenbin，PU Junxiang To improve the re-centering capacity of damper, a dual self-centering driven system composed of reset spring and shape memory alloy (SMA) is proposed. A novel dual self-centering friction damper is designed, and its configuration and working principle are summarized. The effects of preloading force, loading displacement amplitude and the reset spring module stiffness on the re-centering and energy dissipation capacity were investigated by cyclic loading tests. The simplified mechanical model of the damper is established, and the analysis of numerical simulation is carried out. The results show that although increasing the preloading force can improve the energy dissipation capacity of the damper, it also increases the residual deformation rate. Under relatively large preloading force and loading displacement amplitude, the reduction of residual deformation rate caused by dual self-centering driven system is obvious, which is beneficial to improve the re-centering capacity of the damper with high energy consumption demand. The hysteresis curves and mechanical performance parameters of the damper obtained by simplified mechanical model and finite element simulation using OpenSees match well with the experimental results, which verifies the accuracy of the mechanical model. The contribution of each functional component to the overall performance of the damper is analyzed by finite element simulation. The analysis results reflect that the friction energy dissipation device has a good contribution to the overall energy dissipation capacity of the damper, and the contribution of the reset spring to the re-centering capacity of the damper becomes obvious with the increase of the preload. 2024 Vol. 43 (8): 127-135 [Abstract] ( 59 ) HTML (1 KB)  PDF (3635 KB)  ( 55 ) 136 Research on coal and gangue recognition method based on auditory feature fusion YANG Zheng1，WANG Shibo1,2，RAO Zhushi3，YANG Shanguo1,2，YANG Jianhua1,2，LIU Songyong1,2，LIU Houguang1,2 Aiming at the problem that it is difficult to recognize the caving coal gangue in the process of fully mechanized caving mining under the background of strong noise, a coal and gangue recognition method fusing low-level auditory feature Mel spectrum and high-level auditory feature auditory neurotransmitter firing rate is proposed. Firstly, according to the frequency spectrum characteristics of the sound signal of the tail beam of collapsed coal and gangue impact hydraulic support, an auditory model suitable for the coal gangue recognition task is established based on the auditory neural filter bank model. Then, the auditory model is used to analyze the sound signal of collapsed coal and gangue to obtain auditory neurotransmitter firing rate. Afterwards, the auditory neurotransmitter firing rate is fused with the peak feature extracted by Mel spectrum to obtain the auditory perception diagram of coal and gangue sound. Finally, coal and gangue were recognized with the ConvNeXt model based on the fusion auditory features constructed. The experimental results showed that the proposed coal and gangue recognition method with fusion auditory features had high recognition accuracy under different signal-to-noise ratios, and its superiority was particularly evident under the condition of large background noise (signal-to-noise ratio of -5dB), with accuracy reaching 91.52%, which was significantly superior to the method using low-level auditory features and spectrum as recognition features and using time-frequency domain features combined with machine learning, verifying the robustness of the proposed method to noise. 2024 Vol. 43 (8): 136-144 [Abstract] ( 105 ) HTML (1 KB)  PDF (2430 KB)  ( 51 ) 145 Remaining useful life prediction of component kernel density estimation considering environmental changes ZHAO Bin，LI Jiajuan，SHI Hui，REN Qianli，KANG Hui To address the problem that the remaining useful life prediction accuracy of a component is affected by environmental changes during operation, a kernel density estimation remaining useful life prediction model considering the impact of environmental shocks is proposed. Firstly, the non-parametric estimation method of adaptive kernel density is used to model the continuous natural degradation process of the component; secondly, assuming that the impact of the harsh environment on the component is the random shocks on the component, the remaining useful life prediction model is established by introducing a virtual age function and a variable sudden failure threshold under the consideration of changing the operating environment conditions to correlate the impact on the component with the continuous degradation process stochastically, and its reliability is analyzed. Finally, the accuracy and validity of the proposed model are verified by the experimental simulation analysis of wind turbine degradation data and gearbox wear measurement data. 2024 Vol. 43 (8): 145-154 [Abstract] ( 70 ) HTML (1 KB)  PDF (2716 KB)  ( 62 ) 155 Numerical simulation of droplet microdroplet movement in a flat finned tube under vibration GUAN Weijuan1,CHEN Qinghua2,3,ZHANG Bin3,JI Jiadong3,WANG Jiangang3,4,LIU Ping3 In the flat finned tube heat exchanger working in low temperature and high humidity environment, frost phenomenon is easy to occur, resulting in increased energy consumption and failure rate. The vibration effect on the microdroplet at the initial stage of frost formation can accelerate the sliding process of the microdroplet and thus achieve the effect of frost formation. The growth process of microdroplet in the early stage of frosting was numerically simulated and analyzed, and the growth characteristics of microdroplet on different surfaces were obtained and verified by the literature values. Then, the effects of different vibration frequencies were studied by using the data of microdroplet at different times through numerical simulation, and finally an experimental platform was built for verification. The results show that for different surfaces, the larger the surface contact Angle is, the slower the growth rate of microdroplet is. The optimal vibration frequency corresponding to different volumes of microdroplets is different. When the volume of microdroplets is small, the higher vibration frequency makes the microdroplets oscillate back and forth on the wall surface of the base tube, which is not easy to slip off. When the volume of microdroplets is large, the higher vibration frequency is conducive to the microdroplets overcoming the wall friction and the droplet sliding off. 2024 Vol. 43 (8): 155-161 [Abstract] ( 57 ) HTML (1 KB)  PDF (1370 KB)  ( 15 ) 162 Pre-tightening state identification of a wedge-ring connection structure based on thesiamese neural network SHENG Junjie,WANG Jiulong,LI Shuyong,WEN Yong Because of its simple and reliable connection, as well as the advantages of space saving and weight reduction, the wedge-shaped ring connection structure is often used in torpedoes, aerospace vehicles and other weapons and equipment. Aiming at the problems of complex mechanism model, small sample size and class imbalance of wedge-shaped ring connection structure, a method of Pre-tightening state identification based on the siamese neural network is proposed in this paper. A time-frequency feature enhancement technology is used to improve the efficiency and effect of model training. Based on the enhanced features, a three-layer siamese neural network classification model is established to realize the macroscopic classification of Pre-tightening state identification of wedge-ring connection structure. On this basis, in order to guide the precision assembly, the feature clustering effect of siamese neural network is deeply analyzed by feature visualization technology. The pre-tightening state quantitative characterization model is established by using two-dimensional features, and the target state clustering center and acceptance domain are introduced to realize the quantitative evaluation of the pre-tightening state of the wedge-ring connection structure. Experiment has verified the effectiveness of the proposed method. The research results provide a new technical approach and solution for Pre-tightening state identification of wedge-ring connection structure. 2024 Vol. 43 (8): 162-168 [Abstract] ( 46 ) HTML (1 KB)  PDF (2053 KB)  ( 15 ) 169 A study on the damping performance alteration of a fluid viscous damper considering oil leakage and temperature variation effect YANG Menggang1,CAO Kaiyue1,LI Xin2,HU Shangtao1 As a widely used passive vibration control device, the fluid viscous damper exhibits mechanical performance alteration throughout the entire service life. To explore the mechanical parameter changing mode and reveal the mechanism of performance alteration, experimental and simulation studies were conducted with oil leakage and temperature effects as the main influencing factors. Firstly, cyclic tests and viscousity-temperature analysis were carried out on viscous dampers under different oil leakage levels and ambient temperatures, respectively. Secondly, fluid dynamics simulations were performed to obtain the alternating tendency of the hysteresis performance. Finally, an analytical model reflecting the performance alteration of viscous dampers under combined oil leakage and temperature effects was established and verified. The results show that oil leakage will cause a “zero-force gap” appearing in the hysteresis loop, of which the length is proportional to the leakage level. Temperature increase will lead to a decrease in the damping coefficient, which affects the peak damping force. The established performance alteration model can accurately reflect the changes in mechanical performance of viscous dampers. 2024 Vol. 43 (8): 169-177 [Abstract] ( 48 ) HTML (1 KB)  PDF (2746 KB)  ( 16 ) 178 Dynamic response of asymmetric integrated underground structures under multilayer traffic loads QIAN Jinsong1,CHEN Zheng1,OUYANG Wei1,2,LIU Haiyang1,ZHOU Yiheng1 The dynamic response of underground structures under traffic loads has a significant impact on their safety and stability during operation. In order to investigate the dynamic response characteristics of the asymmetric integrated underground structure with large cross-section under the action of multi-layer traffic loads, this paper establishes a finite element model based on a typical cross-section of a project, simulates the application of traffic loads on road surface, municipal layer and railway layer, analyzes the vibration response and stress distribution characteristics of the asymmetric integrated underground structures, and explores the superposition law of structural dynamic response generated by the joint action of multi-layer traffic loads. The results show that the vibration response of the asymmetric integrated structure is the highest in the middle of the left top plate of the municipal transportation layer, reaching 0.5~0.7m/s2, and the dynamic stress is the highest at the bottom corner of the rail transportation layer, reaching 0.08~0.1MPa. The subway train load is the main source of the dynamic stress of the structure, but the soil nail support and pile foundation support can effectively reduce the effect of the dynamic stress. The vibration response of the integrated structure is significantly affected by the vehicle load on the ground. During the operation period, special attention should be paid to structures located in densely populated road sections with ground vehicles. The research results can provide reference for optimization design and maintenance of underground asymmetric integrated structures during operation. 2024 Vol. 43 (8): 178-185 [Abstract] ( 54 ) HTML (1 KB)  PDF (2244 KB)  ( 20 ) 186 Dynamic analysis and optimization of the belt feed arm of a cased telescoped ammunition machine gun LIU Qiang1,ZHOU Kedong1,LI Donghao2,LU Ye1,HE Lei1,REN Haiyue1 A cased telescoped ammunition machine gun uses a cased telescoped ammunition which is completely different from the traditional one. In order to adapt to this kind of ammunition, the structure of the cased telescoped ammunition machine gun is also very different from the traditional machine gun. Compared with the traditional machine gun, the cartridge feeding travel of the cased telescoped ammunition machine gun is at the rear part. In order to reduce the length of the whole gun, the length of the curve groove in the belt feed arm has to be shortened. This makes the impact force of the guide pillar of bolt carrier on the ammunition transfer lever very large when the guide pillar enters the curve groove of the belt feed arm. This impact will have a very adverse impact on the reliable operation of the entire feed transfer mechanism, and will also seriously decrease the kinetic energy of the bolt carrier, making it difficult to complete the ammunition ramming action. Now the maximum impact force between the guide pillar and the belt feed lever is taken as the objective function, and the quintic function is selected as the the theoretical contour curve of the belt feed lever curve groove. The genetic algorithm is used to optimize the theoretical contour, so that the maximum impact force between the guide pillar and the belt feed lever is reduced to 1/3 of that before optimization. The test verification shows that the speed loss of the bolt carrier is reduced from 0.94m/s to 0.28m/s when the guide column enters the curve groove of the belt feed arm, and the optimization purpose is achieved. The research results in this paper provide a reliable theoretical basis for the improvement of the gun. 2024 Vol. 43 (8): 186-192 [Abstract] ( 39 ) HTML (1 KB)  PDF (1560 KB)  ( 5 ) 193 Experimental study on rock fracturing mechanism of high speed Kinetic energy hydraulic fracturing WU Feipeng1,2,ZHAO Zhiqiang1,YAN Bingfu2,DING Qianshen3,LIU Jing1,2,QI Ning1,2,LUO Mingliang1,2 High-velocity and hydraulic kinetic energy fracturing can achieve hydraulic penetration impact with strong dynamic load. This technology mainly utilizes the water hammer effect, which has many unique advantages, such as high peak pressure, high loading rate, and repeated progressive expansion of cracks. The evolution mechanism of rock damage-fracturing process under the hydraulic penetration impact of charged fluid is the core issue in the optimization design of this technology. Therefore, a rock dynamic damage simulation experimental device was employed to conduct a series of rock dynamic failure experiments under strong hydraulic penetration impact. The influence law was analyzed based on loading rate, impact times, and combined repeated impact on rock failure morphology. The results indicate that, If a single hydraulic penetration impact is conducted on rocks, three different rock failure modes are presented in sequence as the loading rate increase. These are near wellbore crushing damage (8.5MPa/ms), forming macroscopic cracks due to the aggregation and concatenation of microcracks (13.4MPa/ms), fluid wedging brittle cracking (15.5MPa/ms). Under repeated impacts with low peak pressure and low loading rate, rock damage and failure exhibit three stages: near wellbore crushing damage (1-2 times), cracks initiation and propagation (3-5 times), and stress compression crushing (6-10 times). As the number of impacts increases, the damage around the hole intensifies, forming cracks of varying length. 2024 Vol. 43 (8): 193-201 [Abstract] ( 44 ) HTML (1 KB)  PDF (2540 KB)  ( 52 ) 202 Identification of CFST voids based on mutual information and MiniRocket network QIN Yue1,XIE Kaizhong1,2,3,GUO Xiao1,2,3,WANG Hongwei4,WANG Qiuyang1,PENG Jiawang1 In order to improve the efficiency and accuracy of concrete filled steel tube（CFST） void detection， an intelligent recognition method based on FFT (Fast Fourier Transform), MI (Mutual Information) and MiniRocket neural network is proposed in this paper. First, the time domain signal of the CFST percussion wave to be measured is converted to the frequency domain signal using FFT. Secondly, MI is used to establish the correlation between the frequency domain signal and the void state, and the top 30 features with the largest correlation are extracted to establish the data set, which avoids complex mathematical operations and redundant information. A MiniRocket deep learning network is established, and by using fewer parameters and smaller feature sizes improving the speed and accuracy of classification. Finally, the noise robustness of the model is investigated and compared with other algorithms, feature extraction methods and recognition methods. The results show that the proposed method achieves 100 % average prediction accuracy in 100 repetitions of the experiment for different void depths and void widths. At high SNR, this method is less affected. In addition, compared with other algorithms, feature extraction methods and recognition methods, this method has better prediction performance. Therefore, the proposed method has great application potential in the actual intelligent void identification of CFST in the future. 2024 Vol. 43 (8): 202-212 [Abstract] ( 42 ) HTML (1 KB)  PDF (3938 KB)  ( 72 ) 213 A study on pipeline vibration reduction technology based on a magnetic damping dynamic vibration absorber ZHOU Shuai,GAO Hongbo,LIN Lei,CHEN Zhilin,XU Decheng,CHEN Mingya (五号加粗) In order to solve the problem of pipeline vibration in power industries such as nuclear power and thermal power, a one-way damped dynamic vibration absorber suitable for three-dimensional pipelines based on fixed point theory was developed and designed. And a key parameter calculator based on visual basic was compiled. The effectiveness of the dynamic vibration absorber in three-dimensional pipeline vibration reduction was verified through finite element simulation, installation location parameter optimization, and experimental verification. The conclusion is as follows: The dynamic vibration absorber developed can effectively reduce the vibration of three-dimensional pipelines. The vibration reduction effect verified by experiment is similar to that verified by simulation calculation. 2024 Vol. 43 (8): 213-220 [Abstract] ( 55 ) HTML (1 KB)  PDF (2345 KB)  ( 27 ) 221 Linear variable parameter μ synthesis robust control of solenoid valve semi-active suspension KOU Farong1,LI Shenglin2,YANG Xudong2,XING Longlong2 A linear parameter varying(LPV) μ synthesis robust controller is designed for the nonlinearity, uncertainty problem, and the contradiction between multiple performance objectives in solenoid valve semi-active suspension systems. A nonlinear damping force dynamics model of the solenoid valve was established and performed on a bench test to verify the accuracy of the model. A nonlinear LPV model for a seven-degree-of-freedom suspension system was constructed. An LPV-μ synthesis robust controller based on nonlinear and mixed uncertainties is designed with analysis of suspension parameter uncertainties and system modeling errors and consideration of the effects of sensor measurement noise. Finally, the full vehicle solenoid suspension system simulation and real vehicle test were conducted. Simulation results show that the controller reduces the root mean square value of body vertical acceleration for 46.47%, the pitch angle acceleration for 46.47%, and the roll angle acceleration for 50.68% under random disturbance. It has excellent anti-jamming ability and controllability. The test results show that the root mean square values of the vertical acceleration, pitch angle acceleration, and roll angle acceleration are reduced by 36.6%, 30.14%, and 39.47%, respectively, under the LPV-μ synthesis control. In addition, the dynamic deflection of the suspension is ensured to be less than 0.06 m, which verifies the effectiveness of the control strategy. 2024 Vol. 43 (8): 221-231 [Abstract] ( 60 ) HTML (1 KB)  PDF (4717 KB)  ( 14 ) 232 Adaptive PI control research for precision platform magnetic-sensitive intelligent vibration isolation system ZHONG Can,HUANG Zhen,FU Jie,HAN Jinyu,YU Miao,QI Song To suppress time-varying vibrations in precision machining processes, a semi-active adaptive PI control method based on magnetorheological elastomer (MRE) was proposed. Firstly, the dynamic model of the MRE isolation system was established based on the variable stiffness isolation principle,and then the semi-active control conditions were derived. Secondly, taking the response acceleration and target acceleration deviation as the input of the PI controller, the optimal PI control parameters under different vibration frequencies and amplitudes were optimized by genetic algorithm, and the frequency amplitude dependent adaptive law was obtained based on the passive reference model.This method does not need to identify the frequency by complicated Fourier transform, and has high real-time performance. Finally, the effectiveness of the designed controller was verified by simulation and experiment. The results show that compared with the traditional PI controller, the proposed method has greater suppression at 40Hz-50Hz and 1.0 m/s2 - 3.0 m/s2 time-varying vibration. 2024 Vol. 43 (8): 232-237 [Abstract] ( 47 ) HTML (1 KB)  PDF (2129 KB)  ( 24 ) 238 Structure-acoustic coupling modal analysis and multi-objective optimization of an EMU head car YU Yang1,2, CAO Qijun2, LIU Chunyan1, CHEN Bingzhi2, YU Chunyang1 Currently, the generation mechanism and influencing factors of the structure-acoustic coupling resonance phenomenon in the realm of high-speed trains have not been thoroughly examined. Furthermore, the corresponding optimization design based on the structure-acoustic theory needs to be further developed. Based on the principles of modal and mass equivalence, this study establishes a finite element model for the head car of Electric Multiple Units (EMU). The modal analysis of the structural, acoustic, and structure-acoustic coupling systems is performed where the coupling influence of internal and external sound fields is taken into account. The results of the finite element analysis show that the modal frequencies of the structure conform to the relevant design standards. The acoustic frequency at a certain order closely aligns with the structural one, providing a reference for the subsequent coupling resonance optimization. The variation of the modal parameters demonstrates the necessity of considering the structure-acoustic coupling. Finally, based on the modal analysis results, two optimization designs are implemented for the head car: the first one aims to lighten the weight with adjusting the thicknesses of various areas, adhering to the constraint of the frequency of the first-order vertical bending structural mode; the second seeks to mitigate the effects of coupling resonance where a multi-objective optimization model is formulated aiming at maximizing the frequency difference between the structural and acoustic modes and minimizing the vehicle mass. 2024 Vol. 43 (8): 238-247 [Abstract] ( 49 ) HTML (1 KB)  PDF (1442 KB)  ( 63 ) 248 Wave input for foundation with horizontal layered overburden under seismic wave oblique incidence WANG Fei1,2, SONG Zhiqiang2, LIU Yunhe2, LI Chuang2, LI Zhenggui1, HU Ankui1, TIAN Qing3 The overburden has the characteristics of soil dynamic nonlinearity and structural layering, which increases the difficulty of free field calculation of foundation with overburden under seismic wave oblique incidence and affects the energy absorption capacity of artificial boundary. They restrict the accuracy and application of seismic wave input. The horizontal layered overburden is taken as the research object, the potential function theory is introduced, the dynamic transitive relation between the amplitude matrix of the top layer and the amplitude matrix of any layer is constructed under seismic wave oblique incidence, and the time domain strain of soil is calculated. Based on the two-dimensional strain state theory, the equivalent linearization method is used to reflect the dynamic nonlinearity of soil, the analytical calculation method for the free field of foundation with nonlinear horizontal layered overburden under seismic wave oblique incidence is established. Then, the nonlinear viscoelasticity artificial boundary element developed by the authors is used to simulate the radiation damping effect of the overburden. In near-field wave analysis, the boundary element parameters change with the dynamic shear strain of the inner soil element, the boundary element has the optimal energy absorption ability. Finally, combined with the equivalent input load obtained from the analytical free field, a seismic wave input method suitable for the foundation with nonlinear horizontal layered overburden under seismic wave oblique incidence is established. This method can achieve wave input for the overburden layer foundation based on the oblique incident waves at deep and surface ground motion. The implementation of wave input based on surface ground motion avoids the process of forward modeling free field through base ground motion. The seismic responses of foundations with elastic horizontal double layers and nonlinear horizontal multiple layers overburden are studied. The results show that the displacements and stresses obtained by wave input have a high degree of fit with the analytical solutions, and the calculation accuracy is high, it can provide a basis for the study of seismic response of embankment dam on the foundation with horizontal layered overburden. 2024 Vol. 43 (8): 248-256 [Abstract] ( 51 ) HTML (1 KB)  PDF (1865 KB)  ( 8 ) 257 An ultrasonic liquid level detection method based on the variation of reflected energy on the inner wall of a container ZHANG Tiaotiao, HE Xiping, LIU Yu The acoustic beam emitted by the transmitting and receiving probe located near the liquid surface height of the liquid tank outer wall passes through the tank wall to generate a projected area on the inner wall. In this paper, the relation between the proportion of liquid in the projected area and the energy is used to detect the change of liquid level in the range of probe height. The energy of the echo signal received by the probe is inversely proportional to the height of the liquid level, thus enabling determination of its position. The experimental system is set up, the echo signal is collected, and the liquid surface position relative to the probe is obtained by substituting the received energy value into the expression of the proportion of area. The liquid level calculation results are consistent with the actual liquid level position, and the error between the two is only less than 2.465 mm. The finite element simulation calculation also verified the relationship between the energy received by the probe and the changes in liquid level. 2024 Vol. 43 (8): 257-262 [Abstract] ( 48 ) HTML (1 KB)  PDF (1345 KB)  ( 6 ) 263 An adaptive equalization algorithm for active sound quality control of wiper-windshield friction noise FAN Huizhi1, GUO Hui1, FENG Qingbao2, SUN Pei1, WANG Yansong1, LU Zhonghui3 Wiper-windshield friction noise is one of the important factors affecting the vehicle interior sound quality, so it is beneficial for improving the interior acoustic environment by active sound quality control. A Weight Constrained Adaptive Noise Equalizer algorithm based on Ensemble Empirical Mode Decomposition (EWCANE) is proposed to control the wiper-windshield friction noise sound quality actively. Firstly, the EEMD method is used to decompose the wiper-windshield friction noise to obtain the lower non-stationary intrinsic mode function components, and the variance ratio of each component is calculated to characterize the degree of influence of each component on the noise. Then, the filter weight is adaptively constrained to reduce the transient shock characteristics of the noise through the Euclidean norm of the input signal and error signal. Finally, the sound gain factors are adjusted according to the variance ratios to balance the active control of sound quality for each component. The simulation results show that this method can significantly reduce the loudness value in the wiper-windshield friction noise signal of an actual vehicle and improve its sound quality. 2024 Vol. 43 (8): 263-271 [Abstract] ( 65 ) HTML (1 KB)  PDF (2291 KB)  ( 20 ) 272 Uncertainty quantification based on a covariance-driven stochastic subspace method LUO Jie, KANG Jie, SUN Jiabao, ZENG Shuhong Modal parameter identification based on covariance-driven stochastic subspace identification (SSI-COV) method has the advantages of strong robustness and high precision, and is widely used in structural operational modal analysis. In order to ensure the accuracy of modal parameter identification, the newly proposed uncertainty quantification method of modal parameters based on stochastic subspace identification (SSI) can effectively estimate the variance of modal parameters, but because when calculating each intermediate variable, it is necessary to display the Jacobian matrix, resulting in high matrix operation dimension and low calculation efficiency. Therefore, this paper proposes an efficient calculation method for modal parameter uncertainty based on SSI-COV. Firstly, calculate the variance of the vibration response correlation function, and the appropriate singular value truncation order is selected by singular value decomposition (SVD), and multiple sets of Hankel matrix perturbations are assembled from each order singular vector. Secondly, according to the first-order matrix perturbation theory, the first-order perturbations of each intermediate variable of the SSI-COV algorithm are implicitly calculated, and finally, the variance is calculated by the perturbation superposition of multiple sets of modal parameters. Finally, taking the truss structure model as an example, the proposed method is used to identify the modal parameters of the structure and calculate the modal parameter variance, and the influence of the truncated order of the singular value of the Hankel matrix dimension and related functions on the identification results is analyzed, and the results show that the calculated modal parameter variance is very close to the MCS result, and the modal parameter uncertainty can be used as an effective basis for eliminating false modes. 2024 Vol. 43 (8): 272-279 [Abstract] ( 60 ) HTML (1 KB)  PDF (1268 KB)  ( 103 ) 280 Effect of an inducer on cavitation flow field of a high-speed liquid-oxygen-pump DOU Wei1, JIANG Wenshan1, LI Chaoqun2, GAO Yongxin2, YAO Cheng2 High anti-cavitation inducer improves the cavitation characteristics of the liquid-oxygen-pump and enhances the reliability of heavy-lift rockets. Based on the computational fluid dynamics method, a geometry of the high-speed liquid-oxygen-pump is established to simulate its flow field. The accuracy of numerical model is validated with three test conditions. Effects of inducer-blade number on the performance and cavitation characteristics of the liquid-oxygen-pump are investigated in the present work. It is found that implementing inducer compensates for the cavitation in the centrifugal wheel by reducing the cavitation area and improves the pumping head of the liquid-oxygen-pump. When the inflow mass flow rate and the outflow pressure keeps constant, increasing the inducer-blade number enhances the liquid-oxygen-pump efficiency, but reduces the pumping head. Meanwhile, the ability of compensating cavitation weakens where the cavitation area increases in the centrifugal wheel. Considering the performance and cavitation characteristics of the pump, the inducer with three-blades satisfies the high reliability requirement for the heavy-lift rockets. 2024 Vol. 43 (8): 280-286 [Abstract] ( 61 ) HTML (1 KB)  PDF (1459 KB)  ( 21 ) 287 Design of a snowflake-shaped two-dimensional coupled vibration sandwich piezoelectric ultrasonic tranducer XU Long1,2, WANG Weizhen1, GONG Tao2, LI Guo3, ZHAO Lun2, ZHOU Guangping2, LIANG Shaofeng2 In order to realize the multi-directional ultrasonic radiation for a single transducer, a new type of snowflake-shaped two-dimensional coupled vibration sandwich piezoelectric ultrasonic transducer was proposed, which consists of a hexagonal prismatic metal block, six groups of piezoelectric ceramic crystal stacks and six metal cover plates. Based on the coupled vibration theory and the principle of electromechanical analogy, the equivalent circuit model of the transducer is established, and the resonance and anti-resonance frequency equations are derived. The two-dimensional coupled vibration characteristics of the transducer are studied by equivalent circuit method, finite element method and experiments. The results show that the effective electromechanical coupling coefficient of the transducer is higher when the piezoelectric ceramic stack is closer to the hexagonal prism central metal block. The longitudinal coupling resonance frequency decreases with the increase of the axial size of the transducer. In the longitudinal coupling resonance mode, the six output ends of the transducer can output consistent longitudinal displacement amplitude. The equivalent circuit method, finite element simulation and experimental test have achieved relatively consistent results. The research results of this paper provide a concise design theory for the engineering application of this kind of transducer. The research results are expected to be applied to multi-dimensional ultrasonic machining, multi-directional ultrasonic radiation and other fields. 2024 Vol. 43 (8): 287-293 [Abstract] ( 46 ) HTML (1 KB)  PDF (1475 KB)  ( 33 ) 294 Numerical simulation of glass panel impact damage based on peridynamics LI Songbo, WANG Zhiliang, SHEN Linfang, HUA Tao, LI Ze Based on the peridynamics method, a three-dimensional numerical model for rigid ball impact on glass panel was proposed considering the effects of material damage. And the effectiveness of the presented model was verified according to the Kalthoff-Winkler experiment. Finally, the impact failure evolution and crack propagation mechanism of the glass panel were explored considering the effects of the rigid ball initial impact velocity, the rigid ball diameter, and the glass panel thickness. The results show that the cracks in the glass panel exhibit a radial shape when the initial impact velocity is law. As the impact velocity increases, the circumferential cracks appear and a complex crack network gradually form in the glass panel. Meanwhile, the total length and the proportion of cracks in the glass panel increase with the increase of initial impact velocity, and the relationship between them is approximately linear. With the increasing of the rigid ball diameter, the contact area between the ball and the glass panel expands, which results in the more severe damage and easier formation of complex crack networks in the glass panel. In addition, increasing the glass panel thickness can prolong the impact duration, which makes the glass panel withstand greater impact energy. When the glass panel thickness is relatively thin, it results in more severe local structural damage and the smaller damage area; When the panel thickness is thicker, the structural damage area expands, while local damage weakens. 2024 Vol. 43 (8): 294-302 [Abstract] ( 62 ) HTML (1 KB)  PDF (1909 KB)  ( 38 ) 303 Aerodynamic noise characteristics and noise reduction design of fuel control valves for gas turbines ZHU Zhijie1, XU Qian1, FAN Xuefei1, WEI Xueyang2, CHEN Fuqiang2 Fuel control valve is a key flow valve used to control fuel flow in gas turbines. In the whole flow process, turbulence degree increases and aerodynamic noise is induced due to the valve spool throttling design. In order to reveal the formation mechanism of aerodynamic noise of the fuel control valve and propose the corresponding noise reduction design method, this study adopted the hybrid fluid-acoustic calculation method, and took methane (CH4) at 200℃ as the working medium to solve the steady-state flow field of the fuel control valve at five open degrees of 10%-100%. Taking steady flow field as the initial solution, the transient flow field parameters required for aerodynamic noise calculation of fuel control valve are solved. The aerodynamic noise propagation model is established and the aerodynamic noise characteristics of fuel control valve are solved. The noise reduction design of fuel control valve is carried out based on the theory of porous noise reduction. The results show that the omnidirectional aerodynamic noise characteristics of the fuel control valve show continuous broadband characteristics dominated by middle and high frequency, and the multi-hole muffling and throttling design can effectively reduce the noise. This study provides an important basis for suppressing pneumatic noise of control valve. 2024 Vol. 43 (8): 303-309 [Abstract] ( 40 ) HTML (1 KB)  PDF (2308 KB)  ( 31 ) 310 Dynamic characteristic analysis of machine tool bed considering contact stiffness of joint surface LIU Shusheng1, SHI Jun2, SUN Jianhong2, QIN Wenqiang3, ZENG Yanhong3, ZHANG Song1 The stiffness of the joint surface is an important factor that affects the dynamic characteristics and machining accuracy of a machine tool. To accurately determine the dynamic parameters of the machine tool, a prediction model is used to obtain the contact stiffness of the bed joint surface, and an equivalent dynamic model is established. Firstly, the contact stiffness prediction model is developed. Secondly, the prediction model is used to identify the contact stiffness of the joint surface between two materials (cast iron and mineral composite). Thirdly, using the contact characteristic parameters of the joint surface, a finite element model based on spring element constraint is created. Finally, comparing the finite element modal frequency with the experimental modal frequency reveals that the finite element modal frequency, based on the spring element constraint, aligns well with the experimental modal frequency. This indicates that the model is effective for both cast iron and mineral composites. The results demonstrate that incorporating the contact stiffness of the joint surface in the finite element model of the machine tool bed leads to a more reasonable representation. This provides a theoretical foundation for analyzing the dynamic characteristics of the machine tool and optimizing its structure. 2024 Vol. 43 (8): 310-318 [Abstract] ( 114 ) HTML (1 KB)  PDF (2289 KB)  ( 97 )

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