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2023 Vol. 42, No. 1 Published: 2023-01-15 1 Dynamic decoupling control of super static active vibration isolation platform with large mass eccentricity and spring lateral stiffness YANG Hongjie1,2, DAI Feng3, LIU Lei1,2, LI Xinguo1,2 Aiming at the multi-degree-of-freedom dynamic coupling problem of the ultra-quiet active vibration isolation platform induced by the eccentricity of isolated payload and the transverse stiffness of spring, the dynamic coupling characteristics of the vibration isolation platform and the decoupling vibration isolation control method are studied. Integrating the influence of the payload mass eccentricity and the spring transverse stiffness, a coupled dynamic model of the ultra-quiet active vibration isolation platform is first established. Subsequently, according to the established dynamic model, the dynamic coupling characteristics of the vibration isolation platform are analyzed, and the analytical relationship among coupling resonance frequency, spring transverse stiffness, and payload mass eccentricity is given. Finally, a decoupling vibration isolation control method based on modal space is presented, and an active vibration isolation platform based on voice coil motors is developed. The accuracy of the established dynamic model and the effectiveness of the modal decoupling vibration isolation control method are verified through experiments. 2023 Vol. 42 (1): 1-9 [Abstract] ( 144 ) HTML (1 KB)  PDF (2746 KB)  ( 79 ) 10 Tests and numerical simulation for hemispherical EFP penetrator damaging a concrete wall HAO Likai1,2, GU Wenbin1, ZHANG Yadong3, YUAN Qi4, ZOU Shaoxin1, LIU Mingjun5, LIU Sengqi2 To deeply study the penetration effect and damage mechanism of concrete targets under the action of the shaped charge, Φ 120 mm EFP with hemispherical liner was designed to carry out experiments of penetrating a concrete wall at different standoff distances. Based on the RHT model with modified parameters, the maximum relative error between simulation results and experimental data is 9.8 %, indicating that the RHT model has a good correction effect and the numerical model is reliable. On this basis, the impact of the standoff distance on the penetration damage effect is analyzed, and the combined damage element characteristics of the EFP penetrator and the explosion shock wave are studied. The results show that when the designed EFP penetrates the concrete wall, a funnel pit with a large diameter and depth is formed on the wall. When the standoff distance changes from 20 cm to 60 cm, with the increase of blasting height, the diameter of the funnel pit decreases gradually, and the depth of the funnel pit decreases first, then increases and then decreases, and tends to be stable. When the standoff distance is 20 cm (1.67 times of charge diameter), the funnel pit with a large diameter and depth can be obtained. The diameter is about 6.83 times the charge diameter, and the depth is 2.3 times the charge diameter. EFP penetration plays a leading role in the formation of the funnel pit, and within a certain explosion height range, the explosion shock wave can increase the diameter of the funnel pit, and its coupling with the EFP penetrator can improve the depth of the funnel pit to a certain extent. 2023 Vol. 42 (1): 10-18 [Abstract] ( 127 ) HTML (1 KB)  PDF (2821 KB)  ( 48 ) 19 Shaking table test of a RC frame structure with different cross-section columns of stilted floor TANG Yangyang1, LI Yingmin1,2, LIU Liping1,2, JIANG Baolong1, YU Hongxiang1, JI Shuyan3 In order to study the seismic response and seismic performance of stilted RC frame structure on a slope, the shaking table test of a 1/8 scaled stilted RC frame structure model was performed. The structural damage, dynamic property, acceleration response, deformation characteristics, story shear and torsion effect were analyzed. The results show that the damage of the stilted story and the 2nd story of the model is very uneven. At stilted floor, the damage state is slight, and the short column at the top of the slope is damaged early than other columns. However, the damage of the column bottom at 2nd story is serious, and the degree decreases from the side of the column at the bottom of the slope to the side of the column at the top of the slope. The main damage is located at floors above the stilted story, and partial-column yield failure mechanism is displayed. When the earthquake intensity is greater than the rare earthquake, the acceleration amplification coefficient of the stilted story is greater than that of the upper floors, and the increase of shear force of the stilted story is greater. The deformation of the stilted story is small, and the maximum story drift appeared at 3rd or 4th story. The maximum inter-story torsion angle shifts from the 2nd story to the stilted story with the increase of earthquake intensity. 2023 Vol. 42 (1): 19-27 [Abstract] ( 108 ) HTML (1 KB)  PDF (3446 KB)  ( 43 ) 28 Near field dynamic modeling of saturated concrete impact failure WU Liwei, MA Qipeng, HUANG Dan An intermediately homogenized peridynamic (IH-PD) model for saturated concrete has been proposed under the configuration of the ordinary state-based peridynamic theory, and the pore of saturated concrete is considered as well. The information from the composition at the mesoscale is linked to the macroscale fracture behavior in this model, where the heterogeneity of concrete is taken into account, and the calculation cost does not increase. The pore of concrete is implemented by deleting the bond between two material points, and its effect on the mechanical properties of concrete is further analyzed. Moreover, the effective bulk modulus and shear modulus of cement mortar in saturated concrete is obtained based on the two-phase spherical model. In the last, the validity of the proposed model and algorithms is established through simulating the wave propagation in a saturated concrete slab and the impact failure experimental test. The numerical results are in good agreement with the corresponding experimental observations. 2023 Vol. 42 (1): 28-37 [Abstract] ( 106 ) HTML (1 KB)  PDF (3135 KB)  ( 42 ) 38 Axial crushing response of multi-cell tube enhanced by secondary ribs like parallel veins HU Jingkun1, XU Peng1, FAN Zhiqiang1,2, LI Yaozhou1， TAN Xiaoli1 Inspired by the parallel veins of leaves, a new bionic multicellular tube (BMT) was constructed by introducing secondary ribs on the inner shell of the lateral cylindrical shell of the multicellular tube (MT) to improve the energy absorption characteristics by inducing and improving the deformation mode of the thin-walled structure. The samples were prepared by 3D printing technology to carry out quasi-static compression experiments. Combined with numerical simulation, the effects of tube wall thickness, impact velocity, secondary rib shape on structural deformation and energy absorption were studied. The results show that: 1) Compared with MT, the specific energy absorption of BMT had tilted secondary ribs increases by 31%~59% and 20% ~ 35.2%. The introduction of secondary ribs can induce the interlacing of thin-walled structures in the direction of ±45°to produce large plastic hinges. The improvement of bending deformation performance of thin-walled structures is the main factor to enhance the energy absorption characteristics of structures. 2) When the width of the secondary ribs of BMT is less than 1mm, the deformation of the outer cylindrical shell cannot be induced, and the energy absorption characteristics of BMT increase with the increase of the impact velocity in the range of 10~70m/s. 3) The introduction of secondary ribs has little effect on the energy absorption of main ribs and inner shell in MT, but can significantly improve the energy absorption of outer shell and reduce the dependence of deformation mode on loading rate. 2023 Vol. 42 (1): 38-45 [Abstract] ( 70 ) HTML (1 KB)  PDF (2770 KB)  ( 24 ) 46 Damage characteristics of intercalary rock in bifurcated tunnel under alternate blasting excavation YANG Hangpeng1, YU Jin1, FU Xiaoqiang1,2, YAO Wei1, LIN Congbo1, CHANG Fangqiang1 Clarifying the law of rock damage in the bifurcation small net distance tunnel under the condition of alternating blasting construction will help to better ensure the construction of the tunnel site and the stability of the surrounding rock. The three-dimensional finite difference software FLAC3D simulated the excavation process of the bifurcated small net distance tunnel under the action of blasting load, focused on the damage distribution and evolution of the middle rock under different excavation conditions, and finally verified by the on-site acoustic damage range detection results of the Xiamen Haicang Dredging Channel Bifurcation Tunnel Project. The results show that the stress wave generated by blasting reflects at the fork to form tensile stress, which makes the damage to the fork section more serious; the damage to the sandwich rock in the tunnel is asymmetrically distributed, and the damage from the inside of the middle sandwich rock to the contour line gradually increases, the maximum damage of the middle rock on the main tunnel side is in the range of 90 ° to 120 °, the maximum damage of the middle sandwich rock on the ramp side is within the range of 90 °, and the thickness of the middle sandwich rock has a greater influence on the damage of the middle sandwich rock, and with the increase of the thickness, the degree of damage of the middle between the rock decreases and the damage range does not penetrate the left and right tunnels; Through the simulation to change different approaches, excavation staggered distance and excavation sequence, it is found that compared with 2m, the complete damage area of 5m approach is increased by 58.5%, the damage penetration area is increased by 70%, the complete damage area of the staggered 1 step is increased by 1.27m compared with the staggered 4-step working condition, and the damage penetration range is also increased, and the excavation of a smaller section is conducive to the stability of the middle rock, and the symmetry of the surrounding rock damage is better, but the damage to the rock mass on the side of the middle sandwich rock will be expanded, and the numerical simulation results are basically consistent with the actual measurement results of the site. The simulation results provide certain references for the construction of the small net distance tunnel of the bifurcation of the highway.  2023 Vol. 42 (1): 46-53 [Abstract] ( 86 ) HTML (1 KB)  PDF (3275 KB)  ( 29 ) 54 Implementation of WFEM for broadband vibration analysis of high modal density structures GENG Jia1,2, LI Ming1,2, ZHANG Xingwu1,2, YANG Laihao1,2, CHEN Xuefeng1,2 The dynamic analysis of high-modal density structures in a wide-frequency domain is a significant problem in the field of acoustic and dynamic analysis. As well known, the numerical methods should provide the accurate numerical solutions in both low and high frequency domains when proceeding the dynamic analysis in a wide-frequency domain. However, due to the obvious dispersion errors and high computational cost, Traditional Finite Element Methods (TFEMs) are difficult to provide accurate numerical solutions in the high-frequency domain when performing the dynamic analysis of high-modal-density structures. Fortunately, the Wavelet Finite Element Methods (WFEMs) have potential solution to provide the accurate numerical solutions with low computational cost when proceeding the structural analysis. Meanwhile, the WFEMs can greatly reduce the impact of dispersion errors when proceeding the dynamic analysis with refined mesh. Firstly, this paper will mainly introduce the formula to construct the self-coupling algorithm based on the WFEMs and discusses the detailed procedure of the wavelet finite element methods when performing the dynamic analysis of the high-modal density structures in a wide-frequency domain. In view of the above, a thin plate, which has analytical solutions, with high modal density is adopted for analyzing the numerical stability and validity of wavelet finite element in a wide-frequency domain when proceeding the dynamic analysis. Therefore, the convergence and validity of wavelet finite element method in high-frequency domain and wide-frequency domain is compared with the traditional finite element methods based on the numerical and experimental studies. It provides a theoretical reference for solving the problem of wide-frequency dynamic analysis of high-modal density structures, such as cylindrical and shells based on wavelet finite element methods. 2023 Vol. 42 (1): 54-65 [Abstract] ( 118 ) HTML (1 KB)  PDF (2488 KB)  ( 19 ) 66 Instantaneous phase difference between nonlinear vibrations of double cables and its origin SUN Ceshi1, LIN Junqiang1, DENG Zhengke2 In order to ascertain the phenomenon of synchronous and asynchronous vibration between cables, the instantaneous phase-frequency characteristics of double cables with different parameters are studied. The dimensionless dynamic equations of motion for the dual-cable-mass model were derived. The discrete ordinary differential equations were obtained using the Galerkin method and solved by the Method of Multiple Scales. The Runge-Kutta method and the Finite Element method are used parallelly to execute verification, and the results agree well with each other. The sources of the instantaneous phase difference of two cables with different parameters are analyzed, which show that the influence of high-order approximation on instantaneous phase cannot be ignored in some frequency range. The instantaneous phase difference of the double cables comes from two aspects: one is the difference in the phase shift value γ in the linear solution; the other is the difference in the proportion of the drift term parameters 𝛽 in the high-order approximate solution. 2023 Vol. 42 (1): 66-73 [Abstract] ( 126 ) HTML (1 KB)  PDF (1992 KB)  ( 14 ) 74 Identification of misalignment load of wind turbine rotor system based on improved trust region model management technology MAO Wengui, LI Jianhua, GUO Jie, ZHOU Zhou In order to solve the time-consuming problem of misalignment load identification of wind power rotor system, an identification algorithm based on improved trust region model management technology is proposed. The method transforms the misalignment load identification problems in the entire prior distribution space into a series of approximation problems in trust region, in which, the regional genetic intelligent sampling technology is used to collect samples, the extended radial basis function is adopted to build a global metamodel, and then employs the genetic algorithm for approximate optimization. in the following, the minimum objective function and optimization result determine the reliability of center and radius of the next region. With constantly zooming, translating the trust region, the method ensures the misalignment load solutions in consistent with the true problem. The comparison of four methods shows that this proposed method can inherit samples falling in the next trust region to reduce the number of experimental design samples，and thus the efficiency is increased；Trust center adjustment strategy improves the accuracy of the metamodel in concerned space to accelerate convergence and reduces the dependance on metamodel accuracy. Key words: rust region model management technology；Metamodel；Intelligent sampling；wind turbine rotor；misalignment load 2023 Vol. 42 (1): 74-80 [Abstract] ( 145 ) HTML (1 KB)  PDF (2078 KB)  ( 38 ) 81 Rotor fault diagnosis method based on parametric optimization SDP analysis WAN Zhou1,2, HE Junzeng1,2, JIANG Dong2,3, LI Jian4, ZHANG Dahai1,2 Based on parameter optimized symmetrized dot pattern(SDP) analysis, an intelligent method is proposed to diagnose rotor faults with various types and severity. Firstly, the fault features of multiple sensor signals were extracted by SDP analysis and fused into SDP images; Then, the image discrimination function defined based on Euclidean distance was used as the fitness function, the optimal values of angle domain gain factor and time lag coefficient in SDP analysis were obtained based on the beetle antennae search algorithm; Finally, the SDP images were used to train the convolutional neural network to obtain the rotor fault diagnosis model. Experimental results show that the diagnosis accuracy of the proposed method was higher than other fault diagnosis methods, and performed well in strong noise environment. The parameter optimized SDP analysis enlarges the characterization differences of rotor faults with various types and severity, and improves the fault diagnosis accuracy. 2023 Vol. 42 (1): 81-88 [Abstract] ( 154 ) HTML (1 KB)  PDF (3464 KB)  ( 40 ) 89 Numerical simulation and parametric analysis for aseismic capacity of self-resetting swing double-column pier JIA Junfeng1, BIAN Jiachen1, BAI Yulei1, WEI Bo1, GU Ranxing1, ZHOU Shumei2 Self-centering rocking pier is an important structural form of bridges whose function can be restored after earthquakes. In order to investigate the influence of different design parameters on the seismic performance of self-centering rocking double-column piers, the first self-centering rocking bridge (Hongshizhuang overpass bridge of Jingtai Expressway) in China was selected as the research object of this study. The bearing capacity calculation formula of self-centering rocking double-column piers was derived; ABAQUS finite element software was used to establish the numerical simulation model of self-centering rocking double-column pier, and the accuracy of the model was verified based on the quasi-static test results. Considering the design parameters such as the initial tension of prestressed tendons, the cross-section area of energy dissipaters and prestressed tendons, the influence of these parameters on the seismic capacity of self-centering rocking double-column piers were analyzed. The results showed that with the increase of initial tension and cross-section area of prestressed tendons, the maximum lateral bearing capacity of piers increased, the residual displacement decreased, and the energy dissipation capacity had negligible change. The maximum bearing capacity, residual displacement and energy dissipation capacity of piers increase significantly with the increase of cross-section area of energy dissipaters. The parameter analysis showed that the self-centering rocking pier can have good energy dissipation capacity and small residual displacement at the same time, and the residual displacement rate is 0.56% when the maximum displacement rate of the pier is 4%. The recommended design parameters to form aforementioned situation were that the ratio of prestressed tendons is 0.26%, the initial tension control stress is 0.4 times of the ultimate strength, and the contribution rate of energy dissipaters to the horizontal bearing capacity of the pier is 44.4%. Achievement in this study could provide references for design and assessment of seismic performance of self-centering rocking double-column piers. 2023 Vol. 42 (1): 89-97 [Abstract] ( 112 ) HTML (1 KB)  PDF (3418 KB)  ( 122 ) 98 Transmission characteristics of high order Lamb wave modes at corrosion damages CHEN Feiyu1,2, LUO Zhi3, CAO Xuwei4 The cutoff property of higher order Lamb modes is a powerful tool for the detection of corrosion in large-area plate and shell structures. Investigation on the transmission characteristics of higher order Lamb modes at corrosion with different widths and depths provides a theoretical basis for optimizing the excitation mode and frequency. Based on finite element method and single mode excitation technology, the variation of the time of flight (ToF), the amplitude of transmitted wave and the deformation of waveform are analyzed, when the A1 mode slightly above its cutoff frequency encounters corrosion. This study lays a foundation for exploring the mechanism of damages inversion based on high-order mode Lamb waves. 2023 Vol. 42 (1): 98-104 [Abstract] ( 155 ) HTML (1 KB)  PDF (2813 KB)  ( 109 ) 105 Damage detection of offshore wind power structures considering pile-soil interaction and scour LU Guangkun1, CHEN Xuguang1,2, DU Wenbo3, NIU Xiaodong1, LIU Jinzhong4, TANG Hanfeng1, LIU Xixi1, XIE Anqi1 Offshore wind turbine structures continually serve in atrocious ocean environment, and the damage continues to accumulate, leading to overall failure in severe cases. Existing damage detection methods can identify structural damage, but ignore the influence of pile-soil interaction and scour effect on the structural dynamic features. If it is directly applied to the actual project, it will easily cause misjudgment of damage. Based on the cross-model cross-mode method(CMCM method), considering the pile-soil interaction and scouring effect, the pile boundary conditions were optimized, and the CMCM structure damage detection method was developed. The pile-soil finite element model was established, combined with the existing test data, to verify the numerical model and detection method under the sand foundation. Furthermore, pile-soil interaction and scouring effect on the structural modal was studied, and the numerical model damage was detected based on the baseline model for different foundation assumptions. Results show that the foundation stiffness decreases after considering the pile-soil interaction and scouring effects, which leads to a decrease in the structure frequency and a change in the mode shape; The model boundary is more in line with the actual engineering foundation status; After the interference items are eliminated, the structural damage location and severity can be accurately identified, which improves the accuracy and engineering applicability of the CMCM method. Key words: offshore wind turbine; damage detection; modal analysis; foundation; scour 2023 Vol. 42 (1): 105-114 [Abstract] ( 136 ) HTML (1 KB)  PDF (4250 KB)  ( 60 ) 115 Dynamic hysteresis modeling and feedforward compensation of MFC actuatedresonant underwater flexible structures WANG Zekai1,3, LOU Junqiang1, 2, CHEN Tehuan1, DENG Yimin1, CUI Yuguo1, WEI Yanding2 Macro Fiber Composite (MFC) actuated underwater flexible structure with the advantages of motion flexibility and operation convenience, is widely used in underwater bionic propulsion and deformation control systems, nevertheless, the positioning accuracy and control performance are seriously affected by the nonlinear hysteresis of MFC material. In this paper, a compound model containing modified Prandtl-Ishlinskii (MPI) static model and transfer function dynamic model in series is proposed to describe the dynamic hysteresis phenomenon of MFC actuated underwater flexible structure in resonant state. Firstly, the parameters of the MPI model are obtained based on the quasi-static hysteresis characteristics of the proposed underwater flexible structure, and then the underwater resonant characteristics are captured by the dynamic model of the transfer function added feed-through term. The experimental results show that the dynamic hysteresis behavior of MFC actuated resonant underwater flexible structure can be matched relatively well by the proposed compound dynamic hysteresis model and keep high accuracy in a certain bandwidth range near the natural frequency. Based on feedforward compensation of the inverse compound model, the measured displacement of underwater flexible structure in resonant state is essentially coincident with the desired displacement of that in sine trajectory tracking achieving a high compensated linearity and significantly improves the dynamic positioning and tracking accuracy. Accordingly, the effectiveness of the proposed dynamic hysteresis model and compensation method is verified. 2023 Vol. 42 (1): 115-122 [Abstract] ( 81 ) HTML (1 KB)  PDF (2434 KB)  ( 18 ) 123 Damage characteristics of ore pillars induced by deep buried orebodystope blasting ZHANG Xiangyu1,2, YAN Peng1,2, LU Wenbo1,2, ZHANG Lixin3, SONG Liang3, CHEN Ming1,2 In the kilometer-level mining process of mineral resources using the room-pillar method, the deep mining is faced with unpredictable disasters due to the "three high" of the deep rock mass and the "strong disturbance" of the blasting mining, the blasting damage research on the damage mechanism and effects of pillars under high in-situ stress is of great significance to the safety of stope operations. Based on the deep blasting excavation of Chentaigou Iron Mine, a three-dimensional numerical model of fan-pattern blasting holes in the stope was established to study the damage characteristics of the pillars caused by stope blasting under different in-situ stress. At the same time, the mechanism of the interaction between in-situ stress and blasting load was revealed from theoretical analysis and numerical simulation. The results show that in the near area of the blast hole (5 times the blast hole radius), the surrounding rock is mainly subjected to compression and shear stress, in the middle and far area of the blast hole (10 to 25 times the blast hole radius), the surrounding rock is significantly affected by the hoop tensile stress; the peak compressive and shear stress in the vicinity of the hole is mainly contributed by the explosive load and is less affected by the in-situ stress. The peak hoop tensile stress in the middle and far region is greatly affected by the in-situ stress, and the peak hoop tensile stress decreases with the increasing in-situ stress, the damage depth at different heights of pillars has different attenuation trends under different in-situ stress. When the in-situ stress is greater than 20~30MPa, the attenuation of the damage depth in different areas of pillars tends to the same degree, the existence of in-situ stress reduces the damage depth by suppressing the tensile stress in the pillar area. Through the estimation of the influence range of the tensile stress, the recommended value of the safety distance during blasting at different buried depths is given. 2023 Vol. 42 (1): 123-131 [Abstract] ( 73 ) HTML (1 KB)  PDF (20312 KB)  ( 49 ) 132 Identification of hydraulic turbine operation state based on improved limit learning machine LAN Chaofeng, SONG Bowen, GUO Xiaoxia 针对水轮机远程运行状态监测困难的现状，本文提出了基于模拟退火算法的粒子群算法（Simulated annealing algorithm-Particle swarm optimization, SA-PSO）优化极限学习机（Extreme learning machine, ELM）的方式，建立水轮机运转状态识别模型SA-PSO-ELM。对水轮机信号进行互补集合经验模态分解（Complementary ensemble empirical mode decomposition, CEEMD）获得IMF分量，引入皮尔逊相关系数计算各个IMF分量与水轮机信号的相似度，判断信号主导模态和噪声主导模态的分界点，用小波去噪对噪声主导模态降噪，并与其余的IMF分量重构得到去噪信号，同时对去噪后的信号进行分解，计算每个IMF分量的排列熵，构建特征向量。由于SA-PSO精度高不易陷入局部最优的特点和ELM的性能受权值、阈值共同影响的特点，用SA-PSO优化ELM的权值和阈值，构建水轮机运转状态识别模型SA-PSO-ELM。对不同工况下采集的水轮机压力脉动数据，分析了基于PSO-ELM、ELM 及SA-PSO-ELM模型的水轮机运转状态识别正确率、均方误差、决定系数3个指标。结果表明：SA-PSO-ELM更适合于水轮机运转状态识别。 关键词：水轮机；互补集合经验模态分解；粒子群算法；极限学习机；状态识别 2023 Vol. 42 (1): 132-138 [Abstract] ( 108 ) HTML (1 KB)  PDF (2116 KB)  ( 31 ) 139 Reconstruction of RGR pavement model in virtual proving ground ZHOU Shuai, YU Huili, HUANG Yongwang, ZHOU Yunping Road model is an essential input to analyze vehicles' performance in application of Virtual Proving Ground Technique. In order to digitize the real road of an automobile proving ground located in western China, the Mobile Road Scanning System which consists of PPS laser scanner, IMU inertial navigation module and GNSS base station was constructed to acquire physical roads’ 3D point cloud. The centerline of physical road was fitted by spline curve, and then 2D planar point cloud was generated along it. Next, the elevations corresponding to those 2D scattered points were calculated by natural neighbor interpolation method. Finally, the 3D point cloud was transformed into RGR model. Combining RGR road model with FTire tire model and vehicle multi-body dynamics model, a fully functional virtual proving ground simulation system was built. In order to check the accuracy, a road load data acquisition test was carried out by a SUV equipped with 6-axes Wheel Force Transducer and certain acceleration sensors. In both cases of Pothole and Cobblestone road, the simulated wheel center vertical forces and accelerations are in good agreement with measured data, which indicates the constructed RGR model and its virtual proving ground has a superior accuracy. Key words: Virtual Proving Ground; RGR road model; road scanning; road load spectrum 2023 Vol. 42 (1): 139-145 [Abstract] ( 112 ) HTML (1 KB)  PDF (3715 KB)  ( 43 ) 146 Effects of near-field rotating seismic waves on seismic vulnerability of multi-span high-pier continuous rigid frame bridge ZHAO Jingang1, JIA Hongyu2, ZHAN Yulin2,3 In order to study the influence of near-fault rotational seismic waves on the fragility of multi-span high-pier continuous rigid frame bridge, a five-span high-pier continuous rigid frame bridge is taken as the research object. Firstly, based on the improved cloud chart method, 100 near-field translational seismic waves are selected from Pacific Earthquake Engineering Research Center ground motion database, and the rotational seismic waves are synthesized using the frequency domain method. And then, the random variables of bridge design parameters are selected, 100 sample points are extracted by the Latin hypercube method and randomly combined, and the OpenSees is used to establish 100 whole bridge finite element models to carry out dynamic nonlinear analysis under the action of near-field translational seismic waves and near-field translational + rotational seismic waves for obtaining the maximum curvature values of the key sections of high-piers. Finally, taking the critical values of the section curvature as the damage index, the seismic intensity index which suitable for fragility analysis under near-field translational + rotational seismic waves is studied, and the seismic fragility analysis is performed. The results show that the seismic intensity indexes PGD and Sdmax are most suitable for the fragility analysis of the multi-span high-pier continuous rigid frame bridge under the action of near-field translational + rotational seismic waves. The near-field rotational seismic waves significantly increase the damage probability of multi-span high-pier continuous rigid frame bridges. Therefore, ignoring the effects of rotational seismic wave would seriously underestimate the damage probability of multi-span high-pier continuous rigid frame bridges, and using the sectional curvature as the damage index can not well reflect the damage caused by the torsional component seismic waves. The research results of this paper are of great significance for a more comprehensive understanding of the seismic performance of multi-span high-pier continuous rigid frame bridge and improving the bridge seismic design and reinforcement theory. Key words: multi-span high-pier continuous rigid frame bridge; rotational seismic wave; seismic fragility analysis; improved cloud chart method 2023 Vol. 42 (1): 146-159 [Abstract] ( 93 ) HTML (1 KB)  PDF (4290 KB)  ( 72 ) 160 Analytical solution to low strain testing of large diameter cast-in-situ concrete pipe pile in saturated soil considering reflected wave oscillation DI Tongyu1, 2,WU Wenbing1, 2, ZHANG Yunpeng1,2, LIU Hao1,2 Compared with the traditional solid pile, the large-diameter cast-in-place concrete pipe pile has larger bearing capacity and dynamic stiffness under the premise of the same concrete consumption, despite that its low strain detection theory still lags behind the engineering application. Specifically, the influence of the soil plug effect and the wave oscillation after the arrival of reflected signal are still vague. As a result of that, it is necessary to establish a rigorous surrounding soil-pipe pile-soil plug model for low strain integrity signal interpretation. In this paper, the Biot continuum equations are used to simulate the interaction between soil skeleton and pore fluid of the saturated soil. From the perspective of strain energy, the Rayleigh Love rod model is modified to suit for pipe piles. Through Fourier transform, decoupling partial differential equation by utilizing potential functions, and variable separation method, the radial and longitudinal displacement of the pile-soil system is solved. The time-domain response at the pile head under half sinusoidal pulse is obtained by Inverse Fourier Transformation. Through comparing with the previous solution, the validity of the solution is verified. The main conclusions of this paper are: with the increase of Poisson's ratio of the pipe pile, the amplitude of the reflected signal at the pile tip becomes smaller, and the oscillation of the wave is more obvious. The thicker the pipe pile wall is, the larger the reflected signal amplitudes are. The oscillation effect of reflected wave signal becomes smaller as the decrease of the pile-soil modulus ratio. 2023 Vol. 42 (1): 160-168 [Abstract] ( 67 ) HTML (1 KB)  PDF (1415 KB)  ( 20 ) 169 Vibration characteristics of ball bearing for air conditioning sliding vane compressor excited by time-varying load TANG Zhilin1, JIANG Diyong2, ZHANG Wenhu1, DENG Sier1, HU Yusheng3 Based on the theory of rolling bearing dynamics, the nonlinear dynamic equations of ball bearing for air-conditioning vane compressor excited by time-varying load were established, and were solved by the Gear Stiff (GSTIFF) variable step integral algorithm. Then, analyzed the effects of structural parameters and working conditions on the vibration characteristics of the ball bearing. The results show that: under time-varying load, the vibration response frequency of the ball bearing is dominated by the time-varying load frequency, which shows forced vibration, and the vibration velocity amplitude is much higher than that under constant load. Among the structural parameters, the original radial clearances significantly effect on the vibration characteristics of the ball bearing, and adopting zero clearance or negative clearance can effectively suppress the impact of time-varying load on the bearing. The cage pocket clearance has little effect on bearing vibration, and there is an optimal cage pocket clearance to minimize cage vibration. Considering the effects of time-varying load, applying an axial preload of 0.3-0.6% dynamic load rating to the ball bearing can achieve the purpose of reducing bearing vibration. 2023 Vol. 42 (1): 169-180 [Abstract] ( 113 ) HTML (1 KB)  PDF (4149 KB)  ( 48 ) 181 Simulation and optimization method of vehicle frame structure based on measured load spectrum and its application JIN Hongjie1, ZHOU Zhongsheng2, ZANG Liguo3,WANG Xingyu3 In order to solve the vehicle frame fractures happened during the reliability running test, an optimization method for vehicle frames based on measured test road load spectrum and numerical simulation analysis was given, and the method was applied and verified in the test. The main contents include: firstly, a multi-channel data acquisition system integrating six component force sensor, acceleration sensor, displacement sensor and strain sensor is established to obtain the original data of chassis load spectrum of actual driving test, and the load spectrum analysis data is obtained by using signal processing technologies such as zero drift, trend term removal and noise removal. The failure causes of frame structure cracking are analyzed by the combination of qualitative and quantitative methods. Secondly, through the establishment of vehicle frame simulation finite element model, the optimization scheme was proposed without affecting the overall structure, the mechanical characteristics of the frame structure before and after optimization under typical stress conditions were calculated and compared to ensure that the stress after optimization meets the requirements. Meanwhile, the RPC iterative technology was used, and the response driving signal is obtained by iterative calculation based on the measured load spectrum data, which is applied to the vehicle road simulation test-bed to carry out bench test to verify the effectiveness of frame design optimization. In the end, through the reliability running test of the optimized frame, the results showed that the optimized frame did not fail and met the reliability index. The research provides the most effective and feasible method for vehicle high reliability design technology. 2023 Vol. 42 (1): 181-189 [Abstract] ( 146 ) HTML (1 KB)  PDF (4163 KB)  ( 50 ) 190 Nonlinear connection layer modeling and parametric identification for single bolt connected beam LIU Pengtao, GUAN Tianci, WANG Xiaopeng Aiming at the problem that the linear equivalent model of bolted joint layer can not characterize the dynamic behavior of the joint after entering the micro slip state, the linear equivalent model of bolted joint layer is improved by using Voce constitutive relationship to characterize the nonlinear dynamic behavior of bolted joint. Taking the single bolt connection beam as the research object, the influence of different pre tightening torques on its natural frequency was investigated experimentally, and the frequency response function under different amplitude harmonic excitation force was tested. The four nonlinear parameters of the equivalent model of the connection layer were identified by genetic algorithm，including initial yield stress, tangent modulus and two shape parameters. After identifying the parameters, the error between the calculated value of the model frequency response function and the experimental value is less than 10%, which shows the accuracy and feasibility of the improved model. The improved equivalent model of connecting layer can be used to predict the nonlinear behavior of assembly structure. Key words: bolted joint; parameter identification; nonlinear; connective layer model 2023 Vol. 42 (1): 190-197 [Abstract] ( 67 ) HTML (1 KB)  PDF (1827 KB)  ( 34 ) 198 Applicability of equation of motion and damping matrix of  base-isolated structure in dynamic response analysis LI Shiyuan1, TAN Ping1,2,3, MA Haitao1,2,3 As the damping model and equation of motion have significant impacts on the accuracy of structural dynamic analysis algorithms. Because the seismic behavior of base-isolation structures has remarkable characteristics, dynamic analysis algorithms for conventional structures may not be suitable for the base-isolated structures any more. From this point of view, this paper presents a study with the emphasis on the structural damping model and equations of motion with different seismic input. It is found that use of the conventional method to construct the damping matrix for the base-isolated structure will cause the superstructure produce damping force with the rigid displacement of the isolation bearing and this may cause significant in numerical accuracy loss. A new scheme is proposed for the determination of damping matrix of the base-isolated structure, and general expressions are presented in terms of the damping matrix of the superstructure and the damping constant of the isolation layer. Analytical expressions of structural matrices are presented for a shear-type model of base-isolated structures, and then a numerical study is conducted to demonstrate the feasibility and effectiveness of the proposed methods. The numerical results obtained confirm that use of the conventional method to construct the damping matrix for the base-isolated structure overestimates the damping effect of the structure, and the displacement input model overestimates the deformation of the isolation layer and underestimates superstructure responses, when the damping of the isolation layer is 0.3, the relative deviations can reach 34.6 and -31.1% , by using the displacement-velocity input model, the analysis results are consistent with the acceleration input model, so the displacement-velocity input model should be used instead of the traditional displacement input model. Key words: base isolation; equation of motion; damping matrix; displacement input model; seismic motion input mode 2023 Vol. 42 (1): 198-206 [Abstract] ( 123 ) HTML (1 KB)  PDF (1807 KB)  ( 42 ) 207 Prediction of pick wear degradation states of road header based on Wiener process ZHANG Qiang1,2, ZHANG Jiayao1, L Fuyan2 In order to solve the problem of picking gear wear state of road header, the wear state prediction model based on Grey-Markov chain model, Gamma process prediction model and Wiener process prediction model were constructed.The vibration and acoustic emission data samples were extracted by building a test bench. Considering the influence of experimental environment on the extraction of experimental data, the wavelet packet decomposition method was used to de-noise the data.Define 6 kinds of cutter tooth wear state, each state take 50 groups of data samples, verifies the accuracy of model, all conform to the requirements of the precision, data prediction research and application model, contrast is the experimental data, the results show that the vibration acceleration signal energy and the Grey-Markov model relative error is 0.89%, Gamma model relative error is 0.47%, wiener process relative error is 0.39%;The relative error of AE signal acceleration energy and lower Grey-Markov model is 1.02%, the relative error of Gamma model is 0.84%, and the relative error of Wiener process is 0.47%.The prediction accuracy of the three models are all good, and the prediction error of Wiener process is the least, which provides a new method for the prediction of the degradation state of road header pick wear. 2023 Vol. 42 (1): 207-214 [Abstract] ( 90 ) HTML (1 KB)  PDF (3419 KB)  ( 35 ) 215 Vibration control of TMD based on position of inertial system LIU Xinpeng1,2, YANG Yingwen1,2, SUN Yi1,2, YAN Zhitao1,2 In order to study the influence of inertial system position on the vibration reduction performance of tuned mass damper (TMD), firstly, based on the dynamic principle, the parameters of SDOF structural system were optimized by using the fixed-point theory, and the analytical solutions of optimal frequency ratio and optimal damping ratio were obtained. Secondly, the influence of frequency ratio and damping ratio on structural vibration characteristics is discussed. Finally, the robustness of tuned mass damper inerter is studied. The results show that the connection position of inertial system has a significant effect on the vibration absorption capacity of TMD. Compared with the conventional TMD and unground TMDI, the dynamic magnification factor of grounded TMDI decreases about 8.4% and 16.5%, respectively. Compared with traditional TMD, the frequency modulation width of grounded TMDI is increased by about 6%. In the range of damping ratio perturbation, the dynamic amplification coefficient of grounded TMDI damping system increases by about 1.5 times. Grounded TMDI has better robustness, which can provide theoretical reference for the design of new TMDI model. Key words: inerter; tuned mass damper inerter; fixed point theory 2023 Vol. 42 (1): 215-223 [Abstract] ( 171 ) HTML (1 KB)  PDF (2130 KB)  ( 121 ) 224 Probability characteristics and extreme POT estimation of wind pressure coefficient of high-rise building envelope LI Shouke1, MAO Dan1, LIU Min1, GUO Fan1, SUN Hongxin1, CHEN Yuankun2, DENG Shengxiang3 As determining the design wind loads of facades of high-rise buildings, the probability characteristics of pressure coefficients should be taken account into the estimation of extreme pressure coefficients. For overcome the deficiency of hardness for determining the threshold in the POT (Peak over threshold) method for extreme estimation, the wind tunnel tests of CAARC building were conducted in wind tunnel. Firstly, the probability characteristics of pressure coefficients are specially studied, and it is shown that Gaussian distribution is good for the pressure coefficient in the upwind region, as well as the Gamma distribution is good for the pressure coefficient in the leeward region, the GEV (Generalized Extreme Value) distribution is good for the minimum pressure coefficient in the upwind region. Secondly, a modified POT method is proposed to estimate the extreme of pressure coefficients, it is indicated that the modified POT method is more accurate and more stable than the other extreme method. The bias between modified POT method and standard extreme is lower than 5% with 5 time-history samples. At last, the distributions of extreme pressure coefficients are given out for designing. 2023 Vol. 42 (1): 224-231 [Abstract] ( 143 ) HTML (1 KB)  PDF (2889 KB)  ( 50 ) 232 Vibration localization with strong disturbance ZHAO Peng, JI Gang, ZHOU Qidou The vibration localization effect is typical of an aperiodic structure, and the degree of perturbation is an important indicator of structural aperiodicity. In order to study the general law of strong disturbance degree on vibration transfer characteristics, the strong localization coefficient is calculated by modal analysis method and wave transfer method based on statistical theory, taking spring oscillator system as an example. Meanwhile, based on equivalent method of passband approximation, the conclusions of one-dimensional system are applied to two-dimensional structure to derive strong localization coefficient of aperiodic ring-rib cylindrical shell. The results achieve quantitative calculation of vibration localization coefficient under strong disturbance degree, and the conclusions obtained can provide theoretical support for reducing vibration transmission performance of structure by increasing disturbance degree. 2023 Vol. 42 (1): 232-237 [Abstract] ( 133 ) HTML (1 KB)  PDF (1758 KB)  ( 17 ) 238 Damage identification of transmission tower based on BO-BiLSTM model WEI Jiaheng, GUO Huiyong The structure’s acceleration response sequence reflects the original structural state information and contains many damage characteristics. In response to the problem that the current transmission tower health monitoring system generates a large amount of data and cannot effectively analyze and diagnose the damage of the transmission tower, based on the time series relationship of the the structure’s output acceleration response data, this paper proposes a damage identification method based on a Bi-directional Long and Short-Term Memory (BiLSTM) network, and adopts a probability optimization method Bayesian optimization(BO) to determine the neural network hyperparameters. Firstly, this article describes the related theories of BiLSTM.Then it proposes a hyperparameter selection strategy based on Bayesian optimization and a damage identification method based on the BO-BiLSTM model. Then the method is applied to the finite element model of the transmission tower for damage localization and pattern identification, and the overall identification accuracy rate of test set reaches 94.2%. Finally, in order to verify method on the actual structure, a damage identification method based on heterogeneous data is proposed: the transmission tower finite element model data is used as the model training sample to train the BO-BiLSTM model, and the experimental data is used as the test set to test the damage recognition effect . The results show that the BO-BiLSTM can identify the real structure damage accurately, and the recognition effect is more stable than BiLSTM and BO-LSTM. 2023 Vol. 42 (1): 238-248 [Abstract] ( 114 ) HTML (1 KB)  PDF (2909 KB)  ( 64 ) 249 Anti-lock braking control of heavy multi-axle special vehicle based on LADRC CHENG Hongjie, HE Xinglei, LIU Zhihao, GAO Lei, YANG Jianfu In view of the characteristics of long body length, large inertia, multiple axles, special purpose and complex transportation environment of heavy-duty multi-axle special vehicles, the Anti-lock Braking System (ABS) has a slip rate during braking. Non-linearity, time-varying and parameter uncertainty, and other issues, based on the Linear Active Disturbance Rejection Control (LADRC) heavy-duty multi-axle special vehicle anti-lock braking control optimization research has been carried out. First of all, using Matlab/Simulink to establish the integrated single-wheel dynamic model, slip rate model, tire model and brake model and other controlled dynamic system models, and design a slip rate-based ABS second-order LADRC controller model, ABS simulation and experimental verification were carried out on the road with high adhesion coefficient at an initial speed of 30 km/h. The comparative analysis of ABS braking effect of fuzzy PID control and LADRC control verified that LADRC control has a better braking effect; then, Taking a heavy-duty five-axle special vehicle as an example, Trucksim is used to build a complete vehicle dynamics system model for a heavy-duty multi-axle special vehicle such as integrated body, tires, suspension, steering, power transmission and braking; Finally, a heavy-duty five-axle special vehicle conducted ABS co-simulation at an initial speed of 60 km/h on high, medium, and low adhesion coefficient roads, which verified the feasibility and superiority of LADRC control in ABS applications. 2023 Vol. 42 (1): 249-258 [Abstract] ( 140 ) HTML (1 KB)  PDF (4283 KB)  ( 33 ) 259 Evolution of dynamic characteristics of large diameter monopile of offshore wind turbine under ultra-long term cyclic load GONG Min1, ZHU Tao2, CHEN Shouxiang1, ZHANG Dongming1, HE Rui2 As one of the most widely used supporting structures for offshore wind turbines, monopile foundation mainly focuses on bearing capacity, initial dynamic impedance and accumulative deformation. However, the offshore wind turbine is very sensitive to the dynamic loads such as wind, wave, current, seismic wave and its operation load in the marine environment. Therefore, in the process of long-term cyclic load, the law of its vibration characteristics must be fully studied. Through the indoor 1g model test of monopile in dry sand, taking the bearing capacity of model pile as reference value, applying cyclic load of the same frequency and different amplitude, and analyzing the frequency response during the loading process, the frequency response function of horizontal displacement of pile top is obtained, and then the following conclusions are drawn: (1) the resonance frequency of pile increases with the number of cycles; (2) the damping ratio decreases with the times of cyclic loading; (3) the stiffness of pile top is affected by many factors, such as the compaction of cyclic load and the formation of vibration pit; the secant stiffness decreases and the unloading stiffness increases. Key words: Offshore wind turbine; monopile; indoor 1g test; long-term cyclic loading; frequency response analysis; resonance frequency; damping ratio; horizontal stiffness of pile top 2023 Vol. 42 (1): 259-266 [Abstract] ( 120 ) HTML (1 KB)  PDF (2117 KB)  ( 39 ) 267 Effects of silicon steel sheets consolidation mode on modal characteristics of new energy vehicle motor SONG Jinyuan, JIANG Weikang With the increase of the motor speed, the working frequency of the motor increases continuously and it is easy to bring high-frequency resonance with the stator, leading to severe vibration and noise. Two kinds of connective methods affecting dynamic characteristics of the stator lamination core are researched. The lamination theory is used for the dynamic modeling of the bonded stator, and the semi-finite element method is used to simplify the modeling of the welded stator. Natural frequencies of stators with different connecting methods are studied, which are verified by experimental mode analysis. Finally, the optimization design of the welded stator is proposed to reduce the vibration at its work condition. The results show that the consolidation method directly affects the stiffness of the stator and has a huge impact on its dynamic characteristics. The results of the two modeling methods proposed in this paper are accurate and have guiding significance in the initial stage of motor design. Key words: stator lamination core; vibration and noise; connective method; influence law 2023 Vol. 42 (1): 267-272 [Abstract] ( 151 ) HTML (1 KB)  PDF (1784 KB)  ( 56 ) 273 Aseismic performance tests of precast shear wall-slab structure with UHPC-reinforcement dislocation connection LI Xinxing1,2, ZHOU Quan1,2, LI Shuisheng1,2 A connection form of precast shear wall joint with misplaced UHPC reinforcement is proposed. In order to study the out of plane seismic performance of the joint, five out of plane quasi-static tests of shear wall with slab structures are designed and completed, including three UHPC reinforcement misplaced precast shear walls, one UHPC reinforcement discontinuous butt joint shear wall and one cast-in-situ shear wall structure with 60d reinforcement binding and overlapping. The failure mode, hysteretic curve, bearing capacity, stiffness degradation and force transfer performance of vertical reinforcement at horizontal joints are compared and analyzed. The results show that the failure mode of the dislocation connected shear wall is the same as that of the cast-in-situ shear wall, which is out of plane bending failure. Compared with the cast-in-situ shear wall, the ultimate bearing capacity of the dislocation connected shear wall is increased by 5.1%, and the storey displacement angle is between 1/80 ~ 1/50; The initial stiffness is higher than that of cast-in-situ specimens, and the later stiffness degradation, ductility and energy consumption are equivalent to that of cast-in-situ specimens; Increasing the height of UHPC post cast section can improve the overall stiffness of the structure, but the seismic performance of the structure is reduced; The stress of the vertical reinforcement at the edge of the post cast section reaches yield after the concrete cracks at the joint. The stress of the reinforcement in the UHPC post cast section is small, and the joint shows good force transfer performance, which can be designed according to the “equivalent cast-in-situ” shear wall structure. Key words：precast shear wall; ultra high performance concrete; out of plane ;dislocation connection of reinforcement; low cycle repeated loading test; seismic performance 2023 Vol. 42 (1): 273-281 [Abstract] ( 99 ) HTML (1 KB)  PDF (1912 KB)  ( 31 ) 282 Dynamic response analysis of sub-conductor non-synchronous deicing during DC ice-melting of four-bundle conductor spacer system ZHU He1, WANG Weiqi1,2, XING Hongchao1,2, LIAO Hanliang1, CHEN Huan1,2， WU Wentao1,2， ZHOU Yueshuai1,2 In order to study the problem of ice melting and falling off of iced conductor under DC ice melting process, taking the lgj-400/50 transmission conductor as the research object, the finite element model of quad bundle conductor system in actual operation process is established by using ANSYS LS-DYNA preppost and nonlinear structural dynamics model. In the process of finite element analysis, solid45 element is used for layered modeling of the conductor, and the life and death element method is used to kill the icing element in the calculation, so as to more accurately simulate the actual situation during ice melting. At present, most studies on deicing of split conductors are equivalent to single conductors for calculation，During the actual ice melting operation, the split conductor has the phenomenon of asynchronous deicing. The deicing conditions of different sub conductors are analyzed. The results show that the jump height of deicing conductor under DC deicing is smaller than that of normal deicing, and the jump height and tension of conductor deicing decrease with the increase of deicing current; For the quad bundle conductor spacer system, when the sub conductors are not de iced synchronously, the diagonal de icing of the two sub conductors and the de icing of the two sub conductors below are relatively stable. When the sub conductors are not de iced synchronously under other working conditions, the quad bundle conductor spacer system has lateral swing, resulting in torsional risk, which will cause conductor wear and strand breakage accidents. 2023 Vol. 42 (1): 282-291 [Abstract] ( 107 ) HTML (1 KB)  PDF (2564 KB)  ( 48 ) 292 Mechanical response of asphalt pavement structure under non-uniform aircraft wheel load YOU Qinglong1, HUANG Zhiyi1, MA Jinglian2, ZHAO Zhi3, BI Jiefu1,4 In order to study the mechanical response of asphalt pavement structure under the action of non-uniform aircraft wheel load, based on the hypothesis of wheel stripy contact area and tire pattern, the vertical stress function of tire was determined, and then the longitudinal and transverse contact stress of tire was determined based on existing research, the three-dimensional non-uniform contact stress of A380-800, B747-400 and B777-300ER was calculated; based on the three-dimensional finite element analysis model, the mechanical responses of aircraft pavement structure under three-dimensional non-uniform wheel load are obtained, and the differences of mechanical responses of three types of aircraft are analyzed. The results show that the mechanical response of asphalt pavement under three-dimensional non-uniform load is greater than that under uniform vertical load. The influence of load inhomogeneity on the mechanical response of asphalt pavement decreases gradually from asphalt pavement to soil foundation. The mechanical response of asphalt pavement is affected by the maximum taxiing mass of aircraft, landing gear configuration, tire pressure, number of wheels and other factors under three-dimensional non-uniform load. With the increase of modulus of asphalt mixture, the change rate of mechanical response parameters decreases gradually. Key words: Airport engineering; Non-uniform load; Asphalt pavement; Finite element analysis; Mechanical response. 2023 Vol. 42 (1): 292-300 [Abstract] ( 127 ) HTML (1 KB)  PDF (3588 KB)  ( 33 ) 301 Dynamic stress concentration of a circular cavity near the interface of orthotropic bimaterials under SH wave incidence LAN Guoguan 1, ZHANG Cunfeng1, XU Huanan1, ZHANG Jianwei2 Based on the complex function method and Green's function, the scattering of SH wave in orthotropic bimaterials with a circular cavity iwas discussed, and the dynamic response around the cavity iwas analyzed. Firstly, the two-dimensional analytical model of the problem iwas established, and the whole space iwas divided into two parts: the homogeneous isotropic upper half space and the orthotropic lower half space with a cylindrical cavity. Using Green's function method, the Green’s function expression of each point at the interface of two half spaces iwas derived, and the complex variable iwas introduced to construct the wave field expression for solving the displacement and stress in the region under the incidence of SH wave. Considering the continuity condition of the interface, the undetermined anti-plane force iwas loaded on the horizontal interface of two half spaces, and then the Fredholm definite solution integral equations awere derived and solved by the direct discretization method of weak singular integral equations. Finally, through the calculation and analysis of examplesthrough a series of calculating analysis, it iwas found that the orthotropic parameters of the medium, the number of incident waves, the angle and the buried depth of the cavity have significant effects on the dynamic stress concentration factor (DSCF) around the circular cavity in the lower half space. Key words: SH-waves; Green’s function; anisotropic bimaterials interface; circular cavity; DSCF 2023 Vol. 42 (1): 301-307 [Abstract] ( 66 ) HTML (1 KB)  PDF (3313 KB)  ( 28 ) 308 Multi-field coupling nonlinear vibration analysis of cross shaped micro resonant beam HAN Guang1,2, XU Lizhong1 In order to improve the detection accuracy of capacitance detection sensor, a cross microresonator was proposed. The cross microresonator was simplified to a multi-field coupling vibration model, and the dynamic equation was established considering the molecular force and electric field force. The inherent frequency and its variation law of nonlinear vibration were obtained, and the effects of different structural parameters on displacement responses were analyzed. Moreover, with electrostatic excitation-capacitance detection method, we tested the cross microresonator which was fabricated utilizing micromachining technology. In order to make the output voltage signal undoped with excitation signal, the resonator was innovatively separated into excitation end and vibration picking end with insulation tape, thus the result was more realistic and accurate. In addition, Owen AC bridge was used for detection. The results show that when the size of resonator is small, the molecular force has a great influence on nonlinear vibration of resonator. The relative errors are 4.706% and 1.971% with and without consideration of the molecular force respectively, and the calculated value is closer to measured value. Furthermore, the quality factor of cross microresonator is 105.8, and the detection signal is more obvious than traditional beam. Key words: MEMS; nonlinear vibration; molecular force; multi-field coupling; cross resonator 2023 Vol. 42 (1): 308-317 [Abstract] ( 90 ) HTML (1 KB)  PDF (2362 KB)  ( 25 ) 318 Free vibration analysis of BCCZ lattice sandwich beam structure manufactured with additives ZHANG Wukun1,2, TAN Yonghua3, GAO Yushan1,2, WANG Jun1,2, ZHAO Jian1, GENG Xiaoliang4 The vibration behavior of a cantilevered sandwich beam with BCCZ (boundary of BCC lattice added with bar in Z direction) lattice sandwich structures was studied by theoretical, numerical and experimental methods. The equivalent shear modulus of BCCZ lattice under constraint boundary was used to obtain the nature frequency based on the "improved fold-line" deformation theory and Hamilton principles. The BCCZ lattice specimen was fabricated by selective laser melting (SLM) and TC4. Modal test experiments were also carried out to verify the accuracy of the theoretical model and finite element model. The structural geometric parameters, such as cell diameter, panel thickness and core height, and the influence of materials on the vibration properties of BCCZ lattice structures were studied as well. The results show that the 1st frequency parameters (the ratio of the 1st frequency to the solid structure with the same mass and panel area) of BCCZ lattice sandwich beam can be improved by reducing the cell diameter, reducing the panel thickness and increasing the core height. The effect of cell diameter is the most obvious. The 1st frequency is the highest when the material combination of panel-core-panel is Ti-Al-Ti. This paper will be useful for the design and engineering applications of BCCZ lattice sandwich. 2023 Vol. 42 (1): 318-325 [Abstract] ( 107 ) HTML (1 KB)  PDF (2802 KB)  ( 40 ) 326 Numerical simulation analysis and optimization of aerodynamic noise of roof duct of car rear air conditioner HUANG Yi, WANG Weijiang, QIN Wang, LONG Shucheng, FU Yule It is confirmed that the main noise problem of the ceiling duct of a large SUV with rear air conditioning in high-end operation is the low-frequency booming sound in the frequency band of 200 ~ 450Hz through the noise test and subjective evaluation in the semi anechoic chamber first. Then, the CFD model of the ceiling duct including the passenger compartment is numerically simulated based on the large eddy simulation (LES) and acoustic analogy FW-H equation, and the mechanism of vortex pressure pulsation and acoustic mode near by the deflectors in the ceiling duct to the low-frequency band noise is analyzed. Finally, the structure of the the deflectors is optimized on the basis of not affecting the air distribution ratio of the air outlets. The calculation results show that the vortex intensity and the pressure pulsation of observation points near by the deflectors in 250 ~ 450Hz frequency band are significantly reduced, the total sound pressure level of this band is reduced by 4.8 dB (A), and the average value of three peak magnitudes is reduced by 5.5 dB (A). 2023 Vol. 42 (1): 326-334 [Abstract] ( 129 ) HTML (1 KB)  PDF (4331 KB)  ( 45 )

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