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2024 Vol. 43, No. 11 Published: 2024-06-15 1 Dynamic modeling and simulation verification of deepwater riser-BOP stack coupled system CHANG Yuanjiang, WANG Shichao, LI Jian, LIU Xiuquan In the process of deepwater drilling, the riser and blowout preventer system are an essential part of the entire operation process. Due to many risks involved in the operation process, therefore, establishing an accurate mechanical analysis model of the coupling system between riser and BOPs, accurately analyzing its mechanical behavior and performance, is of great significance for guiding the safety of drilling operations. At present, most people only focus on independent modeling of the riser and ignore the potential impact of the blowout preventer group, which will lead to differences between the established model and the actual situation, and making it difficult to accurately analyze the mechanical properties of the riser system. This paper puts forward the rigid-flexible coupling concept of riser and BOPs, derives the kinetic energy and potential energy of the coupling system, establishes the theoretical model by Lagrange method, and uses Newmark- β Perform numerical calculations on the dynamic model using the direct integration method. A simulation modeling was established using ADAMS software to conduct comparative analysis of dynamic response under different operating conditions. The results indicate that the lateral displacement envelope and bending moment envelope of the riser obtained from the theoretical model in this paper, as well as the lateral displacement time history curve and bottom bending moment time history curve of the middle node of the riser, are in good agreement with the ADAMS simulation results, indicating the importance of the theoretical model in this paper, which can provide reference and support for the design and analysis of risers in China. 2024 Vol. 43 (11): 1-8 [Abstract] ( 138 ) HTML (1 KB)  PDF (2773 KB)  ( 58 ) 9 Experimental study on working performance of stacked piezoelectric smart aggregate based on piezoelectric admittance LAN Chengming1, LIU Honghui1, WANG Jianjun2, LI Weijie3 The smart aggregate based on piezoelectric stacks is a new type of transducer, which usually use piezoelectric stacks as the core element. Compared with traditional smart aggregates, it has superior electromechanical coupling performance, which can effectively improve the accuracy and reliability of structural damage diagnosis and has important application prospects in the field of structural health monitoring. However, the current study mainly focused on the device design and theoretical modeling, the device performance based on electromechanical admittance needs to be further evaluated. A temperature-sensitive experiment was designed to analyze the variation of the resonant frequencies of the device under temperature gradient; a 28-day water immersion experiment was carried out to plot the variation of the resonant frequencies of the device with the number of water immersion days; three soil specimens with dimensions of 200 mm 200 mm 200 mm were prepared, and the devices were embedded into the soil specimens to conduct water content monitoring experiment. The water contents of the soil specimens were monitored by the quantitative indicators under different water contents. The results show that the resonance frequencies of the smart aggregates based on piezoelectric stacks decrease linearly with the increase of temperature; the maximum shift of the resonance frequencies do not exceed 10% during 28 days of water immersion, indicating good stability; the quantitative indicators calculated based on admittance signals all increase with the increasing moisture content of the soil specimens, which can effectively monitor the changes in soil moisture content. 2024 Vol. 43 (11): 9-18 [Abstract] ( 63 ) HTML (1 KB)  PDF (3466 KB)  ( 28 ) 19 Dynamic coupling response analysis of floating base multi-robot suspension system ZHAO Zhigang, WANG Baoxi, SU Cheng, ZHAO Xiangtang, GUO Xin, YAN Jiliang In order to study the dynamic coupling relationship of the floating base multi-robot suspension system under the action of irregular waves, firstly, the dynamic model of the floating base robot is established by using the theorem of momentum and the theorem of moment of momentum. Secondly, the dynamic model of the suspension system is established by using the D 'Alembert principle, and the coupling relationship analysis steps of the system dynamics are proposed. Finally, combined with an example, the dynamic coupling response process of the floating-based multi-robot coordinated suspension system under different wave heights, different wavelength ratios and different lifting speeds is simulated and analyzed. The conclusions obtained complement and improve the theoretical research of the system, and also provide technical support for judging the safe lifting environment of the floating base multi-robot suspension system in the actual lifting process. 2024 Vol. 43 (11): 19-30 [Abstract] ( 51 ) HTML (1 KB)  PDF (4494 KB)  ( 23 ) 31 Overturning behavior analysis of curved single column pier bridge under combined action of heavy load and moderate-strong earthquake YIN Xinfeng1, FANG Yaru1, YAN Wanli1, HUANG Zhou1, LI Maonong1,2 To explore the combined effect of mobile vehicles and moderate-strong earthquakes on the anti-overturning effect of curved beam bridges, a vehicle bridge seismic analysis model is established, and a vehicle bridge coupling vibration analysis method considering seismic effects is proposed for curved beam bridges. This research focuses on multi-span curved continuous beam bridges and analyzes the support reaction force and overall turning angle of the main beam during overturning caused by a combination of moderate-strong earthquakes and overload from eccentric vehicle loads. The study also investigates the influence of seismic motion type, peak values, and key vehicle parameters on the overturning stability of curved beam bridges. The results indicate that different combinations of vehicles and seismic loads can change the stress situation of the bridge. When three 100t vehicles with a longitudinal spacing of 2m are driving at a speed of 3m/s, the overturning of the three-span curved beam bridge is most obvious; Revise the formula for calculating the stability coefficient in the anti-overturning specification; Analyzed the eccentricity of the pier supports in a five span curved beam bridge and its impact on the anti-overturning stability coefficient. The calculation example shows that the maximum safe anti-overturning coefficient of the curved bridge is 1.55 when the two adjacent supports of the pier are set with eccentricity. 2024 Vol. 43 (11): 31-40 [Abstract] ( 30 ) HTML (1 KB)  PDF (3942 KB)  ( 37 ) 41 VIV Performance and optimization measure mechanism of PK box girder with cantilever arm LI Chunguang, HE Xiaolong, HUANG Xiao, YAN Hubin, HAN Yan In order to study the vortex-induced vibration(VIV) performance and aerodynamic optimization measures of PK box girder with cantilever, the VIV performance of PK box girder at 0 ° and ± 3 ° wind attack angle is studied through segmental model wind tunnel test, and the effects of aerodynamic measures such as sidewalk height, closing the bottom of cantilever, change of railing air permeability and deflector with different inclination angles on the aerodynamic stability of box girder with PK section are tested. The results show that the main beam has strong vertical VIV resonance and multiple vertical vortex vibration intervals at 0 ° and + 3 ° wind attack angle. At the same time, the main beam has obvious torsional vortex vibration at high wind speed. Increasing the height of the sidewalk can reduce the vertical VIV response of the main beam at each angle of attack, and the torsional vortex vibration at high wind speed can be greatly depressed; Through the study of changing the air permeability by closing the railing, it is found that spaced closing the outside guardrail of the sidewalk at vertical can destroy the correlation of vortex induced aerodynamic force in the spanwise direction and reduce the vortex induced peak response of the main beam to 55.8% of the specification limit; The deflector with 0.25m can effectively improve the aerodynamic stability of the main beam. When the inclination of the deflector changes between 20 ° ~ 75 °, it can completely suppress the vortex vibration response of the main beam. 2024 Vol. 43 (11): 41-49 [Abstract] ( 28 ) HTML (1 KB)  PDF (4782 KB)  ( 14 ) 50 Ultrasonic guided wave phased array pulse compression full focus defect imaging method XU Caibin1, ZUO Hao2, CHEN Yixin2 A pulse compression based total focusing method using ultrasonic guided wave phased array for defect imaging was proposed. Firstly, under the excitation of a linear frequency modulation signal with a long duration and a large bandwidth, the full matrix capture data for the tested structure was obtained. Then signals were processed by pulse compression technique to compress the long duration wave packets. Next, the virtual time reversal method was used to compensate the dispersion and amplitude to eliminate the phase distortion caused by the large bandwidth and the amplitude reduction caused by the wave diffusion. In such a way, signals without phase distortion and with narrow durations were obtained. Finally, an imaging index including both phase and amplitude information was designed. Experiments were carried out in carbon steel plate with a crack and two defects and the results show that the proposed method can achieve high quality imaging for both defects. 2024 Vol. 43 (11): 50-57 [Abstract] ( 21 ) HTML (1 KB)  PDF (2339 KB)  ( 7 ) 58 Semi-analytical modeling and vibration characteristics analysis of perforated hard coated thin-walled cylindrical shell composite structure WEI Dezheng, YANG Jian, ZHANG Yue In order to solve the circular perforation problem of the composite thin-walled hard-coating cylindrical shell, a parameterized circumferential domain decomposition method is proposed. On this basis, a semi-analytical model of free vibration of the perforated thin-walled hard-coating cylindrical shell is established based on the Rayleigh-Ritz method. Taking the perforated thin-walled cylindrical shell coated with NiCoCrAlY+YSZ hard coating material as an example, the rationality of the semi-analytical model is verified by comparing the analytical and finite element results. Meanwhile, the effects of the circumferential perforation number, the axial perforation position, the perforation radius, and the coating elastic modulus on the vibration characteristics of the perforated hard-coating thin-walled cylindrical shell are discussed. The results show that the natural frequencies of the composite structure decrease with the increase of the circumferential perforation number, and will increase abruptly when the perforation number is equal to the circumferential half-wave number or its multiple. As the elastic modulus of the hard coating increases, the natural frequencies of the shell continue to increase. With the increase of the axial perforation position, the natural frequencies gradually decrease, and the decrease amplitudes will greatly increase when the perforation number is equal to the circumferential half-wave number or its multiple. Moreover, the natural frequencies decrease with the increase of the perforation radius on the whole, but the impact pattern will be opposite when the perforation number is equal to the circumferential half-wave number or its multiple. 2024 Vol. 43 (11): 58-65 [Abstract] ( 24 ) HTML (1 KB)  PDF (3212 KB)  ( 13 ) 66 Reliability analysis of anti-pressure fluctuation for direct action type relief valve in vibration environment ZHA Congyi1, SUN Zhili1, LIU Qin2, PAN Chenrong3 Hydraulic equipment typically operates in complex working conditions that frequently involve adverse factors, including vibrations and impacts. The coupling of unfavorable and uncertain factors can easily result in misadjustment of the relief valve and ultimately lead to equipment failure. To solve this problem, a reliability analysis model for anti-pressure fluctuation of a direct-operated relief valve is proposed, which considers parameter uncertainties. A mathematical model of the relief valve in a vibration environment was established through appropriate simplification. Furthermore, a performance function for pressure fluctuation failure of the relief valve was constructed based on whether the pressure fluctuation amplitude exceeds the specified value in the national standard. As the performance function is strongly nonlinear and implicit, a reliability analysis method for anti-pressure fluctuation in the relief valve is established by combining MATLAB/Simulink simulation with an active learning Kriging model. The failure probability was subsequently computed. The obtained results not only provide new guidance for the reliability assessment and design optimization of the relief valve but also hold certain academic value for the development of reliability techniques in hydraulic-related components. 2024 Vol. 43 (11): 66-71 [Abstract] ( 21 ) HTML (1 KB)  PDF (1494 KB)  ( 18 ) 72 Dynamic response analysis of ice-bridge pier collision in water medium GONG Li, DONG Zhouquan, YANG Tengteng, CUI Yue, DU Yunfei In order to accurately simulate the dynamic response of the pier structure during an ice-pier collision, the dynamic response of ice sheet and piers in a water medium under different collision impact parameters is numerically simulated using ANSYS/LS－DYNA software based on the fluid-solid coupling (FSI) calculation method. The results show that the results of the constant added mass (CAM) model are larger than those of the FSI model because the CAM model neglects the "water cushion effect" which reduces the velocity of the ice sheet, but its calculation efficiency is high and the calculation time is 1/10 of that of the FSI model, which is more conducive to the design of bridge pier collision avoidance. The FSI model is able to simulate ice-bridge pier collision scenarios more realistically. A comprehensive analysis of the different ice displacement conditions simulated in this study reveals that the bridge piers show obvious ice excited structural vibration characteristics under the effect of ice displacement impact, and the lateral displacement cloud of the bridge piers shows an obvious laminar distribution with the transfer of stress waves, with the largest lateral displacement amplitude at the top, so its impact on the overall safety of the bridge should be fully considered in the engineering design; With the increase of ice sheet speed, ice sheet thickness and ice sheet compression strength, the average value of ice load shows an approximate polynomial function relationship. In addition, it is found that when the compression strength of the ice sheet is less than 2.668MPa (the ambient temperature is higher than -15℃), the average value of the ice load decreases significantly, which indicates that the change of the ambient temperature has a significant difference for the bridge pier subjected to ice damage by the ice sheet impact and extrusion. The simulation research results are proposed to provide reference for the design of bridge and bridge pier collision avoidance facilities. 2024 Vol. 43 (11): 72-82 [Abstract] ( 19 ) HTML (1 KB)  PDF (4508 KB)  ( 14 ) 83 Terminal sliding mode control for multi-mode switching of composite air suspension KOU Farong1, YANG Xudong2, LI Shenglin2 Aiming at the problem of difficult coordination between body height and suspension damping under complex operating conditions of vehicle air suspension system, a multi-mode switching terminal sliding mode control strategy for composite air suspension was proposed. Considering the effects of suspension system nonlinearity and external disturbances, a nonlinear dynamics model of composite air suspension was established. A multi-mode switching controller was designed to determine the optimal damping control mode under different body heights. An unknown input observer was used to estimate the suspension system state quantity, and a non-singular fast terminal sliding mode controller based on radial basis neural network was designed to control the linear motor output under the corresponding mode of electromagnetic. Finally, the dynamic performance of the suspension under the multi-mode switching terminal sliding mode control strategy was simulated and tested on the bench. The simulation results show that the control strategy can effectively coordinate the body height and suspension damping, and improve the smoothness and stability of the vehicle under complex working conditions. The test results show that compared with the passive suspension, the acceleration of the reed mass of the system is reduced by 32.5% and 33.7% in the time domain and frequency domain respectively, which verifies the effectiveness of the control strategy. 2024 Vol. 43 (11): 83-93 [Abstract] ( 35 ) HTML (1 KB)  PDF (3801 KB)  ( 15 ) 94 Effects of hole structure of brake pad friction block on stick-slip vibration of disc-block interface WANG Quan1,2, WANG Zhiwei1,2, MO Jiliang1,2, FAN Zhiyong1,2, ZHOU Zhongrong1,2 The perforated structure is widely adopted on the surface of the brake pad friction block to improve interfacial friction, wear behaviors and heat distribution characteristics. To further investigate the relationship between the perforated structure of the brake pad friction block and stick–slip vibration of the disc–block interface, in this research, the tribological experiments are conducted to analyze the stick–slip vibration respectively affected by perforated and unperforated friction blocks. The Stribeck model parameters are identified to characterize the coefficients of friction of the disc–block interface. Further, a numerical model of the disc–block friction system is constructed. Based on the identified Stribeck model parameters and the theoretical analysis, the key influence factors of stick–slip motion is discussed and the mechanism of the perforated structure of the friction block on stick–slip vibration is revealed. The results show that the negative damping effect generated from the negative friction–velocity slope continuously inputs energy into the disc–block friction system, causing the instability and stick–slip vibration of the system. A greater difference between the static and kinetic coefficients of friction results in a stronger negative damping effect, leading to more obvious stick–slip vibration and worse stability of the system. The difference between the static and kinetic coefficients of friction for the perforated friction block is less than that for the unperforated friction block through regulating the interfacial friction characteristics, thereby effectively reduces stick–slip vibration of the disc–block interface and improves the system stability. 2024 Vol. 43 (11): 94-101 [Abstract] ( 26 ) HTML (1 KB)  PDF (2795 KB)  ( 6 ) 102 Effects of initial rotating speed and guide vane control strategy on pump power outage process of variable speed pumped storage unit CHEN Yongyan1, CHEN Diyi1, DENG Yuwen1, MA Cheng1, ZHOU Ye2, SUN Huifang3, ZHOU Daqing4 The adverse phenomena such as pressure fluctuations, backflow and double peaks in speed caused by the closing of the guide vane during pump outage condition of variable speed pumped storage units, which greatly affect the safe and stable operation of the units. The initial speed, as an important parameter affecting the dynamic characteristics of the unit, is not yet clear as to the law of its influence on the speed and flow rate during pump outage. To address the above problems, a model of the regulation system of variable speed pumped storage units is constructed based on the one-dimensional transient flow theory characteristic line method and the improved Suter transformation method. By simulating the pump outage process of variable speed pumped storage units, the influence law of the guide vane closing time on the characteristic parameters is analysed and the intrinsic link between the initial operating speed and the reversing flow and reversing speed poles is elucidated. The results show that the time domain response trends of the characteristic parameters are very similar during the positive velocity positive flow phase and the early positive velocity negative flow phase. Meanwhile, a comparison of the results of different guide vane closing times led to the conclusion that entering the shutdown from the negative velocity negative flow phase enhances the safety and stability of the unit. In addition, simulations of the pump disconnection process using different initial operating speeds at the same head and input power conditions led to the conclusion that the flow rate and speed extremes characteristics were negatively correlated with the initial operating speed. 2024 Vol. 43 (11): 102-110 [Abstract] ( 18 ) HTML (1 KB)  PDF (3281 KB)  ( 4 ) 111 Vibration characteristics of carbon fiber circular tube reinforced super-elastic porous structure FAN Yongle1,2, YANG Jinshui1,2, LI Shuang1,2, LIU Yanzuo1 With the rapid development of shipbuilding industry technology, the power system vibration isolation device put forward more stringent requirements, although the existing rubber damping material has a good vibration damping effect, but there are still problems such as large mass, mechanical bearing performance and insufficient energy absorption performance, in view of the background of the appeal, this paper combines rubber damping material with excellent mechanical properties of carbon fiber round tube to design a carbon fiber round tube reinforced super-elastic porous structure with both light weight, impact resistance and vibration isolation. In previous studies, it has been verified that the structure has excellent impact absorption performance. On this basis, the vibration behavior and damping performance of the structure are studied by experimental and numerical characterization, and the influence of carbon fiber round tube on the inherent vibration characteristics and damping performance of the structure is revealed. The results show that compared with the unreinforced structure, the super-elastic porous structure filled with carbon fiber round tube can significantly improve the vibration damping performance while enhancing the overall stiffness of the structure. The experimental results verify the reliability of the established numerical model of the structure, and compare the simulation and test of different reinforced structures and show that with the increase of the thickness of the carbon fiber round tube, the natural frequency of the structure first increases and then decreases. The research results can provide a reference for the design of new lightweight, high-stiffness and high-damping structures. 2024 Vol. 43 (11): 111-117 [Abstract] ( 24 ) HTML (1 KB)  PDF (2070 KB)  ( 16 ) 118 Cross-bearing fault diagnosis based on JMFAN LIU Zhihong, SHI Liping, CHEN Kaixuan, CHEN Rui, HAN Li In industrial production, there are various types of motor bearings, and it is often the case that certain models of bearings lack labeled data due to the high cost of annotation. To address this issue, this paper proposes a Joint Multi-Scale Feature Adaptation Network (JMFAN) for unsupervised learning. The JMMD algorithm is utilized to measure the distance between different domains, and cross-bearing fault diagnosis is achieved by minimizing the joint probability distribution across domains. The research focuses on transfer learning concerning the faults of different models of bearings under different operating conditions, and experimental verification is conducted. The results demonstrate that compared to traditional unsupervised transfer learning methods, this approach significantly improves the accuracy and model generalization capability in different bearing fault diagnosis tasks. The average accuracy rate reaches 99.06% in eight different transfer tasks using the bearing data from Western Reserve University. 2024 Vol. 43 (11): 118-125 [Abstract] ( 29 ) HTML (1 KB)  PDF (1743 KB)  ( 7 ) 126 Distributed dynamic load identification based on LSTM deep learning network GUO Anfeng1, WU Shaoqing1,2 A novel distributed dynamic load identification method based on LSTM deep learning network is proposed. Firstly, finite element model of structure is built and flatting as well as sub-regions partitioning on the area where load acts is conducted, the transitive relationship between dynamic load on sub-regions with the form of shape functions and nodal dynamic response on finite element model is constructed，then the sample database containing nodal strain response and distributed dynamic load on the corresponding sub-regions can be established; Secondly, Meyer wavelet is adopted to extract the features of the time-domain samples in the database and then the LSTM deep learning network is used to train the transitive relationship between the nodal strain response of finite element model and distributed dynamic load on the corresponding sub-regions; Finally, numerical simulations are conducted in which the simulated strain response is adopted to identify the distributed dynamic load on a three-dimensional panel structure, the effectiveness of the proposed method is verified. This research work aims to provide technical support on dynamic load environment prediction on the panel structure in service. 2024 Vol. 43 (11): 126-134 [Abstract] ( 39 ) HTML (1 KB)  PDF (2978 KB)  ( 14 ) 135 Damage characteristics of T800-CFRP laminates under non-normal impact of ice balls and tungsten beads SHANG Xiaozhuang1, LIU Yaolu1,2, FENG Xiaowei3, HU Ning1,4, TAN Xiaojun3, HU Yanhui3 The damage characteristics of T800-CFRP laminates under non-normal impact of hail ices and wolfram balls were studied by experiments and simulations. Firstly, the experiments of the high-speed impact of hail ices and wolfram balls on T800-CFRP laminates under given working conditions were carried out to verify the effectiveness of the simulation model; and then the damage characteristics and theirs differences of T800-CFRP laminates impacted by two kinds of impact bodies with different impact energies and impact angles were discussed. Research results have shown that wolfram balls can cause the perforation damage to laminates when the impact energy is low, and the damage degree of the laminates decreases with the increase of the impact energy; the impact energy threshold of hail ices causing damage to laminates is much higher than that of wolfram balls, and the damage degree increases significantly with the increase of the impact energy; the damage caused by wolfram balls at the impact angles of 450 and 600 is much more serious than that caused by the normal impact, while the damage caused by the impact angle of 300 is less than that caused by the normal impact; the damage degree of the laminate decreases with the increase of the impact angle by hail ices. This study is helpful to deepen the understanding of the damage and failure behavior of T800-CFRP laminates under impact load, and has important scientific significance and engineering value. 2024 Vol. 43 (11): 135-147 [Abstract] ( 13 ) HTML (1 KB)  PDF (4460 KB)  ( 5 ) 148 Effects of composite spatial cables on transverse stiffness of a long-span railway suspension bridge XIANG Huoyue1,2, TAO Yu2, WANG Zhen2, ZHONG Jinkun2, LI Yongle1,2 To enhance transverse stiffness of a long-span railway suspension bridge, a composite-spatial cable structure consisting of main and secondary diagonal cables is proposed. Then, the parameters of diameter of composite-spatial cables, anchorages of main diagonal cables with stiffening beams and the surface, and the number of secondary diagonal cables on transverse deflection-span ratio of the bridge are optimized by the effective utilization of the materials and static analysis method. Finally, the analysis method for coupling vibrations of wind-vehicle-bridge system is used to obtain the limit of transverse deflection-span ratio of the bridge based on the driving performance, and the influence of the main and secondary diagonal cables on the enhancement rate of the limit of transverse deflection-span ratio is analyzed. The results show that on the basis of considering the effective utilization rate of composite-spatial cables, anchorages of main diagonal cables and stiffened beams should be located near 1/4 of the main span, and it is optimal when the vertical distance between anchorages of main diagonal cables with stiffening beams and the surface and the tower is equal, and it is enough to set a secondary diagonal cable for each group of composite-spatial cables; in the optimal layout of composite-spatial cables, transverse deflection-span ratio of the bridge can be reduced by 14.18%, the limit of transverse deflection-span ratio can be increased by 16.79%. 2024 Vol. 43 (11): 148-154 [Abstract] ( 231 ) HTML (1 KB)  PDF (2913 KB)  ( 20 ) 155 Dual-channel broadband noise suppression method based on double-layer anti-symmetric damping phononic crystals BAI Xiaotian1, XIAO Zhaoyang1, SHI Huaitao1, LUO Zhong2, ZHAO Jinbao1, HE Fengxia1 The paper proposes a solution to the problem of insufficient noise reduction bandwidth in both structural and air propagation pathways, which cannot be applied to existing engineering equipment with wide band sound radiation. A double-layer anti-symmetric damping phononic crystal is introduced in this paper, with the double-layer damping phononic crystals as the unit cell, and two identical unit cells are arranged in antisymmetric manner to achieve a weak coupling effect while controlling the transmission of forward and backward sound waves to improve noise reduction. The finite element method and force-sound analogy method are used to calculate the energy band diagram, transmission curve and sound absorption coefficient of this structure, and comparative analyses are carried out on the differences in sound absorption performance between the proposed structure and traditional structure. Then the results are validated through experiments. Results show that the double-layer anti-symmetric damping phononic crystal effectively controls structural noise, the noise reduction bandwidth is expanded to 3.3 times that of traditional structures, with the additional mass of only 53.3% compared to traditional phononic crystals while maintaining the same volume. For the noise transmission through the air, the anti-symmetric structure shows excellent noise reduction performance by achieving a high sound absorption coefficient. The results indicate that this model can realize dual channel noise control over a wide frequency range and has the advantage of lightweight, which effectively supplement the shortcomings in broadband noise control in existing models. 2024 Vol. 43 (11): 155-164 [Abstract] ( 23 ) HTML (1 KB)  PDF (3072 KB)  ( 6 ) 165 Rolling bearing fault diagnosis based on RegNet-CSAM and ZOA-KELM model QI Xiaoli, WANG Zhaojun, MAO Junyi, WANG Zhiwen, CUI Dehai, ZHAO Fangxiang To address the issues of poor diagnostic performance and high computational complexity in existing deep convolutional neural network models for rolling bearing fault diagnosis, a novel model based on RegNet-CSAM and ZOA-KELM is proposed. Firstly, the attention mechanism CSAM that combines channel and spatial features is combined with the group convolution residual module to improve the representation ability of the structure. The RegNet-CSAM network constructed thus has a model complexity of 0.48GF; Secondly, during the classification stage, the Zebra Optimization Algorithm-based Kernel Extreme Learning Machine (ZOA-KELM) is used to replace the original Softmax function in the network to accomplish the final classification task. Experimental results for rolling bearing fault diagnosis indicate that the RegNet network is prone to misjudge some samples with mixed faults. The integration of CSAM into the RegNet network improves the accuracy by 0.5%, but does not effectively address the problem of misjudgment for mixed faults. However, by employing ZOA-KELM to replace the Softmax function for feature classification in the RegNet-CSAM network, it can effectively identify both single and mixed rolling bearing faults, achieving an accuracy rate of 99.92%. Compared with other networks, the proposed method can improve the diagnosis accuracy by up to 5.02%, and reduce the model complexity by up to 32 times. 2024 Vol. 43 (11): 165-175 [Abstract] ( 15 ) HTML (1 KB)  PDF (3944 KB)  ( 4 ) 176 Test study on dynamic mechanical properties of cement mortar-granitecomposite layer after high temperature GU Linlin1, YIN Kefei1, WANG Zhen2, WU Gu3, HE Pengtao2 In order to study the dynamic mechanical characteristics of cement mortar-granite composite layer after high temperature, the dynamic compression test and static pressure comparison test of composite layer specimens were carried out using the split Hopkinson pressure bar (SHPB) equipment, taking temperature and loading rate as variable parameters. The results show that: both dynamic compressive strength and dynamic strength growth factor (DIF) has significant strain rate effect. When the strain rate is lower than 45s-1, DIF decreases monotonically with temperature increaseing, while DIF decreases and then increases with temperature increasing when strain rate higher than 45s-1. After the high temperature, the interface bonding of the composite layer weakens, and the differentiation of failure morphology of cement mortar and granite increases with temperature rising. The clipping energy dissipation characteristics of the composite layer specimen shows low sensitivity to loading rate and high sensitivity to temperature. The peak stress ratio and energy dissipation rate do not change significantly with the change of loading rate. As high temperature reduces the equivalent wave impedance of the composite layer, the clipping ability is enhanced and the energy consumption effect is weakened. As the temperature increases, more incident energy is converted into reflection energy, the proportion of transmission energy and destruction energy decrease. 2024 Vol. 43 (11): 176-184 [Abstract] ( 14 ) HTML (1 KB)  PDF (3186 KB)  ( 7 ) 185 Multi-material microstructure topology optimization design considering macroscopic structural performance ZHANG Lei1,2, NI Shaohao1,2, JIANG Guozhang1,2,3, ZHANG Yan1,2,3, GONG Yiwen1,2 Porous microstructure materials are widely used in aerospace and other engineering fields due to their excellent mechanical properties, such as lightweight, high specific stiffness/strength, and impact resistance. Compared with conventional design with one single material, topological design with multiple materials can provide a microstructure with better mechanical properties. And topology optimization is one of the effective design methods for multi-material layouts. This paper proposes a parametric level set-based multi-material microstructural topology optimization method by combining a difference-set-based multi-material level set description model and an alternating active phase algorithm. In this method, firstly, a difference-set-based multi-material level set description model is constructed to accurately describe the topologies of N+1 phase materials only by using N level set functions. Then, an alternating active phase algorithm is employed to split the original N+1 phase multi-material optimization problem into N(N+1)/2 binary-phase sub-problems, so as to reduce design variables and constraint conditions for improving computational efficiency. Finally, a numerical homogenization method is used to calculate the effective elastic tensor of a multi-material microstructure. With the minimum macrostructural compliance as objective function, and the allowable material amount of each phase as constraint condition, a topology optimization model for the multi-material microstructure is constructed. The optimization criteria algorithm is used to numerally solve the above optimization model. The numerical results show that the proposed method can effectively achieve the topological design of multi-material microstructures, and the resulting microstructures have also smooth structural boundaries and distinct material interfaces. 2024 Vol. 43 (11): 185-193 [Abstract] ( 22 ) HTML (1 KB)  PDF (1740 KB)  ( 6 ) 194 On site testing and numerical analysis of ground vibration characteristics of embankments and cutting sections under high-speed rail load I Junwei1, ZHANG Jiyan2,3, GAO Guangyun4, WANG Yimin1 A field measurement of ground vibration was performed on the Paris-Brussels high-speed railway, the ground vibrations generated by embankment and cutting are analyzed in detail. Based on the 2.5D finite element method (FEM), 2.5D FE models both for the embankment and cutting were established to investigate the effects of the design parameters for both embankment and cutting on ground vibration responses. Results show that, in the near track zone, the amplitudes of ground vibrations are dominated by the axle weight of train, but are mainly influenced by superimposed effect far away from the track which is induced by the adjacent wheelsets and bogies of middle cars. With the increasing distance from the track, the ground vibrations decrease gradually, and the decay rate for the medium and high frequency vibrations is higher than others. The primary frequency of ground vibrations is dominated by the basic frequency of train loading f1, which increases with the raising train speed. Embankment and cutting have a significant influence on the attenuation law of ground vibrations. The process of ground vibration attenuation could be divided into two stages for the embankment section, but three stages for the cutting section. And there are rebound phenomena of ground vibrations occur at the top of cutting slope. For the embankment section, when the distance to the track is beyond 19.0 m (23.0 m for the railway cutting), the frequency-weighted vertical acceleration levels of ground vibrations (VLZ) could stay below 80.0 dB. The ground vibration decreases with the increasing embankment height or cutting depth. However, when the height or depth is beyond a critical value, such benefit of earthwork profiles on vibration reduction can hardly be increased further. Meanwhile, the ground vibration decreases with the increasing elastic modulus of embankment. Additionally, in the precondition of the cutting slope stability, a larger inclined angle is really beneficial to the reducing ground vibration. 2024 Vol. 43 (11): 194-205 [Abstract] ( 21 ) HTML (1 KB)  PDF (4875 KB)  ( 10 ) 206 Structural response reconstruction under non-Gaussian measurement noise QI Yibo, PENG Zhenrui The accuracy of response reconstruction using the Kalman Filter (KF) algorithm is degraded under non-Gaussian noise. To tackle this issue, a non-Gaussian Kalman filter algorithm for structural response reconstruction is proposed. Firstly, the L1 Kalman Filter (L1KF) algorithm is introduced to structural response reconstruction, followed by a revised definition of the loss function within the L1KF. Secondly, the coefficient matrix derived according to the loss function penalizes the noise covariance matrix of the state equation and the observation equation, making the KF algorithm applicable to non-Gaussian noise. Finally, the acceleration, velocity, and displacement responses of the structure are computed from a limited number of acceleration measurements. Both numerical simulations and an overhanging beam test show that the proposed method has good noise robustness using only a limited number of accelerometers, effectively reducing the reconstruction error. The large bias in response reconstruction using KF algorithm under multiple non-Gaussian noises is improved. 2024 Vol. 43 (11): 206-216 [Abstract] ( 17 ) HTML (1 KB)  PDF (4976 KB)  ( 16 ) 217 Comfort control strategy for human-vehicle cooperative steering based on torque closed-loop WEI Baolü1,2, BU Tengchen1, HE Zhicheng1, WANG Yufan1, PENG Xiaoyan1 In order to solve the problem that the steering wheel torque of the traditional electric power steering system affects the driver's comfort under the conditions of variable road adhesion coefficient and load change, a torque closed-loop human-vehicle coordination model is proposed based on the modified linear three-degree-of-freedom dynamics model. Turn to comfort control strategy. Firstly, the nonlinear relationship between yaw rate, vehicle speed and steering wheel torque is established through driver style identification; secondly, the driver's expected righting moment is obtained according to the nonlinear relationship and the steady-state characteristics of steering dynamics, and it combines with the righting moment accurately calculated by the modified linear three-degree-of-freedom model considering the roll of the carriage and the deformation of the suspension guide device and tire model to form a torque closed-loop controller; then, the compensation assist torque calculated by the torque closed-loop controller and the basic assist torque are superimposed to obtain the final control torque. Finally, the simulation model of the torque closed-loop system is established by Matlab/Simulink, which verifies the accuracy of the modified dynamic model, and also verifies that the proposed control strategy can effectively reduce the fluctuation of the steering wheel torque and improve the comfort of the driver. 2024 Vol. 43 (11): 217-226 [Abstract] ( 16 ) HTML (1 KB)  PDF (3097 KB)  ( 3 ) 227 Fault diagnosis of generator bearings based on MACDCGAN CAO Jie1,2, YIN Haonan1, WANG Jinhua1,2 In actual working conditions, the fault sample data collected by sensors in the generator is limited, and there is over-fitting problem in fault diagnosis based on deep learning method, which leads to poor generalization ability of the model and low diagnosis accuracy. In order to solve this problem, this paper adopts the idea of sample expansion, and proposes an improved fault diagnosis method of auxiliary classifier Conditional Deep Convolutive Generative Adversarial Network (MACDCGAN). By enhancing the characteristics of the collected one-dimensional time series signals by wavelet transform, the conditional depth convolution of simplified structural parameters is constructed to generate the samples of the countermeasure network model, and the Wasserstein distance optimization loss function is used in the model to solve the shortcomings of pattern collapse and gradient disappearance in the training process. An independent classifier is added to improve the compatibility of the classification model, and the learning rate attenuation algorithm is introduced into the classifier to increase the stability of the model. The experimental results show that this method can effectively improve the accuracy of fault diagnosis, and verify that the proposed model has good generalization performance. 2024 Vol. 43 (11): 227-235 [Abstract] ( 18 ) HTML (1 KB)  PDF (2736 KB)  ( 11 ) 236 CFD/CSD coupled analysis method for wind-induced vibration responses of TLCD-structure system HUANG Peng, WU Jiurong, FU Jiyang, SUN Lianyang, WANG Jialei In view of the challenges in establishing an accurate nonlinear theoretical analysis model for the Tuned Liquid Column Damper (TLCD), as well as the high cost and time-consuming of its mechanical performance testing, the Computational Fluid Dynamics (CFD) method is utilized to analyze the mechanical properties and dynamic characteristics of the TLCD system. Furtherly, a coupled analysis method based on Computational Fluid Dynamics/Computational Structural Dynamics (CFD/CSD) is proposed to analyze the wind-induced dynamic response of high-rise structures equipped with TLCD systems. Through conducting the mechanical performance and dynamic characteristic tests on a typical TLCD system under a specific bottom excitation, the wave height of free liquid surface and sloshing force are obtained, which verifies the accurate analysis capability of the CFD numerical method regarding the nonlinear characteristics of sloshing liquids within the TLCD water tank. Subsequently, the widely adopted 76-story benchmark model for vibration control study in wind engineering is selected, with the TLCD system installed at the top of the main structure. Utilizing the proposed CFD/CSD coupled analysis method, numerical simulations are carried out to assess the wind vibration control efficiency under the dynamic across wind loads corresponding to design wind speed with three different return periods (10, 50, and 100 years). The results of the coupled analysis show that the TLCD system could produce a certain control effect on the wind-induced acceleration, velocity, and displacement responses of the benchmark model, with a more pronounced control effect on the acceleration response than the displacement response. The presented method offers an effective reference for the wind vibration control analysis of high-rise buildings with complex TLCD systems. 2024 Vol. 43 (11): 236-245 [Abstract] ( 40 ) HTML (1 KB)  PDF (4264 KB)  ( 14 ) 246 Intelligent fault diagnosis of rolling bearing based on EMDPWVD time-frequency images and improved ViT network FAN Hongwei1,2, MA Ningge1, MA Jiateng1, CHEN Buran1, CAO Xiangang1,2, ZHANG Xuhui1,2 Rolling bearing is one of the key components of mechanical equipment, and its fault diagnosis is crucial for the safe and stable operation of equipment. For rolling bearings with non-stationary vibration signal, a new intelligent fault diagnosis method of EMDPWVD time-frequency images combined with improved Vision Transformer(ViT) network model is proposed. For the actual signals, three time-frequency analysis methods as Short-time Fourier Transform(STFT), Continuous Wavelet Transform(CWT), and Empirical Mode Decomposition & Pseudo-Wigner-ville Distribution(EMDPWVD) are firstly studied. Considering that STFT and CWT cannot simultaneously achieve the high time and frequency resolution, EMDPWVD is selected as the time-frequency image preparation method used for the intelligent fault diagnosis network. Secondly, a typical ViT is used as the basic fault diagnosis model, which divides time-frequency images into the blocks with predetermined size and then linearly maps them into input sequences. Meanwhile, the global information of the images is integrated by a self attention mechanism, and the network transmission is completed using a stacked Transformer encoder to finally achieve the fault diagnosis. To further improve the accuracy of fault diagnosis, the pooling layer is used as the preprocessing network of ViT to obtain an improved Pooling Vision Transformer(PiT) model, which extends the spatial features of time-frequency images and enhances the sensitivity of the model to the input images. The results show that the proposed method has the high diagnosis accuracy for different fault types of rolling bearings, and the accuracy of PiT is 4.40% higher than that of ViT, which proves that adding pooling layers to ViT can improve the effect of rolling bearing fault diagnosis. 2024 Vol. 43 (11): 246-254 [Abstract] ( 17 ) HTML (1 KB)  PDF (2362 KB)  ( 32 ) 255 Dynamic characteristics of tilting pad journal bearing-rotor system considering pad wear ZHANG Chaodong1,2, YU Wennian1,2, ZHANG Lu1,3 Aiming at coupling modeling of lubrication and vibration characteristics for tilting pad journal-rotor systems with pad wear fault, an original mixed-lubrication dynamic model for the tilting pad journal bearing-rotor system is proposed considering the effects of pad wear, rotor and pad horizontal-rocking vibrations, and bearing mixed lubrication. The dynamic responses of the rotor vibration and the bearing lubrication under different wear rates are studied. The effects of different parameters (rotor eccentricity, rotating speed and preload factor, etc.) on the dynamic characteristics of the tilting pad journal bearing-rotor system with worn pads are evaluated. Compared to the bearing without worn pads, the acceleration peak frequency of the rotor for the bearing with worn pads excites the additional even harmonics of the rotating frequency. The occurrence of multi-pad wear can cause a significant increase in the vibration response of the rotor and the oil film pressure of the bearing. These results provide a theoretical basis for condition monitoring and fault identification of tilting pad bearing and rotor systems. 2024 Vol. 43 (11): 255-263 [Abstract] ( 11 ) HTML (1 KB)  PDF (2825 KB)  ( 3 ) 264 Noise reduction method for blasting vibration signals based on improved EMD-wavelet packet YAN Peng1, ZHANG Yunpeng1,2, HOU Shanying1, ZHANG Weiwei3, YANG Xi1,2 Aiming at the problems of mode aliasing and poor signal noise reduction effect in empirical mode decomposition (EMD), according to the idea of decomposition-orthogonal-clustering-noise reduction-reconstruction, a blasting vibration signal noise reduction method based on improved EMD-wavelet packet was proposed. The method combined the orthogonality of kernel principal component analysis (KPCA), the clustering property of K-means algorithm and the noise reduction advantage of wavelet packet. This method could not only eliminate the modal aliasing of EMD, but also had a good noise reduction effect. The results show that compared with CEEMDAN and EMD methods, the improved EMD- wavelet packet method has the highest signal to noise ratio (7.9dB) and the lowest root mean square error (RMSE) in analog signal simulation test. In the noise reduction of the measured blasting vibration signal, the correlation coefficient between the original signal and the signal after noise reduction by improved EMD- wavelet packet method is maximum 0.91. The improved EMD-wavelet packet and CEEMDAN methods have better performance, improved EMD-wavelet packet has the best performance in preserving low frequency vibration signals at 10−60 Hz, the best filtering effect on medium and high frequency noise above 60 Hz. 2024 Vol. 43 (11): 264-271 [Abstract] ( 21 ) HTML (1 KB)  PDF (2659 KB)  ( 18 ) 272 Coastal near ground actually measured wind field characteristics in typhoon “Soudelor” moving process ZHANG Jianguo, WEN Zujian, LEI Ying Based on the field measurements of matrix layout anemometers in Dadeng island of Xiamen city, the wind velocity and direction data in four time intervals of typhoon ‘Soudelor’ are selected to analyze the coastal near ground wind characteristics during the typhoon moving. The mean wind speed and direction, wind profile, gust factor, turbulence intensity, turbulence scale and spectra in different time interval are discussed in detail. The four time intervals are corresponding to the typhoon center distance of 400km, 250km, 150km and 120km from the wind measurement towers respectively. The relationships between these parameters and typhoon center distance and height are presented. The results show that the wind profile meet the logarithmic law and the roughness length equals to 4.0m or so. The variation of gust factors and turbulence intensities is slow during whole process of moving. There is a linear relationship between gust factors and turbulence intensities. The ratio of turbulence intensity in alongwind, across-wind and vertical direction is 1:0.8:0.45. The power spectra in alongwind, across-wind agree with von Karman spectrum, but that in vertical direction does not meet. The outputs in this study are very useful for further understanding of the typhoon influences to coastal area during typhoon moving. It is also helpful to improve the wind resistance capacity of coastal engineering structures. 2024 Vol. 43 (11): 272-278 [Abstract] ( 19 ) HTML (1 KB)  PDF (2522 KB)  ( 13 ) 279 Protective coating thickness measurement based on genetic algorithm optimization in sparse decomposition LIU Yiyi1, CHEN Yao1, LI Qiufeng1, WANG Zhigang2, WANG Haitao3 In the simulation experiment of using high-frequency ultrasonic water immersion method to detect the thickness of protective coatings of assembled steel structures, the interfacial reflected echoes of the protective coatings are overlapped with each other, resulting in the inability to extract the time-domain information of the coatings, and the genetic algorithm-based optimization of the matching tracking process in the sparse decomposition is used to separate and reconstruct the overlapped signals. The algorithm optimizes the search process of the optimal atomic parameters in the constructed Gabor atom library by using genetic algorithm, and optimizes the inner product operation in the traditional sparse decomposition matching tracking algorithm to a mutual correlation operation, thus optimizing the operational efficiency of the sparse decomposition. Compared with the results of metallographic inspection of coating thickness, the inspection relative error of this improved algorithm is 2.50%, which is within the acceptable range and has a higher detection accuracy than the traditional sparse decomposition matching tracking algorithm with a large inspection relative error of 5.01%, while the computing speed is greatly improved. 2024 Vol. 43 (11): 279-287 [Abstract] ( 22 ) HTML (1 KB)  PDF (1804 KB)  ( 1 ) 288 Bending performance of RC beams reinforced with UHPC CHANG Yue1, HUANG Junqi1,2, ZHONG Xun1,2, ZHAO Meng1, JIANG Qing1,2, FENG Yulong1,2 Ultra-high performance concrete (UHPC) can be used as an ideal inorganic strengthening material owing to the high strength and improved durability. Based on the existing experimental results, this research proposed a refined finite element modeling method. The proposed method can be used in the numerical simulation of reinforced concrete (RC) beams strengthened with UHPC, and considering the cohesive contact between the reinforcement layer and the concrete beam contact surface. Then, finite element models of 162 reinforced beams were established and numerical simulation analysis were conducted, emphasizing on the influence of key parameters (e.g., such as cross-sectional area of reinforcement bars, thickness of reinforcement layer, and whether the reinforcement layer has joints) on the failure modes and bearing capacity of the components. The results indicated that the numerical model considering cohesive contact behavior could well predict the flexural behavior of RC beams strengthened with UHPC; the thickness of the strengthening layer and the cross-sectional area of the reinforcement bars both influenced the failure mode and the increasing of the load capacity, but for the specimens with joints, the thickness of the strengthening layer presented marginal influence on the behavior mentioned above. 2024 Vol. 43 (11): 288-296 [Abstract] ( 16 ) HTML (1 KB)  PDF (3819 KB)  ( 5 ) 297 Stochastic resonance driven by self-constructingly correlated noise and its application in fault diagnosis XU Haitao1,2, YANG Tao1,2, ZHOU Shengxi1,2 Rolling element bearings are the crucial component of rotating machine, timely health monitoring can effectively avoid the breakdown of the machine, further reduce the loss of the economic. Firstly, this paper proposed a stochastic resonance system driven by self-constructingly correlated noise (DSCSR), and theoretically analyzed the signal-to-noise ratio (SNR), which examines that the stochastic resonance can occur by adjusting the systems parameters. Secondly, aiming at the drawback that the accurate prior knowledge should be obtained before analysis, the paper suggested to calculate the SNR based on the power spectrum (〖SNR〗_P). Based on 〖SNR〗_P, the optimized system parameters can be achieved. Therefore, the fault type can be determined according to the output signal of the optimized system. Finally, the bearing fault diagnosis experiment and the bearing inner race fault of an actual wind turbine validate the capability of DSCSR in enhancing the weak fault characteristic and in suppressing the interference of other harmonics or random noise. 2024 Vol. 43 (11): 297-305 [Abstract] ( 12 ) HTML (1 KB)  PDF (3680 KB)  ( 10 ) 306 Annoyance level of metro train-induced environmental vibration based on evaluation index conversion method MA Meng, WANG Tingting, WANG Jiaxin To investigate the relationship between metro train-induced environmental vibration level and human subjective annoyance, the index conversion method was employed. The conversion relationship between the maximum Z-vibration level VLz,max and vibration dose value VDV was derived. The undetermined coefficients in the conversion equation were fitted using in-situ measurement results. Finally, the index VLz,max -based exposure-response curves were obtained using the index VDV -based exposure-response relationship. The evaluation of resident annoyance is preliminary achieved based on the index suggested by Chinese national standards. The results indicate that, the annoyance percentage increases with the number of pass-by trains. The annoyance corresponding to the vibration limit values recommended by GB10070, GB/T50355 and GB55016 are basically consistent with those in international standards. The highly annoyance percentage for the strictest limits is approximately 3%. 2024 Vol. 43 (11): 306-311 [Abstract] ( 21 ) HTML (1 KB)  PDF (1362 KB)  ( 16 ) 312 Typical features of sites in Shanghai based on HVSR method ZHAO Peng1,2, WEI Xiao1,3, HU Jun1,2 The Shanghai Strong Earthquake Network obtained several strong earthquake records such as the 6.0 magnitude earthquake in Kyushu, Japan, on May 3, 2020. By analyzing and processing the seismic records, the H/V spectral ratio curves of each strong earthquake station are calculated respectively, and the fundamental resonance frequency and sediment thickness of each station are obtained by combining with the distribution map of the buried depth of bedrock of Shanghai Institute of Geological Survey. The results show that: (1) there is an obvious correlation between the peak value of H/V spectral ratio curve and the thickness of the sedimentary layer, and the empirical formula of the thickness of the sedimentary layer and the resonance frequency of the fundamental order in Shanghai is established through data fitting, and the basic period distribution map of the Shanghai market is drawn, which can provide a certain reference for the seismic fortification of Shanghai. (2) There will be multiple peaks in the spectral ratio curve of seismic records on the thick sedimentary layer site, and the second peak represents the higher-order resonance frequency of the sedimentary layer. (3) The empirical formula of shear wave velocity and sediment thickness in Shanghai area is obtained through data fitting. 2024 Vol. 43 (11): 312-319 [Abstract] ( 43 ) HTML (1 KB)  PDF (2887 KB)  ( 10 ) 320 Dynamic characteristics and crushing features of high-strength concrete under impact load HAN Changjun, ZHOU Hailong, WANG Hailong In order to explore the influence of the replacement rate of fly ash and the type of fine aggregate on the impact compression performance of high-strength concrete, C80 high-strength concrete was prepared with the proportion of fly ash replacing cement as 0, 10%, 15%, 20% and 25% as cementitious materials, basalt manufactured sand and natural sand as fine aggregate, and the split Hopkinson pressure bar was used to carry out impact compression tests on it, and calculate the Fractal dimension of the broken body to quantify the crushing characteristics of concrete, And analyze the microstructure of concrete using scanning electron microscopy (SEM). The results show that the peak stress and toughness of manufactured sand concrete (MSC) are higher than those of natural sand concrete (NSC); As the replacement rate of fly ash increases, the peak strain of concrete gradually decreases; When the replacement rate of fly ash is 10%, the peak stress and toughness of concrete reach the highest value, and the Fractal dimension of the broken body is the smallest, the average block diameter is the largest, and the comprehensive broken characteristics are the simplest; Compared with the concrete without fly ash, when the fly ash substitution rate is 10%, the microstructure of the concrete is dense, the number of pores is reduced, and the overall compactness is improved. 2024 Vol. 43 (11): 320-326 [Abstract] ( 64 ) HTML (1 KB)  PDF (2378 KB)  ( 24 )

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