The dominant flutter mode of long-span suspension bridges varies with the erection stage of the main girder.This study investigates the mode transition during construction and its impact on aeroelastic stability.A 2 300 m-span suspension bridge with a closed-box girder was analyzed through free and forced vibration wind tunnel tests on segmental models at different erection stages.Critical flutter wind speeds and flutter derivatives were obtained.A double-mode coupled analytical method was employed to evaluate flutter performance throughout the erection process.The results indicate that before 58% of the main girder is erected, flutter is governed by symmetric mode combinations.During the transition stage from 58% to 66% erection, the dominant flutter modes gradually shift from symmetric to antisymmetric combinations.After 66% erection, flutter is controlled by antisymmetric mode combinations.The transition is caused by a rapid decline in aerodynamic damping of the antisymmetric mode.At the transition, the phase difference of antisymmetric motion drops sharply, vertical motion lags behind torsion, torsional energy contribution decreases, mode coupling intensifies, and aerodynamic energy dissipation increases.

Dynamic displacement is of great significance for evaluating the safety performance of structures.In practical engineering, it is often difficult or expensive to directly measure structural displacement.In this paper, a method of reconstructing the dynamic displacement of cantilever beam structure by strain response was proposed. different structural curvature symbols and standard side judgment criteria were defined for the first time, and the stochastic subspace algorithm was used to calculate the strain mode of vibration, which solved the problem that the calculation process of traditional mode superposition method was not clear and the number of measurement points required was large.Then, the corresponding displacement vibration mode was obtained by integral, and the modal coordinate time history was solved by strain data and strain vibration mode, and finally the dynamic displacement was obtained.The effectiveness of the proposed method was illustrated by the numerical simulation parameter analysis of a cantilever beam.The results show that the error is only 1.21% when there are only four strain measuring points.Finally, the feasibility of the proposed method is further verified by model test, and the results show that the maximum error is about 2.00%.The proposed method can reconstruct the dynamic displacement at any position only by arranging a small number of strain measuring points, which can provide a new idea for the deformation measurement of cantilever structures.

To investigate the nonlinear mechanical characteristics of the helical tube hydraulic inerter, a nonlinear dynamic model was established and its accuracy was verified through AMESim simulations and bench tests.The effects of helical tube structural parameters, working fluid properties, and hydraulic cylinder internal leakage on the inerter force were analyzed, and the damping force, inertial force characteristics, and failure states were discussed.The results show that the inerter force consists of inertial force, fluid parasitic damping force, and friction force, with the fluid parasitic damping force being the primary source of nonlinearity.The inerter force increases with the decrease in helical tube diameter, the increase in length, or the increase in surface roughness, while tube wall thickness has no significant effect.Compared to metal tubes, rubber hoses exhibit a damping effect on the force.High-density and high-viscosity working fluids increase the inerter force, but high viscosity also raises friction.Reducing the piston rod diameter increases the inerter force, whereas increasing internal leakage in the hydraulic cylinder decreases it.Excessive leakage leads to device failure.The findings provide a theoretical basis for the optimal design of hydraulic inerters.

To evaluate the axial compressive performance of transmission tower angle steels strengthened with CFRP (carbon fiber reinforced polymer) sheets, a series of axial compression tests were carried out, including one group of unstrengthened specimens and five groups of strengthened specimens. The experimental investigation focused on the failure modes, load–displacement responses, and load–strain behaviors of the specimens. A finite element model, calibrated and validated against the test results, was subsequently employed to conduct parametric analyses on the influence of fiber orientation, number of CFRP layers, bonded length, and slenderness ratio on the axial bearing capacity.
The results demonstrate that global buckling was the dominant failure mode. Strengthening with CFRP sheets markedly enhanced the ultimate axial compressive capacity of the angle steel specimens, with improvements exceeding 20%. The most favorable strengthening effect was achieved when the fiber orientation was aligned with the longitudinal axis of the specimen. It is recommended that the bonded length of CFRP sheets be set to approximately 75% of the specimen length, with two layers of CFRP applied. Furthermore, a theoretical approach for predicting the ultimate bearing capacity of strengthened specimens was developed based on the equivalent stiffness method. Comparisons with refined numerical simulations confirmed that the proposed method exhibits high predictive accuracy, with deviations generally within 10%.

Encapsulated bubbles are widely used in medical ultrasound imaging and targeted drug delivery. Understanding the dynamic properties of encapsulated bubbles in different environments is of great significance. In this study, numerical calculation of the dynamic equations for encapsulated bubbles near elastic walls was performed. Based on the computational results, the effects of three wall materials (plastic, biological tissue, and aluminum) on bubble pulsation were investigated. Utilizing the Poincaré analysis method and bifurcation diagrams, the nonlinear characteristics of bubble pulsation were thoroughly examined. The findings reveal that, in contrast to free bubbles, soft boundaries like a plastic wall and a tissue wall elevate the threshold of driving sound pressure amplitude necessary for inducing nonlinear bifurcation and chaotic behavior in bubble pulsation. Conversely, stiff boundaries such as an aluminum wall exhibit the opposite effect. Analysis on frequency response indicates that the soft wall attenuates the chaotic intensity of bubble pulsation and shift the resonance frequency to high range, whereas rigid wall intensifies the chaotic dynamics and lowers the resonance frequency. As the distance between the bubble and the wall increases, the nonlinear pulsation for bubble near the plastic wall becomes pronounced, while it diminishes for bubble near the aluminum wall. Notably, as the thickness of the wall increases, the nonlinearity of pulsation for bubble near plastic wall and bubble near aluminum wall increase in general, and the nonlinearity of bubbles near aluminum wall will increase more significantly. Additionally, both the distance from the bubble to the biological tissue wall and the thickness of the tissue wall have relatively minor effects on bubble pulsation. This research offers theoretical insights for the manipulation of encapsulated bubbles in proximity to different walls, thereby facilitating their application across diverse scenarios. 

To address the challenges of determining the mode decomposition number K and quadratic penalty factor α in Variational Mode Decomposition (VMD), and the low accuracy of Continuous Wavelet Transform (CWT) in identifying closely spaced modal parameters of structures, this paper proposes a novel method that combines parameter-optimized VMD with CWT for the identification of densely spaced structural modal parameters. A new composite objective function is constructed based on Energy Concentration (Ec) and Mutual Information (MI), and the Dung Beetle Optimization (DBO) algorithm is introduced to adaptively search for the optimal combination of [K, α]. Subsequently, the vibration response signal containing closely spaced modes is decomposed using VMD with the optimal parameters, and effective modal components are selected based on the Pearson Correlation Coefficient (Corr) criterion. Finally, CWT is applied to the selected modal components to extract the modal frequencies and damping ratios. Numerical simulations on a four-degree-of-freedom system with closely spaced modes demonstrate that, compared to conventional CWT methods, the proposed approach achieves higher accuracy in identifying densely spaced modal parameters and exhibits a certain degree of noise robustness. Experimental validation on a five-story frame structure further confirms the practical applicability of the proposed method.

The accurate identification and classification of coal and gangue is the key technology to realize the intelligent mining of fully mechanized top coal caving, which plays a vital role in improving the efficiency and quality of coal mining. In view of the problem that the current coal and gangue two-classification recognition technology can only simply divide the target samples into displaceable and closed categories, and can not monitor the mixed proportion of coal and gangue flow in real time, the task of coal and gangue multi-classification recognition is studied in this paper. First of all, the coal gangue impact-slip test bench is set up, and the samples with different coal-gangue mixing ratio are allocated for the coal-gangue impact-slip test, and the sample data that can be used for identification training are collected by DHDAS dynamic signal analysis system. Secondly, the collected sample data is divided into four categories according to its gangue content, and the signal preprocessing and feature extraction are carried out to construct the effective original signal matrix data set and the feature matrix signal data set respectively. Then, different data sets are combined with a variety of recognition algorithms to build a number of coal gangue recognition training models to carry out coal gangue multi-classification recognition training. Finally, based on the analysis of the recognition results of several training models, and taking the recognition accuracy as the evaluation standard, the combination model of the optimal data set and classification algorithm is found. The results show that the best combination of Resnet and effective original signal matrix data set, the highest single recognition accuracy is 97.3%, the average accuracy is 91.92%, which confirms the feasibility of coal and gangue multi-classification recognition research, and provides technical support and theoretical basis for the real-time monitoring of fully mechanized top coal caving mining.

During the operation of the electromagnetic launch microgravity device, vibrations caused by factors such as guide wheels and motors will directly affect the operational stability and microgravity level of the system. Guide rail excitation is identified as a critical factor inducing device vibration. Based on the technical characteristics of the device, a dynamic model was established, and the structural features of the guide rail were analyzed. Four excitation forms (sinusoidal, step, triangular, and pulse) were introduced to simulate guide rail irregularities. Dynamic responses of the device under different excitations were subsequently simulated. The results show that the device exhibits effective vibration isolation performance, with the vibration acceleration amplitude of the outer chamber being approximately one-tenth of the motor's; Horizontal vibrations are prominent under different guide rail excitations, particularly under step and pulse excitations, necessitating strict control of joint smoothness in engineering applications; The outer chamber shows higher vibration frequencies under pulse excitation, though its overall vibration frequencies and distribution ranges remain lower than those of the motor.

To investigate the influence of key design parameters of electromagnetic transducer on hearing compensation of round-window stimulating active middle-ear implant, a finite element model of the transducer and human ear was constructed. The human ear module of the model was established based on a fresh human temporal bone specimen using CT scanning and reverse modeling technology, and the reliability of the model was verified by comparison with experimental data. The transducer module, which incorporates its internal mechanical structure, was coupled with the human ear module through a coupler. Its response characteristics and the excitation characteristics of the human ear module have been verified by experiments. Based on this model, by changing the key design parameters of the electromagnetic transducer and its coupler, the response characteristics of the stapes were compared and analyzed, and their influence on round window excitation hearing compensation was studied. The results show that: increasing the permanent magnet mass in the electromagnetic transducer enhances round window excitation hearing compensation more significantly at low frequencies with little effect on other frequency bands; reducing the transducer housing mass improves compensation more notably at medium-high frequencies with minimal impact on other frequency bands; a larger coupler tip cross-sectional size enhances compensation across all frequencies.

In order to better meet the long-term monitoring needs of engineering structures, an automatic modal parameter identification method based on multiple density clustering was proposed. This method used the covariance-driven stochastic subspace identification algorithm to calculate modal information and mainly involves four stages: stability diagram cleaning, mode clustering, representative mode value extraction and true-false mode cluster identification. In the stability diagram cleaning stage, false modes are removed using the damping ratio-complex conjugate pair hard criterion, modal energy level soft criterion, and the first density clustering that only considers frequency distances. In the mode clustering stage, the second density clustering was first performed based solely on frequency distances to form multiple stable lines, followed by the third density clustering for each stable line considering only mode shape distances. In the mode representative value extraction stage, the mode corresponding to the median value of the damping ratios in each cluster was selected as the representative mode. In the true-false mode cluster identification stage, mutual exclusion-based true cluster selection was performed based on the similarity between the representative values of the mode shapes of all clusters. The k-means clustering algorithm was applied to iteratively remove false clusters located on different stable lines, and then iteratively remove false clusters within each stable line. The representative mode values corresponding to true clusters were selected as the final modal identification results. Analysis shows that the proposed method can effectively clean the stability diagram and enhance the frequency and mode shape similarity of mode clusters, so that the identification accuracy of weak modes can be ensured. Moreover, it features a relatively wide range for the two key parameters (the estimated numbers of physical modes and the maximum system order), which helps to effectively prevent mode omission and false modes. 

Vortex-induced vibration (VIV) performance of twin-box girders is critical in the design of long-span bridges. This study proposes a numerical approach combining forced and free vibration methods to predict VIV response. Specifically, the potential wind speed range for VIV is first identified through forced vibration analysis, followed by free vibration simulations to determine the VIV amplitudes within this wind speed range. This methodology aims to investigate the VIV behavior of a twin-box girder section and elucidate the underlying mechanisms. The feasibility of the numerical approach is validated through comparisons with wind tunnel test results. The results indicate that the central slot is a significant factor inducing VIV. At a +3° wind attack angle, installing spoiler at the opening slot effectively reduce the maximum VIV amplitude by 50%. The analysis of the flow field reveals that the interaction between vortices shed from the upstream girder and the flow through the slot generates large-scale vortices near the slot and the downstream deck. The fairings, positioned at the slot entrance, redirect most of the upstream vortices, forcing them to convect downstream. This manipulation of the flow pattern eliminates vortices on the downstream deck and minimizes adverse flow interactions within the slot, thereby optimizing the VIV performance of the main girder.

The catenary system of high-speed railway, as an overhead power transmission system with a complex structure, will produce dynamic responses under the conditions of wind load, seismic action, pantograph-catenary interaction, etc. Therefore, the analysis of the dynamic response of the catenary suspension system has become a hot research topic in this field. As the basis of dynamic response analysis, it is particularly important to perform form-finding analysis on the catenary suspension system. Based on the Absolute nodal coordinate formulation (ANCF method) and Newton iteration method, the article conducts form finding research on the catenary suspension system. In the research process, the ANCF static equilibrium equation needs to be established first, and the basic equation and variables of Newton iteration need to be determined based on this. Then, the reliability of this method is verified through the form finding results of a single cable. Finally, form finding research is conducted on the standard model of one span and an actual multi span catenary contact suspension system, respectively, After comparing the calculation results of the two suspension chord lengths with the reference values in the European standard EN50318-2018, it was found that the relative errors did not exceed 0.2%, which verified the accuracy and practicality of this form finding method.

Lamb wave is widely employed in structural health monitoring and damage localization for metal plates due to its long propagation distance and high sensitivity to damage. To address the issue of high computational complexity associated with the large number of sensors required in multi-path probabilistic damage imaging algorithms, this paper proposes a damage probability imaging method that uses transfer entropy between Lamb wave signals as the damage index and incorporates a multi-point ellipse method to screen effective paths. A steel plate model was established using ABAQUS, and the transfer entropy from the undamaged to the damaged Lamb wave signals was adopted as the damage index. The multi-point ellipse method was applied to identify the approximate damaged region. Sensor paths passing through this region were selected as effective paths. Damage location imaging was achieved by accumulating the damage indices along these effective paths, and experimental verification was conducted. The results demonstrate that the number of effective paths screened by this method is reduced by 86.1% compared to using all detection paths. The damage imaging results are consistent with the actual damage location, confirming that the method can accurately identify damage in steel plate structures.

Nose jet water entry of transmedium vehicles has been proven to be an efficient and adjustable active load reduction method. However, maintaining high load reduction efficiency requires a large amount of gas, which is unfavorable for practical applications. To reduce the saturated gas injection volume required for the jet-assisted water entry load reduction method, a study is conducted based on the VOF (volume of fluid) multiphase flow model. The study investigated the influence of gas injection volume on the load reduction efficiency during jet-assisted water entry, explored the optimization effect of vehicle shape modification on the saturated gas injection volume, and further analyzed the underlying mechanism by which shape modification optimizes the gas injection volume. The research indicates that increasing the gas injection volume can improve the load reduction efficiency of jet-assisted water entry. However, there is a saturation point for the gas injection volume. For instance, in the benchmark model with an entry velocity of 50m/s, when the gas injection volume increases to 25.5g/s, the generated cavity completely envelops the vehicle. Further increasing the ventilation volume yield only marginal gains in load reduction efficiency; Modifying the vehicle's shoulder helps reduce the saturated gas injection volume without compromising the baseline model's inherent drag reduction advantages. Under identical operating conditions, the modified model's saturated gas injection volume can be reduced to below 25.0g/s; Modifying the vehicle's shoulder can reduce the saturated gas injection volume. On the one hand, this reduction is due to the combined advantages of active and passive load reduction methods. On the other hand, it is because the shoulder modification optimizes vorticity distribution and sustains favorable longitudinal flow within the cavity, thereby mitigating boundary layer instabilities and internal flow separation. This enhancement contributes to improved cavity pressure persistence.

Multi-link mechanisms are widely utilized in industrial fields. However, their dynamic performance is significantly affected by dry friction clearances under impact loads and the uncertainty of system parameters, resulting in reduced motion accuracy, intensified vibration, accelerated wear, and control difficulties. To address this issue, a study on the rigid-flexible coupling dynamics of a mechanism with dry friction clearances and interval uncertain parameters under impact load was conducted, with a hybrid-driven nine-bar mechanism selected as the research object.Firstly, the rigid-flexible coupling dynamic equations for the mechanism with dry friction clearances and deterministic parameters were derived using the Lagrange multiplier method and were subsequently solved by the Runge-Kutta method. The influence of impact loads on the rigid-flexible coupling dynamic response characteristics was analyzed, and the validity of the model was verified through experiments. On this foundation, a rigid-flexible coupling dynamic model that considers the clearance values and friction coefficients as interval uncertain parameters was further established. The influence of these uncertain parameters on the dynamic response characteristics of the mechanism was investigated using the Chebyshev polynomial interval uncertainty algorithm. The effectiveness of the theoretical model and numerical results was then validated by the scanning method. A theoretical basis for the optimal design and precision assurance of multi-link mechanisms containing dry friction clearances is provided by the findings of this research.

The drilling and blasting construction of a water diversion tunnel may endanger adjacent water supply pipelines. To assess and control the adverse effects of blast-induced vibrations, this study first conducted monitoring and analysis of vibration waves generated during tunnel blasting. Subsequently, a finite element model was established to investigate the propagation characteristics of peak particle velocity (PPV) and peak equivalent stress along the pipeline axis and critical cross-sections, enabling the development of safety criteria for blasting vibrations during tunnel construction beneath water pipelines. Finally, hypothesis testing was performed on the distribution pattern of measured PPV values, leading to the calculation of safe charge weights considering probabilistic approaches. The results indicate that vibration intensity inside the pipeline decreases with increasing scaled distance. Among the three directional components, vertical vibrations exhibit the highest intensity, fastest attenuation rate, clearest directivity, and more concentrated frequency distribution. The vibration energy on the pipe wall is primarily concentrated in the medium-to-high frequency range, with minimal energy accumulation at low and high frequencies. Along the pipeline axis, the vibration intensity in the X-direction initially increases and then decreases, while the Y- and Z-directions show continuous attenuation. At critical cross-sections, the vibration intensity on the blast-facing side significantly exceeds that on the opposite side, with the lowest point experiencing the strongest vibrations but relatively lower peak equivalent stress. Water exerts a damping effect on pipe wall vibrations, with higher water levels providing more substantial vibration reduction. Energy attenuation of vibration waves propagates faster in granite than in tuff, with Y-direction vibrations being more sensitive to surrounding rock variations. Based on the relationship between peak resultant velocity and peak equivalent stress, the safety threshold for water pipeline vibration was determined as 9.24 cm/s. Distribution hypothesis testing revealed that the field-measured PPV values better fit a t-distribution pattern. The safety charge calculation formula was improved based on the t-distribution, and the enhanced probabilistic approach significantly increased the reliability of blast vibration control.

This study addresses the technical challenge of safe demolition of tall structures in harsh environments. Taking the demolition of a 210 m double-tube chimney at Zhengzhou Xinli Power Plant as a case study, a novel technique, "co-directional folding directional blasting," is proposed. The key achievements are as follows:①A precise control method based on dynamic analysis of the overturning moment time-history is established. The method uses the zero point and slope of the overturning moment as criteria for a delay optimization model. Through precise timing control of 6 seconds, the length of the blast debris from a 210 m chimney is reduced by 65%. This approach provides a new solution for the safe demolition of tall structures in dense environments.②A dynamic overturning bending moment model under the action of two-time-delayed cuts is constructed. The critical conditions for structural instability are quantitatively revealed. The safety margins for tensile and compressive stress at the upper cut initiation are 3.1 and 206%, respectively, with an overturning moment exceeding the resistance by 29%. For the lower cut, the safety margins for tensile and compressive stress are 3.2 and 110%, respectively, with an overturning moment exceeding the resistance by 34.6%. This forms a controllable "side-folding and downward seating" motion mode, eliminating the risk of reverse collapse.③By integrating dynamic control technology and mechanical theory, the spatial constraints of 200 m-scale tall structure groups are overcome. The positioning accuracy of the cut and the debris control accuracy are achieved at ±0.5 m and ±5%, respectively, demonstrating effective blasting outcomes.

Aiming at the problems of large load and strong impact during the operation of the swing lever forging manipulator, the traveling system of its cart was analyzed, and a correlation model between the driving motor parameters and the braking acceleration was constructed. Through the analysis of the hydraulic control circuit of the buffer cylinder of the swing lever forging manipulator's suspension mechanism, the matching rules between the buffer stiffness and damping and the hydraulic parameters were clarified. The dynamic differential equations of the suspension mechanism under the horizontal lifting and braking conditions were established by using the Lagrange method, and the dynamic equations were solved with the help of the fourth-order Runge - Kutta method. Based on the analysis of the time-varying characteristics of stiffness and damping, the relationships between the vibration suppression of the forging, the buffer stiffness, damping and the accumulator parameters under the horizontal lifting and braking conditions were studied through numerical analysis and multi-body dynamics simulation. The research results show that the buffer stiffness and damping have nonlinear characteristics. Appropriately increasing the buffer stiffness and damping within the allowable load range can shorten the system vibration attenuation time and improve the buffer performance. Correspondingly, the initial inflation pressure of the accumulator should be increased, and the initial inflation volume should be decreased. Comparing the numerical analysis and simulation results, after considering the mass of each part of the swing lever manipulator, the convergence time of the suspension system increases while the amplitude decreases. The research results provide a reference for the structural design, parameter optimization and accumulator selection of the swing lever manipulator.

Intense X-ray radiation in space can generate thermal shock waves on the surface of space objects, which has the characteristics of narrow load pulse width, high peak value and high synchronism in the irradiation range, and may cause serious damage to the structure. Honeycomb structures, known for their low density and high energy absorption capacity, are promising for space object protection. In this study, a performance evaluation experiment was designed based on light-initiated explosives loading technology. The light-initiated explosives were evenly sprayed on a 1mm-thick aluminum plate as the loading source. The surface density of light-initiated explosives was 40mg/cm 2. The loading peak value was about 189MPa, pulse width is less than 5μs, loading area is 16cm × 16cm, and load synchronism is better than 3μs.The protective effect of honeycomb plate with different thickness on the load of extremely narrow pulse width was studied experimentally. Honeycomb structures significantly reduced the peak explosive load. And as the increase of the thickness of honeycomb plates, the decline amplitude of peak pressure increased. The experimental results show that the design method is feasible.，and honeycomb structures have good application prospects in the protection of space targets.

This paper selects two types of multi-span long-span runway bridges of Boeing 737-800 landing as the research object, and establishes the aircraft-bridge coupling model based on the joint simulation technology. Firstly, taking the impact coefficient as the index, the impact effect of the rigid frame runway bridge under different aircraft landing states and bridge structure parameters is systematically studied, and it is compared with the continuous beam runway bridge. The results show that the variation trend of the impact coefficient of the rigid frame runway bridge and the continuous beam runway bridge with the two types of parameters is similar, but the former is generally larger than the latter, which is due to the larger overall stiffness of the rigid frame bridge. From the distribution range, the former is mainly distributed in 0.50-0.80, while the latter is distributed in 0.20-0.60. Subsequently, the multi-parameter sensitivity ranking of the impact effect of the two types of runway bridges under aircraft landing is systematically evaluated based on the orthogonal test method. The research shows that for the rigid frame runway bridge, the landing mass has the most significant influence, followed by the touchdown speed and the landing pitch angle; while for the continuous beam runway bridge, the sink speed is the most important influencing factor, followed by the landing roll angle and the touchdown speed.

The high-fill open cut tunnel structure traverses the mountainous area of gully and valley, and then achieves the integration of airport, high-speed railway and urban rail transit through backfilling. In order to clarify the dynamic response characteristics of vibration compaction around the open cut tunnel structure, this paper adopts a combination of field test and numerical simulation to analyse the acceleration response and safety factor of the open cut tunnel structure. The results show that: for the backfill soil, its compaction effect is positively correlated with the thickness of the false pavement and the number of rolling times, and the ideal compaction effect can be achieved by rolling 6 times; for the open cut tunnel structure, in the process of vibration load moving on both sides of the structure, the transverse and vertical acceleration attenuation law is similar, and the transverse acceleration is more prominent than the vertical acceleration response, and the percentage of the transverse acceleration attenuation for each working condition is 63.4%,57.1%,41.3%和24.8%, the average attenuation rate of vibration wave in the soil is about 8.2%/m; the top of the structure is the vertical acceleration response is more obvious, the peak acceleration of vibration with the increase of the filling height and decrease, large vibratory roller acceleration attenuation presents a non-linear law, the maximum attenuation of a single machine is about every 10cm attenuation of 110mm/s2, the double machine about 142, that is to say, the dissipation of vibration energy propagation by filling medium is gradually enhanced with the change of filling height, and the friction energy dissipation between soil particles is significantly enhanced with the increase of filling thickness and the prolongation of vibration wave propagation path; the error of numerical analysis and field test for each working condition is basically within 10%, and the negative impact of vibration response has obvious spatial limitation, which mainly focuses on the structure nearer to the vibration source. The negative impact of vibration response has obvious spatial limitation, which mainly affects the structure closer to the vibration source. For the structural parts farther away from the vibration source, the structural safety coefficient basically stays unchanged or changes very little at the moment of the vibration peak, which indicates that the vibration energy attenuates rapidly with distance. This study can provide a reference for similar projects.

To address the safety and environmental limitations of traditional explosive blasting, this study investigates a novel non-explosive rock fracturing device based on chemical gas generation—the Chemical-Energy Transient Gas-Expansion Fracturer(CTGF)—using a combined methodology of theoretical analysis, model experiments, and numerical simulation to explore its rock fracturing characteristics and underlying mechanism. Theoretically, the core mechanism is established as the generation of quasi-static gas pressure via a millisecond-scale deflagration reaction, which drives tensile failure in the rock mass. Comparative experiments in concrete models revealed that under identical charge conditions, although the peak strain induced by the CTGF was only 1/9 to 1/2 that of the explosive, it achieved a comparable strain impulse by extending the duration of energy application, ultimately resulting in similar macroscopic fragmentation. A numerical model was developed and validated using field experiment data. The simulation results revealed that the CTGF's "low-pressure, long-duration, quasi-static" loading mode efficiently concentrates energy on crack extension rather than crushing the borehole wall, thereby ensuring the effective propagation of primary cracks. Building on the validated model parameters, a subsequent parametric study clarified the critical influence of peak pressure and pressure loading rate on the macroscopic failure mode. These findings can provide a theoretical basis for the engineering application and parametric optimization of this novel technology.

Overturning instability induced by second-order effects can compromise the attainment of self-centering functionality in rocking systems following seismic events, and existing column-base-uplift self-centering configurations have difficulty reconciling the competing demands of large displacement capacity and overturning resistance. To address this issue, a Column Mid-height Uplift Rocking Frame (CMURF) is proposed, wherein the uplift location is optimized to the mid-height of the first-story columns to induce a double-curvature deformation mechanism that coordinates displacement demands and overturning stability. Quasi-static testing was conducted on a 1/2-scale specimen, and numerical analyses were performed for 13 full-scale models, the parameters of which included frame height and span, prestressing force, and damper configuration, in order to investigate the seismic performance and control mechanisms of the CMURF system. The specimen’s hysteretic response exhibited the characteristic flag-shaped envelope, demonstrating excellent load-bearing capacity, self-centering capability, and controllable damage. It was found that energy dissipation was governed primarily by the vertical shear displacement of the damping system. Geometric parameters of the rocking frame were shown to significantly influence the lateral response of the CMURF by modifying the structural lever arm: an increase in height reduced load-bearing capacity, initial stiffness, and energy-dissipation efficiency, whereas an increase in span produced the opposite effects. The initial prestressing force of the strands primarily regulated self-centering capability, with limited benefit to load-bearing capacity and stiffness, and lower prestressing levels were associated with reduced energy-dissipation efficiency. Optimization of the configuration of low-yield-point steel web hourglass-pin dampers (LYP-WHP) enhanced energy-dissipation efficiency. For synergistic optimization of self-centering capability and energy dissipation while maintaining elastic behavior in critical components, it is recommended that the self-centering coefficient (SC) be maintained within 1.52–2.25 and that the height-to-span ratio be kept between 1.8 and 3.63.

To investigate the impact of underfilled grouting defects on the seismic performance of prefabricated bridge piers, produced three groups of grouting sleeve connectors specimens and carry out pull-out tests. According to the tests results, cast-in-place single-column pier, fully grouted assembled single-column pier and assembled single-column pier with grouting defect were designed as specimens and the pseudo-static tests were carried out. In addition, verified finite element pier models were established, and an extended parametric analysis was conducted regarding the length, location and quantity of the grouting defects. The results showed that: when the length of grouting defects in grouted sleeve connections exceeds 2.5 times the diameter of the reinforcement, the damage mode will change; the use of grouted sleeve connections will reduce the ultimate bearing capacity of the abutment specimens by 6.8%, and grouting defects will reduce the unloaded stiffness of the structure. In order to make the existence of grouting defects of the bridge pier still have sufficient seismic performance, should ensure that the grouting defects of the length of less than 2 times the diameter of the rebar, grouting defects in the number of sockets accounted for less than 40% of the defects do not appear in the middle of the assembly end and the end of the defects, this time, assembly of a single-column pier of cumulative hysteresis dissipation of the reduction in the amount of energy can be less than 10%.

Lightweight structure and portable facility are important future for prefabricated bridge construction. To achieve lightweight construction of ultra-wide multi-column bridge pier, this study proposed an segmental assembled construction scheme for the ultra-wide cap beam in the multi-column bridge pier. The 40-m ultra-wide cap beam was divided into three prefabricated segments, connected with two C50 delay-casted joints, thereby enabling lightweight construction of the 40-m ultra-wide cap beam. To investigate the seismic performance of assembled ultra-wide cap beams, a refined numerical model of the multi-column bridge pier was established. Through incremental dynamic analysis, the interfacial behavior of the prefabricated segments and the delay-casted joints was obtained. The results show that the interface was the weakest section for cracking in the assembled cap beam, as interfacial cracking reduced the beam stiffness and weakened the coupling effect between the columns. Under design-based intensity, the interfacial crack width didn’t exceed 1.0 mm, and the interface automatically closed after the earthquake. Furthermore, the macro-responses, such as pier-top displacement and bearing deformation, using the prefabricated cap beam were similar to those using cast-in-place cap beam, while the shear force and strain of the piers were partially reduced. These findings indicated that the segmental assembled cap beam essentially achieved the equivalent performance with cast-in-place cap beam.

The mechanical properties of steel play a pivotal role in determining the nonlinear structural response under cyclic loading in seismic analysis. While classical constitutive models can accurately describe the elastoplastic mechanical behavior of materials, but the model parameters to be determined are usually complex and require extensive experimental calibration. Although data-driven constitutive models can solve the problem with parameter calibration, the tangent stiffness of such models is usually difficult to obtain directly, making them unsuitable for nonlinear finite element analysis. Therefore, this paper proposes an elastoplastic operator-guided data-driven constitutive model (DD-PIHC) to solve the mentioned problems. which features a concise formulation with a small parameters scale and can explicitly output tangent stiffness with the help of elastoplastic operators, can direct integration into fiber beam-column elements for structural finite element analysis. The state update algorithm combining DD-PIHC with fiber beam-column elements is presented. The proposed model is validated based on rebar test data from various types of steel reinforcement. Comparative analysis with RNN model and the Steel02 constitutive model in OpenSees demonstrates that the proposed model exhibits superior accuracy and computational efficiency in capturing material constitutive behavior. On this basis, the model was applied to a quasi-static cyclic loading analysis of a three-story steel frame structure, verifying its feasibility for nonlinear structural analysis. This provides a reliable analytical tool for subsequent seismic performance optimization design.

Wind turbine generators operating in low-temperature and high-humidity environments are prone to blade icing, which significantly affects power generation efficiency. Most existing studies have concentrated on single turbines, while severe data imbalance remains a major challenge during icing sample collection. To address these challenges, this paper proposes an unsupervised domain adaptation model named Convolutional Attention-bidirectional Transformer (CA-BiTrans) for cross-turbine blade icing detection. First, SCADA data are cleaned by removing invalid entries, and features highly relevant to the icing mechanism are selected using Pearson correlation analysis. The processed data are then fed into the CA-BiTrans model, which efficiently extracts cross-channel features from both global and local perspectives. Finally, a domain adaptation strategy is designed by integrating class-sensitive and local maximum mean discrepancy losses, dynamically adjusting weights to address class imbalance and feature distribution shifts across different turbines. Engineering data validation shows that the proposed method performs excellently in cross-turbine icing diagnosis, achieving a maximum accuracy of 99.12%, significantly outperforming CNN, DAN, VIT and SDAGN models. This provides an effective solution for multi-turbine blade icing detection.

To address the challenge of extracting fault features of planetary gear bearing under strong background noise, a fault diagnosis method based on Multipoint Optimal Minimum Entropy Deconvolution Adjusted (MOMEDA) combined with soft threshold processing is proposed. First, the fault signal was processed by MOMEDA to obtain multiple channel filter signals. Then, the fault pulses were extracted by soft threshold denoising. Next, the optimal parameters of MOMEDA were selected by choosing fault cycle T and optimal filter length L using Multipoint Kurtosis (MK) and Crest Factor (CF). Finally, envelope analysis was performed on the processing results of MOMEDA with the optimal parameter combination [T, L] to complete the fault diagnosis. Simulation and experiments show that this method can effectively extract fault features from complex signals. Comparative analysis indicates that the parameter combination [T, L] selected by this method is optimal and that it outperforms Maximum Correlation Kurtosis Deconvolution (MCKD) and Ensemble Empirical Mode Decomposition (EEMD) in feature extraction.

This paper takes a certain underwater vehicle as the research object and adopts the modeling approach of "bottom-up, level-by-level modeling, and level-by-level validation" to establish its structural noise prediction model. Firstly, the finite element modeling method for typical connection structures of underwater vehicles was studied; Secondly, the component level, segment level, and full vehicle finite element models of underwater vehicles were established level by level, and the models were verified level by level through modal test data; On this basis, a low-frequency structural noise prediction model for all aircraft was established based on finite element method-boundary element method(FEM-BEM), and low-frequency structural noise was predicted. Compared with the measured values, the maximum error of the predicted value within 1/3 octave is 4.4dB, indicating the effectiveness and feasibility of the prediction method. This method can be used for low-frequency structural noise prediction of underwater vehicles.

Clunk noise caused by torque ripple under transient operating conditions is one of the main vibration and noise problems of IWM (in-wheel motor) drive systems. Large torque ripple may cause torsional vibration in the drive transmission system, seriously affecting ride comfort and safety. Therefore, conducting research on Clunk noise of IWM drive systems is of great engineering significance for improving the NVH performance of the system. The driving system of the inner rotor permanent magnet synchronous IWM is taken as the research object, and the mechanism of Clunk noise generation during vehicle testing is analyzed. Through bench testing, it was found that the impact vibration between teeth caused by the cogging torque of the motor is the main cause of Clunk noise. A multi-body dynamics analysis model of the IWM drive system was established based on Masta software, and the effectiveness of the model was verified through experimental data conclusions. The influence of various parameters on Clunk noise was analyzed using the control variable method. Through the analysis of key parameter influencing factors, it was found that motor speed and cogging torque have a significant impact on Clunk noise. A control scheme was proposed to suppress Clunk noise by reducing torque ripple caused by cogging torque. By optimizing the rotor skewed pole and injecting harmonic current, the torque fluctuation can be reduced from 3.8Nm to 0.24Nm, achieving the effect of improving the sound quality of Clunk noise. After optimizing the NVH test of the sample, the Clunk noise level was significantly reduced, and the subjective evaluation was acceptable. Solved practical engineering problems and improved the NVH performance of the wheel hub motor-driven transmission system.