To evaluate the seismic performance of stud steel reinforced concrete (SSRC) columns after repair and strengthening following post-earthquake damage, two widely used reinforcement materials were adopted: carbon fiber-reinforced polymer (CFRP) sheets and high-strength steel wire (HSSW) meshes.Five SSRC columns with torsional damage were repaired and strengthened via single or composite techniques, and quasi-static torsion tests were conducted on all strengthened specimens.The failure modes of each specimen were observed, and comparisons were carried out between the multiple seismic performance indices, such as hysteresis curves, backbone curves, strength and stiffness degradation, damage evolution, etc.before and after strengthening.The results show that both types of reinforcement can effectively inhibit crack development.Specifically, CFRP sheet reinforcement exhibits a more significant effect in enhancing the torsional bearing capacity, ultimate displacement, and energy dissipation capacity, while also reducing the strength degradation rate and damage degree.In contrast, HSSW mesh reinforcement demonstrates superior performance in improving the torsional ductility coefficient compared to CFRP.For the specimen R-H-CT-4 under combined loading, its rotational ductility coefficient increases by 1.84.For the specimen R-HC-PT-3, the peak torque and ultimate rotation angle increase by 32.25% and 48.70%, respectively.In conclusion, practical recommendations for the application of these two reinforcement materials were proposed based on the experimental results.

When high-speed electric multiple units (EMUs) operate on curved tracks, their dynamic behavior becomes more complex compared to straight-line operation condition, making the vibration characteristics of the gearbox housing challenging to predict.Therefore, investigating the vibration response of the housing under curved track conditions is essential for ensuring operational safety.A rigid-flexible coupled multi-body dynamics model of the high-speed EMU was developed in the SIMPACK software by integrating the finite element method with vehicle dynamics theory, in which the gearbox housing was treated as a flexible body.The model was used to analyze the vibration behaviors of the housing under the coupled excitation of rail corrugation and wheel polygonal wear on curved tracks.The results indicate that curved conditions amplify the housing vibration induced by wheel-rail excitations.The curve influence factor varies significantly under different excitation conditions, exceeding 70% in specific scenarios.Furthermore, resonance occurs when the frequency of the wheel-rail excitation approaches the natural frequency of the gearbox, leading to a substantial increase in housing vibration.These findings provide a theoretical basis for the dynamic optimization and vibration control of gearboxes in high-speed EMUs.

To investigate the often-overlooked effects of eccentric ice accretion and uneven ice-shedding in bundled conductors on the dynamic response of transmission lines during ice shedding, finite element models were established for a single conductor and a quad-bundled conductor-spacer system with 300 m span.The model accuracy was validated against experimental data from the literature.The variations in jump height, lateral displacement, and torsion angle under different eccentricities during both complete and partial ice-shedding scenarios were analyzed.The results show that for a single conductor with 300 m span, eccentric icing induces transient torsion and minor lateral oscillation but has negligible influence on the vertical jump displacement and end tension.For complete ice-shedding in quad-bundled conductors, increased eccentricity significantly amplifies the lateral displacement and torsion angle, while jump height exhibits only marginal changes.During partial ice-shedding, the dynamic response varies markedly with shedding patterns: shedding ice from lower sub-conductors leads to greater jump heights, pronounced lateral displacements, and larger torsion angles, whereas shedding ice from upper or diagonal sub-conductors yields relatively stable responses.The study reveals that eccentric ice accretion, especially when coupled with uneven shedding, substantially intensifies the complexity and instability of conductor dynamic responses.For manual de-icing operations, priority removal of ice from upper or diagonal sub-conductors is recommended to mitigate instability risks.

To explore the vibration characteristic of a simply-supported pipe with a circumferential through crack, a new equivalent stiffness model for a thin-walled pipe with a through-thickness circumferential crack is established based on the strain energy release principle and the linear fracture mechanics theory. The mathematical model of a simply-supported pipe with a leakage is derived based on Hamilton's principle. The internal flow effect and the crack model are verified adopting a rubber hose and a marine riser respectively. A simulation study is performed employing the marine riser assuming the crack (leakage) occurs at different locations with different severities. At first, the critical internal flow velocity U_cr  is predicted and it has found that U_cr depends on the combined effects of crack and leakage. ①the crack decreases the critical velocity as it decreases the equivalent stiffness, and this effect becomes more notable with the increase of crack severity. ②The leakage increases the critical velocity as it decreases the centrifugal force and this effect becomes notable with the increase of leakage severity. Then The displacement and the curvature responses of the pipe within the critical internal flow velocity range is analyzed. It has demonstrated that the curvature response exhibits much richer dynamics, which can provide information for online identification and location detection of a through-thickness circumferential crack (leakage). ①The first model is always dominant in the displacement response. The maximum displacements at a fixed simulation time increases in the decay process as the crack severity increases, the crack location approaches the midpoint (i.e., the extreme point of the first-order curvature mode) and the leakage effect becomes more remarkable. ②The dominant mode of the curvature response varies with time increases and a protrusion at the crack location is witnessed. The abrupt peak value increases as the crack severity increases, the crack location departs from zero points of the dominant mode (i.e., the ineffective positions for crack) and the leakage effect becomes more remarkable. This study benefits for optimizing health diagnosis and safe assessment approaches of pipelines. 

Based on the first-order shear deformation theory, the continuity condition of the displacement of the layers of the structure and the ZigZag theory, the coupling relationship of the displacement field of the structural constraint layer, damping layer and base layer is constructed. The general boundary conditions of the structure are simulated by the penalty function, and the first type of Chebyshev orthogonal polynomial is used to characterize the displacement field components of the structure. On this basis, the natural frequency characteristics and loss factors of the composite damping sandwich rectangular plate structure are solved according to the Rayleigh-Ritz method. Finally, by comparing the numerical results obtained by this method and the finite element method, the correctness of the prediction model is verified, and the influence of the main parameters on the free vibration characteristics and loss factors of the structure is analyzed.

This study investigated the cable-single damper system by analyzing the hyperbolic characteristics of the frequency equation. The research mathematically revealed the mechanism behind the imaginary periodicity of the system's complex eigenvalues, characterized by equally spaced imaginary parts. By leveraging this periodicity, the numerical algorithm was optimized, and its accuracy was validated through specific case studies. The findings are as follows: (1) The imaginary periodicity of complex eigenvalues occurs when the damper is located at a rational position. Under this condition, the imaginary parts of the eigenvalues (natural frequencies) exhibit a periodic distribution. (2) The damping characteristics remain independent of the natural frequency order. For any damping coefficient, the real parts of the eigenvalues (damping characteristics) stay consistent across different periods. (3) The numerical solutions based on the imaginary periodicity show errors within acceptable limits for practical applications. 

As a typical flexible load-bearing member, the suspended cable is characterized by its low damping and light weight, and is thus prone to large-amplitude parametric vibrations under end-support excitation. Its dynamic characteristics are also highly sensitive to environmental factors such as temperature variation and structural damage, which can affect overall structural safety. Although the individual effects of temperature or damage have been previously studied, a comprehensive understanding of the complex nonlinear resonance behavior of parametrically excited suspended cables under their coupled influence remains insufficient. This paper aims to reveal the governing principles and underlying mechanisms of the combined effects of temperature variation and local damage on the principal parametric resonance response of suspended cables. To this end, an in-plane nonlinear differential equation of motion that considers the coupled thermo-damage effects is established. By applying Galerkin's method and the method of multiple scales, the amplitude-frequency response equation of the system is derived and used to conduct qualitative and quantitative analyses of the resonance characteristics. The research indicates that the coupled effects of temperature and damage not only change the cable's modal frequencies and the crossover characteristics of the frequency curves but also significantly affect the system's effective nonlinear coefficient, principal resonance amplitude, and stability boundaries. This influence is amplified as the initial sag-to-span ratio increases. A notable discovery is that for a sufficiently large sag-to-span ratio, a decrease in temperature can induce a fundamental reversal of the cable's equivalent stiffness, leading to a fundamental transition of the cable’s equivalent stiffness from softening to hardening behavior. These findings provide a more comprehensive theoretical basis for the prediction of dynamic behavior and the long-term safety assessment of suspended cables in complex environments.

Tuned Mass Damper Inerters (TMDIs) have garnered significant attention for their compact physical mass and high robustness in structural vibration control. This study proposes a Tuned Mass Damper-Clutching Inerter (TMDCI) by incorporating a clutch-inerter system into the conventional TMDI to enhance vibration suppression performance. A unidirectional-bearing-based clutch-inerter system was developed, and its dual-mode operating mechanism (engaged/disengaged states) was rigorously investigated. A two-degree-of-freedom experimental setup simulating primary structure-TMDCI dynamics was established, accompanied by an energy-consistent equivalent inertance model for parameter identification. Free-decay and forced vibration tests demonstrated the TMDCI’s superior performance, achieving vibration reduction rates exceeding 70% at critical frequencie, and its control frequency band is wider than that of TMDI. The results validate the TMDCI’s efficacy in adaptive vibration mitigation and provide a practical framework for its implementation in bridges, high-rise structures, and offshore platforms. 

Limiters, common in rotating machinery, primarily restrict abnormal rotor vibrations and significantly enhance system disturbance rejection. This paper presents an experimental study on rub-impact in a vertical high-speed rotating machine with a flexible support structure. First, a systematic analysis of the system is conducted. Based on the rotor-support-limiter system’s structural characteristics, a direct method for measuring rotor-limiter collision contact time is proposed. Using dynamic equations and the measured contact time, an indirect approach to determine the average friction force during rub-impact is developed. Subsequently, horizontal vibration table tests under base excitation validate the proposed methods, investigating how contact time and average friction force vary with rotor speed and excitation intensity. Finally, experimental results are compared with theoretical predictions to refine the rub-impact model for rotor-limiter systems, bridging the gap between test and simulation. 

This study proposes a novel integrable structure-performance integrated metallic locally resonant structure fabricated via additive manufacturing. The bandgap characteristics were systematically investigated through numerical analysis and experimental validation. Results demonstrate that the proposed structure exhibits a low-frequency bandgap, whose formation mechanism arises from the coupling between elastic waves in the matrix and the resonant characteristics of locally resonant units, effectively confining elastic waves around the resonant units rather than transmitting them through the matrix. Subsequently, the regulatory effects of resonant unit parameters on bandgap characteristics were explored. Based on these findings, a gradient design strategy was implemented to overlap bandgaps from different unit cells, thereby extending the effective bandgap range. Simulations and experiments confirmed that the gradient structure achieved a 2.35-fold expansion in bandgap coverage compared to single-parameter configurations, reducing the vibration peak of a cantilever beam by 79.85%. These results highlight the structure’s exceptional low-frequency broadband vibration suppression performance, demonstrating significant potential for engineering applications in vibration and noise reduction.

Honeycomb sandwich structures used in aircraft are subjected to severe high-frequency acoustic loads during service. Accurate analysis of the high-frequency dynamic response characteristics of these structures is of great significance for aircraft structural design. A method based on wave finite element (WFE) was developed for predicting the dynamic response of honeycomb sandwich structures, which enables accurate prediction of high-frequency localized dynamic behavior. First, the dispersion characteristics of typical honeycomb sandwich structures were analyzed to investigate their free wave propagation properties; Subsequently, dispersion analysis and waveform matching were performed on the dominant wave modes under forced excitation, evaluating the influence mechanisms of different wave types on the structural dynamic response; Finally, the influence of design parameters such as the thickness of the top/bottom face sheets, core layer height, and honeycomb wall thickness on the structural response were studied. The results demonstrate that: (1) The WFE method can accurately capture the high-frequency localized response characteristics of honeycomb sandwich structures. (2) Increasing the upper and lower panel thickness transitions the dominant influence from mass to stiffness, causing the peak response to shift to lower frequencies and then to higher frequencies. (3) Increasing the thickness of face sheets and honeycomb walls affects structural mass more significantly than stiffness, causing the response peaks to shift toward lower frequencies. (4) Increasing the core height enhances structural stiffness more significantly than mass, resulting in an upward frequency shift of response peaks and reduced modal density in the high-frequency range.

To address the incomplete coupling factors and oversimplified rotor structure in the motorized spindle dynamic model, a multi-physics coupling dynamics simulation model was developed. The bearing model was coupled with the motor model, spindle thermal model, and shaft model, considering the standard rod, tool holder, and shaft hollow structure. Due to the significant impact of internal hollow factors, coupling factors, and additional structures on the dynamic performance of the spindle system, this model is more closely aligned with the actual situation of the spindle. The bearing model utilized a quasi-static nonlinear restoring force model, while the motor model employed a stator-rotor double-cylinder unbalanced magnetic pull model. The spindle thermal model included bearing and motor heat generation and dissipation models. Dynamic characteristic analysis tools such as Campbell diagrams and waterfall plots were generated. Spindle rotation error tests and hammering experiments showed that the model’s time-domain radial displacement error remained below 10μm at all speeds. The frequency-domain results from hammering tests exhibited a maximum error of 12.66%. The model’s validity is confirmed through both dynamic and static analyses.

To address the mismatch between the design parameters of space borne camera vibration isolators and the complex dynamic environment during the satellite launch phase, this paper presents an optimization study on the parameters of the Bipod constrained damping isolator. Firstly, mechanical model of the constrained damping rod and dynamic model of the Bipod are established, and the theoretical model accuracy is analyzed and validated. Then, taking the system's acceleration transmissibility as the optimization objective, the natural frequency and damping ratio as constraints, and the length of the damping layer and the hinge support installation angle as design variables, a heuristic algorithm is employed to optimize the Bipod constrained damping structure. Finally, the proposed heuristic optimization method is validated through the design of a vibration isolation system for a specific satellite camera model. Quasi-static simulation and frequency sweep test results show that the theoretical model accurately characterizes the Bipod isolator's performance, and the optimized isolator meets all performance requirements for the satellite launch phase.

Based on the shear lag model theory, this study systematically analyzes the mechanical properties and load transfer mechanisms of the three components in an internally anchored bolt system—the bolt, the grouting material, and the surrounding rock. A calculation formula for the internal force of the internally anchored bolt structure is derived. Through indoor pull-out tests, the distribution pattern of internal forces within the anchoring structure is investigated. On this basis, a comparative analysis is conducted between the shear lag model and the Kelvin model in simulating the mechanical behavior of the bolt, leading to the proposal of a segmented composite calculation model that integrates the advantages of both approaches. The results indicate that the shear lag model effectively characterizes the stress characteristics and load transfer process of the internally anchored bolt. The axial stress of the bolt decays exponentially along the anchoring length and can be divided into three segments: rapid decline, slow decline, and a relatively stable segment. The distribution of interfacial shear stress evolves dynamically with the variation of the pull-out load. Under low load levels, the peak shear stress occurs near the loading end of the anchoring section. As the load increases, the peak shifts toward the deeper part of the anchor, and the shear stress at the loading end approaches zero. Compared to using a single model, the segmented composite calculation method based on the shear lag model and the Kelvin model shows significant improvements in both accuracy and practicality, offering better alignment with engineering reality. This research provides a new theoretical framework and calculation method for analyzing the anchoring mechanism of bolts, with important theoretical significance and practical application value for the design optimization and safety assessment of anchoring engineering.

Dynamic trajectory serves as a critical basis for evaluating transient and steady-state responses of a drum-type washing machine. Due to the hollow structure of the drum and the coupling of translational and rotational motions, dynamic trajectory of the drum's geometric axis is hard to be measured directly. For addressing this issue, a dynamic trajectory measurement method based on multi-sensor fusion technology is proposed. First, considering rigid-body motion characteristics of the drum, constraint governing attitude matrix of the drum and relative vibration displacement between the sensors is established. The attitude angles of the drum are solved using Newton iteration method, and vibration displacement at the front and back geometric center points of the drum are calculated, based on which dynamic trajectory of the drum’s axis is obtained; After this, constraints governing the first/second order derivatives of the drum’s attitude angles and relative vibration velocities/accelerations between the sensors are established. The derivatives of the drum’s attitude angles are solved, and vibration velocity/acceleration of the drum at any position are obtained. Based on the above method, numerical simulations of dynamic characteristics of a specific drum-type washing machine is performed, trajectory parameters of the drum are identified based on fusion of the simulation results at three points, and the effectiveness of the method is validated by comparing results from identification and those from simulation. At last, an experimental platform is made, dynamic position and attitude parameters of the drum are identified through fusion of vibration data from three sensors, in the meanwhile, data from the fourth sensor is employed for verification, and the effectiveness of the method is confirmed by comparing trajectory measured directly with that identified at the fourth sensor.

As a highly destructive mixed fluid, the impact mechanism of the block-carrying debris flow on the frame structure has not been fully studied. In order to reveal the dynamic response and damage mechanism of the frame structure impacted by debris-containing debris flow, this paper constructs a multi-coupled numerical model of slurry-block-structure based on the coupled numerical method of smoothed particle hydrodynamics-discrete element method-finite element method, simulates the damage process of the frame structure under different impact velocities and angles, and verifies the model validity by combining with the two-phase dam failure test. The study shows that the structural damage caused by the impact of debris flow goes through the four stages of ‘contact-diffusion-rebound-accumulation/impact’, and when the impact velocity exceeds 6m/s, the structure generates irrecoverable damage, and blocks effect makes the impact force of the slurry in the upper part of the slurry body larger than that in the lower part, which triggers the central part of the structure to be the first to experience centralized damage; moreover, the peak impact force increases with the velocity and angle in a non-linear manner. In addition, the peak impact force increases nonlinearly with velocity and angle, and the impact force at the bottom of the frame column reaches 497.17kN under 10m/s and 90° conditions, which exceeds the structural impact bearing capacity; finally, the error between numerical simulation and empirical formulae of the impact force results is in the range of 13.95-29%, which is consistent in the order of magnitude, and the reliability of the model is verified. The research findings can provide reference for the impact-resistant design of frame structures in areas prone to debris flows.

To investigate the mechanical response of prestressed anchorage bodies under cyclic impact loading, this study conducted cyclic impact tests using specimens with different prestress levels based on a modified split Hopkinson pressure bar (SHPB) experimental system. The study focused on the stress wave propagation in rockbolts and surrounding rock, the attenuation characteristics of peak strain, and the governing laws of prestress degradation, and the fracture behavior of the anchorage body, so as to explore the dynamic response mechanism of prestressed anchorage under cyclic impact. The experimental results indicate that the peak values of both incident compressive waves and reflected tensile waves in the rock bolt and surrounding rock decay gradually with increasing propagation distance. Under cyclic impacts with the same incident energy, the peak value at different locations of the rock bolt and surrounding rock showed no significant change during the initial impact phase; however, as the number of impacts increased, the peak strain gradually decreased at all locations. The evolution of prestress in the anchor body can be divided into four characteristic stages: the tension stage, the stabilization stage, the loss stage, and the residual stage. The number of impacts required for complete failure of the anchorage specimen first increased and then decreased with the prestress level, with. The optimal impact resistance was achieved at a prestress level equivalent to 0.6 times the ultimate pull-out capacity of the rockbolt. All anchorage specimens developed only a single spalling crack, with damage concentrated mainly in the unanchored zone at the impact end, while no obvious spalling was observed in the anchored zone of the surrounding rock. The research findings provide theoretical support for the optimized design and safety service of rock bolt support systems in deep rock engineering.

For mechanical components with self-healing characteristics, a dynamic reliability evaluation method considering intensive impact failure is proposed. Based on the consideration of intensive impact failure, the product's entire life cycle is divided into a storage stage and an operation stage, focusing on the interrelationship among the mechanical component's strength degradation process, impact failure process, and self-healing process. First, according to the impacts experienced by the mechanical product during the operation period, the relationship between the product's self-healing capability and the self-healing threshold under different impact intervals is analyzed, examining the effect of different self-healing thresholds on product reliability, and a self-healing model for mechanical components is established. Next, the natural degradation process of the product during the storage and operation periods is described using the Wiener process, and, combined with the threshold-varying strength degradation failure process, the reliability function expression considering the Wiener degradation model and the self-healing process is derived. Finally, using a vehicle tie rod as an example, the model's effectiveness and practicality are verified through comparative analysis and sensitivity analysis, providing a new approach for reliability analysis of mechanical components with self-healing characteristics in complex working environments.

To elucidate the lateral propagation and superposition mechanism of ground shock waves in layered rock-soil media, a combined approach of experimentally validated numerical simulations and theoretical analysis was employed. This study systematically investigates the superposition and evolution mechanism of the incident wave in the explosion layer and reflected waves from various interfaces. A parametric analysis was conducted to evaluate the influence and mechanism of geomechanical parameters on the peak value of the superimposed wave. Based on the stress wave propagation theory in continuous media, a calculation method for the superimposed wave in the source layer was established, incorporating the effect of interface slip. The results demonstrate that: 1) Interface slip significantly affects the characteristics of reflected waves, leading to an increase in amplitude, with greater wave impedance contrast amplifying this effect; 2) The superimposed ground shock waveform in the source layer exhibits four typical types: amplitude increase, double peaks, amplitude decrease, and rapid attenuation; 3) Within the scaled distance range of 0.5–0.8 m•kg⁻¹/³, the amplitude ratio of the superimposed wave to the incident wave is higher at the sand-rock interface, lower near the free surface, and close to 1 in the intermediate region. The revealed superposition mechanism and proposed analytical method can provide theoretical support for calculating blast loads and optimizing blast-resistant designs of structures traversing complex geological strata.

To clarify the influence of impactor geometry on the impact resistance of reinforced concrete (RC) slabs, this study analyzes the dynamic response, failure modes, and damage evolution process of RC slabs subjected to typical impactor types: flat-head and curved-head hammers. The research further investigates the effects of impact velocity, drop hammer mass, reinforcement ratio, and rebar spacing on impact resistance performance. A damage assessment method incorporating joint indicators is then proposed. The results show that, under identical contact areas, a rectangular hammerhead produces the most extensive damage, followed by a square one, while a circular one causes the least; the damage range increases with the aspect ratio of the rectangular hammerhead. With the increase of the hemispherical hammerhead radius, the maximum impact force gradually increases, The impact force curve transitions from Type I, which exhibits only a single main peak, to Type III, which includes both a main peak and a plateau phase. The central area of contact between a flat surface and the concrete slab bears high hydrostatic pressure; concentrated shear stress at the contact edges forms circumferential cracks. Hemispherical or small area contact, however, causes high stress concentration in the initial stage; high tensile stress is generated at the contact center, initiating radial cracks and ultimately leading to petal-shaped tearing. Based on the response parameter residual displacement and the characteristics of cross-sectional damage, a damage assessment model using combined indicators is proposed. Achieved quantitative grading of the damage states in RC slabs under impact. It provides a basis for the impact-resistant design and safety condition assessment of RC protective structures.

Aiming at the problem of actuator drift faults occurring in the wind turbine generator main drive system, a fault diagnosis and adaptive feedback fault-tolerant control method based on P-type learning sliding mode observer (P-ILSMO) is proposed. First, a wind turbine main drive fault system model is established considering the system unmodeled dynamics and external noise interference. Second, in order to accurately track the system state and improve the accuracy of fault estimation, an iterative learning algorithm is combined with a sliding mode observer, and P-ILSMO is adopted as the observer for fault diagnosis. Finally, the adaptive feedback fault-tolerant control method based on P-ILSMO is designed by simultaneously considering the system output error and system disturbance, which utilizes the fault learning law to compensate the system error caused by faults and ensure the stable operation of the system. The simulation study of a 5MW wind turbine system shows that at an average wind speed of 7.5m/s and a turbulence intensity of class A, the system returns to the normal state after the addition of the fault-tolerant controller, and the error of the generator's electromagnetic torque is only 1.43%, and the simulation verifies the effectiveness of the proposed method.

To achieve optimized estimation of dynamic parameters in the instantaneous angular speed (IAS) mechanism model of rolling bearings with outer race faults and to address the excessive deviation between simulated and measured signals caused by empirically selected parameters, a physics-informed neural network (PINN) and an angular-domain dynamics-based parameter estimation method are proposed. First, a three-degree-of-freedom (3-DOF) dynamic model of the bearing with an outer race fault is established in the angular domain. Then, the dynamic differential equations are incorporated into the neural network to formulate a physics-informed loss function that embeds the angular-domain differential constraints, with torsional damping and stiffness implicitly encoded in the network weights. A data loss term is constructed to evaluate the residuals between the network output and both simulated and measured IAS signals. Finally, under the joint guidance of the bearing–rotor system’s physical mechanism and the measured IAS responses, parameter optimization and estimation are achieved through the network parameter updating mechanism. Experimental validation on faulty bearing IAS tests demonstrates the accuracy and robustness of the proposed method. 

The elevator car pulley bearings in elevator systems are subjected to multi-stages operational conditions characterized by significant variations in speed and load, which renders them susceptible to the development of compound fault involving both the inner and outer rings. And the signals are typically contaminated by high levels of noise and exhibit weak characteristic features, thereby posing significant challenges for the accurate extraction of fault-related information. To address this issue, a dynamic model was established to simulate compound fault in elevator car pulley bearings. The dynamic response characteristics under multi-stages speeds and variable load conditions were thoroughly analysed. Consequently, the challenge of extracting compound fault features from elevator car pulley bearings was effectively addressed. Firstly, a dynamic model is constructed based on Hertz contact theory and time-varying displacement excitation of compound fault. Then, the vibration responses of multi-stages speeds were analyzed. Subsequently, considering the actual load conditions of the elevator, the influence law of load variation on the vibration characteristics of compound fault was obtained. Finally, experiments are carried out to verify the accuracy of the model. The research results show that with the increase of load, the amplitude response and frequency domain characteristics of the vibration signal of the compound fault of the inner and outer rings are significantly enhanced, but the compound fault characteristic frequency and its second to fourth harmonics remain stable with the change of load. By extracting the characteristic frequencies such as the fault characteristic frequencies, double frequencies and modulation frequencies of the inner and outer rings, the compound fault of the car pulley bearing can be diagnosed. The research results can provide a reference basis for the identification of compound fault of bearings under complex operating conditions such as elevators.

To address the challenges of difficult sparsity evaluation in traditional compressed sensing and the strong randomness in signal compressive sampling, this study proposes a deep compressive feature extraction method based on dual-branch wavelet convolution and sparse sensing, which is successfully applied to bearing vibration signals. First, a feature extraction module with a dual-branch heterogeneous wavelet convolutional architecture is designed to fully exploit the advantages of different-sized convolutional kernels in feature extraction, thereby capturing bearing vibration characteristics across multiple scales. Second, leveraging the energy-preserving property of compressed sensing, a deep compressed feature reduction module is developed. A compression strategy driven by the synergy of energy and information entropy is formulated to optimize the reduction process, significantly improving the quality of compressed features. Subsequently, a novel loss function incorporating spatial-spectral joint optimization is constructed to enhance the model's ability to learn sparse representations. Finally, the proposed method is validated using experimental data from a thrust bearing extreme-state performance test rig. The results demonstrate that the proposed approach achieves effective feature extraction under strong background noise while maintaining an optimal balance between model complexity and performance.

To address the low fault diagnosis accuracy of gearboxes under complex and variable operating conditions caused by load fluctuations, a variable-load gearbox fault diagnosis method combining multi-band filtering and multi-scale residual learning is proposed. First, vibration signals are preprocessed using multi-band filtering and a sliding window approach to highlight fault features across different frequency bands. Then, multi-scale features are extracted via a residual network, and feature distributions between the source and target domains are aligned using the maximum mean discrepancy criterion, effectively improving transfer performance. Experimental results demonstrate that the method achieves high fault diagnosis accuracy across various variable-load transfer tasks, confirming its excellent diagnostic performance and generalization capability. 

Tailings dam failures exhibited high suddenness and destructive power, often causing severe casualties, ecological damage, and economic losses. The failure process was difficult to intervene in, and theoretical analyses and simulations yielded uncertain results. Typical cases provided empirical references of significant value for disaster prevention, emergency response, and post-disaster recovery. This study examined three major failures—Mount Polley (Canada), Fundão (Brazil), and Feijão I (Brazil)—and analyzed 379 cases with complete information from 1915 to 2025. It discussed construction methods, causal factors, monitoring and regulation, inundation ranges, and remediation strategies. Results showed: (1) upstream dam failures frequently resulted from management deficiencies and extreme external factors rather than inherent flaws in the method; (2) monitoring and early warning systems failed in all three cases, while aerial and satellite remote sensing could serve as important supplements; (3) safety regulation should cover the entire life cycle, with strict control of design changes during construction; (4) released tailings volume correlated with dam height and storage capacity, while downstream topography determined inundation range; (5) there was no effective post-failure intervention, highlighting the need for decision-support tools to enhance emergency efficiency. The findings offer insights for scientific management, disaster prevention, and emergency preparedness of tailings storage facilities in China.

Vibrations induced by the movement of large coaches in bus terminals may lead to serviceability issues in office spaces within the building, yet mitigation measures for such vibrations remain scarcely studied. Taking a bus terminal as the research object, a structural finite element model and a 7-degree-of-freedom vertical vehicle multibody dynamics model were established to conduct coupled vehicle-structure vibration analysis. The accuracy of the computational model was verified through comparison with field-measured data. The vibration serviceability of the structure caused by coach operation was evaluated, and a floating slab track solution was proposed as a mitigation measure when vibrations exceeded permissible limits. The results demonstrate that the dominant frequency range of coach-induced vibrations in the terminal is 10–40 Hz, which is close to the fundamental frequency of the floor slabs. The vibration response correlates positively with vehicle speed. Floor vibrations in the office areas above the traffic lanes significantly exceed serviceability criteria, but the floating slab solution achieves a vibration reduction of over 10 dB, ensuring compliance with comfort requirements. The findings provide a reference for vibration mitigation design in similar structures.

To address the demand for low-cost and convenient inspection of large-scale small and medium-sized bridge groups, a vibration frequency inspection method for bridge structures utilizing smartphone sensors was developed. Firstly, the performance parameters of several common smartphone accelerometers on the market were investigated. Taking a simply-supported beam bridge as an example, the influences of different weather conditions, mounting methods, sampling frequencies, and sampling durations on data acquisition effects were explored. Secondly, a large-span continuous rigid frame bridge equipped with a structural health monitoring system was taken as a case study for verification, and an intelligent duration-based acquisition algorithm was proposed. The research results demonstrate that: The performance parameters of smartphone accelerometers generally meet the requirements for structural inspection. Both freely placed and fixed mounting methods are viable for data collection, with fixed mounting proving relatively more stable. A sampling frequency of 100 Hz or higher can reasonably capture the bridge's vibration characteristics. Under significant external vibration excitation, a sampling duration of less than 5 minutes is sufficient to obtain data with a high signal-to-noise ratio. The modal frequencies identified from smartphone-acquired data were essentially consistent with those derived from the dedicated SHM system data. The proposed intelligent duration algorithm effectively reduces inspection time while ensuring inspection accuracy. This method eliminates the need for specialized inspection equipment, offering a low-cost, easy-to-operate new approach for bridge inspection and providing technical support for routine bridge inspection.

When unsteady vortices shedding from high-speed rotating propeller impinge UAV’s Λ empennage, buffet happens easily. Utilizing dynamic patched grids and interface interpolation technique, the numerical simulation of unsteady aerodynamic forces around the rotating domain of the propeller and the stationary domain of the Λ-shaped tailplane. Based on URANS & RANS/LES(DES) hybrid method, rotary propeller’s unsteady flow structure & wake vortex fluctuating pressure distribution are separately calculated. Verifying through TB2 similar Type of UAV’s calculation results, RANS/LES(DES) hybrid method is capable of accurately acquiring different dimensions vortices of high-speed rotary propeller, the calculation results show better consistency with wind tunnel test. On the other hand, according to steady ergodic random verification, buffet response calculation procedure is simplified by using modal transient response analysis method and calculation accuracy is greatly increased. 

A calculation method for the connection stiffness of a point-type satellite-launch vehicle is proposed. This method can obtain the connection stiffness during the design stage of the point-type separation device and apply it to the satellite-launch vehicle coupling analysis. Compared with the traditional mode of conducting tests for verification in the later stage of development, this method features low cost and efficient iteration, and is particularly suitable for commercial space missions. On this basis, the problem of preload loading encountered in aerospace engineering is analyzed. The curve of connection stiffness varying with preload is obtained, and the influence of preload on connection stiffness is quantified. The research shows that significantly increasing the preload does not significantly enhance the connection stiffness. Finally, an engineering calculation method for axial tensile stiffness was proposed, and the reason why significantly increasing the preload force could not correspondingly increase the connection stiffness was theoretically analyzed; This method can also be used to guide the structural design of point separation devices.