In the southwest region of China, the construction of highways has resulted in the formation of many cutting slopes due to the special terrain conditions of the region. Therefore, the stability of highway cutting slopes under earthquake conditions has become a critical issue in the stability evaluation of highway engineering. In this research, the acceleration response of stepped bedding rock slopes is analyzed by conducting large-scale shaking table tests, and the seismic response of each platform is investigated.A ratio of acceleration amplification factor is proposed to characterize the differences in dynamic responses of various slope patterns and analyzes the seismic wave propagation in the slope using Snell’s law. The test reveals that the acceleration amplification factor of the slope exhibits an elevation amplification effect as the amplitude of the excitation increases. When the excitation amplitude exceeds 0.6g, the continuous accumulation of slope shattering damage and the enhancement of the filtering effect lead to a leveling off of the acceleration amplification factor with increasing elevation. Besides, slopes with uniform step width demonstrate better aseismic performance, while stress concentration is more likely to occur at the corners of each step, making them as key fortification sites. The analysis of the monitored acceleration data is consistent with the model damage patterns recorded by a high-speed camera during the shaking table tests. Based on the cumulative shattering damage process of the slope, four stages of damage are identified: shallow creep (0.1g~0.4g), local tension (0.4g~0.6g), accelerated deformation (0.6g~0.8g), and overall instability(0.8g~1.0g), exhibiting a slip-tensile damage mode. The research findings provide essential theoretical support and technical guidance for understanding the shattering damage mechanism and seismic fortification of rock slopes with complex formations and geological structures, and offer a reference for disaster prevention and mitigation measures for stepped bedding rock slopes in mountainous areas.

In order to evaluate the fatigue performance of the steel anchor box (SAB) when its stay cable experiences large-amplitude vortex-induced vibration (VIV) under in-service condition, continuous monitoring was conducted on a long-span cable-stayed bridge. The acceleration of the stay cable undergoing VIV and the stress at the SAB details were measured. The characteristic of stay cable vibration, as well as the stress at the SAB details due to VIV of the stay cable, vehicles loading, and thermal effects, were investigated in both time and frequency domains. Hence the loading mechanisms of VIV, vehicle loading, and thermal effects on the SAB were discussed. Based on the nominal stress method, the fatigue performance of the SAB under the joint action of VIV, vehicle loads and thermal effects were evaluated. The results show that the significant vibration of stay cable, characterized by the high-order multi-mode VIV, dominated by in-plane vibration with peak frequencies between the fifth and the seventeenth modes, occurring within a mean wind speed range of 2 m/s to 9 m/s, with observed maximum in-plane peak acceleration of 25 m/s².Thermal effects significantly contribute to the maximum stress range at the SAB details, although they only generate one stress cycle per day. Compared to the thermal action, the stress range generated by the passage of vehicles is relatively low, but trucks produce a large number of loading cycles. The inertial force generated by VIV of the stay cable applies very low stress to the SAB, making its effects on stress and fatigue negligible. It is concluded that the fatigue evaluation of the steel anchor box should consider the thermal effects. However, even when considering the combined effects of VIV loading, thermal effects and vehicle loading, the fatigue life at the critical details of the SAB—specifically the deck-side welds of the upper and lower plates to the outer web, as well as both weld ends of the bearing plate to the outer web of the steel box girder—exceeds 100 years. Therefore, the fatigue performance of the SAB under in-service conditions meets the bridge design requirements, even with large-amplitude VIV of the stay cable.

When braking is applied to a heavy-haul train, the dynamic behavior of the train becomes more complex compared to when there is no braking, which poses significant challenges to the safety of train operations. In order to study the vehicle dynamics behavior at the maximum coupler force of a heavy-haul train under emergency braking conditions, a vehicle-track and longitudinal-vertical coupled dynamic model, considering the effects of shoe friction braking, is established with a 25 t axle heavy-haul wagon from China as the research object. On this basis, this study systematically examines the impact of varying running speeds and adhesion conditions on the dynamic wheel-rail interaction and vehicle vibration response during emergency braking. The results show that under braking conditions, the brake shoe pressure and longitudinal coupler force exacerbate the wheel-rail dynamic interaction and cause changes in the displacement of the under-rail structure. The low adhesion condition has a significant effect on the longitudinal interaction of the wheelsets, leading to a sharp increase in the longitudinal creep rate and wear number, thus increasing the risk of wheel slip and wear. This effect is more pronounced at low speeds. Moreover, the low adhesion condition and longitudinal coupler force significantly affect both the rotational and longitudinal motion of the wheelsets, leading to increased wheelset vibration and deterioration of vehicle dynamics.

In order to prevent unseating during earthquakes, both domestic and foreign seismic codes for bridges require the use of unseating prevention devices. However, research on the effectiveness of these devices is limited. This article focuses on a bridge using a longitudinal barrier-type unseating prevention beam device, examining the limitations and effectiveness of such devices in preventing unseating. First, the working principle of the longitudinal barrier-type unseating prevention device is introduced. On this basis, a five-span simply supported beam bridge is studied, considering the nonlinear mechanical behavior of concrete blocks as a typical longitudinal barrier-type unseating prevention device. The study analyzes and compares the effects of block device strength, clearance, and the installation of rubber pads on the limiting and unseating prevention capabilities of the device. Research has shown that the effectiveness of the devices is closely related to its strength , initial clearance, and the intensity of seismic motion.Proper device strength and initial clearance can help reduce collision forces and frequencies, lower the risk of beam unseating, and control bridge pier damage within an ideal range. Furthermore, placing buffer rubber pads at the contact surfaces between the unseating prevention device and the substructure can effectively reduce pounding forces and minimize pier damage.

In light of investigating the interplay between the instantaneous angular speed (IAS) signal and mechanical dynamics of bearings, alongside addressing the vulnerability of rotary arm bearings within industrial robot RV reducers to failure under lowspeed conditions, this paper presents a novel three-degree-of-freedom dynamics model to explain the IAS perturbations resultant from localized roller bearing failures. The model, rooted in the Hertz line contact theory, dissects the influence mechanism of localized deformations stemming from roller-raceway interactions on the IAS. A comprehensive approach to computing the coupled tangential force and torque is outlined. The integration of failure-induced impacts into torque analysis computes torque variations introduced by the failure zone, thereby augmenting angular degrees of freedom. As a result, a three-degree-of-freedom bearing IAS disturbance dynamic model, coupling both normal and tangential forces, is established. Employing fourth-order Runge-Kutta numerical integration, the model is solved, and its results are meticulously compared and analyzed against experimental approximations under near-approximate conditions. The findings underscore the model’s ability to effectively expound upon the origins of IAS perturbations in cylindrical roller bearings while adeptly reflecting the ramifications of outer ring failures on IAS. This work contributes to the refinement of rolling bearing dynamics theory, advancing the comprehension of intricate mechanical systems.

A typical streamlined closed-box girder is taken as the research object in this paper. Utilizing the wind tunnel tests with a section model, vortex-induced vibration (VIV) responses of the grinder section were obtained, and the contribution values of the distributed aerodynamic torques were analyzed for both the original and improved girder designs (the improved girder with spoilers and the improved girder with guide vanes for maintenance rails) under typical wind conditions. By combining the simplified vortex method (SVM) with numerical simulation, the torsional VIV of the bridge girder and its suppression mechanism with additional aerodynamic countermeasures were further revealed. This paper provides a new methodology for analyzing the VIV mechanism of bridge girders and the VIV suppression mechanism of aerodynamic countermeasures. The results reveal that an obvious torsional VIV phenomenon was observed on the original girder, with a maximum amplitude of 0.112°. After adding guide vanes for the maintenance rail, the torsional VIV amplitude of the section was reduced by 35.7%, and the torsional VIV phenomenon disappears after the addition of the spoilers on the sidewalks’ handrails. For both the original and guide vane girders, the contribution values of the distributed aerodynamic torques on the upper surface to the global vortex excited force (VEF) were much greater than those on the lower surface. The VIVs of the original and guide vane girders were dominated by the periodic drift of the large-scale vortices generated from the leading edge to the trailing edge on the upper surface. The drift time of the vortices was approximately 2.5 vibration cycles, which corresponds to the second-order torsional simplified vortex mode. After the installation of guide vanes for the maintenance rails, the contribution values of the distributed aerodynamic forces to the global VEF were significantly reduced, and the scale and intensity of vortices around the girder were reduced, so the VIV amplitude decreased. After adding spoilers, the contribution values of the distributed aerodynamic forces to the global VEF became more evenly distributed and were greatly reduced.Spoilers inhibited the formation of separation vortices at the leading edge of the upper surface, effectively eliminating the VIV phenomena.

Clustering analysis is a commonly used unsupervised method in data processing. However, the difficulty in accurately determining clustering parameters limits the application of this method in structural damage identification. To address this issue, a non-parametric Bayesian clustering method is proposed in this study, which combines structural modal parameters for structural damage identification and quantitative analysis, thereby expanding the application range of the non-parametric Bayesian model.First, the natural excitation method is used to extract the natural frequency from the measured vibration data of the structure.Then, the non-parametric Bayesian clustering method is employed to cluster the data. Finally, maximum likelihood heteroscedastic Gaussian process regression and Bayesian factors are combined to quantitatively analyze the clustering results for damage quantitation analysis. The results of the damage identification method are verified by the actual engineering case of Yonghe Bridge in Tianjin. The results show that this method can accurately cluster the natural frequency data and identify the different damage states of the structure without the need to pre-set clustering parameters.

Due to the differences in data distribution caused by different locations of multiple measuring points, the fault diagnosis of the harmonic reducer is often ineffective. A fault diagnosis method for the harmonic reducer, based on a multiple feature spaces adaptation network (MFSAN), is proposed. Firstly, the vibration signal of the harmonic reducer is transformed using continuous wavelet transform to construct a time-frequency diagram that characterizes its operational state. Secondly, the data measured by sensors at different positions are divided into multiple source domain and target domain data, which are mapped to different feature spaces to obtain feature representations for each measuring point position. Then, the adaptive network is used to automatically transfer the knowledge learned from the source domain to the target domain features and automatically align the feature distribution of a specific domain to learn multiple domain-invariant representations. Finally, a domain-specific decision boundary is used to align the output of the classifier, effectively solving the data distribution differences caused by sensor location. Experimental results of harmonic reducer diagnosis of an industrial robot show that the identification accuracy of this method is 99.72%, which is higher than that of other comparison methods. The effectiveness and feasibility of this method are thus verified.

To address the problem of contact between the slender rods and tubes immersed in fluid, a numerical method is established to model the coupling vibration and collision between slender rotating rods and the produced fluid, based on the overset mesh technique. The outer annulus fluid domain is divided into two overset subregions: a background mesh and a component mesh. The interpolation formula is derived to transfer fluid field boundary information in each overset region. The subdomain method is used to solve the coupling between the produced fluid domain and the rod solid domain. Additionally, the transfer method of physical variables and a normalized convergence criterion are established for the coupling interface. A coupling simulation device for a vertical rotating rod and produced fluid is established, and the numerical simulation results are compared with experimental results to validate the correctness of the numerical method presented in this paper. The coupled vibration and collision characteristics between the slender rods and tubes are studied under different fluid viscosities and rotational velocities. The results show that as fluid viscosity increases, the influence of viscous resistance on the motion of the rod becomes more pronounced, leading to lower contact pressure and reduced vibration. As the rotational speed of the rod increases, the vibration becomes more intense, the influence of torsional deformation on the rod’s motion becomes more significant, the normal acceleration during collision decreases, and the contact pressure decreases accordingly. When the collision occurs between the rods and tubes, the acceleration at each point of the rod changes abruptly, and the vibration intensity increases.

Parametric vibrations are commonly observed in microelectromechanical systems(MEMS) coupled with multi-physical fields. To study the parametric resonance nonlinear dynamics problems in electrostatically driven micromirror systems, a class of electrostatic comb-driven micromirrors is used as an example to study the parametric resonance response variation of the system under different factors by fitting a seventh-order polynomial to the comb capacitance variation and establishing a micromirror dynamics model. The influence of changes in the micromirror’s structural parameters on the torsion angle under static conditions is investigated. The multi-scale method is applied to analyze how system parameters affect the variation in resonance amplitude during the resonance state, and numerical verification of system parameter resonance is performed. Finally, the stability of subharmonic parametric resonance in the system is analyzed and verified using the Runge-Kutta method. The results show that subharmonic parametric resonance exists in the micromirror system. Factors such as excitation voltage and capacitance fitting parameters can affect the system’s resonance amplitude. Damping can alter the system’s instability region, increase the instability threshold, and influence the occurrence of subharmonic parametric resonance in the system.