The camshaft is an important component that ensures the timely opening and closing of valve in marine diesel engines. Due to the poor contact lubrication state and excessive friction excitation，it is easy to cause larger interface torque on the camshaft. Considering the effects of transient excitation and interfacial friction，the tribo-dynamics model of the valve camshaft in V20 diesel engine is established. The forced vibration results of the camshaft are obtained，and the friction and lubrication performance of the cam-tappet pair is also analyzed under the fluctuating speed. The results show that，by thoroughly considering both the transient excitation and frictional excitation of each cam pair，the additional stress in each shaft section of the valve camshaft increases by about 4 MPa，while the transient speed fluctuation at the camshaft end increases by roughly ±30 r/min. Under the combined effects of speed fluctuation and surface roughness，the film thickness is dramatically reduced in some positions，especially in the cam base circle section where the film thickness decreases by about 0.3 μm. At the reverse motion position and nose of the cam，the temperature rise at the interface of the tappet exceeds the material’s scuffing temperature，thereby increasing the risk of scuffing wear.

Gear systems in precision machinery and aerospace applications are subjected to complex vibration problems due to mass eccentricity, time-varying backlash, and dynamic meshing parameter variations. A nonlinear dynamic model with six degrees of freedom is established, incorporating time-varying meshing stiffness, derived using the potential energy method and mass eccentricity. The Runge-Kutta method is employed to solve the system response under varying eccentricities and rotational speeds. Time-domain and frequency-domain analyses, phase portraits, and Poincaré maps are used to investigate the dynamic characteristics. The results indicate that mass eccentricity significantly influences system behavior, leading to the evolution from single-period to multi-period motions (e.g., 20-period cycles), and aggravates bifurcation and oscillation phenomena. The findings provide theoretical support for structural optimization and vibration control of gear transmission systems.

In order to clarify the collapse mode of multi-span simply-supported beam bridges of high-speed railway，a 10-span high-speed railway simply-supported beam bridge in northwest China is taken as the actual engineering background. Combined with the characteristics of double block ballastless track structure on the bridge，the track-bridge integration research model is established. The collapse mode of this kind of ballastless track bridge in high intensity earthquake zone is studied by using explicit integral method and energy method. The results show that the key parts of the destruction of high-speed railway multi-span simply-supported beam bridge mainly concentrate on the track area of the bridge expansion joint，the concrete area of the support and the support contact surface，and the bottom area of the pier. The energy ratio of the 10-span high-speed railway simply-supported beam bridge collapse discrimination is 89.33%. By coupling the track plate and the groove section at the bridge expansion joint to optimize the structural system，the integrity of the track and bridge connection is improved，so that the track at the bridge expansion joint avoids becoming the key part of the destruction at the early stage of the earthquake. The collapse time of structural system is prolonged by about 45%，and the probability of the beam falling is reduced，so that the overall collapse resistance ability of the bridge is improved.

As a core component of an aero-engine, the structural integrity of a blade directly determines the engine’s performance and flight safety. Under extreme working conditions such as high temperature, high pressure, and high-speed rotation, blades are prone to generating micro-cracks under the action of complex stress fields. Once cracks propagate and cause blade fracture, they will trigger chain damage, posing significant safety hazards. Based on the damage tolerance concept, the critical duration during which a blade can still operate safely after crack initiation is defined as the remaining useful life (RUL).To address this, this study proposes a mechanism-data dual-driven RUL prediction method integrating the Paris crack propagation law and physics-informed neural networks (PINN). By constructing a loss function that incorporates physical constraints, this method regularizes and constrains the gradients of the neural network. It enables inverse identification of crack propagation parameters while effectively improving the model’s prediction accuracy under limited monitoring data. For aero-engine blades and CT (compact tension) specimens, compared with traditional physical models and data-driven methods, the proposed method dynamically updates characteristic parameters to adapt to system changes, significantly reducing prediction errors under limited sample conditions. Additionally, the PINN model developed in this study features lightweight architecture and fast inference capabilities, meeting the requirements of online monitoring and predictive maintenance. This method provides a new technical pathway for health management and intelligent operation and maintenance of aero-engines.

Research on magnetically levitated rotors has been heavily influenced by studies on slender shaft magnetic levitated rotors. In the study on a certain magnetically levitated flat rotor for a centrifugal pump structure，both experiments and finite element analysis revealed that the support characteristics of the radial permanent magnetic bearings，with the same dual-ring structure，exhibited the significant differences from the known experience when applied to flat rotors. The translational stiffness and torsional stiffness showed substantial variations. This paper analyzes the variations in translational and torsional stiffness of permanent magnetic radial bearings for flat rotors based on changes in the bearing’s structural dimensions. Based on the analysis，a flat rotor magnetic levitation structure is proposed，which can increase and adjust the torsional stiffness of the permanent magnetic bearings，while also allowing for a rational ratio between translational and torsional stiffness. A finite element analysis is used to identify the structural conditions that yield maximum translational and rotational stiffness. The effectiveness of the proposed methodology is subsequently validated.

As a component widely used in various industries, the noise problem of fans has always attracted people’s attention. In equipment with relatively low noise energy levels, abnormal noise, such as whistling, or rattlesing, from fans are key factors that lead to user complaints. Taking laptop fans with various abnormal noises as an example, the correlation between the severity of fan abnormal noise and the main psychoacoustic parameters of sound quality was studied, and a linear regression model between the subjective score of abnormal noise and the objective parameters was established. The results show that loudness, sharpness, prominence ratio, and the frequency corresponding to the maximum value of pitch affect the subjective feeling of abnormal noise. The multivariate linear model including loudness and sharpness can better evaluate the subjective score of the severity of abnormal sound.

In the dynamic impact response analysis of the structure，the dynamic amplification factor（DAF）is usually used to simplify the calculation of the dynamic response of the structure. However，the size of DAF in engineering structures is still controversial. In order to solve this problem，the analytical expression of DAF of multi-degree-of-freedom system（MDOF）is derived in this paper，and the precondition of DAF greater than 2.0 is analyzed. The accuracy of the analytical expression is verified by the single-degree-of-freedom（SDOF）and MDOF example models，and the reason why the DAF of the MDOF is greater than 2.0 is explained. Finally，based on the DAF analytical method proposed in this paper，the DAF distribution law of beam string under cable breaking impact is analyzed. The analysis results show that when the contribution of a first-order modal shape is opposite to the static response，the DAF of the beam string may be greater than 2.0. Even for the damping system，the DAF of the beam string may be greater than 2.0.

Key components of industrial robots are prone to early-stage performance degradation under complex operating conditions, characterized by strongly non-stationary responses and significant heterogeneity across sensing channels. Traditional diagnostic methods struggle with robust and interpretable fusion of multi-source information, limiting their practical deployment. This paper proposes a dual-channel intelligent diagnostic method for robotic transmission mechanisms, integrating physics-driven sensitivity weighting and residual uncertainty compensation (RUC). Specifically, vibration and torque signals, representing structural response and driving excitation respectively, are selected due to their distinct temporal scales and complementary physical characteristics. A three-layer mapping (fault type-dynamic response characteristic-sensing channel) is constructed to quantify channel dominance for different fault modes. Then, a multi-scale sensitivity evaluation mechanism based on signal-to-noise ratio (SNR), modulation index (MI), and kurtosis guides adaptive weight allocation, while the RUC strategy enhances the expression of features from weakly dominant channels, improving fusion stability. Finally, a physically interpretable and lightweight diagnostic framework is established. Experiments conducted on a public gearbox dataset validate that the proposed method provides superior diagnostic accuracy, interpretability, and deployment potential, demonstrating significant promise for physically consistent multi-source fusion diagnosis in robotic transmission systems.

In order to improve the dynamic output performance and environmental adaptability of the tri-stable piezoelectric energy harvester （TPEH），a new flexible tri-stable piezoelectric energy harvester （FTPEH） with double flexible auxiliary beams for real-time adjusting the potential well depth and barrier height is proposed. Based on the traditional magnetic coupling tri-stable piezoelectric energy harvester，two auxiliary flexible beams with the same structure and size are introduced，and the two external magnets are fixed at the tip ends of the two auxiliary flexible beams. When the harvester is excited by the external excitation，the two auxiliary beams oscillate with slight amplitude in the horizontal direction，thus the horizontal distance between the external magnets and the tip magnet of the piezoelectric cantilever beam can be adjusted in real-time，so as to tune the potential energy well depth and barrier height，resulting in improving the dynamic output performance and environmental adaptability. The electromechanical coupling dynamic model describing the dynamic responses of the new tri-stable piezoelectric energy harvester is established based on Euler Bernoulli theory and Hamilton principle，and the influences of system parameters on the nonlinear magnetic force and dynamic performance are simulated and analyzed. Compared to the traditional tri-stable harvester，the new tri-stable harvester has a wider bandwidth of inter-well motion and lower excitation for jumping from intra-well motion to inter-well motion.

The wind uncovering effect of the roof of a large-span terminal building is one of the important factors affecting its structural safety. Existing studies only consider the benign wind climate and static wind load effects，which are difficult to explain the real wind uncovering pattern and occurrence mechanism of the roof structure under the strong typhoon dynamic load. Based on WRF，CFD and LS/DYNA，this paper carries out the numerical simulation of continuous wind damage of a large-span terminal building under the action of typhoon. The wind field simulation of typhoon "Hegeby" was carried out firstly. The continuous wind uncovering process of the terminal roof under the typhoon was simulated by taking an international airport terminal building as an example，and the wind damage pattern and wind damage rate of the roof cover under different wind angles were compared and analyzed to reveal the wind damage mechanism of the large-span terminal building under the typhoon. The results show that the extreme wind pressure at the windward edge of the terminal roof is higher，and the effect of upward and downward pressure is obvious，and the maximum pressure difference coefficient is 12.41. When the critical wind speed is reached，the windward edge of the roof is partially lifted by the wind，and then the "chain effect" triggers the continuous wind damage of the roof，and the tearing direction of the roof is consistent with the incoming flow direction. The energy failure index K is given based on the law of internal energy change before and after the failure of roof units，which can be used to guide the design of large-span terminal building roofs against wind uncovering.