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The droplet impact on solid surfaces is a popular research topic in which many researchers focus on stationary surfaces, only a few researches have been conducted for moving surfaces. In this paper, a high-speed photography-based droplet impact experimental platform and a VOF-based numerical simulation model are built to study the morphology of motion of a droplet after it impacted a horizontal uniformly moving surface. In the present study, the tangential and normal Weber numbers range within 70. This is because at such low Weber numbers the droplets initially spread to their maximum diameter after impacting the moving surfaces and subsequently start to rebound. The studies have confirmed that the maximum spreading factor of the droplet increases linearly with the tangential Weber number, and the spreading time increases as well. The maximum spreading factor of the droplet increases nonlinearly as a function of the normal Weber number and corresponding time initially increases and then decreases. Finally, the expression for the maximum spreading factor is fitted according to its correlation with the We number. [ABSTRACT FROM AUTHOR]

In improving the comfort of vehicles, air spring suspension has obvious advantages, but under the action of transient impact load, the damping effect of air spring suspension is not ideal due to the hysteresis phenomenon of air spring stiffness regulation. In order to analyze the mechanism of the above problems, the dynamic mathematical model and simulation model of air spring suspension are established. And the nonlinear characteristic of the elastic characteristics of the suspension is expounded theoretically. The simulation results show that the stiffness of the air spring increases with the increase of the transient impact load, and the peak value of the transfer function increases and moves to high frequency near the natural frequency of the body. And the peak value and the peak frequency of the transfer function only change slightly near the natural frequency of the wheel. There are bifurcations and secondary shocks at the wave crest of the acceleration curve under impact loads of 30 mm and 50 mm. The type of research can provide theoretical basis and reference for the design, analysis and optimization of air suspension. [ABSTRACT FROM AUTHOR]

As a vital road construction machine, the bridge erecting machine works in a very complex environment. The brake as an important link to maintain the safety and stability of the bridge erecting machine, it will have serious consequences if it is failed. Establishing the brake simulation model and specifying the fault characteristics according to the actual operation status will make it more efficient to find the cause of faults and maintain the safety of machine for a long time. A simulation model of brake of the bridge erecting machine was established by Adams. The brake arms and center axis with obvious data characteristics were flexibly processed, and finite elements were analysed using Abaqus. To verify the accuracy of simulation models, rectangular rosettes were applied to special geometric points, and the strain data were gathered by using the DH3816N collector and compared with the simulation model. The Adams kinematic simulation model was used to simulate the actual operating conditions by the experiment of the disc springs. Two typical fault phenomena were selected: reduced insufficient of disc spring and oil pressure, and two fault characteristics were extracted: variation of the brake shoe clearance and variation of the braking system pressure. When the brake generates the fault characteristics, the normal operation of the brake will not be affected if the fault characteristics are in the first stage. When the fault characteristics are beyond the critical threshold, the faults phenomena of the brake are generated. The results of the simulation experiments proved that the method of using the simulation model to extract the fault characteristics of the braking system and distinguish the causes of the fault was feasible. [ABSTRACT FROM AUTHOR]