This paper is concerned with the application of energy efficient fluid power in mobile robots system and proposes a new fluid power converter system which is analogous to a boost converter in power electronics. The fluid power converter system is based on the principle of pulse-width modulation. The fluid power converter has an effect akin to an electrical switched inductance transformer, wherein the output pressure or flow rate can be stepped up or down. Using an inductive reactance device (an inertia mass-block), the output flow and pressure can be varied to meet the load by a means that does not rely on dissipation of power (the resistance control). The simulation model based on the mathematics models of the components is built to analyse the performance of the fluid power converter. It is clearly shown that the fluid power converter has higher energy efficiency than conventional resistance control manners.
In the present study, the effects of Nb addition on Charpy impact properties of TiVTa refractory high-entropy alloy with high strength-ductility trade-off were systematically studied by using the instrumented Charpy impact testing machine. The experimental results showed that the impact toughness was remarkably improved by Nb addition in TiVTa to form TiVTaNb alloy. The crack initiation energy and propagation energy of TiVTaNb were 67.3% and 24.9% higher than that of TiVTa, indicating that Nb addition simultaneously reinforced the resistance to crack initiation and propagation. The impact fracture of TiVTaNb exhibited larger bending degree of shear lips, deeper dimples and more secondary cracks which effectively dissipated more impact energy. The deformation mechanism of TiVTa alloy was dominated by dislocation activities. While in TiVTaNb, the deformation mechanism was synergized by dislocation activities and deformation twinning, which were the main contributors for the improved impact properties and the stronger crack resistance of TiVTaNb alloy under impact loading. 相似文献
Bulletin of Engineering Geology and the Environment - In high terrestrial stress regions, rock burst is a major geological disaster influencing underground engineering construction significantly.... 相似文献