Papers by Author: Hong You Li

Abstract: A generalized element which has the behaviors both of dashpot and spring is utilized to describe the visco-elasticity of a type of MR (Magneto-Rheological) Damper. A fractional derivative equation of motion which needs 4 parameters is developed to consider the nonlinear characteristics of the MR Damping system. It is demonstrated that the controlling current affects the order of the fractional system significantly, the increasing of the currents lead to the increasing of systemic order, strengthen the influence of viscosity remarkably and weaken the influence of inertia simultaneously. Nonlinear characteristics for shearing thin MRF damping system are also studied.

Abstract: Mechanical strength and service life of the coatings manufactured by plasma spray forming are significantly reduced by residual stresses. A 2D finite element model constructed for temperature and residual stress simulation of a single stainless steel splat solidifying and cooling on the carbon steel substrate is presented in this paper. Simulated results show that the temperature of the splat rim is higher than that of the central part during the initial stage of solidification, and the temperature difference between the two parts reverse thereafter. The minimum residual stress locates at the rim of the top surface of the splat, and the maximum residual stress, which decreases when the substrate is preheated to a higher temperature, situates at the rim of the interface. Stresses appear as tensile stresses within the splat and compressive stresses within the substrate. The research can provide quantitative understanding of the temperature and residual stress states at the splat level.

Abstract: In this paper, Pulse electrochemical finishing (PECF) and pulse electrochemical compound finishing (PECCF) are introduced. The main technical parameters, including in intereletrode gap, current density, compositions of steel materials and pulse parameters on the resulting surface finish were studied. PECF and PECCF on different surface including plane and shafts surface are done. Well-pleasing experimental results is gained. Results indicate that PECF and PECCF can lead to both good smoothing efficiency and surface finish simultaneity at low costs.