Advanced Materials Research Vols. 97-101

Abstract: In order to find out the effects of tempering process on properties of axle steel, the thesis analyzes the change trend of properties of LZ20Mn2 axle steel pipe with variation of tempering temperature. And SEM was used to observe and analyze the fracture. The results show that the strength and hardness of LZ20Mn2 axle steel drop gradually and its toughness and plasticity are increased when tempering temperature goes up. Change of material properties trends to slow down after tempering at 570 °C. From point view of toughness, the technology for the best quality LZ20Mn2 axle pipe steel is the one with quenching at 880 °C with temperature holding for 30min, and tempering at 530 °C with 90min holding temperature. After heat treatment, the microstructure is fine grain size tempered sorbite structure and has good plasticity and toughness, so it can meet the requirement of both high strength and high toughness for axle.

Abstract: A spindle can be very sensitive to mass unbalance which may have destructive effect on many types of rotating machinery, especially in high-speed rotating equipments. In this paper, a new active on-line balancing device based on static magnetic field with simple structures was proposed. The consecutive configuration of related stator and rotor was designed; the discussion focused on how the structural parameters influence the electromagnetic force. In the end, the influence of the misalignment of both spindle and core on the electromagnetic force was analyzed numerically under a given condition.

Abstract: Tension–tension fatigue tests of notched 18CrNi4A steel specimens were carried out under three different fatigue stresses, and metal magnetic memory (MMM) signals were detected. The effects of fatigue damage and fatigue stress on MMM signals were investigated. The results show that the absolute values of the feature parameters Hp(y)max, Hp(y)min and Hp(y)sub increase with the aggravation of the fatigue damage. There is an inherent relationship between the fatigue stress and the values of the Hp(y)sub; the larger the fatigue stress is, the larger the absolute values of the Hp(y)sub is. Fatigue-damaged locations can be effectively predicated according to the mutational character of the Hp(y) curve and the K curve, and zero-crossing points of the Hp(y) curve, respectively. Fatigue damage degree can be effectively predicated according to the value of the Kmax and the Hp(y)max, Hp(y)min and Hp(y)sub.

Abstract: A calculation model is developed for mechanical seals with a laser-textured micro-pore face. The dimensionless hydrodynamic pressure distribution on the seal face at various operating conditions and micro-pore geometry parameters is obtained from a solution of the Reynolds equation by the finite difference method. An optimum micro-pore geometry parameter is found and consistent with experimental results. Results of parametric study demonstrate that the substantial hydrodynamic effect can be produced on the seal face with micro-pores.

Abstract: The goal of this paper was the development of a visual monitoring system for the management of stacking crane (moving within the aisles of the warehouse) using finite state machine (FSM). As usual, the implementation of a monitoring system required four preliminary steps: development of plotting FSM model, design of data exchange protocol, procession of operational monitoring data, visualization of a monitoring system. The paper was also presented form above contents. First, the operating characteristics of stacking cranes were analyzed to gain the operation control information and establish the plotting FSM model. Second, the data exchange protocol between the monitoring computer (MC) and the programmable logic controller (PLC) of stacking crane were designed based on the FSM model. Three, through the monitoring program, the operational data of stacking crane were gained and displayed in the visual monitoring platform. Finally, the visual monitoring system of stacking crane had been realized.

Abstract: In this paper, an insect-based flapping-wing flying microrobot was built which can successfully fly in the sky. The unsteady aerodynamics associated with this microrobot was studied by using the method of computational fluid dynamics (CFD). On the basis of numerical simulation, the Fluid-Structure coupling mechanics for flexible flapping-wings were studied and discussed. According to the practically developed flapping-wing microrobot, a 2-D simulation model for flexible flapping-wings was established. Fluid-Structure coupling deformation and the effects of this model on the aero dynamic performance were analyzed, which have offered a theoretical basis for design of the aircraft with flexible flapping-wing. In order to verify the results of numerical simulation, aerodynamic performance tests have been conducted for the rigid and flexible flapping-wings in a low turbulence and low Reynolds number wind tunnel.

Abstract: Based on the passivity theorem, an approach of the rotor resistance estimation and sliding mode position control for induction motor drives is proposed in this paper. Owing to values of the moment of inertia and the viscous coefficient of induction motors are generally small, the load torque disturbance is a critical term to create the chattering phenomenon. The adaptive laws are taken into account for estimating the rotor resistance and the gain of a load torque. Therefore, the chattering associated with the conventional sliding mode controller can be alleviated. The stability analysis of the estimator and the position control system is carried out by employing the passivity theorem. Finally, experimental results are presented to show the performance and robustness of the estimator and the controller with the variations of the motor mechanical parameters, rotor resistance, and load torque disturbances.

Abstract: Tri-objective optimization of time, cost and quality is complex and valuable research hotspot which is of expansive practice application foreground. Exact method can only solve some small scale optimization problem, but the practice problem is usually large scale. In order to analyze and research the complex large scale optimization problem, the integrative optimization model of time-cost-quality is set up according to the action rules and relations of three objectives. Tri-population genetic algorithm is put forward for the optimization model based on the idea of intellective stochastic search. The algorithm adopts different populations to carry out the parallel search to realize rapid optimization. Finally the methods put forward are applied to manufacturing case of airplane part, and a series of optimization result is achieved. The case application validates the correctness of the model and the availability of the algorithm.

Abstract: The grinding simulation system of ball-nose end mill rake face is developed based on the four axis linkage mathematical model using Solidworks and Visual Basic for Applications (VBA). Effects of grinding wheel diameter change due to wear on geometrical parameters of ball-nose end mill, such as ball-nose rake angle, column rake angle and edge strip width are investigated.

Abstract: Chatter is one of the unwanted noise and vibration phenomenon which are generated during the wiper operation. It is a low frequency and self-excited vibration that is often generated before and after the wiper reverses its direction. This leads to a poor visibility and annoying sound to the driver and passengers. Therefore, this paper is aimed to propose a technique that can be apply to tackle this problem. Hence, an existing two-dimensional mathematical model of a wiper system available in the open literature is adopted. Firstly, the baseline model is simulated in order to observe its vibration response. Then, an input shaping control scheme is introduced into the baseline model. It is found that the input shaping control scheme can reduce the vibration level approximately by 30 percents from the baseline model.