Advances in Science and Technology Vol. 111

Abstract: This paper proposes a method of predicting pitting fatigue in gear material by utilizing an eddy current sensor. The proposed method is based on the theory behind mechanism of pitting occurrence, i.e., cracks occur on a contact surface and lead to pitting. The eddy current sensor detects the cracks as the pulse, which is added to the synchronous vibration. The sum of the harmonics of the sensor output was measured as the damage value on the contact surface. The damage value increased over the course of the experiment. We found that pitting occurred at a damage value of 15 dB in all tests. The results show that pitting occurrences can be estimated by measuring the determined damage value.

Abstract: This study involved an experimental investigation of the hydrodynamic lubrication performance of dimpled seal-like thrust bearings. Circular dimples were created on lubricating surfaces and the hydrodynamic effects were evaluated. The load-carrying capacity and frictional torque were measured under a constant film thickness. The lubricating surface was observed to make clear the effect of the cavitation area on the load-carrying capacity and the frictional torque. Dimpled specimen produced the load-carrying capacity and it showed a signature hysteresis phenomenon. Cavitation strongly affected the phenomenon. In addition, the dimpled specimen could reduce the frictional torque compared with the plane (dimple-free) specimen. However, the hysteresis phenomenon of the frictional torque was not clear compared with that of the load-carrying capacity.

Abstract: Tribology applied method (TAM) is a method to investigate the interacting surface in relative motion includes the principles of friction, lubrication, and wear. The main objective of this study is to investigate the effect of structural material property on Multi-body dynamic. The stick-slip friction (SSF) and the contact normal force is used as influence of machine tools in numerical simulation. The numerical simulation is conducted on three axes CNC machine without friction, with sliding friction and with SFF to find out the effect of the influence parameter. The PID controller is used as the compensation in the numerical simulation. The result show that the unsmooth motion of CNC machine due the friction will affect the accuracy and the performance of the CNC machine.

Abstract: The purpose of this paper is to investigate the effect of friction on two wheels vehicle control. First, the two wheels vehicle model is presented. Then, the dynamic analysis are performed by studying the dynamic of inverted pendulum. The PID control is used as the control method to control motor for balancing two wheels vehicle. Furthermore, the numerical modeling is created and the friction is given on joint with varying the coefficient of friction in numerical simulation. Moreover, the optimize PID value is presented and then the numerical simulation is performed.

Abstract: This research presents a numerical analysis of hydraulic actuator dynamics considering the effect of elastic material components. A hydraulic position control is established with dynamically parameters basing on mechanic theories. In which, coefficients of viscous damping, stiffness of hydraulic oil and friction of polymer seals are considered. Hence, the model can be analyzed as a mass-spring-damper system. This research employs numerical simulation for obtaining system dynamic responses. The results are consistent with theories and reality. These are useful in design and calculations of hydraulic control systems.

Abstract: Aeroelasticity is a science to study interaction between aerodynamic, elastic and inertial forces. Flutter is the most dangerous aeroelasticity phenomena, that is defined as the dynamic instability of an object in an airstream. Following flutter phenomenon, unsteady aerodynamic forces generated from elastic deformations of structure. It can lead to a disastrous structural failure. This paper examined aeroelasticity properties of a flat copper alloy plate by combining simulation methods using ANSYS software and experimental methods with help of subsonic wind tunnel at M = 0.1. At the first stage, elastic properties of this thin plate were carried out by using vibrational experiments and modal method to determine the specific vibration frequencies. Then, these aeroelasticity properties were estimated at three different attack angles of 0^o, 5^o and 10^o. Finally, instability phenomenon of this flat plate was investigated within limited experimental conditions to be able to select objects and experimental solutions to be feasible and effective.

Abstract: Helicopter Unmanned Aerial Vehicle (HUAV) is recently used in agriculture due to its dynamic, flexible, vertically take-off/landing, hover and to laterally fly. The HUAV was researched and designed with purpose of greatly reducing manpower, limited direct contact of human with toxic substances, reducing time working in parallel with improving quality and yield. This paper focused on the main rotor blades of HUAV with 15 kg useful load. The main rotor was first designed and then numerically validated by using computational fluid dynamic (CFD) tool in ANSYS software. The aerodynamics characteristics of main rotor blades of HUAV such as pressure, velocity, thrust, drag ...were carried out at hovering flight mode. Finally, strengthen analysis of main rotor blades were checked using computational solid dynamic (CSD) tool in ANSYS software. The aim of this paper was to check whether the designed blades of main rotor were durable enough or not to continue the next design steps.

Abstract: Steel wire coil is the raw material for the screw or nut manufacturing process. It’s common that the surface of the wire is covered with wire drawing powder. Wire drawing powder is necessary and served as the solid lubricant while drawing the wire. However, it’ll be flushed out by the forming oil during the screw or nut manufacturing process. The mixing of the forming oil and the wire drawing powder makes the oil more viscous and generates more sludge. In this paper, we propose a very promising approach to solving the above-mentioned problem. A surface powder removing device with an internal helical brush installed inside to wipe out the wire drawing powder. The performance of this powder removing device was evaluated on the cleanness of the wire surface and the quality of the oil. Results show no damage was observed with the hair diameter equals to 0.08 mm. Almost 100% of the wire surface powder wire surface was removed and the oil quality is 6 times better than that without using this device.