Papers by Author: Feng Zhou Fang

Abstract: Tool wear and failure monitoring has raised quite a lot of interests among researchers and has consequently been studied in a number of research projects by a number of research organisations. However, few researchers monitored tool wear in rotary ultrasonic machining (RUM) using various sensors. This paper, for the first time in literature, presents an experimental monitoring on tool wear in RUM of silicon carbide (SiC) using accelerometer, force and acoustic emission sensors. A digital microscope was used to observe the actual tool wear during the experiment. After describing the experimental procedures, it presents and discusses the results on tool wear and acceleration signal, force signal and acoustic signal in RUM of SiC

Abstract: A novel adaptive force control table for rotary ultrasonic machine tool was developed for processing micro holes. The adaptive force control table, a mechanical balancing device by which the load can be adaptively adjusted without numerical control was adopted as an attachment in an ultrasonic machine tool. To verify the performance, micro holes were drilled on SiC workpiece. The drilling force, tool wear and profiles of these machined micro holes were investigated. According to the experimental results, it is confirmed that the newly developed table attached on the ultrasonic machine tool is an economical and efficient approach for machining micro holes on hard and brittle materials.

Abstract: The solar concentrator is the primary means of solving the contradiction between cost and photoelectric conversion efficiency. The design and fabrication of concentrator are the key techniques to accelerate the application of photovoltaic systems. A novel type of composite concentrator is designed, including two mirrors and one planar lens. The primary mirror focuses the sunlight on the secondary condenser, which is one multi-segmented cone mirror to produce homogenization on the solar cell. The selection strategy of structure parameters is analyzed by the numerical calculation methods. The concentration ratio and homogenization on the receiving surface are also obtained using the optical simulation method. The designed mirrors are fabricated by the ultra-precision turning method, and then assembled according to the location parameters designed. The proposed methods are proved to be satisfied with the solar application efficiently by the experiments.

Abstract: Carbon nanotube (CNT) probe used in atomic force microscopy (AFM) was fabricated by using electron beam induced Pt deposition method. The bonding force for CNT probe was found to be larger than 500nN. The nanotube probe’s length was shortened by focused ion beam milling process. It is confirmed that the CNT probe shows higher aspect ratio than the Si probe. The nanotube probes with fullerene-like cap end present higher imaging resolution than those with open end.

Abstract: A new method on examining the micro cracks of monocrystalline silicon during nano indentation is proposed. It is established based on a study of the increasing rate of absorbed energy in nano indentation. This method provides a simple approach in understanding whether cracks on the silicon surfaces occur, while it is tedious in conventional method.