Fengzhou Fang

Fengzhou Fang
University College Dublin | UCD · School of Mechanical and Materials Engineering

PhD

About

403
Publications
128,802
Reads
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8,168
Citations
Citations since 2017
220 Research Items
6386 Citations
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201720182019202020212022202305001,0001,500
201720182019202020212022202305001,0001,500
Introduction
MNMT is specializing in design and manufacturing of medical devices, bio-implants, photonic systems, moulding and tooling, as well as high precision manufacturing and metrology. MNMT also carries out the systematic study on Atomic and Close-to-atomic Scale Manufacturing (ACSM).

Publications

Publications (403)
Article
Vergence-accommodation conflict (VAC) is an obstacle in approaching the natural visual perception in near-eye see-through display. Conventional stereoscopic displays provide virtual images in a single focal plane, which are unable to satisfy the accommodative perception of the human eyes. The geometrical waveguide can be employed to achieve a large...
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We present experimental evidence of reusable, reliable cyclic olefin copolymer (COC)moulds in soft contact lens manufacturing. The moulds showed high performance surface roughness characteristics despite >20 kW exposure to 365 nm ultraviolet (UV) light from repeated use. Ultra-precision manufacturing techniques were used to fabricate transparent CO...
Article
Understanding the relationship between the retinal contour and peripheral aberrations is fundamental for exploring the mechanism of myopia progression. Not much has been known about how the retinal expansion can affect peripheral aberrations across the two-dimensional visual field. This study aims to quantify and analyze the changes in the lower- a...
Article
Optical near-eye see-through displays have a wide range of applications in medical, education, entertainment and other fields. However, most existing displays present virtual stereoscopic images at a fixed focal plane, resulting in vergence-accommodation conflicts. In this study, a see-through display is presented with addressable depth cues and a...
Chapter
The short longevity of current bioimplants is a big issue for the orthopedic industry. In this study, surface texturing is proved to be an effective way to increase the lifespan of artificial joints by improving the tribological performance. We investigated the functionality of surface textures based on the Cobalt-Chromium-Molybdenum on Ultra-High-...
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In this paper, the atomic-scale structure fabrication on Si (100) substrate using atomic force microscopy (AFM) with the aid of electrochemical and mechanical processes in a humid environment and under ambient conditions is studied. The local oxidation patterns are formed using platinum- coated tips with the aid of bias applied to the tip-substrate...
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Atomic force microscopy (AFM)-based electrochemical etching of a highly oriented pyrolytic graphite (HOPG) surface is studied toward the single-atomic-layer lithography of intricate patterns. Electrochemical etching is performed in the water meniscus formed between the AFM tip apex and HOPG surface due to a capillary effect under controlled high re...
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Machine vision significantly improves the efficiency, quality, and reliability of defect detection. In visual inspection, excellent optical illumination platforms and suitable image acquisition hardware are the prerequisites for obtaining high-quality images. Image processing and analysis are key technologies in obtaining defect information, while...
Article
Laser assisted diamond turning is a potential approach to increase the surface finish quality on the hard and brittle materials and to improve diamond tool life. A high effective laser assisted turning (HE-LAT) method is proposed in this article, which guides the laser beam refracts at rake face, cutting edge, and total reflects at flank face. The...
Article
Molecular dynamics (MD) simulation is adopted to discover the underlying mechanism of silicon vacancy color center and damage evolution during helium ions implanted four-hexagonal silicon carbide (4H-SiC) and subsequent annealing. The atomic-scale mechanism of silicon vacancy color centers in the process of He ion implantation into 4H-SiC can be de...
Article
Triangular mesh enables the flexible construction of complex surface geometry and has become a general representation of 3D objects in computer graphics. However, the creation of a tool path with constant residual scallop height on triangular mesh surfaces in multi-axis machining is not a convenient task for current algorithms. In this study, an is...
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This paper presents a study of fabricating micro-dimples with desired morphology characteristics using micro-abrasive jet machining. Experiments are conducted under different processing conditions so that blasted dimples with various sizes and geometries could be obtained and analysed. The results indicated that among all the processing factors use...
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The optical see-through near-eye display finds wide applications in various areas such as medical treatment, education, tourism and entertainment. However, the vergence-accommodation conflict (VAC) is an obstacle in developing the optical performance of high quality. Conventional stereoscopic displays provide the virtual images in single focal plan...
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Geometrical waveguide has great advantages over conventional imaging systems, like larger field of view, larger exit pupil area, lower thickness and lighter weight. Two-dimensional (2D) geometrical waveguide can expand the vertical and horizontal pupil simultaneously, thus becoming a mainstream solution for commercial applications. The transmission...
Article
We present a numerical study on swift ion induced effects in crystalline 3C silicon carbide (SiC) by the two-temperature model, which considering the electronic stopping and electronic-phonon coupling effects simultaneously. Given the results of overlapping radiation, there is only a minority of defects formed in the system during the ionization do...
Article
Surface texturing is an effective technology in improving the tribological performance of artificial joints. However, the mechanism behind it is still a controversial topic, especially when talking about the functionality of hydrodynamic pressure. In this paper, Finite Difference Method was used to solve the steady-state Reynolds equation. It was f...
Article
During the nano-cutting process, monocrystalline gallium arsenide is faced with various surface/subsurface deformations and damages that significantly influence the product's performance. In this paper, molecular dynamics simulations of nano-cutting on gallium arsenide are conducted to investigate the surface and subsurface deformation mechanism. D...
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This paper focuses on the power dissipation of a plasma torch used for an optical surface fabrication process. The process utilizes an inductively coupled plasma (ICP) torch that is equipped with a De-Laval nozzle for the delivery of a highly collimated plasma jet. The plasma torch makes use of a self-igniting coil and an intermediate co-axial tube...
Article
High-precision optical components with nanometric surface finish can be obtained directly through single point diamond turning. However, residual cutting marks on the machined surfaces are likely to cause serious diffraction and deteriorate the optical performance of a machined component. This paper proposes a novel method for diffractive optical c...
Article
As a combination of conventional injection moulding and compression moulding, injection compression moulding is expected to deliver a more uniform distribution of cavity pressure and more precise replication of surface structures. However, processing defects such as flash and design constraints such as thin edges of a product can cause non-uniform...
Article
The removal mechanism of conventional cutting and in-process-heat laser-assisted cutting (In-LAC) of binderless polycrystalline tungsten carbide (WC) material is studied through systematic numerical analysis and experimental investigation. The proposed In-LAC model considers the accumulated thermal effect and the laser in-process-heat thermal bound...
Article
A new surface texturing design was proposed for improving the tribological performance of bioimplants. Theoretical analysis was conducted to reveal the positive impact of round corner patterns. Experimental results indicated that round corner would significantly reduce the chance of interlocking phenomenon. Orthogonal experiments suggest that trian...
Article
Atomic and close-to-atomic scale fabrication with high yield for the color centers in silicon carbide is critical in developing its applications. Combined with Wigner-Seitz method and identify diamond structure method to consider the structure around the silicon vacancy (V_Si), it is found that He ion implantation is more likely to fabricate a smal...
Article
Trace elements are closely related to human health. For example, the homeostasis of metal elements may influence cells' metabolic function, which may result in the production of certain diseases. Laser-induced breakdown spectroscopy (LIBS), a factor-free analysis technique that can be employed for molecularly complex biological materials or clinica...
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3D metal printing process has attracted increasing attention in recent years due to advantages, such as flexibility and rapid prototyping. This study aims to investigate the orientation effect of electropolishing characteristics on different surfaces of 316L stainless steel fabricated by laser powder bed fusion (L-PBF), considering that the rough s...
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Reproduction of the peripheral spherical equivalent refraction (SER) in the eye model is critical for investigations in myopia control. Based on the derivation of a linear relationship between SER and the vergence of the wavefront at exit pupil center, a computing method is proposed to locate the retinal points to reproduce the two-dimensional (2D)...
Article
A new approach to precision electroforming of a wafer-scale nickel shim with rotating cathode using an auxiliary cathode mask is developed to improve thickness uniformity and flatness. The effects of critical process parameters, including cathode rotating speed, cathode mask size, and current density, on the thickness uniformity and flatness of ele...
Article
Surface texturing is an effective approach to improve the tribological performance of artificial joints. In this paper, the frictional performance of Ultra-High-Molecular-Weight-Polyethylene and Cobalt-Chromium -Molybdenum material combination with micro grooves fabricated on the metal bearings is studied. The results show that grooves with width o...
Article
Microstructural replication accuracy in precision micro electroforming process is related to ions transportation inside the micro structure and microstructural feature width and aspect ratio. In this study, a novel star pattern having a varying feature width of 20∼320 μm with a corresponding aspect ratio of 5∼0.3125 is proposed to characterize ion...
Article
In this paper, a new method is developed for tool path planning on triangular mesh surfaces with consideration of the scallop height restriction and the path smoothness. This method first maps the triangular mesh surface into a unit disk region by using a harmonic map algorithm, and then the shortest boundary path graph (SBPG) is constructed on the...
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Haptics plays an important role in grasping and manipulating objects for human hands and artificial robotic hands. The density of tactile receptors at the tips of the fingers is very high, reaching 140 units/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . However, the density of the existi...
Article
Injection moulding has shown its advantages and prevalence in the production of plastic optical components, the performance and functionality of which rely on the precision replication of surface forms and on minimizing residual stress. The present work constitutes a systematic and comprehensive analysis of practical microlens arrays that are desig...
Article
Micro electroforming is a promising electrodeposition-based precision replication technique for the fabrication of microstructured moulds. In this process, a poor mass transfer inside the micro structure with a high aspect ratio significantly affects the replication accuracy of the mould. In this paper, a novel star pattern with a continuously chan...
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Optical interferometry plays an important role in the topographical surface measurement and characterization in precision/ultra-precision manufacturing. An appropriate surface reconstruction algorithm is essential in obtaining accurate topography information from the digitized interferograms. However, the performance of a surface reconstruction alg...
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Gallium arsenide is a typical brittle material, and crack formation is one of the most serious issues in the nanometric processing. This paper majors in studying crack formation mechanism in nano-cutting of gallium arsenide. In the molecular dynamics simulation of nano-cutting process, the main damage changes from dislocation to phase transformatio...
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Phase compensation is a critical step for the optical measuring system using spatial light modulator (SLM). The wavefront distortion from SLM is mainly caused by the phase modulation non-linearity and non-uniformity of SLM’s physical structure and environmental conditions. A phase modulation characteristic calibration and compensation method for li...
Article
Waveguide technology has great prospects of development in optical see-through near-eye displays with larger field of view, lower thickness and lighter weight than other conventional optical technologies. However, the stray light is usually inevitable in current optical design and manufacturing, causing a poor imaging quality. In this paper, the pr...
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Injection moulding is ubiquitous in the production of plastic optical components, the functionality of which depends on minimising residual stress and on precisely replicating surface forms. In this study, variotherm-assisted microinjection moulding is used to manufacture a practical microlens array designed for light-field applications in order to...
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Binderless tungsten carbide (WC) finds widespread applications in precision glass molding (PGM). Grinding and polishing are the main processes to realize optical surface finish on binderless WC mold inserts. The laser assisted turning (LAT) by in-process heating is an efficient method to enhance the machinability of hard and brittle materials. In t...
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Slow tool servo diamond turning has widespread application in fabricating freeform optics. Previous studies are focused on the methods of the tool path generation and verification of zero-rake-angle tools. However, these methods are unsuitable for non-zero-rake tools that are used for machining hard-and-brittle materials. This paper presents a univ...
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Microwave induced plasma torches find wide applications in material and chemical analysis. Investigation of a coaxial electrode microwave induced plasma (CE-MIP) torch is conducted in this study, making it available for glass surface modification and polishing. A dedicated nozzle is designed to inject secondary gases into the main plasma jet. This...
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Optical interferometry is a powerful tool for measuring and characterizing areal surface topography in precision manufacturing. A variety of instruments based on optical interferometry have been developed to meet the measurement needs in various applications, but the existing techniques are simply not enough to meet the ever-increasing requirements...
Article
The dispersibility of graphene oxide particles (GOs) in nickel electrolytes is critical for its uniform incorporation in the nickel matrix during the electrodeposition process. In this study, we study the fundamental interaction of surfactants and nickel ionic strength for uniform and stable incorporation of GOs in nickel electrolytes and their eff...
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As a promising material for quantum technology, silicon carbide (SiC) has attracted great interest in materials science. Carbon vacancy is a dominant defect in 4H-SiC. Thus, understanding the properties of this defect is critical to its application, and the atomic and electronic structures of the defects needs to be identified. In this study, densi...
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Plasma-assisted etching, in which the irradiation of hydrogen plasma and inorganic acid etching are integrated, is proposed as a novel polishing method for sesquioxide crystals. By means of this approach, low damage and even damage-free surfaces with a high material removal rate can be achieved in lutetium oxide surface finishing. Analysis of trans...
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Silicon-vacancy (VSi) centers in silicon carbide (SiC) are expected to serve as solid qubits, which can be used in quantum computing and sensing. As a new controllable color center fabrication method, femtosecond (fs) laser writing has been gradually applied in the preparation of VSi in SiC. In this study, 4H-SiC was directly written by an fs laser...
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Understanding the mechanism for brittle material removal via solid particle impact is important for various areas such as energy and aerospace industries. The existing analytical formulation of erosion damage, consistent with indentation fracture theory, overestimates actual erosion by over 200%. This study complements an existing analysis by presc...
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Precision glass molding is the most appropriate method for batch production of glass lenses with high surface accuracy and qualified optical performance. However, the form error caused by material expansion and contraction is the main factor affecting the precision of the molded lenses, thus the mold must be pre-compensated. In this paper, an effec...
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We present an aided optical alignment method using the liquid crystal on silicon spatial light modulator (LCoS-SLM). An optical system composed of an interferometer and an LCoS-SLM was established to verify the effectiveness of the method. The system was also calibrated to solve the phase modulation nonlinear and nonuniformity problem for better pe...
Article
The ever-increasing requirements for the scalable manufacturing of atomic-scale devices emphasize the significance of developing atomic-scale manufacturing technology. The mechanism of a single atomic layer removal in cutting is the key basic theoretical foundation for atomic-scale mechanical cutting. Material anisotropy is among the key decisive f...
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Micro-milling is a precision manufacturing process with broad applications across the biomedical, electronics, aerospace, and aeronautical industries owing to its versatility, capability, economy, and efficiency in a wide range of materials. In particular, the micro-milling process is highly suitable for very precise and accurate machining of mold...
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The improved scratch resistance of epoxy-based coatings on titanium alloy is greatly needed in the current biomedical device sector. Due to commercial factors, this improvement must be either non-consumptive or inherited from the antecedent machining steps. This study contributes an extensive understanding of Ti-6Al-4 V surface topography, microstr...
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Transparent films are significant industrial components that are widely used in modern optics, microelectronics, optical engineering, and other related fields. There is an urgent need for the fast and stable thickness measurement of industrial films at the micron-grade. This paper built a miniaturized and low-cost film thickness measurement system...
Article
In this paper, β-Ga2O3 single-crystal with three different (100), (010) and (001) orientations and Si-/Mg-/Fe-/Sn-doped are synthesized by EFG method. β-Ga2O3 is investigated by confocal Raman and PL spectroscopy. Raman results indicated that 3D Ga2O3 substrates in the cases of un-/ions-doped growth have superior crystallinity and high uniformity....
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Nano-cutting of brittle material finds wide applications in scientific research and engineering. Numerical simulation is an important tool for understanding the process mechanism, which has many advantages over experimental approaches. Currently, molecular dynamics is the most used method for nano-cutting simulation owing to its explicit descriptio...
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To fill the development gap between computer-aided design (CAD) and computer-aided manufacturing (CAM) on non-uniform rational b-spline (NURBS), a general tool path planning method on NURBS surface is proposed in this study. The generated tool path is composed of a series of closed paths which are derived by mapping the contours of a shortest bound...
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Hard and brittle materials (HBMs) are promising materials for aerospace and astronomy applications, due to their excellent mechanical, optical, and chemical properties. However, they are difficult and costly to machine using conventional machining methods such as single point diamond turning. Laser assisted machining uses a focused laser beam to he...
Article
A R T I C L E I N F O Keywords: Electropolishing 316L stainless steel NaCl-based electrolyte Surface roughness A B S T R A C T Since the environmental and safety issues closely related to the widely used mixture electrolytes of H 2 SO 4 and H 3 PO 4 in electropolishing 316 L stainless steel, the development of new electrolytes, which do not contain...
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Plasma figuring process enables the correction of metre-scale optical surfaces, which has advantages such as rapid convergence to ultra-precision accuracy level, no subsurface damage, ease of upscale thanks to the conditions of operation at atmospheric. Such attributes make plasma figuring a highly competitive technology. To maintain a stable disch...
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Color centers in silicon carbide (SiC) are promising candidates for quantum technologies. However, the richness of the polytype and defect configuration of SiC makes the accurate control of the types and position of defects in SiC still challenging. In this study, helium ion-implanted 4H–SiC was characterized by atomic force microscopy (AFM), confo...
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The surface with high-aspect-ratio nanostructure is observed to possess the bactericidal properties, where the physical interaction between high-aspect-ratio nanostructure could exert sufficient pressure on the cell membrane eventually lead to cell lysis. Recent studies in the interaction mechanism and reverse engineering have transferred the bacte...
Article
Understanding the age-dependent properties of the crystalline lenses of children is fundamental in studying the mechanism of myopic development and progression. A more realistic lens structure has more power for predicting the optical properties of the crystalline lenses. In this manuscript, a new lens model is proposed to predict the age-dependent...
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Off-axis reflective optical systems find wide applications in various industries, but the related manufacturing issues have not been well considered in the design process. This paper proposed a design method for cylindrical reflective systems considering manufacturing constraints to facilitate ultra-precision raster milling. An appropriate index to...
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Hectares of tribological micro-texture must be machined per year to reduce friction and wear in artificial articular joints. Productive and cost-effective tribo-texturing of freeform surfaces consisting of hard-to-machine materials is a current manufacturing challenge. This study evaluates the accuracy and productivity of micro abrasive jet machini...
Article
Homogeneous dispersion of graphene oxide (GO) in nickel sulfamate solution is a significant challenge for electrodepositing high-performance nickel/GO composite coatings. In the present work, three typical surfactants, including anionic surfactant Sodium dodecyl sulfate (SDS), cationic surfactant Cetyltrimethylammonium bromide (CTAB), and non-ionic...
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This article presents the three paradigms of manufacturing advancement: Manufacturing I, craft-based manufacturing by hand, as in the Stone, Bronze, and Iron Ages, in which manufacturing precision was at the millimeter scale; Manufacturing II, precision-controllable manufacturing using machinery whereby the scales of material removal, migration, an...
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Manufacturing at the atomic scale is the next generation of the industrial revolution. Atomic and close-to-atomic scale manufacturing (ACSM) helps to achieve this. Atomic force microscopy (AFM) is a promising method for this purpose since an instrument to machine at this small scale has not yet been developed. As the need for increasing the number...
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Freeform surface is one of the research focuses in the measurement field. A composite module is composed of a plane and rotating paraboloid. The composite module array can identify 21 geometric errors of the machine tool in a wide range, which is composed of several composite modules. Eliminating the error of the array itself is of great significan...
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Deformation behavior at grain levels greatly affects the machining characteristics of crystalline materials. In the present work, we investigate the influence of material anisotropy on ultra-precision diamond cutting of single crystalline and polycrystalline copper by experiments and crystal plasticity finite element simulations. Specifically, diam...