Liam Blunt - Academia.edu (original) (raw)
Papers by Liam Blunt
European Journal of Pharmaceutics and Biopharmaceutics, Jul 1, 2020
The present work aimed at designing and developing a novel 3D printed diffusion cell capable of U... more The present work aimed at designing and developing a novel 3D printed diffusion cell capable of UV imaging using the fused filament fabrication (FFF) method. UV imaging has proven to be very versatile in the area of pharmaceutics giving insights into various phenomena including the dissolution behaviour of dosage forms, intrinsic dissolution rates and the drug precipitation processes. A 3D printed diffusion cell in similitude of a Franz cell was successfully printed using polylactic acid (PLA) filaments equipped with quartz for the imaging area. A model ibuprofen (IBU) gel formulation was tested by introducing the dosage form through the 3D printed donor compartment and the drug concentration permeated through the skin mimic (silicone membrane) was determined from the 3D printed receptor compartment using UV imaging in real-time. The results showed successful UV imaging of the permeation of IBU gel in the novel diffusion cell potentially negating further analytical processes such as the HPLC process required for Franz cell tests thereby reducing costs. Potential interactions between the drug and filament used in the 3D printed process suggests although this concept can be moved towards commercialisation, care should be taken with choice of filament used in the 3D printing process.
University of Huddersfield eBooks, Dec 1, 2010
To investigate the material removal characteristic of paste polishing, experimental investigation... more To investigate the material removal characteristic of paste polishing, experimental investigations based on Taguchi method have been carried out. In the experiments, the dwell time was fixed 300 seconds and the bonnet position was 4. The four variable factors (precess angles, head speed, head pressure and tool offset) with 3 levels were chosen to design the orthogonal array. With the designed orthogonal array, two groups of experiments have been implemented to verify the repeatability of paste polishing. The experimental results indicated that the sizes and shapes of polishing spot varied with polishing parameters, the most influential parameter was precess angle and its contribution was 37.39%. However, the results of material removal rates did not coincide with the principle of Preston equation. This meant that the paste polishing was not a deterministic polishing and cannot be used to correct the form polishing.
It is recognised that surface feature is the one of the most important factors affecting the func... more It is recognised that surface feature is the one of the most important factors affecting the functionality and reliability of micro/nano scale patterned surfaces. The information in all surface geometrical patterns is contained in the attributes of the individual pattern features and the structural relationships between these features. To extract this information the individual pattern features need to be identified [1]. A stable syntactic extraction technique of significant surface features from what is termed a structured surface has been developed. Different feature extraction techniques applied for the different types of structured surfaces are illustrated [2-3]. Examples have been selected to demonstrate the feasibility and applicability of the surface pattern analysis techniques. Finally, experimental results will be given and discussed in this paper.
Measurement Science and Technology, Jan 31, 2006
A multiplexed fibre interferometer (MFI) based on wavelength-division-multiplexing (WDM) techniqu... more A multiplexed fibre interferometer (MFI) based on wavelength-division-multiplexing (WDM) technique is proposed for on-line surface measurement. It combines two fibre interferometers, measurement and reference interferometers, which share a large proportion of their optical paths. The reference interferometer incorporating with fibre Bragg grating (FBG) is used to compensate for environmental fluctuations so that the measurement interferometer can execute high stability and high precision measurements. An active phase tracking homodyne (APTH) technique is applied for signal processing to achieve a phase resolution of 10-6 rad. WDM-FBG techniques provide implementation of phase-to-depth and wavelength-to-field detection and offer a large dynamic measurement ratio (range/resolution) with a high signal-to-noise ratio (robustness). Two types of optical probes, using a dispersive prism and a blazed grating respectively, are investigated to realise wavelength-to-spatial scanning. The experimental results testified the feasibility of on-line surface measurement by this methodology.
Proceedings Of The Institution Of Mechanical Engineers, Part H: Journal Of Engineering In Medicine, Mar 1, 2008
Total joint replacement is one of the most common elective surgical procedures performed worldwid... more Total joint replacement is one of the most common elective surgical procedures performed worldwide, with an estimate of 1.5610 6 operations performed annually. Currently joint replacements are expected to function for 10-15 years; however, with an increase in life expectancy, and a greater call for knee replacement due to increased activity levels, there is a requirement to improve their function to offer longer-term improved quality of life for patients. Wear analysis of total joint replacements has long been an important means in determining failure mechanisms and improving longevity of these devices. The effectiveness of the coordinate-measuring machine (CMM) technique for assessing volumetric material loss during simulated life testing of a replacement knee joint has been proved previously by the present authors. The purpose of the current work is to present an improvement to this method for situations where no pre-wear data are available. To validate the method, simulator tests were run and gravimetric measurements taken throughout the test, such that the components measured had a known wear value. The implications of the results are then discussed in terms of assessment of joint functionality and development of standardized CMM-based product standards. The method was then expanded to allow assessment of clinically retrieved bearings so as to ascertain a measure of true clinical wear.
WIT transactions on engineering sciences, 1970
The needs of modem surface metrology assessment cover not only the extraction of roughness, wavin... more The needs of modem surface metrology assessment cover not only the extraction of roughness, waviness, but also identification of surface texture or the multiscalar properties of a surface topography. In answer to this, the newly developing wavelet theory has been introduced into surface characterisation in 1994. Wavelet analysis employs time-frequency windows and offers the relevant time-frequency analysis, as a result, it can divide surface topography into different frequency components, and then study each component with the multiresolution. This paper provides a survey of the most recent work in the field of surface metrology by using wavelet theory. The major wavelet models used in surface metrology will be introduced and the basic theory, algorithm and the properties of these models will also be discussed.
Eighth International Symposium on Precision Engineering Measurement and Instrumentation, Jan 31, 2013
University of Huddersfield eBooks, Dec 1, 2010
The current concepts in surface texture international standards are considered to be too theoreti... more The current concepts in surface texture international standards are considered to be too theoretical, complex and over-elaborate for industry. A functional approach that completely expresses the complicated surface texture knowledge for designers and engineers is often nonexistent on the shop floor. Based on Geometrical Product Specifications (GPS) philosophy, this paper proposes a modeling of connection between design, manufacture and measurement in surface texture. Explicit specification and verification processes are modeled base on the general GPS matrix and related ISO standards. The goal of the modeling is to bridge the knowledge gap between design, manufacture and measurement in the field of surface texture.
Curran Associates eBooks, Sep 1, 2014
This paper reports on work carried out as part of the EU funded research project "Nanomend". The ... more This paper reports on work carried out as part of the EU funded research project "Nanomend". The project seeks to develop integrated process inspection, cleaning, repair for nano-scale thin films on large area substrates. In order to prevent water ingress into flexible PV modules they are coated with a protective barrier layer of Al 2 O 3 using atomic layer deposition (ALD) technique. Unfortunately defects in this layer have been shown to reduce module efficiency over a period of time due to water vapour ingress. The present work concentrates on defect detection and reports on the use of areal surface metrology parameters to correlate defect morphology with water vapour transmission rate (WVTR) through the protective barrier coatings. The use of advanced segmentation techniques is demonstrated where topographic information on functionally significant defects can be extracted and quantified. The work also reports on the deployment of new in line interferometric optical sensors designed to measure and catalogue the defect distribution and size where they are present in the barrier film. The sensors have built-in environmental vibration compensation and are being deployed on a demonstrator system at a Roll2Roll production facility in the UK.
euspen eBooks, May 27, 2013
In-line metrology of functional surfaces with a focus on defect assessment on large area Roll to ... more In-line metrology of functional surfaces with a focus on defect assessment on large area Roll to Roll substrates Original Citation
Journal for Manufacturing Science and Production, Jun 1, 2003
The nano-scalar measured surface topography generally contains the useful information and noise e... more The nano-scalar measured surface topography generally contains the useful information and noise especially induced from the worktable or base vibration in spite of environment control. To remove or limit the influences of this noise on the surface characterisation, nonparametric estimation methods based on the wavelet analysis are investigated, and an adaptive Bayesian denoising method for the nano-scalar surface measurement has been developed. Proven from the tests on the real surfaces from the Atomic Force Microscope, the results of this adaptive Bayesian denoising method are compatible with the real surfaces with less noise in the real measurement.
Precision manufacturing, 2019
Current criteria used to determine whether rough surfaces affect skin friction typically rely on ... more Current criteria used to determine whether rough surfaces affect skin friction typically rely on a single amplitude parameter to characterize the roughness. The most commonly used criteria relate the centreline averaged roughness, Ra, to an equivalent sandgrain roughness size, ks. This paper shows that such criteria are oversimplified and that Ra/ks is dependent on the roughness topography, namely the roughness slope defined as the roughness amplitude normalized by the distance between roughness peaks, Ra/λ. To demonstrate the relationship, wake traverses were undertaken downstream of an aerofoil with various polished surfaces. The admissible roughness Reynolds number (ρ1u1Ra/μ1) at which the drag rose above the smooth blade case, was determined. The results were used to demonstrate a 400% variation in Ra/ks over the roughness topographies tested. The relationship found held for all cases tested, except those where the roughness first initiated premature transition at the leading edge. In these cases, where the roughness was more typical of eroded aerofoils, the drag was found to rise earlier.
International Journal of Machine Tools & Manufacture, Aug 1, 2002
The electro discharge machining (EDM) process produces surfaces that require some form of finishi... more The electro discharge machining (EDM) process produces surfaces that require some form of finishing operation. This is done in order to improve the surface texture and appearance of the component's surface. However, it is also desirable to remove the white uppermost recast layer (produced by the EDM process) so as to improve the functional performance of the surface. Electropolishing or electrochemical polishing (ECP) is one technique that is used mainly to improve the appearance of steels as well as for passivation of stainless steels. However, this process is very complex in nature, and it is not well understood how the different process parameters influence the surface integrity of the component in salt solutions. The aim of this paper is to present the results of a preliminary design of experiment of an EDM+ECP process sequence using Taguchi methodology. 3D characterisation of the surfaces has been done and ANOVA technique has been used to assess the quantitative influence of the different process factors of ECP. The results have shown that the direct current is the most dominant factor in modifying the surface texture, especially the S q and S m 3D parameters. The interaction effect between current and distance between electrodes is relatively important as compared to the individual effect of the latter variable.
European Journal of Pharmaceutics and Biopharmaceutics, Jul 1, 2020
The present work aimed at designing and developing a novel 3D printed diffusion cell capable of U... more The present work aimed at designing and developing a novel 3D printed diffusion cell capable of UV imaging using the fused filament fabrication (FFF) method. UV imaging has proven to be very versatile in the area of pharmaceutics giving insights into various phenomena including the dissolution behaviour of dosage forms, intrinsic dissolution rates and the drug precipitation processes. A 3D printed diffusion cell in similitude of a Franz cell was successfully printed using polylactic acid (PLA) filaments equipped with quartz for the imaging area. A model ibuprofen (IBU) gel formulation was tested by introducing the dosage form through the 3D printed donor compartment and the drug concentration permeated through the skin mimic (silicone membrane) was determined from the 3D printed receptor compartment using UV imaging in real-time. The results showed successful UV imaging of the permeation of IBU gel in the novel diffusion cell potentially negating further analytical processes such as the HPLC process required for Franz cell tests thereby reducing costs. Potential interactions between the drug and filament used in the 3D printed process suggests although this concept can be moved towards commercialisation, care should be taken with choice of filament used in the 3D printing process.
University of Huddersfield eBooks, Dec 1, 2010
To investigate the material removal characteristic of paste polishing, experimental investigation... more To investigate the material removal characteristic of paste polishing, experimental investigations based on Taguchi method have been carried out. In the experiments, the dwell time was fixed 300 seconds and the bonnet position was 4. The four variable factors (precess angles, head speed, head pressure and tool offset) with 3 levels were chosen to design the orthogonal array. With the designed orthogonal array, two groups of experiments have been implemented to verify the repeatability of paste polishing. The experimental results indicated that the sizes and shapes of polishing spot varied with polishing parameters, the most influential parameter was precess angle and its contribution was 37.39%. However, the results of material removal rates did not coincide with the principle of Preston equation. This meant that the paste polishing was not a deterministic polishing and cannot be used to correct the form polishing.
It is recognised that surface feature is the one of the most important factors affecting the func... more It is recognised that surface feature is the one of the most important factors affecting the functionality and reliability of micro/nano scale patterned surfaces. The information in all surface geometrical patterns is contained in the attributes of the individual pattern features and the structural relationships between these features. To extract this information the individual pattern features need to be identified [1]. A stable syntactic extraction technique of significant surface features from what is termed a structured surface has been developed. Different feature extraction techniques applied for the different types of structured surfaces are illustrated [2-3]. Examples have been selected to demonstrate the feasibility and applicability of the surface pattern analysis techniques. Finally, experimental results will be given and discussed in this paper.
Measurement Science and Technology, Jan 31, 2006
A multiplexed fibre interferometer (MFI) based on wavelength-division-multiplexing (WDM) techniqu... more A multiplexed fibre interferometer (MFI) based on wavelength-division-multiplexing (WDM) technique is proposed for on-line surface measurement. It combines two fibre interferometers, measurement and reference interferometers, which share a large proportion of their optical paths. The reference interferometer incorporating with fibre Bragg grating (FBG) is used to compensate for environmental fluctuations so that the measurement interferometer can execute high stability and high precision measurements. An active phase tracking homodyne (APTH) technique is applied for signal processing to achieve a phase resolution of 10-6 rad. WDM-FBG techniques provide implementation of phase-to-depth and wavelength-to-field detection and offer a large dynamic measurement ratio (range/resolution) with a high signal-to-noise ratio (robustness). Two types of optical probes, using a dispersive prism and a blazed grating respectively, are investigated to realise wavelength-to-spatial scanning. The experimental results testified the feasibility of on-line surface measurement by this methodology.
Proceedings Of The Institution Of Mechanical Engineers, Part H: Journal Of Engineering In Medicine, Mar 1, 2008
Total joint replacement is one of the most common elective surgical procedures performed worldwid... more Total joint replacement is one of the most common elective surgical procedures performed worldwide, with an estimate of 1.5610 6 operations performed annually. Currently joint replacements are expected to function for 10-15 years; however, with an increase in life expectancy, and a greater call for knee replacement due to increased activity levels, there is a requirement to improve their function to offer longer-term improved quality of life for patients. Wear analysis of total joint replacements has long been an important means in determining failure mechanisms and improving longevity of these devices. The effectiveness of the coordinate-measuring machine (CMM) technique for assessing volumetric material loss during simulated life testing of a replacement knee joint has been proved previously by the present authors. The purpose of the current work is to present an improvement to this method for situations where no pre-wear data are available. To validate the method, simulator tests were run and gravimetric measurements taken throughout the test, such that the components measured had a known wear value. The implications of the results are then discussed in terms of assessment of joint functionality and development of standardized CMM-based product standards. The method was then expanded to allow assessment of clinically retrieved bearings so as to ascertain a measure of true clinical wear.
WIT transactions on engineering sciences, 1970
The needs of modem surface metrology assessment cover not only the extraction of roughness, wavin... more The needs of modem surface metrology assessment cover not only the extraction of roughness, waviness, but also identification of surface texture or the multiscalar properties of a surface topography. In answer to this, the newly developing wavelet theory has been introduced into surface characterisation in 1994. Wavelet analysis employs time-frequency windows and offers the relevant time-frequency analysis, as a result, it can divide surface topography into different frequency components, and then study each component with the multiresolution. This paper provides a survey of the most recent work in the field of surface metrology by using wavelet theory. The major wavelet models used in surface metrology will be introduced and the basic theory, algorithm and the properties of these models will also be discussed.
Eighth International Symposium on Precision Engineering Measurement and Instrumentation, Jan 31, 2013
University of Huddersfield eBooks, Dec 1, 2010
The current concepts in surface texture international standards are considered to be too theoreti... more The current concepts in surface texture international standards are considered to be too theoretical, complex and over-elaborate for industry. A functional approach that completely expresses the complicated surface texture knowledge for designers and engineers is often nonexistent on the shop floor. Based on Geometrical Product Specifications (GPS) philosophy, this paper proposes a modeling of connection between design, manufacture and measurement in surface texture. Explicit specification and verification processes are modeled base on the general GPS matrix and related ISO standards. The goal of the modeling is to bridge the knowledge gap between design, manufacture and measurement in the field of surface texture.
Curran Associates eBooks, Sep 1, 2014
This paper reports on work carried out as part of the EU funded research project "Nanomend". The ... more This paper reports on work carried out as part of the EU funded research project "Nanomend". The project seeks to develop integrated process inspection, cleaning, repair for nano-scale thin films on large area substrates. In order to prevent water ingress into flexible PV modules they are coated with a protective barrier layer of Al 2 O 3 using atomic layer deposition (ALD) technique. Unfortunately defects in this layer have been shown to reduce module efficiency over a period of time due to water vapour ingress. The present work concentrates on defect detection and reports on the use of areal surface metrology parameters to correlate defect morphology with water vapour transmission rate (WVTR) through the protective barrier coatings. The use of advanced segmentation techniques is demonstrated where topographic information on functionally significant defects can be extracted and quantified. The work also reports on the deployment of new in line interferometric optical sensors designed to measure and catalogue the defect distribution and size where they are present in the barrier film. The sensors have built-in environmental vibration compensation and are being deployed on a demonstrator system at a Roll2Roll production facility in the UK.
euspen eBooks, May 27, 2013
In-line metrology of functional surfaces with a focus on defect assessment on large area Roll to ... more In-line metrology of functional surfaces with a focus on defect assessment on large area Roll to Roll substrates Original Citation
Journal for Manufacturing Science and Production, Jun 1, 2003
The nano-scalar measured surface topography generally contains the useful information and noise e... more The nano-scalar measured surface topography generally contains the useful information and noise especially induced from the worktable or base vibration in spite of environment control. To remove or limit the influences of this noise on the surface characterisation, nonparametric estimation methods based on the wavelet analysis are investigated, and an adaptive Bayesian denoising method for the nano-scalar surface measurement has been developed. Proven from the tests on the real surfaces from the Atomic Force Microscope, the results of this adaptive Bayesian denoising method are compatible with the real surfaces with less noise in the real measurement.
Precision manufacturing, 2019
Current criteria used to determine whether rough surfaces affect skin friction typically rely on ... more Current criteria used to determine whether rough surfaces affect skin friction typically rely on a single amplitude parameter to characterize the roughness. The most commonly used criteria relate the centreline averaged roughness, Ra, to an equivalent sandgrain roughness size, ks. This paper shows that such criteria are oversimplified and that Ra/ks is dependent on the roughness topography, namely the roughness slope defined as the roughness amplitude normalized by the distance between roughness peaks, Ra/λ. To demonstrate the relationship, wake traverses were undertaken downstream of an aerofoil with various polished surfaces. The admissible roughness Reynolds number (ρ1u1Ra/μ1) at which the drag rose above the smooth blade case, was determined. The results were used to demonstrate a 400% variation in Ra/ks over the roughness topographies tested. The relationship found held for all cases tested, except those where the roughness first initiated premature transition at the leading edge. In these cases, where the roughness was more typical of eroded aerofoils, the drag was found to rise earlier.
International Journal of Machine Tools & Manufacture, Aug 1, 2002
The electro discharge machining (EDM) process produces surfaces that require some form of finishi... more The electro discharge machining (EDM) process produces surfaces that require some form of finishing operation. This is done in order to improve the surface texture and appearance of the component's surface. However, it is also desirable to remove the white uppermost recast layer (produced by the EDM process) so as to improve the functional performance of the surface. Electropolishing or electrochemical polishing (ECP) is one technique that is used mainly to improve the appearance of steels as well as for passivation of stainless steels. However, this process is very complex in nature, and it is not well understood how the different process parameters influence the surface integrity of the component in salt solutions. The aim of this paper is to present the results of a preliminary design of experiment of an EDM+ECP process sequence using Taguchi methodology. 3D characterisation of the surfaces has been done and ANOVA technique has been used to assess the quantitative influence of the different process factors of ECP. The results have shown that the direct current is the most dominant factor in modifying the surface texture, especially the S q and S m 3D parameters. The interaction effect between current and distance between electrodes is relatively important as compared to the individual effect of the latter variable.
Producing components using metal additive manufacturing processes, such as powder bed fusion, pre... more Producing components using metal additive manufacturing processes, such as powder bed fusion, presents manufacturing and measurement challenges, but also significant opportunities. The as-built surface may include overhanging (re-entrant) features not intentionally included in the design, but that aid in component functionality. In addition, the AM process presents opportunities to design and manufacture re-entrant features intentionally. Re-entrant features increase the specific surface area and, in addition, produce mechanical locking to the surface. These features may be intended to improve surface performance in areas such as biological cell attachment, coating adhesion, electrical capacitor and battery plate design, fluid flow and material cooling. Re-entrant features may prove difficult or impossible to measure and characterise using conventional line-of-sight instrumentation. The correct measurement of these surfaces is vital for functional optimisation. This paper reports on the measurement of re-entrant features using X-ray computed tomography and the extraction of actual surface area information (including re-entrant surfaces) from sample AM surfaces. The proposed new parameter, Sdr prime , is discussed. This parameter is intended to relate directly to surface function. Sdr prime is the percentage of additional surface (including re-entrant surfaces) contributed by the texture as compared to a plane the size of the measurement area. In addition to Sdr prime , the actual surface area is discussed, together with the percentage of re-entrant surface. The errors produced using line-of-sight instruments and height map parameter generation per ISO 25178-2 are discussed. Measurement results for EBM and SLM additively manufactured components will be presented.
Assessing functional performance is the most important stage of any component verification. Mecha... more Assessing functional performance is the most important stage of any component verification. Mechanical properties can be evaluated by means of destructive testing which can be both expensive and lengthy in addition to loss of the original component under test. It is therefore advantageous where possible to utilise non-destructive techniques that can achieve the same or similar outcomes through collection of three-dimensional data that can then be used in simulation to determine functionality. Such non-destructive methods are essentially density-and porosity-based testing methods. Additive manufacturing allows for the creation of complex geometrical features that are often defined based on function. Optimisation of AM component geometry based on functionality allows for the specification of components that have features that cannot be mapped efficiently to current GPS standards. In addition, the integrity of complex optimised AM structures that may lie on a critical stress or heat path must be assessed and any elements of unmelted powder must be detected. This study details the development of a Ti6AL4V artefact built using an Arcam Q10 electron beam-melting machine (EBM). Defects of between 50 and 500 microns in diameter were then machined into the surface of the artefact using a CNC machine equipped with nano-drills and end mills. Once this was achieved, the defects were characterised using focus variation interferometer. Virgin Ti6AL4V powder was added to fill 50% of the defects and then the artefact was measured using a Nikon XTH225 industrial CT. This was used to analyse the relative size and location of the defects and assess the capability of the inspection process to both assess the size of pores of this size and to detect the powder-filled defects based on different X-ray detector magnifications. To reduce the number of process variables, all the measurement process parameters, such as filament current, acceleration voltage and X-ray filtering material and thickness, were kept constant. The acquired data processing, surface determination process and defect analysis was carried out using VgStudio Max (Volume Graphics, Germany). The focus of the study is on providing best practice regarding the selection of inspection parameters to accurately perform defect detection.