1,720,998 research outputs found
Investigation of micro-manufacturing process performance via innovative surface characterisation methods
No full textParasitic load components for torque and force calibration: a digital twin concept
Full text linkThe 5 MN m standard torque machine within the Competence Centre for Wind Energy (CCW) was developed at PTB. The Digital Twin (DT) of the torque transducer mounted inside the machine was developed to enable errors eliminations and resources optimization during operation. The machine can apply not only torque, but also bending moments and shear forces. At the same time, the DT concepts of force measurement devices and their application for static, continuous and dynamic calibrations was developed to improve calibration processes, preserve data quality and collect calibration data for improved decision making. In order to illustrate the functionality of both developed DT concepts, a study of parasitic load components in both devices is carried out using simulation with ANSYS and ABAQUS engineering software. The validation of the DT models was carried out using traceable measurements. The way to combine both concepts for comprehensive shading of the standard torque machine is discussed.Technisches Messe
Fabrication and functional evaluation of nature-inspired anti-bacterial surfaces
Full text linkGiusca, Claudiu - Associate Supervisor
Kumar, Vinod - Associate SupervisorThe critical need to develop novel and efficient anti-bacterial strategies,
particularly for biomedical implants, serves as a significant motivation for this
research. The rise in antibiotic resistance continues to pose a threat to
healthcare, making it increasingly important to explore alternative approaches to
combat implant-associated surgical site infections (SSIs). These infections arise
from bacterial attachment and biofilm formation on the surface of implants and
medical devices, leading to costly treatments and high recurrence rates. The
present research was aimed at investigating nature-inspired anti-bacterial
surfaces through a rigorous fabrication and testing campaign.
The study investigated various nanofabrication techniques, such as femtosecond
laser ablation, deep reactive ion etching, focused ion beam lithography and
scanning probe lithography, for creating nature-inspired sub-micron features on
stainless steel and silicon surfaces. The biological response of bacteria (S.
aureus) and osteoblast-like cells (MG-63) was evaluated on these surfaces to
test antibacterial as well as osseointegration response of the surfaces. S. aureus
was chosen due to its high relevance to SSIs and its prevalence in infection and
MG-63 cells served as a model for examining the osteoblast behaviour in
laboratory studies.
The thesis established a novel scale-dependent relationship between surface
topography and biological functionality, characterised by the dominating surface
wavelength and fractal dimension. The anti-biofouling mechanism was influenced
by surface topography, characterised through the fractal dimension, and it was
consistently achieved and deemed more suitable for future applications due to
the high anti-bacterial efficiency achieved compared to the mechano-bactericidal
mechanism. High aspect ratio features (0.056-0.280 µm wavelength, 0.295-
0.765 µm height, 0.045-0.046 µm diameter) did not induce mechano-bactericidal
effects on S. aureus NCTC7791, indicating further research is needed. Moreover,
the thesis demonstrated a predominant attachment of S. aureus and MG-63 cells
on the crystalline silicon surfaces on the (111) orientation.
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For feature sizes below 1 µm, the fractal dimension positively correlated with the
anti-bacterial effect and MG-63 cell spreading. For sizes significantly larger than
bacterial size (> 2 µm), no correlation was found with the anti-bacterial effect, but
surface complexity positively correlated with MG-63 cell spreading. For feature
sizes comparable to MG-63 cell size (10-40 µm), cell spreading was inhibited.
Femtosecond laser ablation emerged as a promising technique for commercial
applications, while scanning probe lithography proved to be a cost-effective,
flexible tool for prototyping and research-scale investigations.
In conclusion, the development and evaluation of nature-inspired anti-bacterial
surfaces have revealed valuable insights into the scale-dependent relationship
between surface topography and biological functionality. The findings from this
research have the potential to improve the performance and safety of implantable
medical devices by reducing the risk of implant-associated SSIs, ultimately
benefiting patients and healthcare providers.PhD in Manufacturin
Towards geometrical calibration of x-ray computed tomography systems - A review
Full text linkIndustrial x-ray computed tomography (XCT) is seen as a potentially effective tool for the industrial inspection of complex parts. In particular, XCT is an attractive solution for the measurement of internal geometries, which are inaccessible by conventional coordinate measuring systems. While the technology is available and the benefits are recognized, methods to establish the measurement assurance of XCT systems are lacking. More specifically, the assessment of measurement uncertainty and the subsequent establishment of measurement traceability is a largely unknown process. This paper is a review of research that contributes to the development of a geometrical calibration procedure for XCT systems. A brief introduction to the geometry of cone-beam tomography systems is given, after which the geometrical influence factors are outlined. Mathematical measurement models play a significant role in understanding how geometrical offsets and misalignments contribute to error in measurements; therefore, the application of mathematical models in simulating geometrical errors is discussed and the corresponding literature is presented. Then, the various methods that have been developed to measure certain geometrical errors are reviewed. The findings from this review are discussed and suggestions are provided for future work towards the development of a comprehensive and practical geometrical calibration procedure
Cranfield University: contribution to the local industrial strategy
Full text linkCranfield University aims to contribute to the development of the Local Industrial Strategy by specifically focusing on potential collaborations with local manufacturing SMEs through its teaching and research portfolio. Local and national manufacturing surveys were reviewed in order to identify the skills needs of the industry and, based on them, potential training collaborations were discussed. In addition, the global trends that are expected to drive the future of the industry were also reviewed and discussed together with Cranfield’s areas of expertise, available funding opportunities and current SMEs’ research interests. The reviews showed that the partnership between local manufacturing SMEs and Cranfield University is hindered by various factors, reduced operational capabilities of SMEs being probably the most significant component. To overcome these issues, Cranfield must consider the needs of each SME and SMEs must understand the benefits partner with Cranfield can provide
In process temperature monitoring of energy beam processing.
Full text linkThe use of non-thermal and atmospheric plasma has been growing in recent
years. Applications in wound sterilisation, food decontamination, cleaning and the
more traditional machining and deposition are just some of the areas in which
new technology is being developed. With the growing use of cool plasma comes
the requirement to test and understand the temperature distribution of the jets.
Current methods into temperature measurement revolve around spectroscopy
and other non-contact methods. Spectroscopy can pose a challenge as a
measurement device as it lacks the ability to measure overall gas temperatures
in non-thermal plasmas. Contact measurement thermometers, such as
thermocouples and resistance temperature detectors are an alternative which
can provide an insight into the temperature of the ions and neutral species.
However these sensors pose a challenge in gaining accurate or precise
temperature measurements due to their susceptibility of electromagnetic
interference.
Fibre Bragg grating sensors have the ability of measuring both temperature and
strain without electromagnetic interference. They possess the ability of
multiplexing, being able to measure multiple temperatures across a single fibre,
which can aid in measuring over a long distance. They also have the added
benefit of being small, lightweight and have quick thermal response times.
Additionally their small heat capacity reduces the effect on the temperature of the
measurand, improving their accuracy over other physical probes. In this
experiment fibre Bragg grating sensors 600 μm and 1000 μm in length and 10μm
in diameter have been used to characterise the temperature distribution of non-
thermal microwave plasma and thermal radio frequency plasma jets.
Thermocouples have been used to compare results against current technologies.
Results show the fibre Bragg grating sensors have been successful in
determining plasma temperature changes over time, distance and across a
variety of different parameters.PhD in Manufacturin
Design of ultra-precision piston/cylinders for directly calibrated hydraulic amplification
Full text linkForce calibrations in the Mega Newton range are not currently providing the accuracy
required by industry. This work addresses a hydraulic force standards, which perform
such calibrations, which work b amplifying the force produced on a small piston/cylinder
assembly (PCA) by connecting it hydraulically to a larger PCA. The force standards are
currently calibrated using a transducer to the more accurate deadweight machines, but not
without a resulting uncertainty of 0.01 % - 0.02 % imparted by the transducer performing
the calibration. Because of this, the potential for evaluating uncertainties within the
machine from first principles and using it as a primary machine, with traceability
maintained to the weights is evaluated. First of all the potential for the resulting reduction
in uncertainties is evaluated analytically, then FEA/CFD work is carried out to produce
analytical formulae which allow for the design of a directly calibrated system. The
analysis is carried out for both the rotational and non-rotational variants of PCA. Finally,
the design of a primary hydraulic standard is carried out using FEA/CFD.PhD in Manufacturin
Ultra precision air bearing development for low cost manufacturing.
Full text linkAir bearings today are extensively used in the industry, the manufacturing processes involved in fabricating these bearings are complicated and have major drawbacks. The current research investigates the failure of aerostatic bearings based upon which a manufacturing process is developed which removes the correlation between the bearing surface and the effective gap between these surfaces. This results in low manufacturing errors due to the omission of repeated machining of the bearing surface.
The second factor that is novelty towards this research is the application of aluminium coated with hard nickel as suitable alternative to bearing base material instead to the current material for aerostatic bearings. This proposed material solution has low density, good wear resistance and good corrosion resistance. This allows the application of diamond turning instead of precision grinding as the bearing machining process. Reducing on majority of the manufacturing while achieving the form accuracy of the bearing surface.
The third novelty factor is the application of bi-conic configuration which would allow self-aligning capability and has a smaller packaging size as compared to any other fluid film mechanical configuration.MSc by Research in Manufacturin
Fabrication of micro-scale features on titanium alloys through micromilling.
Full text linkStructured surfaces are of high interest in the manufacturing world, allowing for functionality to be applied to materials through nothing more than a change in the surface topography or an application of a surface coating. Applications for these surfaces range greatly, including, optical surfaces for antireflective surfaces, thermal structures to assist in heat dispersion and anti-fouling surfaces to reduce organisms from adhering to components. Hydrophobic structures, such as the one that have been examined on the lotus leaf under SEM, generate high droplet contact angles and roll off. The manipulation of surface wettability is of particular interest in areas such as the medical sector for self-cleaning applications or controlling cell adhesion on the surface of an implant.
This work investigates the generation of micron level hydrophobic features on two
Titanium alloys, Ti-6Al-4V alpha-beta alloy and Ti-30Nb beta alloy, with the aim of identifying how accurately surface structures can be produced through micromilling as well as experimentally testing how successfully these surfaces function after being fabricated. On each alloy, nine different 5mm x 5mm test pillars are machined using micromilling, half of each pillar is machined with 200μm wide and 30μm deep channels, generating a hydrophobic groove structure, and the other half being flat machined. Across these nine pillars the feedrate, spindle speed, axial depth of cut and tool step over were varied to optimise these parameters in terms of structure generation, channel bottom surface roughness and tool to workpiece interaction in an attempt to determine how effective micromilling is as at structuring the surface of beta Titanium alloys. Tool condition was assessed qualitatively using SEM imaging and an independent assessment was carried out to determine the mechanical properties of the beta Titanium alloy being machined.MSc by Research in Manufacturin
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