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Subject = mechanical testing;
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Displaying Results 1 - 12 of 12 on page 1 of 1
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A study of the influence of processing parameters on steering of carbon Fibre/PEEK tapes using laser-assisted tape placement
(2019)
Clancy, Gearóid J.; Peeters, Daniël; Oliveri, Vincenzo; Jones, David; O'Higgins, R...
A study of the influence of processing parameters on steering of carbon Fibre/PEEK tapes using laser-assisted tape placement
(2019)
Clancy, Gearóid J.; Peeters, Daniël; Oliveri, Vincenzo; Jones, David; O'Higgins, Ronan M.; Weaver, Paul M.
Abstract:
The full text of this article will not be available in ULIR until the embargo expires on the 11/11/2020
Laser-assisted Automated Tape Placement (LATP) in-situ consolidation of thermoplastic composites has significant potential to produce repeatable and accurate components more efficiently than conventional processing methods. In addition, LATP can process Variable Angle Tow (VAT) laminates, that allow modification of load paths within the laminate to result in more favourable stress distributions and improved laminate performance. Previous studies have reported dry fibre placement and thermoset pre-preg tape placement processed VAT laminates. This work investigates the processing parameters required to produce VAT laminates from carbon fibre (CF)/polyether ether ketone (PEEK) tapes using LATP. Testing was carried out to examine the effect of lay-down speed and steering radii on defect frequency and bond strength. Measurements showed that the width and thickness of the CF/PEEK ta...
http://hdl.handle.net/10344/7528
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An evaluation of the influence of manufacturing methods on interlocked aluminium-thermoplastic composite joint performance
(2021)
Ramaswamy, Karthik; O'Higgins, Ronan M; Lyons, John; McCarthy, Michael A.; McCarth...
An evaluation of the influence of manufacturing methods on interlocked aluminium-thermoplastic composite joint performance
(2021)
Ramaswamy, Karthik; O'Higgins, Ronan M; Lyons, John; McCarthy, Michael A.; McCarthy, Conor T.
Abstract:
Joining techniques for multi-material structures are critical for increased use of lightweight materials such as aluminium alloys and thermoplastic composites in the automotive industry. Interlocking adhesive joints (IAJs) can provide increased mechanical performance over standard adhesive joints, but manufacturing methods suitable for industrial applications must be developed. Here, three methods are examined for fabricating composite adherends with recessed macroscale features. The methods differ in the way the fabric material is draped over a mould and are referred to as “simple stacking”, “moulding-in”, and “fibre-cutting”. The IAJs are tested under quasi-static, 0.5 m/s and 3 m/s loading rates and the fibre-cutting method achieves the best mechanical performance. One reason is that it gives a homogenous fibre distribution across the overlap width, providing good flexural properties at the recessed features. It also results in resin-rich regions along the overlap length, which l...
http://hdl.handle.net/10344/9808
Marked
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Analysis and Evaluation of the Dynamic Performance of SMA Actuators for Prosthetic Hand Design
(2009)
O'Toole, Kevin; McGrath, Mark; Coyle, Eugene
Analysis and Evaluation of the Dynamic Performance of SMA Actuators for Prosthetic Hand Design
(2009)
O'Toole, Kevin; McGrath, Mark; Coyle, Eugene
Abstract:
It is widely acknowledged within the biomedical engineering community that shape memory alloys (SMAs) exhibit great potential for application in the actuation of upper limb prosthesis designs. These lightweight actuators are particularly suitable for prosthetic hand solutions. A four-fingered, 12 degree-of-freedom prosthetic hand has been developed featuring SMA bundle actuators embedded within the palmar structure. Joule heating of the SMA bundle actuators generates sufficient torque at the fingers to allow a wide range of everyday tasks to be carried out. Transient characterization of SMA bundles has shown that performance/response during heating and cooling differs substantially. Natural convection is insufficient to provide for adequate cooling during elongation of the actuators. An experimental test-bed has been developed to facilitate analysis of the heat transfer characteristics of the appropriately sized SMA bundle actuators for use within the prosthetic hand design. Various...
https://arrow.dit.ie/engschmanart/1
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Characterisation of OSB properties for application in gridshells
(2017)
Collins, Matthew; Cosgrove, Tom; Mellad, Abdussalam
Characterisation of OSB properties for application in gridshells
(2017)
Collins, Matthew; Cosgrove, Tom; Mellad, Abdussalam
Abstract:
In order to establish the viability and efficiency of Orientated Strand Board (OSB) for use in bending active gridshells, the relevant material properties need to be established. Standard test methods for OSB assume the material will be used in large panel form. However, gridshells are made from long, relatively narrow and thin strips. To characterize the material properties of OSB for use in bending active gridshells, bending, torsion and compression tests were carried out to determine material strength and material stiffness properties. Test methods different to those in the standards were developed. Relatively high variations were observed in the material properties compared to those given in the standards. In addition, relatively high variations in product thickness were also observed in OSB sections. The variation in material and section properties identified should be considered when formulating design rules. This study shows that, in addition to a thorough understan...
http://hdl.handle.net/10344/7908
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Comparative manufacture and testing of induction-welded and adhesively-bonded carbon fibre PEEK stiffened panels
(2018)
Flanagan, M.; Doyle, A.; Doyle, K.; Ward, M.; Bizeul, M.; Canavan, R.; Weafer, B.; Ó Br...
Comparative manufacture and testing of induction-welded and adhesively-bonded carbon fibre PEEK stiffened panels
(2018)
Flanagan, M.; Doyle, A.; Doyle, K.; Ward, M.; Bizeul, M.; Canavan, R.; Weafer, B.; Ó Brádaigh, C.M.; Harrison, Noel M.; Goggins, J.
Abstract:
This work presents details of manufacturing and testing of a carbon fibre polyetheretherketone (CFPEEK) induction welded hat-stiffened panel. Mechanical testing is carried out to evaluate the performance of the welded assembly and results are compared with similar testing of an adhesively bonded panel. The results show that the welded panel and the bonded panels had similar load bearing capacity (<2% difference) and stiffness (< 1% difference). Optical microscopy is used to verify the weld quality and identify manufacturing artefacts associated with induction welding. Inspection of the panel after welding shows that the induction welding process caused minor warpage, voids, and delamination in the panel. The work addresses the lack of data relating to demonstrator scale welded assemblies in the literature, demonstrates that continuous induction welding is a suitable assembly technique for aerospace and automotive components under uniaxial in-plane compressive loading, and iden...
http://hdl.handle.net/10344/7572
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Computational and experimental analysis of the mechanical performance of SLS generated polymer-ceramic bone scaffold materials
(2015)
Doyle, Heather
Computational and experimental analysis of the mechanical performance of SLS generated polymer-ceramic bone scaffold materials
(2015)
Doyle, Heather
Abstract:
The load-bearing ability of orthopaedic scaffolds in critical-sized defects is of critical importance. 3D printing methods such as selective laser sintering (SLS) have great potential for the fabrication of patient-specific scaffolds. The incorporation of ceramic particles is desirable to promote osteogenesis; however the influence of these particles on the microstructure and mechanical behaviour of SLS materials is unclear. A multiscale modelling methodology is developed to predict the macroscale elastic properties of polymer-ceramic SLS materials with complex microstructures. The relationship between micromechanics-evaluated elastic properties and average grey-value is found to be material-specific. The macroscale elastic modulus of SLS materials with different volumes of beta-TCP particles is accurately predicted when element-specific assignment of elastic properties based on grey-value is used. Increasing the ceramic content of these SLS materials is shown to result in a slight...
http://hdl.handle.net/10379/4829
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Experimental mechanical testing of Poly (l-Lactide) (PLLA) to facilitate pre-degradation characteristics for application in cardiovascular stenting
(2017)
Bobel, Anna C.; Lohfeld, Stefan; Shirazi, Reyhaneh Neghabat; McHugh, Peter E.
Experimental mechanical testing of Poly (l-Lactide) (PLLA) to facilitate pre-degradation characteristics for application in cardiovascular stenting
(2017)
Bobel, Anna C.; Lohfeld, Stefan; Shirazi, Reyhaneh Neghabat; McHugh, Peter E.
Abstract:
Next-generation stents made from Biodegradable Polymers (BPs) aim to address the long-term risks (i.e. late restenosis and in-stent thrombosis) associated with both Bare Metal Stents and Drug Eluting Stents, whilst aiming to reduce the healthcare costs associated with secondary care. However, the true potential of BPs for cardiovascular load bearing applications does not appear to be fully realised. While the literature provides data on stiffness and strength of BPs, it is lacking pre-degradation experimental data on the recovery behaviour and temperature and strain rate dependency. In this paper, an experimental study is undertaken to address this knowledge gap using Poly (L-Lactide) (PLLA) samples, subjected to tensile testing. Stress-strain characteristics, recovery, relaxation and creep data at body temperature are reported and considered in the context of real-life stent deployment. The experimental data herein reveal a strong temperature and strain rate dependency, whilst demo...
http://hdl.handle.net/10379/6325
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Hydrothermal in-plane-shear strength of carbon fibre/benzoxazine laminates manufactured out-of-autoclave by liquid-resin-infusion
(2019)
Comer, Anthony J.; Ray, Dipa K.; Clancy, Gearóid J.; Obande, Winifred O.; Rosca, Inga; ...
Hydrothermal in-plane-shear strength of carbon fibre/benzoxazine laminates manufactured out-of-autoclave by liquid-resin-infusion
(2019)
Comer, Anthony J.; Ray, Dipa K.; Clancy, Gearóid J.; Obande, Winifred O.; Rosca, Inga; McGrail, Patrick Terry; Stanley, Walter
Abstract:
Benzoxazine’s have recently emerged as new candidate resins for elevated temperature structural applications in the aerospace sector offering attractive attributes including infusibility under vacuum, fire-smoke-toxicity performance and room temperature storage/transport. The main objective of this study is to evaluate the hydrothermal in-plane-shear (IPS) strength of carbon-fibre (CF) based laminates manufactured using two benzoxazine (BZ) resin systems (BZ9120 and BZ9130). CF/BZ9130 was evaluated at 160 °C in the wet condition and benchmarked against two commercially available bismaleimide (BMI) resin systems – traditionally considered for wet applications at 160 °C. CF/BZ9120 was evaluated at 120 °C (just below its Tg) in the dry and wet condition and benchmarked against CF/BZ9130. BMI’s remain the benchmark for IPS strength at 160 °C (wet) with 64% retention while BZ9130 only retained 48% of IPS strength at 160 °C (wet) and also exhibited excessive elongation. CF/BZ9130 showed g...
http://hdl.handle.net/10344/7563
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In-line variable spreading of carbonfibre/thermoplastic pre-preg tapes for application in automatic tape placement
(2020)
Clancy, Gearóid J.; Peeters, Daniël; O'Higgins, Ronan M.; Weaver, Paul M.
In-line variable spreading of carbonfibre/thermoplastic pre-preg tapes for application in automatic tape placement
(2020)
Clancy, Gearóid J.; Peeters, Daniël; O'Higgins, Ronan M.; Weaver, Paul M.
Abstract:
This study investigates a device for in-line continuous spreading of carbon fibre/thermoplastic pre-preg tape for potential application in the Laser-Assisted Automatic Tape Placement (LATP) laminate manufacturing process.The spreading device allows variable tape width to be achieved locally during lay-up. Integration of this device in the LATP process would remove gap and overlap manufacturing defects in variable angle tow (VAT) laminates and complex curvature components. During trials different width tapes were produced using the novel spreading device. Three different width increases were investigated, viz. 15%, 30% and 45%, and were compared with as-received tape. Initial trials indicate that it is possible to achieve a tape width increase of 62%. Preliminary charac-terisation tests show that the spreading process does not adversely affect the properties of the tapes. Physical properties including cross-sectional area,fibre volume fraction and void content remain similar to...
http://hdl.handle.net/10344/9095
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Static and high-rate loading of single and multi-bolt carbon-epoxy aircraft fuselage joints
(2013)
Egan, Brian; McCarthy, Conor T.; McCarthy, Michael A.; Gray, P.J.; O'Higgins, Rona...
Static and high-rate loading of single and multi-bolt carbon-epoxy aircraft fuselage joints
(2013)
Egan, Brian; McCarthy, Conor T.; McCarthy, Michael A.; Gray, P.J.; O'Higgins, Ronan M.
Abstract:
Single-lap shear behaviour of carbon epoxy composite bolted aircraft fuselage joints at quasi-static and dynamic (5 m/s and 10 m/s) loading speeds is studied experimentally. Single and multi-bolt joints with countersunk fasteners were tested. The initial joint failure mode was bearing, while final failure was either due to fastener pull-through or fastener fracture at a thread. Much less hole bearing damage, and hence energy absorption, occurred when the fastener(s) fractured at a thread, which occurred most frequently in thick joints and in quasi-static tests. Fastener failure thus requires special consideration in designing crashworthy fastened composite structures; if it can be delayed, energy absorption is greater. A correlation between energy absorption in multi-bolt and single-bolt joint tests indicates potential to downsize future test programmes. Tapering a thin fuselage panel layup to a thicker layup at the countersunk hole proved highly effective in achieving...
http://hdl.handle.net/10344/3411
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The Effect of Physiological Cyclic Stretch on the Cell Morphology, Cell Orientation and Protein Expression of Endothelial Cells
(2006)
Barron, V.; Brougham, Claire; Coghlan, K.; Stenson-Cox, C.; O'Mahoney, D.; McHugh,...
The Effect of Physiological Cyclic Stretch on the Cell Morphology, Cell Orientation and Protein Expression of Endothelial Cells
(2006)
Barron, V.; Brougham, Claire; Coghlan, K.; Stenson-Cox, C.; O'Mahoney, D.; McHugh, P.E.
Abstract:
In vivo, endothelial cells are constantly exposed to pulsatile shear and tensile stresses. The main aim of this study was to design and build a physiological simulator, which reproduced homogenous strain profiles of the tensile strain experienced in vivo, and to investigate the effect of this cyclic tensile strain on the cell morphology, cell orientation and protein expression of endothelial cells. The biological response of human umbilical vein endothelial cells to a uniaxial cyclic stretch, in this newly developed simulator, was examined experimentally using immunohistostaining and confocal imaging and it was found that the cells elongated and oriented at 58.9± 4.5. This value was compared to a mathematical model where it was revealed that endothelial cells would orient at an angle of 60. This model also revealed that endothelial cells have an axial strain threshold value of 1.8% when exposed to a 10% cyclic strain at 1 Hz for 3 h. Cells cultured under conditions of cyclic strain s...
https://arrow.dit.ie/biodevart/8
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Thrombus analogue material: Mechanical characterisation and use in in-vitro modelling of acute ischemic stroke treatment
(2020)
Johnson, Sarah
Thrombus analogue material: Mechanical characterisation and use in in-vitro modelling of acute ischemic stroke treatment
(2020)
Johnson, Sarah
Abstract:
Acute ischemic stroke (AIS), which accounts for approximately 85% of all strokes globally, is among the leading causes of death and long-term disability. It occurs when a blood clot causes an occlusion in a blood vessel, resulting in reduced blood flow to an area of the brain. Mechanical thrombectomy (MT), where the clot is removed from the occluded vessel, has become the new standard of care in stroke treatment. In-vitro thrombus analogs are very useful in the pre-clinical testing of devices intended for use in thrombectomy, where amongst other things they can be used to evaluate the number of attempts required to remove the thrombus and the associated risk of embolisation. Some key determinants for success of the thrombectomy procedure are the mechanical properties and composition of the occluding thrombus. In this thesis, a range of clot analogues with varying compositions and mechanical behaviour are developed. A repeatable test method, that can be used to test a broad range of ...
http://hdl.handle.net/10379/16013
Displaying Results 1 - 12 of 12 on page 1 of 1
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Institution
Dublin Institute of Technology (2)
NUI Galway (3)
University of Limerick (7)
Item Type
Doctoral thesis (2)
Journal article (9)
Other (1)
Peer Review Status
Peer-reviewed (8)
Unknown (4)
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2021 (1)
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2019 (2)
2018 (1)
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2015 (1)
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