Finite element analysis of ultrasonic insertion of SiC fibre in aluminium alloy 6061

In this work, a computational framework has been proposed to successfully simulate the fibre embedding using ultrasonic consolidation process. The main components of the proposed computational approach are a developed constitutive model and a friction model which are especially suitable for the condition of ultrasonic process. The effect of different process parameters, such as velocity of sonotrode, displacement amplitude of ultrasonic vibration and applied loads are studied. The presented work especially focuses on the quality of the developed weld and the fibre coverage due to the plastic flow around the fibre. The areas of maximum plastic flow predicted by the simulation are confirmed by the EBSD microstructural studies. © 2011 Inderscience Enterprises Ltd.

Performance and wear of coated carbide drill in machining of carbon fibre reinforced composite/titanium stack

In this research we investigate the performance of drilling process in carbon fibre reinforced composite (CFC) material, titanium alloy and the hybrid stack of these two materials, using coated carbide drill bit. We study the effect of the process parameters such as the feed rate and speed on the induced forces and torques, also on the wear of drill and surface roughness of the holes. In the composite material the percentage of surface damage in both drilling CFC on its own and drilling in stack form is estimated. Also, the effect of worn drill on the surface damage is identified. In the titanium, the burr formation in stack and non-stack form is investigated. The wear of the drill results in increased forces and torques required for drilling. This increases the surface delaminations substantially at the entrance in drilling of CFC. However, the surface roughness of the holes reduces with the wear of the drill in CFC drilling. Also, the surface delamination and surface roughness of the holes in the CFC whilst drilled in hybrid form reduces significantly. This is despite the increase of the forces and torques required in drilling CFC in stack form. Copyright © 2012 Inderscience Enterprises Ltd.

Application of fibre assemblies as damping elements in the automotive industry

This investigation aims to characterise the damping properties of the nonwoven materials with potential applications in automotive and aerospace industry. Nonwovens are a popular choice for many applications due to their relatively low manufacturing cost and unique properties. It is known that nonwovens are efficient energy dispersers for certain applications such as acoustic damping and ballistic impact. It is anticipated that these energy absorption properties could eventually be used to provide damping for mechanical vibrations. However the behaviour of nonwovens under dynamic load and vibration has not been investigated before. Therefore we intend to highlight these aspects of the behaviour of the nonwovens through this research. In order to obtain an insight to the energy absorption properties of the nonwoven fabrics, a range of tests has been performed. Forced vibration of the cantilever beam is used to explore damping over a range of resonance modes and input amplitudes. The tests are conducted on aramid, glass fibre and polyester fabrics with a range of area densities and various coatings. The tests clarified the general dynamic behaviour of the fabrics tested and the possible response in more real application condition as well. The energy absorption in both thickness and plane of the fabric is tested. The effects of the area density on the results are identified. The main absorption mechanism is known to be the friction. The frictional properties are improved by using a smaller fibre denier and increasing fibre length, this is a result of increasing contact surface between fibres. It is expected the increased friction result in improving damping. The results indicate different mechanism of damping for fiber glass fabrics compared to the aramid fabrics. The frequency of maximum efficiency of damping is identified for the fabrics tested. These can be used to recommend potential applications.

Corrosion resistant fibre reinforced polymer (FRP) reinforcement for bridge deck slabs

This paper discusses the beneficial influence of compressive membrane action in fibre reinforced polymer (FRP)reinforced in-plane restrained slabs in bridge deck slabs and the improved service performance when archingaction occurs. Bridge deck slabs that are exposed to extreme environmental conditions can experience severecorrosion damage. Expansive corrosion in steel reinforcement significantly reduces the design life and durabilityof concrete structures; for example, on one short section of the M1 in Northern Ireland, nearly £1 million was spent last year on the maintenance and repair of bridges due to corrosion. Corrosion-resistant compositereinforcement such as basalt fibre reinforced polymer (BFRP) and glass fibre reinforced polymer (GFRP) provides adurable alternative to reinforcing steel. In this research, two BFRP reinforced slabs and two GFRP reinforced slabswere constructed using high-strength concrete with a target cube compressive strength of 65 N/mm2. The slabsrepresented typical full-scale dimensions of a real bridge deck slab 475 mm wide by 1425 mm long and 150 mmdeep. The service and ultimate behaviour of the slabs are discussed and the results are compared with the relevantdesign guidelines.

Multilayered glass fibre-reinforced composites in rotational moulding

The potential of multiple layer fibre-reinforced mouldings is of growing interest to the rotational moulding industry because of their cost/performance ratio. The particular problem that arises when using reinforcements in this process relate to the fact that the process is low shear and good mixing of resin and reinforcement is not optimum under those conditions. There is also a problem of the larger/heavier reinforcing agents segregating out of the powder to lay up on the inner part surface. In this study, short glass fibres were incorporated and distributed into a polymer matrix to produce fibre-reinforced polymer composites using the rotational moulding process and characterised in terms of morphology and mechanical properties. © 2011 American Institute of Physics.

Optimised extraction of heterocyclic aromatic amines from blood using hollow fibre membrane liquid-phase microextraction and triple quadrupole mass spectrometry

Heterocyclic aromatic amines (HCA) are carcinogenic mutagens formed during cooking of proteinaceous foods, particularly meat. To assist in the ongoing search for biomarkers of HCA exposure in blood, a method is described for the extraction from human plasma of the most abundant HCAs: 2-Amino-1-methyl-6-phenylimidazo(4,5-b)pyridine (PhIP), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx) (and its isomer 7,8-DiMeIQx), using Hollow Fibre Membrane Liquid-Phase Microextraction. This technique employs 2.5 cm lengths of porous polypropylene fibres impregnated with organic solvent to facilitate simultaneous extraction from an alkaline aqueous sample into a low volume acidic acceptor phase. This low cost protocol is extensively optimised for fibre length, extraction time, sample pH and volume. Detection is by UPLC-MS/MS using positive mode electrospray ionisation with a 3.4 min runtime, with optimum peak shape, sensitivity and baseline separation being achieved at pH 9.5. To our knowledge this is the first description of HCA chromatography under alkaline conditions. Application of fixed ion ratio tolerances for confirmation of analyte identity is discussed. Assay precision is between 4.5 and 8.8% while lower limits of detection between 2 and 5 pg/mL are below the concentrations postulated for acid-labile HCA-protein adducts in blood.

A conserved spider silk domain acts as a molecular switch that controls fibre assembly

A huge variety of proteins are able to form fibrillar structures(1), especially at high protein concentrations. Hence, it is surprising that spider silk proteins can be stored in a soluble form at high concentrations and transformed into extremely stable fibres on demand(2,3). Silk proteins are reminiscent of amphiphilic block copolymers containing stretches of polyalanine and glycine-rich polar elements forming a repetitive core flanked by highly conserved non-repetitive amino-terminal(4,5) and carboxy-terminal(6) domains. The N-terminal domain comprises a secretion signal, but further functions remain unassigned. The C-terminal domain was implicated in the control of solubility and fibre formation(7) initiated by changes in ionic composition(8,9) and mechanical stimuli known to align the repetitive sequence elements and promote beta-sheet formation(10-14). However, despite recent structural data(15), little is known about this remarkable behaviour in molecular detail. Here we present the solution structure of the C-terminal domain of a spider dragline silk protein and provide evidence that the structural state of this domain is essential for controlled switching between the storage and assembly forms of silk proteins. In addition, the C-terminal domain also has a role in the alignment of secondary structural features formed by the repetitive elements in the backbone of spider silk proteins, which is known to be important for the mechanical properties of the fibre.

Influence of Boundary Conditions on the Low Velocity Impact Damage Carbon Fibre Reinforced Plastic Plates (ICTWS2014-0501)

No abstract available

POST-TENSIONING OF TIMBER BEAMS WITH BASALT FIBRE REINFORCED POLYMER

Improvements in the structural performance of glulam timber beams by the inclusion of reinforcing materials can improve both the service performance and ultimate capacity. In recent years research focusing on the addition of fibre reinforced polymers to strengthen members has yielded positive results. However, the FRP material is still a relatively expensive material and its full potential has not been realised in combination with structural timber. This paper describes a series of four-point bending tests that were conducted, under service and ultimate loads, on post-tensioned glulam timber beams where the reinforcing tendon used was 12 mm diameter Basalt Fibre Reinforced Polymer (BFRP). The research was designed to evaluate the additional benefits of including an active type of reinforcement, by post-tensioning the BFRP tendon, as opposed to the passive approach of simply reinforcing the timber beam.
From the laboratory investigations, it was established that there was a 16% increase in load carrying capacity, in addition to a 14% reduction in deflection under service loads when members containing the post-tensioned BFRP composite are compared with control timber specimens. Additionally a more favourable ductile failure mode was witnessed compared to the brittle failure of an unreinforced timber beam. The results support the assumption that by initially stressing the embedded FRP tendon the structural benefits experienced by the timber member increase in a number of ways, indicating that there is significant scope for this approach in practical applications.

Development of a Bridge Weigh-in-Motion Sensor: Performance comparison using fibre optic and electric resistance strain sensor systems

This paper addresses the problems of effective in situ measurement of the real-time strain for bridge weigh in motion in reinforced concrete bridge structures through the use of optical fiber sensor systems. By undertaking a series of tests, coupled with dynamic loading, the performance of fiber Bragg grating-based sensor systems with various amplification techniques were investigated. In recent years, structural health monitoring (SHM) systems have been developed to monitor bridge deterioration, to assess load levels and hence extend bridge life and safety. Conventional SHM systems, based on measuring strain, can be used to improve knowledge of the bridge's capacity to resist loads but generally give no information on the causes of any increase in stresses. Therefore, it is necessary to find accurate sensors capable of capturing peak strains under dynamic load and suitable methods for attaching these strain sensors to existing and new bridge structures. Additionally, it is important to ensure accurate strain transfer between concrete and steel, adhesives layer, and strain sensor. The results show the benefits in the use of optical fiber networks under these circumstances and their ability to deliver data when conventional sensors cannot capture accurate strains and/or peak strains.