Determination of void content in filament wound composites

The use of image analysis for the determination of fibre volume fraction void content and void distribution in translucent composite parts was developed in order to reduce time and cost of quality assurance while maintaining reliability. The apparatus and methods are described, advantages and disadvantages are discussed, and typical results are presented. The validity of results was checked using resin bum off and composite density techniques. On the basis of this it is suggested that the techniques described are more than adequate for the assessment of material quality for both development and production purposes

Lightweight high performance materials for car body structures

The choice of materials for vehicle components is dependant on a specific supply and demand process, subject to a stringent set of requirements. Among other things, this includes economic effectiveness, safety, recyclability and lightweight performance. Metals such as steel, aluminium and magnesium are mainly used for elements of the body structure and panels. Plastics are applied for exterior attachments to the body. Cars consist mainly of steel and iron, but it is expected that the amount of steel and iron used is reduced due to the impending use of multimaterial constructions. Materials such as steel will be substituted, in particular by aluminium, magnesium and plastics. Alternatives to the steel unibody are multimaterial unibodies and aluminium space frames. Steel and magnesium space frame concepts for volume applications are still under development. More traditional materials are being replaced by high performance carbon fibre composites for their durability and specific strength/ stiffness

DMA investigation on polyurethane (PUR)

To employ a new material in pipeline application was a subject of research in pipeline technology centre of University of East London. Since the classic mechanical test methods, such as the instrumented penetration and mechanical flexural tests are time consuming and cost intensive, the goal here was to investigate the extent of dynamic mechanical analysis (DMA) to provide correlations with these methods and is thus suitable for quicker and less expensive test for the stated area of application. In this study with help of Dynamic Mechanical Analyser (DMA), the new material was approved to be flexible Polyurethane (PUR)

Assessment of Carbon Fibre Composite Fracture Fixation Plate Using Finite Element Analysis

In the internal fixation of fractured bone by means of bone-plates fastened to the bone on its tensile surface, an on-going concern has been the excessive stress shielding of the bone by the excessively-stiff stainless-steel plate. The compressive stress shielding at the fracture-interface immediately after fracture-fixation delays callus formation and bone healing. Likewise, the tensile stress shielding in the layer of bone underneath the plate can cause osteoporosis and decrease in tensile strength of this layer. In this study a novel forearm internal fracture fixation plate made from short carbon fibre reinforced plastic (CFRP) was used in an attempt to address the problem. Accordingly, it has been possible to analyse the stress distribution in the composite plates using finite-element modelling. A three-dimensional, quarter-symmetric finite element model was generated for the plate system. The stress state in the underlying bone was examined for several loading conditions. Based on the analytical results the composite plate system is likely to reduce stress-shielding effects at the fracture site when subjected to bending and torsional loads. The design of the plate was further optimised by reducing the width around the innermost holes

Finite element stress analysis of a hybrid fracture fixation plate

Metal plates are commonly used in the operative treatment of bone fractures (Figure 1). Rigid metal plates stabilise the fracture site, maintain good contact between bone fragments. However, treatment with rigid metal plates can cause localised bone atrophy due to stress shielding and interference with blood circulation, and the weakened bone can refracture after plate removal. A carbon fibre reinforced plate system that combines the torsional and bending rigidity of a metal plate with the axial compliance of a polymer insert has been designed. A three-dimensional, quartersymmetric finite element model was generated for a canine femur diaphysis plated with this metal/polymer hybrid design. A model with a standard metal fixation plate was also generated for comparison purpose. The stress state in the underlying bone was examined for several loading conditions taken from published in vivo studies. The finite element model was used to study the performance of biodegradable polymer inserts in the plate system. The flexible plate reduced stressshielding effects at the fracture site when subjected to an axial load. The bending strength of the plate was not compromised by the addition of the polymer inserts. Biodegradable inserts further enhanced the performance of the new plate design, transferring less of the axial load to the plate as the inserts broke down

Development of methyl cellulose and carboxymethyl cellulose composite membranes for the separation of miscible liquids by applying pervaporation technique

For the first time pervaporation separation of miscible liquids has been investigated using three and five layered composite membranes. The materials used to construct the different membranes consisted of natural rubber latex (NRL), hydrophilic and/ or hydrophobic polymers, placed sequentially on top of each other. Methyl cellulose (MC) and carboxymethyl cellulose (CMC) were used as hydrophilic polymers to increase the water selectivity of the membrane and in contrast, ultrahigh molecular weight polyethylene (UHMWPE) was used to increase the organic component selectivity in the membranes. Two different miscible liquid solutions were used, including ethanolwater and acetonewater. The composition of organic component in the feed was varied within the range of 20 to 90% w/w. The measured mass and concentration of permeate in the cold trap was related to the pervaporation flux and separation factor. Finally, the proposed mechanisms that may be responsible for enhancing the permeation of water or organic components through the membranes have been discussed. It has been demonstrated that the five layered hydrophilic composite membranes containing MC leads to the best pervaporation separation performance for a feed of 90% concentrated ethanolwater, giving a separation factor of 51 and pervaporation separation index of 6167, as opposed to using a blended membrane which would yield a separation factor of 1.5 and pervaporation separation index of 309

Optimum design of artificial hip joints

This paper describes the biomechanics and designing of the hip joint implants, proposes the ideal requirements of a successful hip joint and studies the current existing artificial hip joint designs on the market where it evaluates the best of those products. Regarding to biomechanics of an artificial hip joint it states the forces applied on the joint and lists various hip joint motions. The statistics of artificial hip joint in UK in terms of type of patients, products, procedures and complications have been cited. . Finally the paper reviews the optimisation process with the aid of FEA technique and specifies the main objectives and progress of this project

Stiffness properties of intraply woven hybrid composites by numerical homogenisation

Hybrid fabrics represent a rapidly emerging branch of reinforcements for composite materials. A justified use of these textiles requires good understanding of their behaviour and their modelling tools. Hybrid composites have significant strain differences amongst their phases. The lack of information on the applicability of the homogenisation methods in finite element and mesomechanical models in predicting the mechanical properties of Intraply Woven hybrid Composites (IWHC) has provided the motivation for this study. The emphasis was put on developing FE model, while investigating other meso-mechanical models concerning their efficiency, accuracy, applicability and limitations. Results were obtained from FEA and meso-mechanical models. Tensile testing was conducted to characterise the properties and mechanisms of failure for different carbon content hybrid composites

Thermo-mechanical performance of a novel composite liner used in cured-in-place pipe renovation process

This paper aims to describe the latest developments in the cured-in-place lining process and present the results of an investigation into the thermomechanical properties of a novel composite material used in the process of cured-in-place pipe renovation. The results include the effect of catalyst content on the dynamic mechanical and thermal properties of the felt liner polyester composites. In this study a novel type of pipe liner was prepared using a special feltpolyester material. It has been found that when the felt material is incorporated in the resin the flexural modulus is reduced by 6%. It has been established that the use of 1.8% catalyst in the resin results in the highest flexural modulus of 2.6 GPa

Performance of crushed fruit pits reinforced epoxy composites under impact loading conditions

In the past decade, widespread research work has been carried out on the natural fibre reinforced composite materials used in many applications. Natural fibres are available in large quantities in nature and can be used to reinforce polymers to obtain light and strong materials. Natural fibres from plants are beginning to find their way into commercial products in both automotive and domestic applications. This paper aims to present the results of an investigation into the mechanical performance of a novel natural fibre composite material developed from the crushed fruit pits (a waste by-product of any fruits) when used as a reinforcing material for epoxy polymer. The paper will present all the relevant results of the different tests including impact and scanning electron microscopy