Experimental investigation of thermoforming carbon fibre-reinforced polyphenylene sulphide composites

Pre-consolidated carbon fibre-reinforced polyphenylene sulphide (CF/PPS) laminates were
thermoformed into V-shaped parts via designed out of autoclave thermoforming experiments.
The different processing conditions tested in the experiment have resulted in final
part angles whose differences ranged from 2.087 to 3.431 from the original mould angle.
The test results show that processing conditions influenced finished part dimensions as the
final sample angles were found to decrease relative to the tooling dimensions, as mould
temperature increases. Higher mould temperature conditions produce thinner parts due
to the thermal expansion of mould tools. The mould temperature of 170C, which can
produce parts with high degree of crystallinity as well as small size of crystal, has been
established as the optimal thermoforming condition for CF/PPS composites.

Finite Element Analysis of Drilling of Carbon Fibre Reinforced Composites

Despite the increased applications of the composite materials in aerospace due to their exceptional physical and mechanical properties, the machining of composites remains a challenge. Fibre reinforced laminated composites are prone to different damages during machining process such as delamination, fibre pull-out, microcracks, thermal damages. Optimization of the drilling process parameters can reduces the probability of these damages. In the current research, a 3D finite element (FE) model is developed of the process of drilling in the carbon fibre reinforced composite (CFC). The FE model is used to investigate the effects of cutting speed and feed rate on thrust force, torque and delamination in the drilling of carbon fiber reinforced laminated composite. A mesoscale FE model taking into account of the different oriented plies and interfaces has been proposed to predict different damage modes in the plies and delamination. For validation purposes, experimental drilling tests have been performed and compared to the results of the finite element analysis. Using Matlab a digital image analysis code has been developed to assess the delamination factor produced in CFC as a result of drilling. © Springer Science+Business Media B.V. 2011.

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.

Glass fibre-reinforced polyethylene composites in rotational moulding

Fibre-reinforced mouldings are of growing interest to the rotational moulding industry due to their outstanding price performance ratio. However, a particular problem that arises when using reinforcements in this process is 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 paper we report on studies to incorporate, short glass fibres into rotationally moulded parts. Four different approaches were investigated; direct addition of fibre in between two powder shots, addition of a layer of pre-compounded polyethylene-glass fibre pellets between two powder shots, addition of a layer of pre-compounded polyethylene-glass fibre powder between two powder shots and a single layer of glass-reinforced, pre-compounded powder. Results indicate that pre-compounding is necessary to gain performance enhancement and the single layer part made from glass-reinforced, pre-compounded powder exhibited the highest tensile and flexural modulus.

Experimental and Numerical Evaluation of Thermal Performance of Steered Fibre Composite Laminates

For Variable Stiffness (VS) composites with steered curvilinear tow paths, the fiber orientation angle varies continuously throughout the laminate, and is not required to be straight, parallel and uniform within each ply as in conventional composite laminates. Hence, the thermal properties (conduction), as well as the structural stiffness and strength, vary as functions of location in the laminate, and the associated composite structure is often called a “variable stiffness” composite structure. The steered fibers lead not only to the alteration of mechanical load paths, but also to the alteration of thermal paths that may
result in favorable temperature distributions within the laminate and improve the laminate performance. Evaluation of VS laminate performance under thermal loading is the focus of this chapter. Thermal performance evaluations require experimental and numerical analysis of VS laminates under different processing and loading conditions. One of the advantages of using composite materials in many applications is the tailoring capability of the laminate,
not only during the design phase but also for manufacturing. Heat transfer through variable conduction and chemical reaction (degree of cure) occurring during manufacturing (curing) plays an important role in the final thermal and mechanical performance, and shape of composite structures.