Plastics,Rubber and Composites: Macromolecular Engineering

A typical metallic main landing gear fitting was designed and manufactured in carbon fibre reinforced polymer (CFRP). The component features wall thicknesses of up to 90 mm due to massive loads and compact dimensions. The aim was to reduce the weight and to provide a distinct cost benefit. Two prototypes of the fitting were produced. Based on the gained manufacturing experience the cost benefit was evaluated for a possible serial production. A new open mould manufacturing process was chosen in order to maximise flexibility and to reduce development costs. The entire manufacturing process was continuously optimised and refined. The gained experience was implemented and combined in a final study of a serial production of the CFRP fitting. In the last step the gained data were compared to the standard metallic fitting. For this example, ultra thick laminates (UTLs) provide a significant cost and weight benefit. The composite design can be categorised as highly manufacturing driven.

This paper presents an overview of the research performed to date by a Swedish interdisciplinary team of scientists striving to develop multifunctional composite materials for storage of electric energy in mechanical load paths. To realise structural batteries from polymer composites, research pursued on carbon fibres for use as negative electrode in the battery as well as on polymer electrolytes for use as polymer matrix in the composite is reported. The work on carbon fibres comprises characterisation of the electrochemical capacity of commercial carbon fibre grades and how this is affected by mechanical load. Co-polymers are studied for their multifunctional performance with respect to lithium ion conductivity and stiffness. Also, rational processing of these polymer electrolytes and the effect of processing on their properties are addressed.

This paper reports recent work on the optimisation of preform manufacture. Producing tailored textile semifinished parts, such as non-crimp fabrics (NCFs) with locally adjusted properties, and processing these in a sequence of automated cutting, handling and joining operations are a promising approach to significantly reduce costs and cycle times within preform production. Additionally, along with the enhancement of machinery, the development of simulation tools for designing efficient process chains and understanding the behaviour of reinforcement textiles along the entire production process is essential. The Institut fuer Textiltechnik (ITA) of RWTH Aachen follows this holistic approach, aiming at preforming processes suitable for mass production. In this paper, enhanced production technologies for tailored NCFs are described. Furthermore, an overview of automated technologies for converting these tailored NCFs to near net shape preforms is given. Methodical process chain development is shown in a case study, proving the possibility to significantly increase the operating efficiency of preform production by means of the introduced approach.

The change of thermoelastic properties of cross-ply and quasi-isotropic laminates with intralaminar cracks in layers is analysed. Predictions are performed using previously derived general expressions for stiffness of symmetric damaged laminates as dependent on crack density and crack face opening and sliding. It is shown that the average crack opening displacement can be linked with the average value of axial stress perturbation between two cracks. Using this relationship, analytical shear lag and Hashin's models, developed for axial modulus, can be applied for calculating thermal expansion coefficients, in-plane moduli and Poisson's ratios of damaged laminates. The approach is evaluated using finite element method and it is shown that the accuracy is rather similar to that in axial modulus calculation.

In this work, organoclay reinforced high density polyethylene (HDPE) nanocomposites were prepared at laboratory scale using a batch mixer. Processing conditions, maleic anhydride modified polyethylene (MAPE) type and MAPE/clay weight ratio were optimised. The microstructure of the resultant nanocomposites was analysed by X-ray diffraction and melt rheology tests, and flexural properties and thermal stability were evaluated. Three types of MAPEs with different melt flow indices (MFI) and maleic anhydride contents all improved the interaction between HDPE and clay and promoted clay dispersion. Nanocomposites where the MAPE with MFI most similar to HDPE was used showed the best exfoliation of clay and the strongest HDPE/clay interface. Mechanical properties were slightly improved, while thermal stability was distinctly enhanced in these HDPE nanocomposites compared with neat HDPE and HDPE nanocomposite without MAPE. The prepared HDPE nanocomposites show the potential to improve the thermal stability of wood–plastic composites for structural applications.