Maciej Wysocki

Structural batteries made from fibre reinforced composites

Abstract Structural, fibre reinforced, battery prototypes with two types of electrolyte matrix material (a gel and a solid polymer) have been manufactured. This was to confirm the concept of using carbon fibres as current collector in the anode as well as providing a mechanical load-carrying functionality. As a result, functioning batteries with gel electrolyte have been produced and their properties have been characterised.

Reuse of polymer materials and carbon fibres in novel engineering composite materials

Abstract The present work was devoted to the development of a technique for manufacture of a novel engineering material from carbon fibres and thermoplastic matrix recyclates. Fibre preforms were manufactured employing a papermaking technique for dispersing the carbon fibres. The polypropylene (PP) matrix recyclate was reprocessed into a film. The carbon fibre preforms and PP films were stacked and composite materials were subsequently manufactured by press forming. The mechanical behaviour of carbon fibre preforms was characterised by a compaction test and compared to the results obtained by consolidation test of the carbon fibres reinforced PP composites. The consolidation experiments were found to follow the trend from compaction tests allowing prediction of the amount of polymer material needed, fibre volume fraction as well as composites thickness. The resulting dispersion of fibres and void content were evaluated by microscopy.

CFRP structural capacitor materials for automotive applications

Abstract In this paper, an approach towards realising novel multifunctional polymer composites is presented. A series of structural capacitor materials made from carbon fibre reinforced polymers have been developed, manufactured and tested. The structural capacitor materials were made from carbon fibre epoxy prepreg woven lamina separated by a polymer film dielectric separator. The structural capacitor multifunctional performance was characterised measuring capacitance, dielectric strength and tearing force. The developed structural carbon fibre reinforced polymer (CFRP) capacitor designs employing polymer film dielectrics (PA, PC and PET) offer remarkable multifunctional potential.

Recycled polypropylene aimed as composites precursor material

Abstract The aim of this research is to assess the stability and processability of recycled polypropylene (PP) materials for their suitability for use as matrix material in polymer composite. The work comprises development and characterisation of matrix precursors from recycled PP. The reused PP considered comes from two sources: PP from the self-reinforced PP Pure processing scrap and an automotive grade developed to offer an even material quality. To assess the thermal stability of two PP qualities for subsequent composite manufacturing, oxidation induction time (OIT), melting point T m, decomposition temperature T d and viscosity μ were investigated. The results indicate, that Pure processing scrap is very well stabilised and therefore suitable for multiple processing, whereas the automotive grade recycled PP cannot be used for this purpose. Fibres for subsequent composite preforming were spun by melt spinning from the Pure scrap processing and its mechanical properties were characterised.

Mechanical performance and modelling of a fully recycled modified CF/PP composite

A fully recycled carbon fiber reinforced maleic anhydride grafted polypropylene (MAPP)-modified polypropylene (rCF/rPP) composite material has been developed and characterized. This new composite was manufactured employing papermaking principles, dispersing the recycled carbon fibers (rCF) in water, and forming them into mats. Two layers of the recycled polypropylene (rPP) films manufactured using press-forming were sandwiched between three rCF preform layers in a stack. The stack was heated and press-formed resulting in a composite plate with a nominal thickness of 1.20 mm and a fiber volume fraction of 40%. A series of tensile tests using rectangular specimens cut in four different directions (0°, 90°, ± 45°) in the composite plate were performed to confirm in-plane material isotropy. Models to predict stiffness and strength of the short fiber rCF/rPP composite were also employed and validated using experiments. The models were found to be in good agreement with experimental results. Fiber length distribution measurements were performed before (unprocessed) and after (processed) composite manufacturing to investigate the influence of processing on fiber degradation. The results revealed a significant reduction in fiber length by the press-forming operation. To model the viscoelastic and viscoplastic responses of the composite an inelastic material model was employed and characterized using a series of creep and recovery tests. From the creep tests, it was found that the time and stress dependence of viscoplastic strains follows a power law. The viscoelastic response of the composite was found to be linear in the investigated stress range. The material model was validated in constant stress rate tensile tests and the agreement was good, even close to the rupture stress.

Two phase continuum modelling of composites consolidation

Abstract In this paper, a finite element (FE) code for modelling of pressure driven axisymmetric consolidation of composite material from commingled yarns is presented. The proposed model is developed on the basis of a two phase continuum model incorporated in an FE framework. The applicability of the code to axisymmetric geometries is demonstrated by analysis of the consolidation, i.e. resin infiltration and fibre bundle network deformation, of a GF/PP pressure vessel. In this numerical example, two different sets of processing conditions are presented. Based on these analysis results conclusions on the process ability of the investigated vessel configuration and manufacturing scheme are drawn and processing recommendations are given.

Holistic modeling of composites manufacturing using poromechanics

Abstract In the present paper, we present a novel finite-element method capable of handling most of the physics arising in the resin wet-out step for any composite system and processing case. The method is based on a compressible two-phase continuum formulation where a key feature is to model the involved physics via innovative use of the compressibility of the phases. On the one hand, the fluid-phase compressibility is used to capture the physics of the advancing resin front as well as the physics behind the flow front. On the other hand, solid-phase compressibility is used to model micro-infiltration of the resin and the corresponding preform compaction, essentially considered as a fluid sink problem. Finally, the generic porous media model is formulated in the finite strain regime. The model is implemented and demonstrated for different manufacturing methods and the results with respect to each example are presented. The degree of saturation, pressure distribution, preform deformation, and reaction forces are some of the post-processed results for different manufacturing methods. The ultimate goal of this contribution is to establish a unified generic and general simulation tool for structural (long fiber) composite processing where, to this date, there is no single FE-based tool available commercially for this purpose.