Abstract

During the last years, the benefits of using carbon reinforced thermoplastic composite materials (CRTP) have been questioned and defended (higher fatigue resistance, greater toughness, better durability, reprocesability, recyclability and so on), they are considered as a future innovative technology allowing  highly integrated structures, impacting in weight reduction and reducing energetic costs by using out of autoclave processes. Therefore, (CRTP) could be considered as a future substitute of metallic materials and composite materials with thermoset matrices for aerospace applications, automotive and other industries.

Under the frame of the OUTCOME project (Clean Sky II), the design and analysis of the Upper Skin (upper coverage of a stiffened wing) for the militar aircraft C295 is developed, a medium tactical transport aircraft of ADS.

The selected material for the work is the unidirectional composite material APC2/AS4, supplied by Solvay, with PEEK as the thermoplastic matrix and carbon fibre as the reinforcement. Flat panels, detailed elementals and subelementals have been manufactured, all of them have been widely characterized attempting to obtain the required design allowables. 

Moreover, with the goal of cost reduction, productivity increases and environmental impact control, the manufacturing selected processes have been: a)  Hot-forming in oven and/or self heated toolings for stringers manufacturing and b) Automatic lamination in one step for the co-consolidation (full-integration) of the skin with the stringers.

The main goal of this review is showing the different steps in the manufacturing of a detailed element for a later structural test. 

Abstract

A study is presented on the response thermoplastic composite to aging conditions in presence of lubricants. Glass Fiber reinforced Polyamaide 66 (GF PA66) are proposed as commercial material already used in the field while Polyether Ether Ketone (PEEK) is proposed as novel polymeric candidate material due to its chemical stability and high mechanical performance. Accelerated aging tests were carried out to study the response of these materials to external chemical agents under different conditions. Afterwards, a complete set of mechanical and physical tests and characterization procedures were carried out, before and after ageing on suitable samples of the polymers in combination with lubricants, to evaluate the effects of the chemical environment on the mechanical and physical properties of the polymers.

Abstract

The transformation processes used for thermoplastic composites, have been increasing their complexity, while incorporating new high demanding materials. From the aeronautic and medical sector, with their restrictions and specific demanding needs. The PAEK materials have been promoted and deeply applied due to their high temperature stability and their chemical resistance. In this research, the work has focussed on the use of the reinforced 40%CF PEEK process through injection moulding. In these over injection moulding processes the joint between 40%CF PEEK and other materials such as Aluminium, or reinforced PA and PEEK has been studied. As well as the adhesion between them and the variation generated on the mechanical properties. It has been observed that this joint is far better between thermoplastic materials than between metals and thermoplastic, this is due to the fact that even tough the PEEK has high processing temperatures, these are not relevant chemically speaking for metals such as Aluminium. Limiting the forces of the interphase to the physical and mechanical interaction between both materials. Nevertheless, in the case of the thermoplastic over injected parts several parameters have been observed to be affecting the final properties of the joint. Firstly, the over injected angle, obtaining higher mechanical properties as the angle increases as well as the contact surface. And the effect of the roughness of the overinjected part, having these a direct impact on the final mechanical properties.

Abstract

In the present work, a graphene nanocomposite material using as matrix a high performance thermoplastic polymer (PEEK) is presented. Composite was made by a simple extrusion-compounding process, followed by an injection-moulding process. The main advantage of this process is that it could produce large quantities at the scales needed for use in industrial applications as structural applications. Nanocomposites with different percentages of graphene 0.5, 1, 3, 5 and 10 wt.% were characterized and compared with neat PEEK as baseline. The mechanical tests showed that the Young´s modulus increased when adding graphene while the strenght remained constant. In addition, a change in the failure mode was observed when the graphene was added. Nanocomposites with high contents of graphene had lower strain at break than neat PEEK.