Technology demonstrator programmes
Project leader
Dr.ir. Harald Bersee
Prof.dr.ir. Michel van Tooren
PhD. student
Ir. Ton van der Laan
MSc. Gianfranco LaRocca
MSc. Giovanni Nino
MSc. Darko Stavrov
Researcher
Ing. Marc van Dongen
Ing. Sebastiaan Lindstedt
Ing. Bert Weteringe
Contactperson
Dr.ir. Harald Bersee
Summary
The research on thermoplastic composites at the Faculty of Aerospace Engineering of Delft University of Technology focuses at the design and manufacture of large primary aircraft structures. The increasing size of aircraft forces the aeronautic industry to extend the limits of technology in order to be able to design and produce such aircraft, as is illustrated by the development of the Airbus A380 (550-800 seat aircraft). The state-of-the-art in aircraft design is the design and manufacture of primary structures in metal or thermoset composites. Over the last 10 years new composites have been developed based on thermoplastic matrices. Compared to metals, these thermoplastic composites offer significant weight reduction at no cost penalty, preservation of environment, preservation of natural resources/energy and improvement of work environment. Compared to thermoset composites they offer a reduction of manufacturing cost, preservation of environment and of natural resources/energy and improvement of work environment. Though growing, the use of thermoplastic composites is currently limited to non-structural interior parts like stow bins and to small secondary structures like ribs for flaps. Also more complex welded structures like the fixed leading edge of the A340-600 have been developed, but primary structures have not been developed so far. The incentive of this research project is to design and manufacture a structural component for a General Aviation aircraft. The design and manufacturing process will be certified according to JAR23. The project can be regarded as a technology demonstrator for thermoplastic composites and as a first step towards the design and manufacture of a large structural aircraft component.
The Eaglet is a 2-Seat aircraft that is being produced by Euro-Enaer, The Netherlands. The airplane has limited aerobatic capabilities, and is designed for pilot training, leisure and surveillance. It has a fully composite structure and is certified according to JAR/FAR 23, utility category. The Faculty of Aerospace Engineering of Delft University of Technology was highly involved in the technical design and prototyping process as well as aerodynamical design and wind tunnel testing. The faculty recently bought the prototype of the Eaglet and because of the faculty's JAR certification license the aircraft can be used as a flying test plane for several development projects, like e.g. thermoplastic composites.
The rudder of the Eaglet was chosen to be redesigned in thermoplastic composites. The reason for this choice was threefold;
The thermoplastic composite rudder can be installed without changes in the fuselage/ tail design.
A similar project has been performed on Vacuum assisted resin transfer moulding.
The manufacture of the rudder incorporates the three main thermoplastic composite processing techniques: welding, diaphragm- and rubber forming.
The current glass/ epoxy sandwich design will be re-designed into a fully thermoplastic composite monolithic structure.
In the design process extensive use will be made of the tool ICAD, with which different concepts can be generated in a very rapid way. The other advantage of using the so-called Design Engineering Engine is the direct generation of mould geometries. The specific mechanical and manufacturing characteristics of thermoplastic composites, such as high toughness and deformability through intraply shear, will be taken into account in the design procedure. In this way, a design optimised for thermoplastic composites will be obtained.
The most promising forming techniques for thermoplastic composites are rubber- and diaphragm forming. These processes have and still are extensively being investigated at the Faculty of Aerospace Engineering of Delft University of Technology. Both processes, given their specific characteristics, will be used for the manufacture of the rudder: the ribs and stiffeners will be produced by rubber forming whereas the skins will be shaped by diaphragm forming.
The existing assembly technologies for composites are still metal based, i.e. adhesion and mechanical fastening. Both are labour- intensive and time consuming, in which the latter is also inefficient from a structural point of view. Thermoplastic composites offer, due to their specific temperature behaviour, an extra potentially efficient assembly process, namely welding. The development of the A340-600 J- nose by Fokker, Bae and Ten Cate Advanced Composites illustrates the cost and structural efficiency of the (resistance) welding process. Resistance welding will also be used for assembling the Eaglet rudder.
The design and manufacturing process will be performed in co-operation with the Dutch Airworthiness Authority in order to certify the rudder according to JAR23. The rudder will be installed on the faculty's Eaglet for a series of test flights scheduled for February 2003.
