MOJO is set to introduce a material driven design for Aeronautics composite components. Composites are associated with integration, complexity, manufacturing risk, weight savings and high costs. Cost savings are achieved with out-of autoclave infusion processes and tailored pre-forms made of high performance textiles. Adhesive bonding, as the most compatible joining method for composite parts, provides also significant cost and weight savings.
The challenge is to create synergy between pre-form infusion and adhesive bonding processes. In this respect, MOJO is representing a boltless differential structural design as a modular approach. MOJO makes a construction set available with cost and weight saving potentials of at least 20% and 15%, respectively. Highly loaded T- or Pi- shaped joints are integrated into the skin using 3D reinforcements in order to take up out-of-plane loads. Simplified structural elements are subsequently inserted into the joints and bonded using adhesives. Here pure shear loads are transferred. The same applies for intersections (e.g. ribs). These are replaced with construction set profiles in shapes of, e.g. H, HL, or HX. To fulfil the objectives, MOJO is focussing on Pi, T, and H profiles.
The profile pre-forms will be realised using advanced textiles, among them a unique 3D profile weaving technology. For precision manufacturing of moderately integrated parts new rig concepts will be developed and proved. For a continuous process pultrusion technology will be investigated. Methods of adhesive bonding (e.g. pressure free bonding) will be investigated.
Analysis and tests will be performed by means of interface failure mechanics and manufacturing simulation. An aeronautical application featuring all elements will prove the design. Results will be summarised in guidelines and design rules. Making parts simpler in design and assembly enables flexibility and rapid adaptation to market demands.
The challenge of the MOJO project was to create synergy between dedicated preformed profiles' infusion and adhesive bonding processes supporting different design principles. The selected principles allow the avoidance of highly demanding integrated components and the reduction of the manufacturing risks.
The MOJO demonstrator is one of the very first representatives aeronautical structures designed for assembly by structural adhesive bonding, which provides damage tolerant characteristics. This closed beam main components have been manufactured with out-of autoclave infusion processes as resin transfer moulding (RTM) for the top and side panels and vacuum assisted resin infusion (VARI) process for the lower panel. Non crimp carbon fabrics (from SAERTEX and CYTEC) and tailored preformed profiles made of high performance textiles (developed by the partners) were used. Considering that structural bonding is the most compatible joining method for composite parts, adhesive processes with both film and paste adhesive have been developed and successfully used for the assembly. The development phases followed the different steps needed for composite manufacturing, i.e. definition of requirements, preformed components preparation, infusion (including tooling), assembly rigs and testing. Testing was performed from the material level to the representative structure level and according the Rouchon Pyramid.
A full size aerospace structure designed to gather all features developed in the MOJO project has been presented as the project's innovation. It has been evaluated from manufacturing to mechanical test (from limit load, through fatigue loading and ultimate loading). A preliminary serial production study and the manufacturing of the demonstrator have shown that respectively 60 % cost savings and 50 % weight savings could be achieved. The applications could well be wings skin stiffened panels, vertical and horizontal tail planes, flap track beams, cargo and pax doors, cargo and pax door surroundings as well as unmanned air vehicles.
The innovation gathers various developed elements. These will ultimately find use in different domains by different end users. The end users are SABCA, Dassault-Aviation, Premium AEROTEC, EADS Military Air Systems and Eurocopter.