Unfortunately, the strike of coronavirus pandemic in Europe made impossible to celebrate a face-to-face meeting. Instead, a virtual General Assembly meeting was carried out on 21st and 22nd September.
Partners discussed the current activities and progress of the project. The meeting had as main aims to monitor and share the results of the tasks carried out in the previous 8,5 months.
Bionanopolys unites European experts in this field to transform these bio-based materials to nano-scale and, moreover, develop an Open Innovation Test Bed (OITB) environment. The aim is to manufacture innovative bionanocomposites from sustainably sourced feedstocks in Europe as well as bio-based nano-products for packaging, textile, agriculture, cosmetics, pharma or food.
For this purpose, Bionanopolys will use high lignocellulosic feedstocks for the production of cellulose nanofibers, cellulose nanocrystals, nanolignin and metallic nanoparticles on the one hand. On the other hand, high sugar content feedstocks will serve for the production of building blocks, organic acids, PHA and active compounds to create nanocapsules.
To speed up the introduction of biobased nano-enabled materials into the market by providing a Single Entry Point (SEP) for stakeholders, Bionanopolys aims at creating a network of 14 pilot plants and their complementary services. In this context, five pilot plants will focus on the development of bionanomaterials from biomass, three pilot plants are dedicated to bionanocomposites and six plants aim at manufacturing bio-based nanoproducts in order to reach a wide range of applications in different sectors. Pilot lines are going to be upgraded and fine-tuned across the entire Bionanopolys value chain.
Thereby, for the first time, Bionanopolys will create an integrated platform of technologies and scientific expertise devoted to the nanotechnology based on bio-based raw materials. This is complemented by a comprehensive portfolio of services for the development and integration of new bio-based nano-enabled products.
Brackets are small elements used as local links between aircraft structure, systems and cabin. Nowadays, most of the components of the structure are made of polymer composites, the majority of them being formed of carbon fibres reinforced thermosetting matrices. The state-of-the-art techniques for joining brackets or other small functional elements to these composite structural components are based on mechanical fastening and adhesive bonding. These joining processes are time consuming, and add significant labour and tooling costs to the assembly process, even for the attachment of such small components. Moreover, the adhesion strength achieved is often limited requiring dedicated surface treatments to be applied. An additional handicap for a strong adhesive bonding happens when the composite component is painted.
The Bracketweld project aims at contributing to the green and cost-efficient integration of systems and aircraft structures by the development of an innovative technology for the rapid assembly of thermoplastic brackets to thermosetting composite components currently used in aircraft structures. This has been done using the fast and efficient ultrasonic weldingtechnology to assemble thermoplastic brackets to thermosetting composite structural components. As thermosetting materials cannot be welded, a thermoplastic surface media will be strongly attached to the thermosetting composite structure by a co-curing process, being this surface media used as an anchor interface for the latterly welding of the thermoplastic brackets by any fusion bonding technique, and especially by the ultrasonic welding.
The first two years of the Bracketweld project have been focused on the development of an innovative Test Method for the evaluation of different materials compatibility. The proposed welded joint combines a thermoset material with a film and a thermoplastic bracket, while the latter do not necessarily need to be the same material (because of cost or processability issues). This methodology is then the basis of the film quick down material selection ensuring a good level of adhesion with this welding method. This methodology was developed in pararell with the investigation, manufacturing and evaluation of the most appropriate surface media for the specific case under study in this project, including the formulation and development of custom surface medias at CIDAUT. Different material combinations were assessed with the Test Method.
The final year of this project has been devoted to the validation of the developed concepts. Having defined a robust and reliable test method, and chosen a film for the project use case, the validation of the methodology has been upscaled to a single curvature panel, from a machine assisted welding to a manual welding operation, and from room temperature and axial testing conditions to shear and hot/wet environments.
Bracketweld project has been running for already two years time (see link). During this period CIDAUT has developed a methodology to adjust the welding parameters, and a methodology to evaluate the performance of the welded brackets. In this process, different surface media have been evaluated selecting the most appropriate one based on different criteria.
The joint between the bracket and the thermosetting composite laminate (having a suitable surface media) will have two joint interfaces: one thermoplastic/thermoplastic interface, developed during the ultrasonic welding process, and one thermoplastic/thermosetting interface, developed during the co-curing of the thermosetting composite laminate with the thermoplastic surface media. Generally, the joint strength of the global bracket-to-component assembly will be limited by the weakest of the two interfaces:
Weld strength at the thermoplastic-thermoplastic interface developed through the ultrasonic welding which depends on the compatibility of the base materials of the thermoplastic bracket and thermoplastic surface media.
Bond strength at the thermoplastic-thermosetting interface developed through the co-curing process depends on the compatibility between the thermoplastic surface media and the thermosetting prepreg.
During the first part of the project, two different test were defined and set up to evaluate these strengths. Additionally, the evaluation of materials compatibility includes complementary laboratory tests like calorimetry (DSC), rheology (MFI) and microscopy that provide valuable information in order to better understand the results from the mechanical compatibility tests
In terms of surface media, different commercial references have been studied; research activities have included the selection/development of a suitable material formulation and the optimization of surface media parameters like thickness and morphology (porosity).
Regarding thickness, the thickness of thermoplastic films was optimized. Regarding morphology, the advantages of using additive manufactured plates were evaluated.
CIDAUT also developed its own surface media to evaluate material blends different from those available commercially.
CIDAUT has recently started the project BRACKETWELD, a 3 years Research & Innovation Action launched under the Platform 2 of the Large Passenger Aircraft IADP program within Clean Sky 2, which is orientated to the development, assessment and selection of integrative concepts to optimize assembly of elementary parts, sub-components and modules in modern aircrafts. The general objective of the BRACKETWELD project is to contribute to the cost-efficient integration of system and aircraft structures by the development of innovative technology for the rapid assembly of thermoplastic brackets to thermosetting composite components like stringers and frames.
Brackets are small fixation elements used as local links between aircraft structure, systems and cabin. The assembly of these elements to structural components made of thermosetting CFRP (Carbon Fibre Reinforced Polymers) is carried out by time-consuming techniques, like adhesive bonding or mechanical fastening, that add significant labour and tooling costs to the whole assembly process. Usually, brackets are made of metals but they could be made by injection moulding of reinforced thermoplastics leading to significant reductions in weight and costs. However, the use of thermoplastic brackets is still very limited because of the increased difficulty of the adhesive bonding process with thermoplastic materials.
Figure 1Thermoplastic bracket example
The present research initiative aims to cope with the limitations mentioned above, by the development of an innovative technology for the rapid assembly of thermoplastic brackets to thermosetting CFRP parts using ultrasonic welding. Since the thermosetting materials cannot be welded, a layer of thermoplastic material will be co-cured with the CFRP component, being this layer an attachment area for the ultrasonic welding of the thermoplastic bracket. Figure 2 shows the general concept for the assembly of thermoplastic brackets to CFRP components:
Figure 2 Thermoplastic bracket welding concept
The key challenge will be the development of an appropriate surface media compatible with the thermoplastic materials of the brackets while at the same time achieving a very high adhesion to the thermosetting composite during the co-curing process.
During the project CIDAUT will contribute to the development of this innovative assembly technology addressing the following objectives:
The development of an efficient test method for the quick evaluation of materials compatibility that will be used for the down selection of surface media alternatives.
The definition, evaluation and selection of the most appropriate surface media for the selected thermoplastic brackets.
The final validation by the assessment of assembly performances according to the usual requirements of bonded brackets.
The succeed in the development of this innovative assembly technology will mean significant advantages in terms of reductions in weight, costs and energy consumptions, avoiding the current needs for complex surface preparations, expensive adhesives, curing times and simplifying quality control procedures. The magnitude of the potential benefits is large, just considering the number of ten thousand brackets that are used in the A350-XWB.
The main results and conclusions obtained during MetalMorphosis were presented in Ghent on the 24th of February 2016. The event was hold in the Belgian Welding Institute facilities and more than 50 experts from different technology fields attended the event.
Every partner in the consortium presented the work done, the knowledge acquired and the next challenges to be faced. The main conclusion of the event was that MetalMorphosis project has been an important step forward in the consolidation of the hybrid joints metal-composite in the automotive sector.
Centimfe as project coordinator presented the main milestones covered by the project and the general targets achieved. Ideko and Cidaut focused their presentation on material selection, process optimization and product design. The joining technology was mainly described by Belgian Welding Institute and Poynting, while the life cycle assessment was explained by Stam.
Finally, each of the end users involved in the project presented their demonstrator. In the case of Tenneco, the bottom closing of a monotube shock absorber was used as a case study. The welded steel loop was therefore replaced by a composite part in PA66 with glass fibres produced by injection moulding. This solution has the advantage of producing lighter shock absorbers (15 % saving) while keeping the requirements for a structural part. The technology can be integrated easily in the manufacturing process, keeping the product at an acceptable cost for the market.
Tool Presse presented his hybrid solution (metal-composite) for a pedal brake with a 17% weight saving and important reduction on cost and production process time. The prototype presented was previously validated attending to the requirements defined during the project.
Regeneracija showed his frontal bumper manufactured in aluminium and CFRP. The manufacturing process has combined RTM with electromagnetic joining in order to obtain a 50% lighter component fulfilling all the requirements of this kind of component.