The key factors to reach competitive composite structures for the challenge of sustainable mobility

With more than 30 years of experience in composite materials, TECNALIA is working on the challenges to reach competitive lightweight and sustainable components in composite materials for the mobility of the future

We are working in electric vehicles and hydrogen-based vehicles, through innovative, fast, efficient, automated manufacturing processes and joining of sustainable composite and multi-material structures.

We developed different competitive technologies based on recyclable thermoplastics such as for example the T-RTM (Thermoplastic Resin Transfer Moulding), with very low-cost raw materials, or the tape laying and forming based on unidirectional thermoplastic tapes, with the possibility of zero scrap.

The main opportunities and benefits for using composite structures in transport applications

There are several opportunities now for composite materials regarding the future mobility:

• Weight reduction is always an important aspect in transport vehicles in order to reduce fuel consumption and emissions to mitigate climate change.
• In the new electric vehicles this is even more important to compensate the relevant weight of the batteries in order to have longer battery autonomy range and better car performance.
• With the new electric vehicles and hydrogen-based vehicles, there are new parts where composite materials can be a competitive solution like for example the battery boxes or the hydrogen tanks that have to withstand high loads but a lightweight and robust material like composites.

The main challenges to introduce composite components in transport applications

The growth in the use of lightweight composite materials in the automotive industry is subjected to meeting challenges such as sustainability. The first relevant applications of composite materials in electric vehicles such as the BMW i3, 7 Series and others, show great potential for weight reduction, but they are based on thermosetting composites and processes with limitations in terms of sustainability.

Therefore, there is a need now to develop sustainable composite materials that are easy to recycle and/ or based on natural material sources.

The key factors to reach competitive composite structures

To achieve lightweight composite automotive components in a competitive and sustainable manner, there are several important aspects to take into account where we are focusing our R&D activities:

• The use of materials that can be recycled like thermoplastic composites that can be melted again to be re used
• Thermoplastic composites based on low-cost raw materials
• Competitive multi-material and hybrid material solutions combining composite and metal or composite and plastic
• Zero or minimal scrap processes taking into account that conventional composite processes generate sometimes a relevant amount of scrap
• Competitive, fast and automated manufacturing technologies with cycle times of a few minutes
• Flexible automated processes that allow variable thickness and customized shapes

The technologies that TECNALIA is developing to obtain competitive and sustainable thermoplastic composites

We can mention for example the following three technologies:

T-RTM (Thermoplastic Resin Transfer Moulding) technology by in situ polymerization

This technology has been developed and patented by Tecnalia and has a great potential. Some of the main advantages of this technology are the following:

• Improved recyclability of the composite thanks to the thermoplastic polyamide matrix
• Low-cost raw materials with matrix cost below 2 €/kg which is really competitive
• Fast manufacturing with injection times of about 5 second and total cycle time of 2-3 minutes
• "One-shot" manufacturing of complex parts with integrated ribs and geometrical details

Zero-scrap forming of customized stacks

This process offers great flexibility in part design based on automated customized stacking. Some of the most relevant advantages of this technology are for example:

• Competitive, fast and automated process with cycle times of 1-2 minutes and a deposition time per layer of about 10 seconds
• Competitive hybrid solutions combining glass fiber and carbon fiber tapes
• Maximum optimization with variable thickness and customized net shape blanks
• Minimum or zero scrap thanks to the combination of tape laying and forming with plastic overmoulding

Metal-thermoplastic multimaterial composite solutions

The objective in this case has been to develop thermoplastic composite reinforcements for vehicle structures, to reinforce the metal bodywork so that the weight of the metal structure can be reduced and, at the same time, the conventional joints of the metal parts in the typical automotive assembly lines are maintained. Additionally, metal-thermoplastic material combination provides good ductility and recyclability.

Nexts steps...

For the industrial implementation and scaling of these technologies, TECNALIA is working with industrial machine manufacturers and with end users to validate the technology technically (to demonstrate material properties according to the requirements of the transport sector) and economically with specific business cases to show the benefits for example if terms of the low cost raw materials.