Overview
In its White Paper, European Transport Policy for 2010: Time to decide, the European Commission estimates that the demand for passenger transport in the EU will rise by 24% between 1998 and 2010, with an expansion of the car fleet by 3 million vehicles a year. This, together with the fulfilment of the EC Directive on end-of-life vehicle recycling of 95% recycling rate, is a key challenge for the European transport industry if it is to enable sustainable mobility in Europe.
As 28% of the emissions of CO2 are related to transport (of which 84% are by road transport), reduction of CO2 emissions in road transport is crucial to achieve the targets agreed in the Kyoto Protocol. Weight saving is one of the most effective ways to reduce fuel consumption and thus CO2 emissions of road transport. An example for the potential environmental impact of weight saving in SLC is described in the figure below.
Addressing these challenges while maintaining a vehicle's safety performance is crucial for the competitiveness of the European automotive industry, which employs over 12 million EU citizens. Only by maintaining the knowledge-intensity of automotive manufacturing at a maximum level can the EU avoid massive transfers of car production to lower wage regions in the world, so it is imperative to preserve and increase the high-quality employment.
Today it is possible to construct vehicles with considerable weight reductions in expensive small/medium volume series. SLC focuses on drastically reducing the weight of mass-produced vehicle structures (for instance Golf, Astra, Megane, Punto, etc.) and addresses specific challenges such as a low acceptance rate of risk and quality variance, short production cycle times, low manufacturing costs, short time-to-market and recyclability.
SLC's main objective is to develop the integrated knowledge and technological capabilities required to design, engineer and manufacture multi-material car bodies at mass volumes (1 000/day) with a substantial weight reduction of up to 50% of body-in-white (BIW), combined with reduced raw material consumption of up to 30%. This will compare to series vehicles at manufacturing and assembly costs that do not significantly exceed those of State-of-the-Art series cars of the same class (i.e. average costs of up to €5/kg weight savings).
To overcome these challenges, knowledge and technological capabilities will be developed in three main areas:
- concepts and design (for parts, modules and BIW)
- forming and joining technologies (including surface quality)
- tools and enabling technologies (design, simulation and multi-parameter optimisation tools)
The main result of SLC will be a virtually designed multi-material lightweight affordable car-body concept (including a front structure demonstrator for results validation) fitting in with the scenario of up to 1 000 cars/day offering 30% reduction in weight compared to the 2004 benchmark cars on the market. SLC experiences will also result in a library of multi-material architectures.
SLC will deliver forming technologies with reduced manufacturing cost and/or cycle times. Other forming technologies shaping high performance external panels (while providing A-class surface quality) and new joining technologies for cost-efficient high-volume multi-material assembly will also be delivered. The body assembling sequence will be optimised. Moreover, SLC will analyse their applicability in less stringent mid-volume vehicle classes as well as in other transport modes (including rail).
Finally, SLC will provide the tools and technologies required for multi-material concept design under industrial conditions. These will be shaped as databases and toolboxes integrated in simulation software for crash, fatigue, static, costs, LCA, and offering robust and accurate predict
The multi-material concepts development approach avoids any mono-material-driven design methodology. It puts the overall vehicle's functionalities first, and then deploys them to sub-modules/parts, making the optimal material choice on a part-by-part basis based on overall vehicle performance. This is the driving force steering the research in other areas, favouring functional requirements-based competition among different materials and technologies.
In parallel to concept development, SLC will research on advanced material processing (FRP, light weight alloys, advanced steel, etc.), multi-material joining technologies (e.g. welding, brazing, adhesive bonding, mechanical joining and others), design/simulation tools needed for multi-material vehicles/parts (crash and fatigue behaviour, LCA and costing) and recycling technology applicability. Finally, the SLC front structure demonstrator will be built up, and virtually and physically tested.
SLC is structured around four technical subprojects covering the following domains:
- vehicle design and engineering
- forming and joining technologies
- design, simulation tools and other enabling technologies
- the actual development of a front-end structure demonstrator and virtual car body.
The exploitation of the research results will be supported to ensure that the first high volume series cars can be on the road in 2012.
Funding
Results
The European project SuperLIGHT-Car demonstrated one efficient solution for the distribution of dissimilar materials in an existing compact class vehicle. As the project came to a conclusion, it displayed an impressive car-body weight reduction of 35 % in a compact car that can be produced at 1000 units per day.
The European automotive industry leads the world in technologies for energy efficiency and CO2 reduction in vehicles; important factors for an industry that seeks to radically reduce its environmental footprint. One key to reinforce these strengths is to decrease the vehicle weight, and thereby the fuel consumption. The concept of lightweight vehicles is nothing new; sports cars have been produced with lightweight materials for decades. Yet steel remains the main material of mass-produced cars, due to the lack of technologies for bringing lightweight vehicle production up to scale.
The SuperLIGHT-Car concept also demonstrated economic potential. Originally targeted at € 5-10 per kg of weight saved, the final additional cost landed at €7,8 per kg of weight saved. Based on the expected fuel savings of 0.3 - 0.5 l/km that the SuperLIGHT-Car concept implied, a fully economic solution would require a reduction of the additional cost to € 5 per kg of weight saved. Future research based on the findings of SuperLIGHT-Car is expected to overcome this economic challenge, while advancing lightweight technologies even further. Clearly, the SuperLIGHT-Car consortium has taken a significant step towards the sustainable mass-produced vehicles of tomorrow.
Innovation aspects
The SuperLIGHT-Car project has successfully tackled the challenge of a feasible car-body concept suitable for high volume production, with an achieved weight reduction of 35 %. A multi-material approach was used where each specific body part is made from the most suitable material to fulfil the requirements while minimising the weight. The car-body is composed from aluminium, new steel, magnesium, and fibre reinforced plastics. Appropriate design and manufacturing technologies were developed to allow for the production of high volume series.
The body-in-white concept developed by SuperLIGHT-Car has exceeded the initial target and offers, with a weight of 180 kg, a weight reduction of 101 kg compared to the reference car (Golf V), showing an equivalent performance. The full body-in-white prototype was recently presented at the international conference 'Innovative Developments for Lightweight Vehicle Structures', where it was enthusiastically received by the automotive industry.
Technical Implications
Advanced joining technologies are the key for cost-efficient high-volume assembling of multi-material structures. The joining work in the SuperLIGHT-Car project was focused on:
- continuous joining (welding/brazing), in particular optimisation towards high strength steels as well as aluminium with laser and laser induction, and multi-material solutions with hybrid technologies;
- cold joining (adhesive structural bonding, pulse magnetic welding, friction spot stir welding) well suited for multi-material joints (and steel-aluminium joints);
- mechanical fasteners and insert techniques;
- high speed joining (>3m/min) enlarging process tolerances (hybrid welding) for mono-side access joining on thinner wall hollow section (profile, roll formed hollow section);
- body assembly sequence optimisation.
The concept developed by SuperLIGHT-Car has exceeded the initial target and offers with 180 kg a 35 % (101 kg) theoretical weight reduction compared to the reference car. The BIW prototype weighs 171 kg. That corresponds to a 39 % weight reduction. The difference between the theoretical (CAD based) and the prototype weight can be explicated by the gauge reduction during the deep drawing process, which is not considered in CAD.
Readiness
In addition to the vehicle body, systematic lightweight design concepts have to integrate equipment, chassis, engine and electronics. Sustainable concepts which benefit from secondary lightweight effects will play a decisive role in future car design. With the SuperLIGHT-Car BIW-prototype the demonstration of a lightweight BIW for series production has been made. Now further research and development work are needed to develop around this BIW a optimal sustainable car concepts.