Results from a Task 17 study on the impacts of the vehicle’s mass efficiency and fuel economy for different drivetrain configurations (conducted by Argonne National Laboratory) highlighted the importance of the topic lightweight, especially in XEVs.
According to a McKinsey study7 (2014), the proportion of high tensile steels, aluminum and carbon-fiber-reinforced plastics in vehicles is set to increase from 30% today to up to 70% in 2030. High-tensile steel will remain the most important lightweight material (market share: 15% to 40%) and carbon-fiber-reinforced plastics are expected to experience an annual growth of 20%.
Following the worldwide trend of dealing with the topic of Lightweight in 2014, Task 17 discussed and analyzed this topic through a workshop.
Task 17 Workshop: Functional and Innovative Lightweight Concepts and Materials for XEVs Major Topic
The workshop took place in Schaffhausen (Switzerland) in October 2014 and was hosted by Georg Fischer Automotive AG, a Swiss company specialized in the field of lightweight design, which is well known for their pioneering materials
developed in-house, bionic design, and optimized manufacturing technologies in the automotive sector. The 28 participants included experts from industry as well as research institutes and representatives from the government. During the workshop experts from different working fields and technologies came together to discuss. The workshop was focusing on Functional and Innovative Lightweight Concepts and Materials for XEVs and covered four sessions about:
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CHAPTER 5 – SYSTEM OPTIMIZATION AND VEHICLE INTEGRATION (TASK 17)
• Lightweight Activities in Switzerland (hosting country),
• Lightweight Materials and Components,
• Simulation and
• Functional & Innovative Concepts and Solutions
The aim of the workshop was an exchange of information in order to identify potentials for improvement in the field of lightening XEVs by giving an update on available lightweight materials and prognoses about future materials. Thus, representatives from all kinds of organizations working in the field of materials were invited to share their opinion. In the workshop it was pointed out, that there is no ultimate lightweight material available at the moment. The future of lightweight materials will be a mixture of the best materials available on the market combining their benefits: there is a need for the right material at the right place.
Beside the sessions, the participants were given the possibility to participate in guided tours:
• Automotive- and R&D- center of Georg Fischer (see Figure 2)
• Iron Library: the library's books and periodicals, offers an in-depth perspective like no other in the world. The collection comprises over 40000 publications that deal with the topic of iron, including classics by masters such as Isaac Newton as well as specialized modern literature.
Figure 2: Impressions from the guided tours: R&D center (left), iron library (right)
Some of the following subjects highlight the range of different materials and topics treated in the workshop:
Bionics: nature has provided ideas for high-strength materials, dirt-repellent
coatings and even Velcro fastenings. This has led to the development of bionic car components, or even whole cars like the Mercedes-Benz bionic-car. The Alfred-
Wegener Institute (AWI) designs and constructs vehicle components with an
2015 IA-HEV ANNUAL REPORT
objectives of a component, the optimization is done by five steps: screening for biological archetypes within 90,000 structures →structure assessment (natural structures are analyzed according to technical boundary conditions) →abstraction and functional transfer of natural structures to CAD model → application of parametric and evolutionary optimization (FEA optimization with focus on feasibility of manufacturing and cost performance) → assembly. Figure 3 shows the development of the ELiSE process using the example of a b-pillar. Finally a weight reduction of 34% – from 8.0 kg to 5.3 kg – can be achieved.
Figure 3: ELiSE process with b-pillar development (image courtesy of AWI)
Materials: despite the above ground-breaking achievements in key areas, OEMs
are still searching for the development of strategies and technical solutions to integrate lightweight materials into multi-material vehicles inexpensively and to secure lightweight materials and components on a global platform. The combined use of various materials makes it possible to generate products displaying a broad spectrum of desired properties. By selecting the appropriate materials many mechanical characteristics can be influenced and optimized. Sandwich structures with 3 or more layers represent the basic technology for lightweight parts. The Austrian company 4a manufacturing8 offers the worlds thinnest sandwich structure used to optimize vehicles weight. There are materials produced having a very high bending stiffness at a low weight and a total thickness of 0.3 mm or more and a surface weight of 100 g/m² or more. Figure 4 shows the schematic build-up of the sandwich material. Automotive application fields are: firewall (-45% weight reduction compared to aluminum), rear panel (-30% weight reduction compared to aluminum).
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CHAPTER 5 – SYSTEM OPTIMIZATION AND VEHICLE INTEGRATION (TASK 17)
Figure 4: Material "Cimera" (left), schematic drawing (right) (image courtesy of 4a manufacturing)
AIREX Composite Structures produces sandwich materials being used in the
application field of roofs for buses and trains. A weight reduction of up to 160 kg (-20%) can be achieved by using sandwich roofs (see Figure 5).
Figure 5: Sandwich technology for buses (image courtesy of Airex Composites)
Functional integration in the field of lightweight construction: functional
integration provides parts with several functions in order to save on the final number of parts. There is for example, the possibility of replacing plastic interior trim with structural parts suitably designed with laminable, visually attractive surfaces. Individual close-to-the-wheel drives open up new possibilities for vehicle dynamics control strategies. This includes an associated increase of driving safety and energy efficiency through the targeted distribution of power and recuperation. On the other hand, the positioning of the motors close to the wheel increases the unsprung mass. This challenge can only be met by consistent lightweight design for all chassis components. The “LEICHT” concept by the German Aerospace
Centre DLR presents a novel, drive-integrated chassis concept which in terms of its
design and construction offers a significant chassis weight reduction (see Figure 6). By integrating the motor into the chassis in an intelligent way, easy modularization
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adoption to a variety of vehicle concepts and an application as front or rear suspension module, by reaching about 30% weight reduction in comparison to conventional reference structures9.
Figure 6: Lightweight Strategies Applied on the “LEICHT“: torque transmission demonstration (left), wheel travel demonstration (right) (image courtesy by DLR)
Another innovative concept called ESKAM was presented by Groschopp AG. In 2014 there were no optimized drive axles for BEVs available on the market. They are too heavy, too expensive, and too big, compared to the available power. The aim of ESKAM (Elektrisch Skalierbares Achs- Modul – electrically scalable axle module) is to develop technologies for flexible standard drive modules (see Figure 7). This innovative concept provides an integration of the drive prior to the axle module by limiting the weight of the drive module to a maximum of 100 kg. For this purpose, it is necessary to couple rapidly rotating electrical machines with corresponding gears and to integrate them in a common housing. In this case, only e-motors are used, which are not dependent on permanent magnets or on ever- increasingly expensive rare earth elements such as neodymium and samarium. The electric drive consists of two identical electrically excited, electronically
commutated motors and transmissions, which are placed together with the power electronics in a housing and fitted to a drive axle module. The power range of the engine is scalable between 20 and 50 kWh.
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http://elib.dlr.de/89144/1/2013_04_08_Presentation%20SAE_The%20LEICHT%20Concept_From% 20the%20Concept%20to%20the%20Prototype%20Andreas%20Hoefer.pdf
CHAPTER 5 – SYSTEM OPTIMIZATION AND VEHICLE INTEGRATION (TASK 17)
Figure 7: Project ESKAM (image courtesy of Groschopp AG)
Magna presented a vehicle called CULT10 (Cars' UltraLight Technologies vehicle), a modern lightweight vehicle fueled by natural gas which shows significantly reduced CO2 emissions (Figure 8). Lead-managed by Magna Steyr, the Polymer
Competence Center Leoben GmbH worked on the development of an ultralight vehicle with minimal CO2 emissions in the CULT project.
One of the methods employed to achieve this objective was the exploitation of the properties of thermoplastic fiber composite materials relating specifically to weight in order to reduce the overall vehicle weight by using lighter components. For example, thermoplastic continuous-fiber-reinforced semi-finished composites were used for the bumper beam, which consists of a crossbeam and shock absorbers. The Fraunhofer Institute presented the requirements for a Composite Wheel with Integrated Hub Motor and described the development of a wheel of carbon fiber reinforced plastics with an integrated electric motor (see Figure 9). The main focus of the development was on the achievement of an optimum of lightweight potential considering structural durability.
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Figure 8: CULT, vehicle (left) and explosion view (right) (image courtesy of Magna)
Figure 9: Wheel with Integrated Hub Motor (image courtesy of Fraunhofer)
During the realization, the technical challenges of multifunctional design were considered in the whole product life cycle. The CFRP lightweight wheel has a weight of approximately 3.5 kg. The motor housing is not directly connected to the rim, but to the inner area of the wheel axle. This prevents radial or lateral loads, especially shocks caused by rough roads or curbstone crossing, from being transferred directly to the hub motor (4 kW). Another advantage of separatign the load paths from the hub motor is that the rim can be more flexible than as if it were directly connected. To increase the flexural rigidity at a constant weight, foam cores were inserted into the spokes. A smaller, commercially available hub motor was used as the electric motor.
Through this workshop Task 17 successfully demonstrated that lightening the car, improving the electric power control unit, optimizing thermal management solutions, and improving the battery management system can help to improve the energy efficiency and the overall system performance of the vehicle. Thus it can increase the drive range and reduce costs and therefore makes the vehicle more attractive.
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5.5
Next Steps
The work in Task 17 will continue till early 2015. Future work within this Task includes:
• Workshop about Electronic/Electrical (E/E)- Architecture
• Final Task 17 report
A further topic of high priority identified in the areas of system optimization and improvements in energy efficiency deals with E/E-Architecture: power electronics and electric energy management. In the future, there might be autonomous cars everywhere. In 2014 (semi-)autonomous cars are in the phase of development and are becoming more and more popular. There are still hurdles to overcome but sooner or later these cars will be introduced into the market. Technologies like Advanced Driver Assistance Systems (ADAS) are representing a first step to fully autonomous driving. In 2014, ADAS is one of the fastest-growing segments in automotive electronics. There are many forms of ADAS available, mostly focusing on safety aspects and the increase in driving comfort. Besides that, they also can improve the overall economics of the vehicle.
As a next step, Task 17 will focus on the improvement of the eco-operational mode of XEVs by having a look at the E/E- Architecture of XEVs (incl. ADAS).
Thus, the last Task 17 workshop will focus on E/E- Architecture, including:
• Electrical Machines: higher partial load efficiency, lower volume and weight, higher failure safety, less dependency on scarce materials,
• Power electronics: higher efficiency, thermal strain on power electronics, resistance to vibration
• Power Tools for system optimization
• Electric energy management
• ADAS systems (evaluation, analyses of the benefits and potentials of existing ADAS especially used in XEVs
Final Task 17 Report: Since the beginning of Task 17 in 2010, seven workshops
and expert meetings have taken place. In order to provide the Task members with these amounts of information, a final Task end report will be produced. Already existing information (status of previous years) has to be updated, in order to produce a contemporary report. The necessary work will be done by the OA in co- operation with the other Task members.
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5.6
Contact Details of the Operating Agent
Task 17 is coordinated by the Austrian Association for Advanced Propulsion Systems (A3PS). For further information regarding Task 17, please contact: Mr. Michael Nikowitz
Austrian Association for Advanced Propulsion Systems (A3PS) Tech Gate Vienna – Donau-City-Strasse 1
1220 Vienna Austria Phone: +43 1 205 01 68 105 Fax: +43 1 205 01 68 110 E-mail: [email protected] Web: www.a3ps.at