BMW & Peugeot save weight with copolymer

28th May 2015
Source: JSP
Posted By : Barney Scott
BMW & Peugeot save weight with copolymer

JSP has announced twin successes arising from its lightweight construction material, ARPRO. The material has been selected by BMW for use in the upward-swinging butterfly door panels of the company's latest menacing supercar, the i8 - a Plug-in Hybrid EV (PHEV). ARPRO has also been chosen for use by Peugeot, in the chassis and frame of its 5-door hatchback, the 308.

Reducing weight by approximately 22% and improving crash performance, leading global automotive supplier Magna International used ARPRO, a synthetic rubber copolymer (polymer made up of more than one type of monomer unit), to develop a completely bespoke door panel carrier. The BMW i8’s butterfly doors are a visual highlight and emphasise the sporty characteristics of the car. Consequently, the structure of the door panel required a strong, yet lightweight material to ensure that the doors met all Magna’s demands for performance and aesthetics; the solution was ARPRO.

ARPRO’s ability to reduce weight, reduce tooling investment by 50% and provide insulation of the door panel, along with integration of the cable channels and switches, has proven fundamental to the use of a butterfly door design for the first time in a series-production vehicle. ARPRO has already been widely used in BMW models including structural applications such as X5/X6 seat benches and the 5 Series seat back.

The development of the door panel was revolutionary, so testing at JSP’s eureka facility was rigorous, overcoming a number of challenges. The engineering process was particularly complex because of multi-functional requirements in one component. ARPRO needed to provide stability, structure and strength, as well as the integration of components: trims, loudspeakers and switches, and heat and sound insulation in a very thin wall.  All this, with the overarching necessity for perfect tolerances appropriate to a premium car.

Equally challenging was the moulding tool. The radical design required multiple iterations to achieve perfection. The resultant part is smooth, sleek and contributes to the success of the interior design. The end result is technically accomplished, as well as beautiful.

“Every gram saved by the ARPRO door panel means less environmental impact, while ARPRO’s energy absorbing capacity enabled crash pad functionality, despite small pack space and the constraint of a complex, aesthetic design,” explained Paul Compton, President and CEO for EMEA, JSP. “Increasing automotive sustainability and producing a door that opens with ease and style is a great achievement, especially as the technology didn’t exist when we started this project. Our part in the BMW i8 project has been recognised and using ARPRO in the BMW i8 door panel has now led on to other exciting developments that will see car production take great strides forward in the near future.”

Named as European ‘Car of the Year’ 2014, the Peugeot 308 has been welcomed by the industry as a landmark in design and engineering, with the model praised for its efficiency and lighter frame. These features have been achieved through the intensive use of composite materials, redesigned impact areas and the development of applications including a universal seat ramp and other key elements made using lightweight material ARPRO.

Introducing such changes to the 308 has improved safety, performance and reduced fuel consumption and CO2 emissions. ARPRO is credited as being one of the main differentiators in reducing the overall weight of the car. ARPRO was used across six applications within the 308, with the integrated seat ramp made entirely from the material, enabling a flat, modular chassis.

Easy to fit by clipping into place, the ARPRO seat ramp in the 308 means there is no longer the need for the past chassis-integrated ramp to be tailored to each model. The ARPRO design has enabled the designers at Peugeot to apply the ramp to various Peugeot models, saving weight, time and the cost of different designs for each model. The use of ARPRO has saved 2kg.

Overall the current model is 140kg lighter than the previous 308 and has also achieved a Euro NCAP 5-star rating for occupant safety, along with a 4-star child occupant safety and 3-star pedestrian protection rating. This would not have been possible without the car’s simplified, streamlined design ethos, using innovative applications to save weight in different areas of the car, without sacrificing strength or space. ARPRO’s qualities of durability, impact performance, and its unrivalled ability to reduce weight made it the perfect material to deliver Peugeot’s vision.

Considering driver comforts and safety, ARPRO has been used in the creation of the knee pads and within the car’s foothold. Providing a robust and adaptable base for the foothold, ARPRO can withstand the pressures of driver use and doesn’t compromise on space to ensure safety. The knee pads by the steering wheel have also been re-engineered thanks to ARPRO, permitting a more compact design and creating more space for the driver, yet retaining all the required impact absorption. This space-saving solution was also applied to the car boot where a one-piece ARPRO component accommodates the spare tyre and creates a flat floor loading area.

Another challenge Peugeot had to overcome was finding an alternative to its traditional method of producing head restraints. With five of these in the car, the weight can add up and using the traditional method of injection moulding is heavier and requires a larger comfort layer. Peugeot therefore evaluated different criteria by performing whiplash tests and ARPRO once again came out on top. Three times lighter than injection moulded plastic, each ARPRO restraint weighed just 29g.

The 308 offers a responsive, controlled driving experience and Peugeot has taken great care over every detail. This includes ensuring performance and experience is perfectly balanced right down to the sound and feel of the drive. With its ability to reduce noise, vibration and harshness, the versatility of ARPRO has meant it was used not only as a material for applications and structure, but to protect the engine and insulate against vibration.

By using ARPRO under the bonnet, Peugeot was also able to reduce the sound levels and achieve energy absorption. Made up of two pieces, totalling just 58g, ARPRO’s unique form provides structurally sound performance and high noise absorption. ARPRO was able to change the dominant frequency, while still giving the driver the experience of a powerful car.

“The extensive use of ARPRO within the 308 demonstrates the unique adaptability and versatility of the material. With six applications throughout the car, Peugeot has demonstrated how the design and manufacturing process is changing within the industry and traditional methods are now being challenged,” commented Paul Compton. “ARPRO has helped to redefine how car designers approach building a new model. They are no longer restricted by one seating platform per model nor do they have to compromise on features or space. Instead, a material such as ARPRO can enable designs to be achieved with ease and aid in efficiency. This has led to the 308 becoming a lighter, stronger and altogether unique innovation in automotive design.”

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