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New 30% Lighter Support Rail for a Bus
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Problem Statement
Support rail of a bus made from aluminium was to be replaced by a fiber reinforced plastic part. The aim was to reduce weight and cost. |
Improvement Approach
Use of simulated fiber orientations for structural analysis. The rib structure was optimised using fiber orientations. |
Benefits
The part weight could be reduced 30 % and also the part cost could be reduced significantly in comparison to the aluminium part. |
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Contact information
simcon kunststofftechnische Software GmbH
Kaiserstr. 100, 52134 Herzogenrath, Germany
Phone +49-2407-908580 ,
Fax
+49-2407-90858 58
e-mail
www.simcon-worldwide.com
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Structural Anaysis of EVO Bus cross bar. |
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Backbone of the whole roof channel of the EVO-Bus is the horizontal cross bar. First concepts showed, that the development aims –reduction of weight and cost – were only achievable by an injection moulded part. The development was started in parallel with plastic injection moulding and aluminium sand casting.
The handrail mounted to the part was expected not to bend more than 10 mm under full load of 1410 N. The functionality of the part needed to be guaranteed in a temperature range of –40 °C until 100 °C.
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Together with the material supplier A. Schulman GmbH, Kerpen Germany, the designers of Cleff Fahrzeugtechnik GmbH, Wuppertal Germany and simcon kunststofftechnische Software GmbH, Herzogenrath, Germany the part geometry was designed according to plastic needs and simulated.
Following the first structural analysis the rheological analysis of the cross bar was made.
With the filling simulation program Cadmould 6, the filling stages had been simulated and so the mould lay out and the way of the manufacturing method of the part could be checked and optimized. Then the influence of the fiber orientations on the structural behaviour of the part were evaluated for different fiber reinforced plastics.
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The part will be manufactured on a injection moulding machine (clamping force 4000 kN) in a cycle time of less than two minutes. The weight of the used plastic traverse of Celstran is 1.9 kg. |
This saves weight of more than 30% compared with the part made of aluminium, which has a weight of more than 2.8 kg.
As 30 of such cross bars have to be assembled per bus, quite a bit could be saved – moreover in an area which is the sensitive centre of a vehicle.
However the savings on the cost side are much more serious. Including the mould costs the manufacturing costs are clear below the costs for a part made of aluminium.
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This success story is based on an article in: Plastverarbeiter 8/2000, p. 58-59, Hüthig GmbH, Heidelberg.
The editors are: Harold Jacobs, Projektleiter Cleff Fahrzeugtechnik GmbH, Wuppertal, Thilo Stier, Projektleiter im Technischen Kundenservice und Bernhard Rzepka, Leiter des Technischen Kundenservice, A. Schuman GmbH, Kerpen
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