JEC COMPOSITES MAGAZINE - Issue #59 - August/September 2010 - 53

USERS’ PLATFORM
Buses & Trucks

Making modular bus body shells from composite materials
This technical paper deals with the development of a body shell mainly made of GFRP materials for small buses (19 to 34 passengers). The main goal was to substitute the monocoque design with a more efficient “modular panels” design. Fundamental aspects such as design, fabrication and the assembly of different parts of the body shell are discussed. The main advantages of the modular design are also discussed.

J. M. MEZA, GRUPO DE CIENCIA Y TECNOLOGÍA DE LOS MATERIALES, ESCUELA DE INGENIERÍA DE MATERIALES UNIVERSIDAD NACIONAL DE COLOMBIA J. A. RESTREPO, ICOLFIBRA MANAGER J. CRUZ, GRUPO DE INVESTIGACIÓN EN NUEVOS MATERIALES, UNIVERSIDAD PONTIFICIA BOLIVARIANA

mould was necessary for each chassis size. Moreover, residence times of the GFRP materials inside the mould were long. For these reasons, a new manufacturing process and a new body shell design were required. The final product was called Evolution-S. This paper describes the main design steps and discusses the main advantages of the final product.

moulds, while obviously being limited by the maximum size of the mould. These parts are assembled using mechanical fasteners and adhesives.

Design procedure
Building on knowledge gained through the construction of earlier bus projects, most of the bus body was designed using sandwich-type structures composed of GFRP skins and a polyurethane foam core. The first design step for the modular solution consisted in drawing a 3D prototype using the Solid Edge software [1]. Critical parts such as girders (see Figure 1) and joining parts were modelled using the ANSYS finite-element software [2]. Several prototypes were constructed and mechanically tested based on the results of these simulations. Based on the experimental results, the parts were redesigned and the results were incorporated in the 3D prototype. This 3D prototype was used to manually construct the models, which were mostly made of wood. These models were used to produce the GRPF moulds. Figure 2 shows a schematic representation of a side wall section, a

The new product
Figure 1 shows the new design concept called modular panels. The principle is based on producing different sizes of floor, roof and side panels using the same

ntroduced in April 2009, Evolution-S is the result of a joint research project led by the Colombian government, the Pontifical Bolivarian University (UPB) and Icolfibra, a private company. The project was launched in May 2007 with the aim of finding a more efficient way to produce a body shell for small buses with a capacity for 19 to 34 passengers. For 20 years, Icolfibra have produced monocoque body shells with GFRP materials using two moulds and a combination of different techniques such as conventional spray lay-up, open-mould laminating techniques and polyurethane injection.

b However, the manufacturing process was inefficient because a different
Fig. 1: Modular panels: a) Exploded view of different panels, b) Partly assembled parts

No59 August - September 2010 / jec composites magazine

JEC COMPOSITES MAGAZINE - Issue #59 - August/September 2010

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