16th International Conference on Composite Structures

ICCS 16

A. J. M. Ferreira (Editor)

FEUP, Porto, 2011

EXPERIMENTAL AND COMPUTACIONAL ANALYSIS OF A

COMPOSITE CHASSIS

Pedro M. Duarte*

, Manuel A. Fonte*

, Virginia I. Infante†

and Carlos M. Branco†

* Escola Superior Náutica Infante D. Henrique (ENIDH)

Instituto Politécnico de Lisboa

Av. Bonnville Franco, 2770-058 Paço de Arcos - Portugal

e-mail: pedroduarte@enautica.pt; fonte@enautica.pt, web page: http://www.enautica.pt

† Instituto Superior Técnico (IST)

Universidade Técnica de Lisboa

Av. Rovisco Pais Lisboa - Portugal

e-mail: virginia@dem.ist.utl.pt; cmbranco@dem.ist.utl.pt, web page: http://www.ist.utl.pt

Key words: Chassis, honeycomb sandwich, FEM, screwed joint, bonded joint.

ABSTRACT:

This study addresses the design of a composite chassis (figure 1) for a race car that fulfils

the standards of the Formula SAE rules.

The monocoque of the chassis is manufactured from only one aluminium honeycomb

sandwich panel.

Figure 1: Composite chassis

Using the finite element code ANSYS, stress fields in the critical areas of the model (figure

2) were evaluated.

Figure 2: FE meshes of composite chassis

Pedro M. Duarte, Manuel A. Fonte, Virginia I. Infante and Carlos M. Branco.

2

The finite element results have shown that the torsion stiffness value is raised when is

compared with other race car values of the same category.

The joints between the tubular and monocoque structure are critical. The tubular structure

in the back side of the chassis allows the use of the engine as structural member to minimize

the global weight of the structure and the accessibility to the mechanical components of the

vehicle.

The critical joints of the sandwich panel were experimental tested, as presented in figure 3.

It was found that, due to the disposal of the specimens, the tension test should be considered

as a shear test of the screwed joint. These loadings simulate the interaction of the monocoque

with the tubular structure and the front suspension. It was found that a structure without

reinforcements is an inadequate solution. An alternative solution to the use of structural

adhesives was the reinforcement of the screwed joints with aluminium bushing. The static and

fatigue design of the bushing were developed and the external diameter of 18 mm presents

good results considering the applied loads to this type of components.

Figure 3: Jumping-up specimen and tension test of the screwed joint

The mechanical behaviour of the adhesive and riveted joints of sandwich panel was studied

including mechanical tests (figure 4) and computational simulations. The obtained results

have shown that the chassis verifies all the design restrictions being the presented hypothesis

a satisfactory solution. The manufacture method of this type of chassis proved to be simple,

efficient and productive. The use of the honeycomb sandwich panel in aluminium, with 25

mm of total thickness and skins of 0.8 mm showed to be the appropriate solution, due to

reduction of weight and the structural stiffness. The bonded and riveted joints of the

monocoque are improved to resist the service loads, not being necessary the reinforcement of

the monocoque with a transversal structural zone (bulkhead).

Figure 4: Compression test of hexagonal profile