Riassunto analitico
In this document is investigated a particular kind of control arm typical of F1 application: a monolithic wishbone with integrated flexure. This technology takes advantage of an intended flexural compliance introduced in the control arm (usually close to the chassis attachment point) to allow the rotation of the external upright attachment point with respect to the chassis.
The aim of this document is to assess whether this kind of solution is not only feasible, but especially advantageous from the performance point of view if integrated in the MMR Hybrid competition race car.
The key points of the document are now briefly introduced.
With this solution it is possible to simplify the wishbone assembly, especially in the inboard region since no ball joints are needed and the control arm can be directly fixed to the chassis; this leads to a reduced number of components, and reduced maintenance thanks to the fact that the number of parts that experience friction, and thus wear, is also reduced.
Other expected improvements form this new design are:
• Improved suspension reactivity since friction is eliminated from the inboard side
• Reduced weight, considering also the new attachments design
• Improved aero performance since frontal area of the wishbone will be reduced as much as possible during the design phase, and the profile will be aerodynamic instead of a circular tube
From the modelling point of view, this study offered the possibility to look deeper into the solution of non-linear analysis with the use of the Optistruct® solver, both for the correct simulation of contacts and large displacement problems; indeed, the particular working principle of the flexure made it mandatory to always utilize large displacement theory together with non-linear analysis, since the deformations wanted by design targets were of important magnitude.
Moreover, linear buckling analysis was exploited to have an indication of the buckling load for both the front and the rear arms of the wishbone at each iteration with different geometry and laminates, which was a critical part of the project since a strong flexural compliance was added to each arm on purpose for the reasons explained above.
A detailed 3D CAD assembly was done from which precise mass of each component was retrieved, for the final weight evaluation with respect to the current configuration.
3D CAD was also fundamental when defining the shape of the wishbone to avoid any clashes with other suspension components, particularly the wheel rim and the pull-rod.
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