The main goal of this work is the study, the development and testing a multi-material lower control arm of a McPherson suspension for a C segment vehicle as Fiat 500X. The hybrid technology applied has been focused to reduce the LCA mass, diminishing the steel thickness and adding a CFRP tailored cover without compromising the global mechanical performance. The hybrid LCA concept has been also designed to be replaceable with the original component, accomplishing specific constraints such as suspension packaging, mechanical coupling to the wheel and chassis, manufacturing process as well. These requirements have been integrated to the component targets of lightweight by using innovative materials and design procedures defined for this specific case study.

A multibody model on ADAMS\\Car has been created to define the load conditions on the lower control arm by considering three different configurations: lateral and longitudinal load for stiffness evaluation, special and misuse events. Then, the baseline LCA has been analyzed on Altair Optistruct to evaluate stiffness, special and misuse events behavior in order to define the reference performance for the hybrid LCA.

Subsequently, the optimization analysis on carbon fiber cover has been addressed to find the optimum combination of ply shape, orientation and stacking sequence accordingly with the multi-material LCA targets of mass reduction and stiffness performance. The simulation has been carried out considering the stiffness load cases of bending and buckling load starting from the maximum arm envelope defined by the packaging analysis. The optimized hybrid LCA achieved a 23% of mass reduction with longitudinal and lateral stiffness diminished of 9% and 7% respectively than the virtual baseline model. Beside all, it is to be highlighted that the stress distribution due to special and misuse events is fully satisfying the safety requirements.

Longitudinal strength test has been conducted on both the arms to compare their experimental performance in terms of stiffness and to validate the methodological design approach by FEM correlation. Experimental longitudinal strength test has highlighted a low difference in performance between the two LCA. The longitudinal stiffness of the hybrid LCA is just 6% less than the baseline one.

Two detailed RADIOSS models have been created in order to reproduce the same scheme and compliance of the test apparatus. The results obtained have demonstrated a high correlation level with their respective experimental tests, with a maximum error on stiffness estimation of -7% and -4% respectively for the baseline and hybrid LCA. Multi-material concepts represent a feasible solution to foster lightweight challenges even though their potential in terms of performance could be limited if adapted to an existing component.

Finally, a complete methodological approach concerning experimental and virtual paths has been studied and validated with high correlation level. In conclusion, multi-material concepts represent a feasible solution to foster lightweight challenges even though their potential in terms of performance could be limited if adapted to an existing component.

Further activities will be necessary to test both at component and at vehicle level this innovative solution to fully accomplish the safety, durability and misuse requirements typical of the automotive world. In particular, at component level it would be important to investigate the environmental and aging effects (i.e salt spray, UV radiation) on the mechanical performance of the multi-material lower control arm. In addition, impact and fatigue test would be performed to fully validate the LCA hybrid solution in terms of strength and mechanical coupling between carbon fiber and steel.

 


Lightweight Design of a Multi-Material Suspension Lower Control Arm

Division / Sponsors: 
Design Engineering Division and Computers & Information In Engineering Division


Paper Proceedings: https://asmedigitalcollection.asme.org/IDETC-CIE/IDETC-CIE2020/volume/83907

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