The Fatigue4Light project has focused on the generation of high added value knowledge concerning the use of new materials in the automotive industry with the aim of achieving lighter and more environmentally friendly solutions. This has been carried out throughout the 3 phases of the project, where the focus has been put on: (i) the material, (ii) the manufacturing operations and (iii) industrial demonstrators and the vehicle.
Regarding (i) materials, AHSS, PHS and multi-material: GFRP-aluminium and CFRP, solutions have been used to replace the sheet steels used in the chassis of LDVs and HDVs. The study has been approached from three different perspectives: experimental, numerical and LCA/LCC. On the one hand, three rapid fatigue testing methodologies have been developed that allow a significant reduction in the time required to characterise the fatigue response of materials, going from weeks to hours and involving a much smaller number of specimens. As a result of this work, two CWAs have been produced, which are the first step in the standardisation of these experimental processes. Regarding the numerical study, progress has been made in the analysis of HCF processes. Taking as a starting point the functionalities allowed by commercial tools, a methodology has been developed in Fatigue4Light allowing for a continuous evaluation of the nonlinearities associated with fatigue. In this way, it is possible to measure phenomena associated to cyclic loads such as the load-sequence effect and also tracking the resulting crack path in this degradation mode, which is generally impossible using phenomenological approaches such as those supported by commercial tools.
Having the fatigue analysis as the backbone of the project, significant efforts have been dedicated to the (ii) characterisation of the impact of the manufacturing operations on the fatigue response of the materials being studied. Therefore, the processes involved in the manufacturing of the chassis components, i.e. trimming, punching, forming and welding, have been studied in detail. This analysis has been carried out experimentally and numerically, characterising the derived effects in order to take them into account in the evaluation of the response of the elements once they are integrated into the vehicle.
Finally, the work at (iii) component level has been developed in 2 stages. On the one hand, the technical feasibility of each of the solutions proposed in the project has been evaluated for several demonstrators: lower control arm, shock tower, cross member beam and wheel. In this way, the functionality of the solutions is ratified while achieving weight reductions of 10-35% with respect to the baseline solutions. On the other hand, a methodology for decision making has been developed in order to decide objectively which of the alternatives analysed is the best. This has been achieved by following a multi-criteria analysis scheme incorporating technical, environmental and economic aspects based on the previous analysis and LCA/LCC information associated to each solution. From this study it is concluded that while composite-based solutions result in the most substantial weight reduction, advanced high-strength steel-based solutions allow for an overall improvement in technical, environmental and economic terms and are more appropriate despite having lower weight reductions associated. Taking all these results into account, work has been carried out to extrapolate the findings to the vehicle level, where the 10% weight reduction target set for Fatigue4Light is achieved.
All these significant results have been shared with the community through 12 scientific publications in Open Access Journals, the participation in 24 events including conferences, congresses, fairs, workshops, etc., also by organising 2 cluster webinars, 3 industrial webinars and 1 workshop, promotional materials such as a project poster and 19 videos, and via the social media activity associated to the X (@Fatigue4Light), Linkedin and YouTube channels.
