The automotive industry continues to pursue lightweight structural solutions to reduce fuel consumption, emissions, and material usage. To achieve these goals requires not only advanced materials but also innovative structural design strategies that minimise weight without compromising manufacturability, structural integrity and in-service performance. This study presents an integrated investigation of a deep-drawn monolithic automotive hard-shell rooftop, encompassing tool design and forming simulations prior to production, the deep drawing process during production, and the post-production evaluation of material thickness distribution and structural stiffness. A specialised deep-drawing toolset, consisting of a punch, die, and blank holder, was designed and manufactured. Finite element simulations were conducted to assess forming feasibility, thinning behaviour, and springback. A physical prototype was subsequently produced using a servo press machine and experimentally evaluated for thickness distribution, structural stiffness, and surface quality. Results demonstrate successful forming without localized necking, wrinkling, or material splitting. Surface inspection confirmed no observable defects. Material thickness analysis using 3D optical scanning revealed uniform thickness of 1.5 mm ± 0.13 mm, with a standard deviation of 0.08 mm (approximately 5% of mean thickness). A strong correlation between simulation and experimental results was observed, with a maximum thinning deviation of 0.012 mm (less than 1% of sheet thickness). Stiffness testing showed a maximum displacement of 24.09 mm under controlled loading conditions, which was obtained after the loading time of 4 min 37 s. This research integrates tool design, forming simulations, and experimental validation, and demonstrates that a hard-shell rooftop can be manufactured as a fully monolithic structure.
Chirinda et al. (Mon,) studied this question.