Auto-support: traction force constrained support structures optimization for bottom-up vat photopolymerization

Bottom-up vat photopolymerisation offers high precision and speed, but the process is influenced by separation forces, which vary with the cross-sectional area of printed layers—often overlooked in existing support structure generation methods. Insufficient supports lead to printing failures, while excessive supports require manual intervention and degrade surface quality. Optimising support structures to account for separation forces is challenging due to the computational expense of repeated simulations. This paper introduces a novel methodology to optimise support structures, minimising support usage while satisfying force and overhang constraints. The approach combines representative layer simulation and geometric optimisation with simulation verification, reducing simulation iterations from hundreds of thousands to a few dozen. Layers are clustered by cross-sectional shape coherence, with representative layers showing the maximum support traction forces identified for full simulations. These simulations guide and validate geometric optimisation to meet both overhang and force constraints. Experimental results show that this approach significantly reduces support contact points compared to commercial software while maintaining structural stability throughout the printing process.