Vat photopolymerization (VPP) printing suffers from severe out-of-plane warpage induced by the coupled evolution of photopolymerization shrinkage and spatially non-uniform thermal accumulation during stitched exposures, fundamentally limiting dimensional fidelity. To reveal the underlying mechanisms of this deformation and enable its scientific suppression, a curing–thermal–mechanical (CTM) multiphysics framework was established to analyse the coupled evolution of curing kinetics, heat transfer, and stress development under UV energy exposure. Guided by the CTM model, a structure–process co-optimization strategy (SGSS–SIE framework) was developed, integrating a stress-guiding substrate structure (SGSS) and a segmented intermittent exposure (SIE) process to synchronously regulate stress distribution and transient thermal evolution during printing. Compared with directly printed structures, the SGSS strategy effectively redistributed internal stresses, reducing simulated warpage by over 60% and increasing the fraction of low-deformation regions ( Δ z ≤ 0.2 m m ) to above 70%. Building upon the SGSS design, simulation results further showed that incorporating the SIE process enabled temporal regulation of exposure and cooling stages to regulate thermal evolution during photopolymerization, achieving up to 83.8% deformation suppression and increasing the low-deformation fraction to 91.5%. To experimentally validate the deformation-suppression capability of the SGSS–SIE framework, a custom-built DLP system implementing this strategy was developed and employed for experimental validation. Experimentally, compared with the widely adopted cylindrical-support structure, which exhibited a bending displacement of 1403 μm, structures fabricated under the SGSS–SIE framework showed reduced displacement of 603 μm and substantially improved surface flatness. Moreover, the experimentally measured structural deformation exhibited good agreement with the CTM analysis, with the overall consistency exceeding 70%, and additional multi-resin validation confirmed robust warpage suppression by the SGSS–SIE strategy, further supporting the reliability of the CTM framework in guiding deformation-suppression strategies. This study establishes a co-optimization strategy integrating multiphysics modelling, structural confinement, and temporal exposure control, offering a scalable, material-agnostic route to high-fidelity, large-area DLP fabrication of flatness-critical optical and microfluidic devices.
Wang et al. (Fri,) studied this question.