Optimizing DLP 3D printing parameters to enhance fatigue performance of photopolymer resins for orthopedic applications

This research comprehensively examines the impact of three critical digital light processing (DLP) 3D printing parameters layer: thickness, exposure time, and light intensity on the fatigue behavior of polymeric specimens fabricated from acrylate-based photopolymer resin. Using a full-factorial design, samples were printed with varying process settings and subjected to four-point bending fatigue testing. Results revealed that the optimal fatigue life, reaching 59,734 cycles, was attained at the finest layer thickness of 25 µm combined with the shortest exposure time of 2 s and the lowest light intensity of 5 mW/cm². This combination fosters superior interlayer adhesion and minimizes residual stresses, thereby enhancing fatigue resistance. Increasing exposure time and light intensity was consistently detrimental, inducing over-curing, microstructural heterogeneity, and embrittlement. A three-way analysis of variance (ANOVA) revealed that light intensity and exposure time were the most statistically significant factors, contributing 29.98% and 26.25% of the total variation in fatigue life, respectively. Their interaction also showed a meaningful effect, emphasizing the need for balanced process optimization. These findings provide critical insights into the intricate relationships between DLP process parameters and mechanical performance, enhancing the durability of photopolymer components in cyclic loading particularly for temporary orthopedic splints and functional biomedical components where long-term fatigue resistance is essential.