Study on the reinforcement mechanism of LCD photopolymerization 3D-printed triply periodic minimal surface structures doped with carbon fiber and hydroxyapatite

This study quantifies how architecture and fillers govern the compressive and energy-absorption behavior of LCD-photopolymerized P-type TPMS lattices. Specimens with unit-cell sizes of 10–20 mm and volume fractions of 10–30% were LCD-printed. Carbon fibers and nano-hydroxyapatite were added as fillers. Mechanical response was evaluated by compression testing and supported by numerical simulations. Unfilled lattices showed overall geometric integrity with localized microporosity and a three-stage stress–strain response dominated by plastic dissipation. Increasing volume fraction raised compressive modulus, yield/ultimate strengths, and energy absorption; the l = 16.7 mm, 30% configuration provided the best overall performance. Under cyclic loading, higher volume fraction increased hysteretic energy at identical maximum strain, while 30% volume-fraction specimens exhibited reduced residual strain at higher maximum strains. Fillers yielded distinct reinforcement profiles. At equal contents, 50-mesh carbon fibers most effectively enhanced energy absorption via plateau extension; 500-mesh fibers primarily delivered modest strength gains; HAP (Hydroxyapatite)increased compressive modulus and ultimate strength with content but decreased yield strength, indicating toughness loss due to particle effects. Simulations reproduced the experimental trends and key stress-localization features. These findings provide design guidance for selecting unit-cell size, volume fraction, and filler systems to enhance strength and energy absorption of LCD-printed TPMS-P lattices within manufacturability constraints. • Quantified architecture–property relations for LCD-printed TPMS-P lattices (unit-cell 10–20 mm; volume fraction 10–30%), identifying an optimal unfilled design at l = 16.7 mm and 30% volume fraction for combined stiffness, strength, and energy absorption. • Revealed three-stage compression with plasticity-dominated plateau; SEM/CT confirmed overall integrity with only localized microporosity; cyclic tests showed higher hysteretic energy and lower residual strain at 30% volume fraction. • Established filler-specific reinforcement: 50-mesh carbon fiber maximized energy absorption via plateau extension; 500-mesh carbon fiber provided modest strength gains; hydroxyapatite increased modulus and ultimate strength but reduced yield strength (toughness loss). • Validated experiments with COMSOL (linear elastic + generalized Maxwell), capturing elastic–plastic transition, stress localization at pore edges/junctions, and volume-fraction-dependent trends.