Cell-size graded sandwich enhances additive manufacturing fidelity and energy absorption

•Novel TPMS lattices with linear, quadratic, and cosine gradients in cell size were proposed to design sandwich structures, fabricated by SLM using Ti-6Al-4 V.•The designed cell-size graded lattices can promote the improvement of manufacturing fidelity and roughness of sandwich panels, solving the problem of insufficient support.•The energy absorption of the proposed quadratic graded lattice was enhanced by 57% due to its higher plateau stress and the deformation behavior of layer-by-layer collapse. The advent and improvement of Additive Manufacturing technologies enable the fabrication of sandwich panels with complex shapes characterized by strength-to-weight ratio properties and multifunctional features. Due to the insufficient support performance for the overhanging panel, effective solutions need to be addressed for designing the internal filling cores. In this work, Triply Periodic Minimal Surfaces (TPMS) lattice of sandwich structures with novel linear, quadratic, and cosine gradient in cell size were designed and fabricated by selective laser melting (SLM) using Ti-6Al-4 V, and their morphology and mechanical properties of the sandwich structures were investigated using SEM, white-light interferometer, Micro-CT, compression experiment, and numerical simulation. The experimental results show that the manufacturing fidelity of the sandwich panel was improved due to the good overhanging support of cell-size graded lattices. Moreover, the plateau stress and cumulative energy absorption of quadratic graded lattices were enhanced by 57% compared to the uniform counterparts, attributing to the critical layer-by-layer collapse mechanism. [Display omitted]