Investigation on the failure mechanism of triply periodic minimal surface cellular structures fabricated by Vat photopolymerization additive manufacturing under compressive loadings

摘要

Triply periodic minimal surface (TPMS) cellular structures have been shown to be a versatile source for biomorphic scaffold designs because of high surface-to-volume ratio, suitable structural geometry for cell growth, and adjustable elastic modulus. Additive Manufacturing(AM) is the most promising technique for producing TPMS due to its capability to control size, size distribution, geometry and continuity of individual pores within the scaffold. In this paper, the effects of pore morphology as well as porosity on the deformation and failure mechanisms of such structures under compression are investigated. To do so, P and G structures with different porosities are fabricated using Digital Light Processing (DLP) technique. All the samples are examined under various compressive loading/unloading cycles, and the stress-strain responses as well as in-situ images of the deformation are obtained. The results show that the main failure mechanism of G structures is the formation of primary and secondary shear bands. Creation of each front of the shear bands and the location of their initiation depend on the amount of porosity and loading conditions. Such influences are also observed in P structures, where failure under compressive loads occurs layer by layer or all at once in the whole specimen.