A novel conservative failure model for the fused deposition modeling of polylactic acid specimens

Abstract

Fused deposition modeling (FDM) is the most common technique used in the additive manufacturing process of polymers. However, there is a need for more accurate failure models for structures made by additive manufacturing, thus limiting the widespread application of this technique. This paper presents a novel conservative failure model to promote the efficient design of FDM products. The conservative model is tailored to provide underpredictions for the ultimate tensile strength (UTS) and presents a safety margin for designers. Two distinct failure modes have been widely reported for FDM parts – the layer separation mode and the layer breakage mode. Consequently, the model consists of a linear interpolation for the layer separation mode and a quadratic simplification for the layer breakage mode. Three data sets have been adopted from the literature to verify the model accuracy with minimized randomness error. The experiments were carried out for polylactic acid specimens with three layer thicknesses (i.e., 0.1 mm, 0.2 mm and 0.3 mm) and seven print orientation angles (i.e., 0°, 15°, 30°, 45°, 60°, 75° and 90°). The trends in the UTS and in-plane shear strength are analyzed and discussed with respect to different layer thicknesses. The results indicate that the failure model correctly underpredicts the UTS in 95.2% of the cases. Furthermore, the accuracy of the model was investigated, and the errors were found to be insignificant. © 2021 Elsevier B.V.