3D Printing

Abstract

The additively manufacturing industry is emerging rather quickly and has find its way within numerous fields of expertise. Slowly the building industry is adopting these fabrication methods as well, but there are still a lot of challenges. Especially the bonds within the layered structure are demand more research. Numerous researches have acknowledged the importance of the bonding strength, but only a few have actually examined its mechanical properties of the bonds.
A distinction between the interlayer and intralayer bonds is made. The former indicates the bonds between vertically stacked layers, while the latter is related to the coalescence between filament within one lamina. This report assesses the relevance of the intralayer bonding strength for extrusion-based additive manufacturing by the large-scale printers of company Aectual. Firstly, the complete fabrication process and the relevant parameters for the construction of 3D printed object are elaborated. Based on the layered structure of prints and regarding the desired geometries, the
additively manufactured products are linked to Unidirectional Fibre Reinforced Composites. Subsequently, the international standards of the ISO and the ASTM are consulted for the design of the test specimens for the estimation of the material properties of interest, namely the tensile and
flexural test for general understanding of the mechanical behaviour of the material and a test method for the Interlaminar Fracture Toughness to evaluate the intralayer bond strength.
As the preliminary have shown promising result, the print geometry and the printing settings are optimised to achieve a high print quality and reliable test result as uniform as possible. The results of the flexural and tensile test indicated that this optimisation have proven to be successful. Despite the high number of test specimen, the interlaminar fracture toughness of the intralayer bond is not quantified. The post-processing of the insert relevant for delamination affected the crack front and reduced the probability of deformation. Nevertheless, almost 30% of the samples have delaminated
and have confirmed the dependability of the bonding strength on the height of the print and the printed pattern. Moreover, the print orientation appears to be of significant relevance. Finally, this research appoints the importance of the intralayer bonds for the mechanical behaviour of the total product as well as for the further development of 3D printed structural elements.