Delamination Strength Comparison of Additively Manufactured Composite Curved Beams Using Continuous Fibers.

The objective of this study is to show the applicability of various 3D-printed composite curved beams using continuous fibers and their delamination strength when they are subjected to bending loading. Four-point bending tests are configured for comparative research on evaluating the effect of fiber types on the delamination strength and failure mode. Out-of-plane tensile properties are calculated analytically by using experimental data. The number of curved beams per build during multiple printing is examined to observe the effect of delay time between each deposited layer of parts. Macro-scale finite element simulations including surface-based cohesive concept for the selected 3D-printed composite curved beam design are also presented and compared. The analytical results show that carbon fiber reinforced curved beam design is superior to the other fiber types by at least 18% in the interlaminar tensile strength and is relatively challenging against the conventionally manufactured composite curved beams in the literature despite its low fiber volume ratio. There is no gross effect of delay time between each deposited layer of parts, although printing a single sample is favorable for better strength. There is a presence of compatibility between the analytical and numerical results as the percentage difference for maximum load, radial tensile strength and maximum displacement are found as 1.8%, 2.4% and 1.5%, respectively, in a 3D cohesive model. A 2D cohesive model offers a fast solution and a competitive agreement with test results when the 2D and 3D finite element models are compared.