An Internal Architecture-Based Strategy to Mitigate Delamination and Improve Flexural Capacity of Composite Beam Structures

Abstract

Delamination is an important failure mechanism that can limit the flexural response of laminated composite beam structures, particularly when increased section depth raises the demand on interlaminar load transfer. This study investigated an internal architecture-based strategy for reducing visible delamination at first failure and improving the flexural response of additively manufactured composite beams. Six beam configurations were manufactured using nylon as the matrix material and continuous carbon fibre as the reinforcing phase. Two reference beams, with depths of 20 mm and 30 mm, were produced without internal nylon corridors. Four modified beams were produced by introducing single or multiple nylon corridor arrangements within selected carbon-fibre reinforced regions. All specimens had a width of 19 mm and were tested under three-point bending over a 100 mm span using displacement-controlled loading. The observed first failure load and mode, load-displacement response, and relative manufacturing cost were evaluated. For the 20 mm deep specimens, the modified B3 and B5 configurations increased the first failure load by approximately 12% compared with the corresponding reference beam. The B5 specimen also changed the observed first failure mode from delamination to flexural failure without visible delamination. For the 30 mm deep specimens, the B4 and B6 configurations increased the first failure load by approximately 45% and 42%, respectively, and both showed flexural failure without visible delamination at first failure. The modified configurations also reduced the software-estimated manufacturing cost by decreasing the amount of continuous carbon-fibre reinforcement. The results suggest that internal nylon corridor arrangements may improve material efficiency and influence the failure response of continuous carbon-fibre reinforced composite beams. However, the findings should be interpreted as preliminary because one specimen was tested for each configuration.