Investigating the fatigue and mechanical behaviour of 3D printed woven and nonwoven continuous carbon fibre reinforced polymer (CFRP) composites

This paper evaluates the mechanical properties of woven continuous carbon fibre composites printed by additive manufacturing (AM). Comparison mechanical test studies (tensile, flexural and fatigue) were carried out with two nonwoven AM printed composites (unidirectional and multidirectional fibres), along with those of both a woven composite, as well as a composite reinforced using chopped carbon fibres. Compared with the 17 MPa tensile strength obtained for the chopped fibre composite, the average strength of unidirectional (nonwoven), multidirectional (nonwoven) and woven fibre composites were 39, 13 and 19-fold higher, respectively. The tensile strength of the woven composites was 52% lower than that attained by the unidirectional (nonwoven) fibre composites; and 38% higher than the multidirectional (nonwoven) fibre composites. A comparison was also made between the flexural and fatigue performance of the unidirectional (nonwoven) and woven fibre composites. The flexural strength of the latter was approximately 39% lower than the nonwoven composites, however, the load bearing capacity of woven fibre was superior. This performance difference was supported by the fatigue testing results. At 70% of maximum tensile load capacity after 2 x 10(5) cycles, the nonwoven composites failed, while the woven composites continued to perform until a level of 85% of maximum load capacity was reached. The superior fatigue strength of the AM fabricated woven carbon fibre composites, demonstrates their potential for use in high cyclic load applications.