Continuous Fiber-Reinforced Material Extrusion with Hybrid Composites of Carbon and Aramid Fibers

Abstract

An existing challenge in the use of continuous fiber reinforcements in additively manufactured parts is the limited availability of suitable fiber materials. This leads to a reduced adaptability of the mechanical properties to the load case. The increased design freedom of additive manufacturing allows the flexible deposition of fiber strands at defined positions, so that even different fiber materials can be easily combined in a printed part. In this work, therefore, an approach is taken to combine carbon and aramid fibers in printed composite parts to investigate their effects on mechanical properties. For this purpose, tensile, flexural and impact tests were performed on printed composite parts made of carbon and aramid fibers in a nylon matrix with five different mixing ratios. The tests showed that the use of hybrid composites for additive manufacturing is a reasonable approach to adapt the mechanical properties to the loading case at hand. The experiments showed that increasing the aramid fiber content resulted in an increase in impact strength, but a decrease in tensile and flexural strength and a decrease in stiffness. Microstructural investigations of the fracture surfaces showed that debonding and delamination were the main failure mechanisms. Finally, Rule of Hybrid Mixture equations were applied to predict the mechanical properties at different mixture ratios. This resulted in predicted values that differed from the experimentally determined values by an average of 5.6%.

Experimental and Numerical Investigation of the Mechanical Properties of 3D-Printed Hybrid and Non-Hybrid Composites

“…Rajpurohit et al [44] also determined a negative hybrid effect for the failure strain for conventional intraply specimens with glass and carbon fiber reinforcement, whereas specimens in the interply approach resulted in an improvement in the failure strain. Additively manufactured tensile specimens in the interply approach [26] and intrayarn approach [28] also showed improvements in failure strains. This could be related to a limitation of damage propagation in the carbon fiber layers in the case of specimens fabricated using the interply approach, as suggested by Rajpurohit et al [44].…”

“…Haung und Joosten [25] investigated printed hybrid composites of glass and carbon fibers to obtain a pseudo-ductile material behavior. In [26], a study was presented in which the mechanical properties of printed hybrid composites consisting of aramid and carbon fiber were determined using tensile, flexural, and impact tests. The hybridization of carbon fiber-reinforced specimens with aramid fibers led to a decrease in tensile, flexural strengths, and stiffnesses, but a significant increase in impact strength.…”

A perspective on biodegradable polymer biocomposites - from processing to degradation

“…For such continuous fibres, the use of a thermoforming approach is commonly adopted. More recent techniques are also being developed, such as 3D printing incorporating continuous fibres either by merging the continuous fibres in the printhead with the surrounding thermoplastic matrix and then depositing them on the print bed or by pre-impregnating continuous fibre filaments in the thermoplastic matrix and immediately extruding [49]. For short-and long-fibre reinforced biocomposites, the most commonly used processes overall are compression moulding, injection moulding, and extrusion.…”

Effects of process parameters on mechanical properties and interface of 3D printed bamboo‐inspired CCFR‐PLA/TPU composites

“…Additive manufacturing technology, known for its low cost and flexibility, offers a new way for the preparation of CFR composite parts. [25][26][27][28][29] When the CFR composites consisting of a single matrix and a single fiber fail to meet the desired performance, commonly employed approaches include fiber hybridization [30][31][32] and matrix modification. 33,34 Matrix modification encompasses techniques such as filler addition (e.g., nanomaterials, 35,36 ceramic particles, 37 and staple fibers 38,39 ) and blending multiple matrices.…”