•typically used for the rapid prototyping of conceptual models geometries with metals, polymers, and more recently with fiber reinforced composite materials.

•Printed composites will display a unique microstructure with morphological features and process artifacts that manifest on multiple length scale.

2. Decrease in materials waste

3. Potential for use in little field -able manufacture units

4. Capacity to create changed structures without retooling

5. Low manufacturing cost

1.How is the microstructure of various printed continuous fiber composite?

2.What is the linkages to consequent mechanical properties?

• Fiber volume ration (using thermogravimetric analysis)

• Hierarchical microstructure (using scanning electron microscopy and optical microscopy)

•Another advantage: nylon reinforced with 14% carbon is only half the weight of aluminium alloys.

•Cannot compare the mechanical strength between 3D printed composite and traditionally prepared composite because printed composite consisted of significantly low fiber amount unlike traditionally prepared composite. (fiber provide toughening mechanism to strengthen the composite- if fiber volume fraction is increased, then the failure strain will also be increased). Solution: future effort to enhance fiber volume ration and explore effect of higher fiber content in 3D printed composites.

•Reason: printing introduce several hierarchies of microstructure to composite materials. (proof: SEM observation identify unique features of printed microstructure which occur on length scales 10μm-milimetre)s

1. Full volume of printed materials was essentially filled line by line then layer by layer. Curing does not occur simultaneously through the parts then new material are printed on partially cured material (incomplete interdiffusion when microstructural created – mechanical properties were diminished- interfaced in multiple scales lead to imperfect fusion between the tow segments and surrounding polymer matrix)

2. Printed polymer was not degassed (micro-voids occur at consolidated parts). 

1. Incorporation of resin degassing

2. Apply post-cure stage to attempt to alleviate the extra interface

3. For poor fiber-matrix interface, apply fiber sizer or surface treatment (potentially to help improve the toughness of the composite- cons: will decrease quadratic stiffness)

•Carbon fiber reinforced has the highest strength but the lowest strain to failure (because of carbon content-its properties)

•Kevlar reinforced composite shows enhance in elongation at fracture (Kevlar has high ductility)

•Fiber alignment play roles in mechanical strength. At 0° direction (unidirectional), the material has 3 times strength than at 45° direction.

•Process parameter such as printing temperature, nozzle geometries, built plate temperature, moisture content can affect microstructure and mechanical properties of the printed materials. 

•The samples were investigated in microstructures and mechanical properties, relationships between fiber content to deploy 3D-printed materials as alternatives to higher-strength components.

•Further investigation showed that 3D-printed polymers’ component are dedicated to fail at lower stresses due to specific microstructural defects during additive manufacturing. It proved that 3D-printed materials are weaker than traditionally manufactured materials due to the mechanical properties such as stiffness and strength

•Future studies will focus on how  to develop if there are any such effects through process modifications and post-processing that can be improved for a printing process.

•Izzudin, Z. et. al. (2010). Influence of Fiber Volume Fraction on The Tensile Properties and Dynamic Characteristics of Coconut Fiber Reinforced Composite. Journal of Science and Technology UTHM. Johor, Malaysia.

•Layth, M. et al. (2015). A Review on Natural Fiber Reinforced Polymer Composite and Its Applications. International Journal of Polymer Science. Pg 1-15. DOI: https://doi.org/10.1155/2015/243947

•Quan Z, et al. Microstructural design and additive manufacturing and characterization of 3D orthogonal short carbon fiber/acrylonitrile-butadiene-styrene preform and composite. Compos Sci Technol 2016; 126: 139–148. 

•Christ S, et al. Fiber reinforcement during 3D printing. Mater Lett 2015; 139: 165–168.

Purpose of research:
•To investigate the mechanical properties of 3D-printed fiber-reinforced composites

•To understand the unique microstructure of printed continuous fiber-reinforced composites

•To understand how microstructure can affect mechanical properties of the 3D-printed fiber-reinforced composites.