2023 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2023): Fiber Composites
Program Organizers: Joseph Beaman, University of Texas at Austin
Tuesday 8:15 AM
August 15, 2023
Room: 616 AB
Location: Hilton Austin
Session Chair: Roneisha Haney, Air Force Research Laboratory; John Pappas, Missouri University of Science and Technology
8:15 AM
3D Printing of Continuous Stainless Steel Fiber Reinforced Polymer Composites: Alison Clarke1; 1University College Dublin
This study investigates for the first time, the incorporation of stainless steel fibers (SSF), as a reinforcement for 3D printed polymer parts. The steel fibre bundle contains 90 fibers each of 14 µm diameter. Polylactic acid (PLA) is co-extruded with the SSF to fabricate PLA-SSF filaments, with a diameter of approximately 0.5 mm. A fused filament fabrication technique was used to print composites, with a fibre volume fraction of up to 30%. Good polymer ingress around the individual steel fibers was demonstrated and part porosity levels down to 2%, were achieved (based on CT scans). Particular attention was given to achieving a homogeneous distribution of the steel fibers within the printed PLA-SSF composites. The composites' exhibited a six-fold increase in interlaminar shear strength (ILSS), compared with PLA only parts. The values obtained of up to 28.5 MPa are significantly higher than the approx. 13 MPa obtained for glass fibre composites.
8:35 AM
3D Printing of High-performance Carbon Fiber Composites via Modified Drop-on-demand Method: John Pappas1; Xiangyang Dong1; 1Missouri University of Science and Technology
This study presents a novel method to fabricate high-strength, continuous-fiber composites through a hybrid drop-on-demand and stereolithography technique. Photopolymer resin was selectively applied onto strategically placed carbon fiber. Control of the composite fiber volume fraction was achieved through compression of the resin-infused carbon-fiber layer using a custom glass plate. Laser-assisted curing resulted in high-resolution semi-cured continuous fiber composites. A thermal post-curing procedure was utilized to achieve the final properties of the printed composites. The effect of electrophoretically deposited nanoporous carbon-nanotube coatings was also investigated to evaluate resin impregnation efficiency due to capillary forces, and hence mechanical properties by three-point bending test on printed test specimens. The microstructure of the resulting composites was also characterized. This study demonstrated the feasibility of fabricating high-performance carbon fiber composites using drop-on-demand printing techniques, while providing potential for customization of mechanical properties through control of fiber placement.
8:55 AM Cancelled
Core-shell-structured High Strength Composite with 3D Aligned Carbon Fiber via Embedded 3D Printing: Qiyi Chen1; 1University of California, Berkeley
The orientation of carbon fibers, induced by shear forces during extrusion, has been demonstrated to significantly enhance mechanical properties, albeit primarily in a two-dimensional (2D) x-y plane. In this study, we present a novel approach for achieving fiber alignment in a three-dimensional (3D) context, with an emphasis on the Z-direction, by utilizing embedded 3D printing techniques. This process involves the extrusion and suspension of composite inks within a viscoelastic gel medium. The embedded printing technique enables the creation of complex architectures that exhibit well-known high-strength characteristics, such as the octet lattice structure. Furthermore, by tailoring specific formulations of elastic-gel resin and stiff-ink resin, we generate an elastic core-stiff shell structure featuring covalent adhesion, which concurrently exhibits remarkable strength and toughness properties.
9:15 AM
Effect of the Print Bed Temperature on Void Distribution and Fiber Orientation within the Microstructure of Short Carbon Fiber Reinforced/ABS Manufactured via Large Area Additive Manufacturing: Neshat Sayah1; Douglas Smith1; 1Baylor University
Short carbon fiber-reinforced polymer composite structures produced using Large Area Additive Manufacturing (LAAM) have garnered significant attention due to the design flexibility, energy savings, and materials selection associated with this process. However, the physical and mechanical properties of the additively manufactured composite parts often fall below expectations due to void formation between printed beads and within the microstructure of individual beads. This study aims to investigate the effect of bed temperature on the microstructure within the beads of two bead layer Short Carbon Fiber reinforced Acrylonitrile Butadiene Styrene (SCF/ABS) manufactured via the LAAM system. This study employs high-resolution 3D micro-computed tomography (µCT) to evaluate the void shape, and distribution within the microstructure of composite parts printed at various bed temperatures. The results of this study demonstrate substantial variation in the void volume fraction among four bead sets deposited at different print bed temperatures. Moreover, within each part, a noticeable discrepancy in void volume fraction is observed between the top and bottom bead of the two-bead test samples. Preliminary results indicate that increasing the bed temperature from 25°C to 75°C reduces void volume fraction within the microstructure of the composite parts. However, an opposite trend emerges when the bed temperature is further increased to 100°C, increasing void volume fraction, which needs further investigation to understand. This study also evaluated the void shapes through the calculation of their sphericity. The preliminary results reveal that as the bed temperature is increased from 25°C to 75°C, the voids exhibit higher sphericity within the printed parts as the amount of interconnected voids decrease.
9:35 AM Cancelled
Direct Ink Writing of Frontally Polymerized Polymer Matrix Reinforced with Continuous Carbon Fiber Tows: Nadim Hmeidat1; Michael Zakoworotny1; Philippe Geubelle1; Sameh Tawfick1; Nancy Sottos1; 1University of Illinois Urbana-Champaign
The development of next-generation high-performance polymer composites for advanced manufacturing demands rapid, versatile, and energy-efficient manufacturing strategies. This work presents a novel approach for the fabrication of frontally-polymerized continuous carbon fiber-reinforced thermoset tows. The proposed process combines the advantages of direct ink writing, pultrusion and frontal-polymerization to enable tow extrusion and consolidation, in-situ curing, and rapid manufacturing of free-standing composite members with reduced processing time, energy, and cost. In this process, a pre-impregnated fiber tow is extruded and then pulled through heated rollers to compact the tow, cure the resin, and form the composite. We investigate the effects of compaction, extrusion rate, and roller temperature on the cure kinetics, front location, fiber volume fraction, and thermo-mechanical properties of the resulting composites. A homogenized thermo-chemical model is developed to capture the effect of process parameters on heat transfer in the tow and curing of the resin, and is compared with experiments.
9:55 AM Break
10:25 AM
Machine Learning-Assisted Prediction of Fatigue Behaviour in Fiber-Reinforced Composites Manufactured via Material Extrusion: Mithila Rajeshirke1; Suhas Alkunte1; Orkhan Huseynov1; Ismail Fidan1; 1Tennessee Tech University
The recent advancements in material extrusion (MEX) have expanded the potential use of polymeric and composite structures in a wide range of structural and load-bearing applications. However, cyclic loads can induce fatigue, resulting in the development of structural damage and potentially leading to catastrophic failure at lower stress levels compared to normal mechanical loading. Therefore, it is crucial to thoroughly investigate and understand the fatigue behavior of composite parts manufactured using MEX. Predicting the fatigue life of polymeric composite components poses a significant challenge due to the complex nature of the materials involved. In this research, the aim is to utilize machine learning techniques to predict the fatigue life of fiber-reinforced composites produced through the MEX process. Machine learning (ML) focuses on developing models that can learn from data, recognize underlying patterns within the data, and use those patterns to make accurate predictions or decisions.
10:45 AM
Process and Material Optimisations for Integration of Chopped Glass Fibres in Laser Sintered Polymer Parts: Hellen De Coninck1; Arnout Dejans1; Sebastian Meyers1; Sam Buls1; Yannis Kinds1; Jeroen Soete1; Peter Van Puyvelde1; Brecht Van Hooreweder1; 1KU Leuven
Additively manufactured polymer composites gain popularity in a variety of industries such as aerospace, biomedical and automotive. Laser sintering (LS) is a well-known AM process that typically uses polyamide which can serve as matrix material. Hence, LS has potential to produce reinforced polymers that can meet demanding requirements. In previous research, issues with powder flowability and poor fibre dispersion led to limited increase of mechanical properties. To overcome this, a novel fibre deposition system was recently developed and optimised at KU Leuven to successfully produce fibre reinforced LS samples with random inter- and intralayer fibre orientations. A limited but promising influence of deposited glass fibres on produced LS parts was noted after mechanical testing. In this work, the influence of different (heat) treatments on glass fibres used during LS will be discussed as well as the resulting differences in the fibre/matrix behaviour as analysed by means of hot stage microscopy.
11:05 AM Cancelled
Additive Manufacturing of Continuously Reinforced Thermally Curable Thermoset Composite: Kelvin Fu1; 1University of Delaware
Additive manufacturing of lightweight and energy-efficient composite using continuous fibers to reinforce thermoset polymers is highly desirable. However, the material, architectural, and technical limitations make existing AM technologies unavailable for printing structural and functional thermoset/continuous carbon fiber composite. In our work, we overcome these difficulties and introduced a new AM technology by creating a controllable resin system and a dynamic curing window to enable fast solidification of composite to hold the shape, realizing a feasible 3D printing of thermoset/continuous carbon fiber composite with near net shape, complex geometry, and programmable performance. Our process enables us to print composite with overhanding structure in free space, without need for support material. This AM technology provides a new 3D printing concept and process knowledge beyond existing AM technologies to potentially enable high throughput processing and geometric complexity of printed composite, and could promisingly produce a transformative impact on the upgrade of additive manufacturing.