Browsing by Subject "carbon fiber"

Now showing 1 - 11 of 11

The Application of Composite Through-Thickness Assessment to Additively Manufactured Structures
(University of Texas at Austin, 2017) Bitar, Isam S.; Aboulkhair, Nesma T.; Leach, Richard
This study looks into the applicability of through-thickness assessment to additive manufacturing (AM) carbon-fibre reinforced polymers (CFRPs). The study utilised a material extrusion printer that uses fused filament fabrication and composite filament fabrication technologies to manufacture functionally-graded polymer and composite polymer parts. The matrix material of choice was nylon 6. Samples were printed exploring a range of reinforcement volume content. In summary, this study presents an assessment of the applicability of through-thickness testing to AM CFRP specimens and provides a performance comparison between AM composite through-thickness properties and the properties of equivalent CM CFRP specimens.
Development of Processing Parameters for the Selective Laser Sintering of Carbon Fiber Reinforced Polyphenylene
(2022) Snarr, Scott E.; Snarr, Patrick L.; Beaman, Joseph Jr
The ongoing development of processing parameters for advanced thermoplastic materials to be fabricated via selective laser sintering (SLS) is rapidly advancing the potential industrial applications of the manufacturing method. This research focuses on the development of SLS processing parameters and a tooling application for carbon fiber reinforced Polyphenylene Sulfide (CF-PPS), a composite material that is novel to SLS. A high temperature SLS research machine was used to identify suitable processing parameters for the material along with the tensile strength and geometrical accuracy associated with those parameters. Utilizing the previously identified parameters, a repair mold for an electronic cable assembly was fabricated. Mechanical tests were performed on fabricated CF-PPS parts to evaluate the performance of the material under the mold’s normal operating conditions. The additively manufactured CF-PPS mold was deemed viable for production and was shipped to our sponsor for further evaluation.
The Effect of Polymer Melt Rheology on Predicted Die Swell and Fiber Orientation in Fused Filament Fabrication Nozzle Flow
(University of Texas at Austin, 2017) Wang, Z.; Smith, D.E.
Short carbon fibers suspended in the polymer feedstock enhances the mechanical performance of products produced with Fused Filament Fabrication (FFF). As the melted filament is extruded and deposited on a moving platform, the velocity gradients within the polymer melt flow orientate the fibers, and the final orientation has a direct effect on the mechanical properties of printed bead. This paper numerically simulates an FFF nozzle flow, including the extrudate material beyond the nozzle exit. Finite element simulations of the extrusion process are performed with Generalized Newtonian Fluid (GNF) models and a viscoelastic rheology model, included in ANSYS Polyflow, to evaluate the polymer melt velocity field and predict die swell. Fiber orientation tensors are computed along streamlines using the Fast Exact Closure and Folgar-Tucker isotropic rotary diffusion. The predictions indicate that shear thinning behavior reduces the die swell but viscoelastic rheology significantly intensifies the extrudate swell. Orientation tensor values calculated from the flow results of the viscoelastic model yields lower principal alignment in printed beads than those computed with GNF models.
A High-Performance Material for Aerospace Applications: Development of Carbon Fiber Filled PEKK for Laser Sintering
(University of Texas at Austin, 2016) Fischer, S.; Pfister, A.; Galitz, V.; Lyons, B.; Robinson, C.; Rupel, K.; Booth, R.; Kubiak, S.
In a time where rapid prototyping successively transforms to additive manufacturing (AM), nylon 11 and 12 and their composite powders, which have evolved to be the most commonly used materials in laser sintering (LS) due to their easy processability, cannot fulfil all challenging requirements of industrial applications any more. Especially in the aerospace industry, there is a high demand for stiff and lightweight parts for interiors, which currently are fabricated from glass fiber reinforced phenolic and epoxy resins by a lamination process. Due to the strong diversity of the parts, this traditional manufacturing is quite labor-intensive and expensive, which makes it very attractive to manufacture these parts with additive manufacturing, especially laser sintering. Additional part design requirements, such as greater chemical and UV resistance, an elevated softening temperature, higher mechanical strength and better performance in flammability and heat release tests generate opportunities for the use of high performance AM polymers. Promising candidates that have the potential of satisfying these demands can be found among the different Polyaryletherketone thermoplastics. In this work we present the development of a carbon fiber filled PEKK composite material for laser sintering, optimized especially for the production of interiors, such as air ducts for cabin ventilation in aerospace application. Based on process tests, powder characterization and test builds, the material and its manufacturing procedure were optimized towards isotropic properties and refreshability. Simulations of building cycles helped to understand the extent of powder ageing, which is directly connected to the ability to recycle the material. Furthermore the laser sintering hardware of an EOSINT P800 and the building processes were adapted to ensure a stable building process and fulfill the requirements of parts on mechanical properties in x, y and z directions, dimensional stability and surface quality.
Material Selection on Laser Sintered Stab Resistance Body Armor
(University of Texas at Austin, 2017) Yuan, Mengqi; Liu, Yu; Qian, Xinming
Stab resistant body armor (SRBA) is essential defensive equipment to protect the human body from injury due to stabbing. The conventional SRBAs are heavy and inflexible. Therefore a new type of SRBA has been recently developed using Laser Sintering (LS), which has resulted in a substantial improvement to SRBA in terms of structure and material design. In this development, carbon fiber was employed in the polyamide matrix to obtain the optimal stab resistant performances. Four kinds of materials were used and showed that the polyamide/carbon fiber (PA/CF) composite improved the stab resistance property compared to pure polyamide (PA). The stab resistance performances of flat plates were weaker than structured plates. The penetration depth of the PA/CF structured plate was 2 mm less than the pure PA structured plate. SEM observations of the products confirmed experimental conclusions that the addition of the CF largely improved the plate stab resistance. Moreover, using the PA/CF structured plate to produce SRBA would reduce the weight of the product by 30-40% comparing to the conventional SRBA, which would greatly reduce the physical burden to the wearer and largely improve the chance that the armor would be used.
Mechanical Behavior of Carbon Fiber Composites Produced with Fused Filament Fabrication
(University of Texas at Austin, 2016) Jiang, D.; Smith, D.E.
Fused Filament Fabrication (FFF) is a commonly used Additive Manufacturing (AM) technique. However, the printed parts often lack sufficient mechanical integrity. Recently, mechanical properties of FFF filament have been enhanced by blending pure polymer with short carbon fibers. This paper presents a study of the mechanical properties for carbon fiber filled (CFF) FFF parts produced with Makerbot printers. Polymer composite and pure polymer tensile test coupons are printed and then tested following ASTM D3039M. Here we consider FFF print orientations that are aligned with the test bar axis at 0 degree, 45 degrees, ±45 degrees, and normal to the bar axis at 90 degrees. The filament considered here was purchased from filament suppliers and included PLA, ABS, and PETG. Results are presented for tensile strength and tensile modulus. Additionally, short fiber composite samples are evaluated for fiber length distribution (FLD) and fiber weight fraction. Fracture surfaces are evaluated under SEM.
MODELING CARBON FIBER SUSPENSION DYNAMICS FOR ADDITIVE MANUFACTURING POLYMER MELT FLOWS
(University of Texas at Austin, 2023) Pierce, Jason B.; Smith, Douglas E.
The addition of short carbon fibers to the feedstock of large-scale polymer extrusion/deposition additive manufacturing results in significant increases in mechanical properties dependent on the fiber distribution and orientation in the beads. In order to analyze those factors, a coupled computational fluid dynamics (CFD) and discrete element modeling (DEM) approach is developed to simulate the behavior of fibers in an extrusion/deposition nozzle flow after calibrations in simple shear flows. The DEM model uses bonded discrete particles to make up flexible and breakable fibers that are first calibrated to match Jeffery’s orbit and to produce interactions that are consistent with Advani-Tucker orientation tensor predictions. The DEM/CFD model is then used to simulate the processing of fiber suspensions in the variable flow and geometries present in extrusion/deposition nozzles. The computed results provide enhanced insight into the evolution of fiber orientation and distribution during extrusion/deposition as compared to existing models through individual fiber tracking over time and space on multiple parameters of interest such as orientation, flexure, and contact forces.
Parameter Optimization for Preparing Carbon Fiber/Epoxy Composites by Selective Laser Sintering
(University of Texas at Austin, 2015) Zhu, Wei; Yan, Chunze; Yang, Jiayi; Wen, Shifeng; Shi, Yusheng
Carbon fiber (CF) reinforced thermosetting resin composites offer a wide range of high performance features including excellent strength, modulus and thermal resistance and light weight. Consequently, they are increasingly demanded by aerospace and automotive industries due to the tighter requirements of the transport vehicles for lightweight as well as higher payloads. Although thermoplastics and their composites have been widely used in additive manufacturing (AM), to date it is difficult to manufacture carbon fibers reinforced thermosetting composite parts via AM technologies. Therefore, this study developed a novel method based on selective laser sintering (SLS) to fabricate high-performance carbon fiber/epoxy resin composites. The response surface method was employed to study the processing parameters affecting the quality of final parts, and an optimized processing condition was obtained.
Thermal Analysis of Thermoplastic Materials Filled with Chopped Fiber for Large Area 3D Printing
(University of Texas at Austin, 2019) Billah, Kazi Md Masum; Lorenzana, Fernando A.R.; Martinez, Nikki L.; Chacon, Sarah; Wicker, Ryan B.; Espalin, David
At room temperature, material extrusion, in the context of large area fabrication, requires thermally stable materials and, as a result, fillers are included to tailor the thermal behavior. This research investigated the thermophysical properties of neat ABS and short carbon fiber (CF) reinforced ABS. Thermogravimetric analysis, differential scanning calorimetry, and thermomechanical analysis were carried out to determine the thermophysical properties. The addition of CF (20 wt. %) to an ABS matrix caused the glass transition temperature to change slightly (110 °C to 105 °C). Also, the CF within the ABS matrix reduced the thermal stability by decreasing the degradation on set temperature by (323 °C to 253 °C). Thermal deformation analysis showed that large area pellet extruded AM machine produces highly anisotropic materials. Thermomechanical analysis results showed that the coefficient of thermal expansion (CTE) reduced 4 times in the perpendicular to the extruded direction. The dataset and knowledge from the thermal analysis can be useful to design optimized printing parameters for highly filled thermoplastics used in large area 3D printing machines.
Towards a Micromechanics Model for Continuous Carbon Fiber Composite 3D Printed Parts
(University of Texas at Austin, 2019) Abdullahi, Adnan; Kankam, Immanuella; Gahloth, Abhay Singh; Arora, Bhavya; Agarwal, Ankit; Eppley, Trevor; Salti, Ziyad; Goss, Derek; Sharma, Raghav; Bhate, Dhruv
Material extrusion is transitioning from a technology mainly for rapid prototyping to one that is increasingly finding use in manufacturing functional parts. Of particular interest in this regard is the reinforcement of extruded parts with Continuous Carbon Fiber (CCF). However, predicting the effective properties of 3D printed composite parts presents a unique challenge because of the strong effects of meso-structure on the mechanical behavior of printed parts. This work aims to develop a mathematical model that would enable such a prediction of behavior by incorporating the rule of mixtures commonly used in micromechanics modeling. Results from tensile tests on composite specimens with varying volume fractions produced from a blend of onyx (nylon and chopped carbon fiber) and CCF are reported. Volume fractions are varied through a range of factors including the layers with fiber, the distribution of fiber within layers and the angle of the fibers relative to the loading direction, though findings suggest that this has no significant influence on the model itself, and that volume fraction is a sufficient parameter. The predictive ability of the micromechanics model is put to the test for composite honeycombs under compression, and a wide discrepancy between model and experimental result is demonstrated, demonstrating the limitations of such a model and suggesting pathways for improvement.
Ultrasonic Embedding of Continuous Carbon Fiber into 3D printed Thermoplastic Parts
(University of Texas at Austin, 2019) Billah, Kazi Md Masum; Coronel, Jose L. Jr.; Chacon, Sarah; Wicker, Ryan B.; Espalin, David
A novel multimaterial fabrication process was developed to embed continuous bundles of carbon fiber (CF) into polycarbonate (PC) substrates using ultrasonic energy. Continuous CF possesses superior reinforcement properties compared to that of chopped or short fibers. In this research, dry continuous CF bundles were impregnated with a PC solution prior to embedding. Three printing raster orientations were studied (0°, 45°, and 90°), where three layers of CCF were embedded within each test specimen. Characterizations including tensile, flexural, and dynamic mechanical analysis were carried out to investigate reinforcement related properties. Results showed an increase in ultimate tensile strength between neat PC (37 MPa) and CF reinforced specimens (141 MPa). An automated ultrasonic embedding process allowed for the selective deposition of CF, regardless of the raster orientation. Future development of continuous CF reinforced parts could enable smart part fabrication, with applications in structural health monitoring, microwave shielding, and thermal management.