Fused Deposition Modeling (FDM) is a widely used additive manufacturing technology for fabrication of complex geometric parts using thermoplastic polymers. The quality issues and inferior properties ...of fabricated parts limited this process to manufacture parts for industrial level applications. Reinforcing the polymer with nanoparticles, short fibers or continuous fibers improve mechanical, thermal and electrical properties compared to the neat polymer. Several works have been carried out since last two decades to print quality products through FDM by using composite materials. The success of expanding this technique to industrial applications depends on the preparation of printable composite feedstock filament and printing without defects. This article reviews the challenges involved in the preparation of composite feedstock filaments and printing issues during the printing of nano composites, short and continuous fiber composites. The printing process of various thermoplastic composites ranging from amorphous to crystalline polymers is discussed. Also, detailed explanation is given about the analytical and numerical models used for simulating the FDM printing process and for estimating the mechanical properties of the printed parts. This critical review mainly helps the young researchers working in the area of processing of composite materials via 3D printing.
In this study, continuous carbon-fiber reinforced thermosetting composites were prepared using 3D printing followed by characterization of their mechanical properties. First, a 3D printing platform ...was fabricated to prepare the composites based on Fused Deposition Modeling (FDM). Then, the composites lamina and grids were manufactured using a FDM-based platform. Finally, the mechanical properties of the composite lamina were characterized. The results showed that the mechanical performance of the 3D printed thermosetting composites was superior to that of similar 3D printed thermoplastic composites and 3D printed short carbon fiber reinforced composites.
•A 3D printing platform was fabricated to prepare the thermosetting composites.•The composites lamina and grids were manufactured using a FDM-based platform.•The mechanical properties of the composite lamina were characterized.•The mechanical properties of these novel printed thermosetting composites were better than others.
•Fracture and tensile tests were performed on 3D-printed PLA samples.•Effects of in-plane raster orientation on tensile and fracture strengths were studied.•Maximum fracture strength was found for ...specimens with 45/−45° raster orientation.•Path of crack extension was dependent on the printed raster orientation.•Failure mechanisms involved in different raster orientations were studied using SEM pictures.
The present paper studies the effect of in-plane raster orientation on the tensile and fracture strengths of poly-lactic acid (PLA) samples made by fused deposition modeling technique. Four different raster angles of 0/90°, 15/−75°, 30/−60°, and 45/−45° are selected for the dog-bone and the semi-circular bending (SCB) specimens to investigate the tensile and mode I fracture behavior of the 3D-printed PLAs. The results demonstrate anisotropic behavior in the both tensile and fracture properties of the material. Additionally, due to the plastic deformations of the material prior to the fracture initiation load, the J-integral is selected as the fracture characterizing parameter. To do so, some elastic-plastic finite element simulations were performed to obtain the critical values of J-integral. The raster orientation of 45/−45° exhibits the best performance with maximum percent elongation and fracture resistance compared with the three other raster angles. While the critical J-integral of 45/−45° sample is 6815 J/m2, this value is 1839 J/m2 for 0/90° sample. In addition, in the samples used for fracture tests, the crack growth path is investigated to analyze the effect of raster orientation on the fracture trajectories of the SCB specimens. Based on the observed crack growth trajectories, the difference between the fracture loads and the amounts of plastic deformation in the SCB samples with different raster orientations are justified. Finally, the scanning electron microscopy (SEM) is utilized to explore the failure mechanism in the dog-bone samples.
•A new pressure sensor was developed based on fiber Bragg grating (FBG) sensor and fused deposition modelling process.•Measurement range and measurement sensitivity of this new FBG pressure sensor ...are 0–800 kPa and 4.26 kPa/pm, respectively.•This pressure sensor is characterized by the advantages of quick encapsulation and ease of fabrication.
Fused deposition modelling (FDM) is a popular technology used for modeling, prototyping, and production applications. In this study, a simple fiber Bragg grating (FBG) based pressure sensor was fabricated using FDM process for monitoring vertical pressures. Raw material used for the fabrication of the pressure sensor was Polylactic Acid (PLA). Measurement performance of this FBG pressure sensor was validated by conducting cyclic loading tests on the FBG pressure sensor. Calibration tests indicate that the maximum measured vertical pressure of this new pressure sensor was 800 kPa with a measurement sensitivity of 4.26 kPa/pm. FMD process is found to be a simple and quick encapsulation method for the fabrication of FBG sensors. It is also found that FBG sensors can be successfully embedded into melted raw PLA materials without sacrificing its sensing performance.
Fused deposition modeling (FDM) has unique advantages in the rapid prototyping of thermoplastics which have been developed in diverse fields. However, although great efforts have been made to ...optimize FDM process, the mechanical properties of printed parts are limited by the weak interlamination bonding as well as the poor performance of raw filaments used, such as acrylonitrile butadiene styrene (ABS), polylactic acid (PLA). Adding fibers into thermoplastic matrix and preparing high-performance filaments have been indicated to enhance the properties of fabricated parts. Recently, heat-resistant polyetheretherketone (PEEK) and its fiber reinforced composites were proposed for FDM process due to overcoming the limitation of equipment and process. However, few researches have been reported on the effects of FDM-3D printing parameters on the mechanical properties of fiber reinforced PEEK composites. Therefore, 5wt% carbon fiber (CF) and glass fiber (GF) reinforced PEEK composite filaments were prepared respectively in this study. The effects of various printing parameters including nozzle temperature, platform temperature, printing speed and layer thickness on the mechanical properties (including tensile strength, flexural strength and impact strength) were surveyed. To analyze the microstructure and failure reasons of printed CF/PEEK and GF/PEEK samples, the tensile fractured surfaces were investigated via scanning electron microscope (SEM).
Fused deposition modeling (FDM) is one of the leading emerging technologies of Industry 4.0, which has been employed to develop sustainable engineering products, customized implants and sophisticated ...biomedical devices. However, the mechanical strength and durability of 3D printed parts is still lower than its conventional counterparts, which restrict its widespread use. In this regard, the use of short fibres (i.e. natural or artificial) and advanced nanomaterials to reinforce the existing polymer matrix has been drastically increased to improve the load bearing capacity of FDM printed parts. Hence, this article aims to provide a systematic review on thermoplastic composite structure prepared through FDM technology and summarizes the current knowledge about the use of various additives to improve the overall quality FDM parts. Moreover, the common defects associated with FDM printed composite structures and the methods required to improve the quality of FDM composite parts are discussed in this article.
The broad technological concept as so-called "hybrid additive manufacturing" is introduced into the fabrication of flexible strain sensing structure, employing the combination process of fused ...deposition modeling (FDM) 3D printing technique and ultrasonic cavitation-enabled treatment. We customize the FDM settings to print auxetic structures with a negative Poisson's ratio (NPR), using the flexible thermoplastic polyurethane (TPU) material. Then, we employ the ultrasonic cavitation-enabled treatment conducted towards the flexible auxetic structure immersing in carbon nanotubes (CNTs) liquid, aiming to embed the CNTs into the surface layer of the auxetic structures. It is equivalent to two additive manufacturing steps, proving effective in designing and fabricating flexible strain sensors. Instead of 3D printing after the hybridization of the TPU matrix material, this manufacturing procedure can ensure that the intrinsic excellent mechanical properties of TPU are not weakened due to the internally mixed conductive materials but able to exhibit usable sensing performances. The Poisson's ratio of the sensor structure is - 0.8. The sensor achieves over 300% strain. The sensitivity within the initial strain range is 2.661. The reliability of signal acquisition during the cyclic deformations is proved. Its response-recovery duration under 5% strain at 500 mm/min deformation rate is 130 ms(response)− 250 ms(recovery). It gives accurate feedback to external stimuli at different frequencies. It can maintain stable output signals during 3000 cycles of stretching. It also can sense 1% minor-strain stimuli. The strain sensing behavior of the fabricated flexible sensor with the auxetic structure is detailed. The CNTs are combined tightly with the TPU surface layer to form a conductive network with variable resistance during recoverable deformation of the auxetic structure. The macro and micro-mechanisms of sensing are dissected, considering the tunneling effect of discontinuous CNTs. The hybrid additive manufacturing process is verified to be feasible, credible, and low-cost for easy fabrication of flexible strain sensors with complex geometry configurations.
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•Hybrid process of FDM and ultrasonic treatment is proposed to fabricate sensors.•Concave curve cell structures give TPU/CNTs composite auxetic performances.•Compositing processes do not weaken mechanical properties of matrix TPU.•Hybrid manufactured TPU/CNTs sensors meet commercialization requirements.•Sensing mechanisms are explained based the seepage theory and tunneling effect.
Fused deposition modeling (FDM) has been successfully applied to fabricating short fiber reinforced polymer composites parts. However, due to the intrinsically limited mechanical properties of matrix ...polymers, there is critical need to develop fiber reinforced high-performance thermoplastic composites for FDM-3D printing to expand engineering applications. In this work, the potential of FDM-3D printing short carbon fiber (CF) and glass fiber (GF) reinforced high-performance PEEK composites has been investigated. Composite filaments with fiber contents of 5 wt%, 10 wt% and 15 wt% were prepared using extrusion process and characterized by micromorphology observation; and thermal properties testing demonstrated its better thermal stability than pure PEEK. The performance evaluation of printed CF/GF-PEEK parts was focused, including mechanical properties, microstructure, surface quality and porosity. The results indicate that the addition of CF/GF to PEEK can significantly enhance the tensile and flexural strength at the cost of ductility. Lower fiber content of 5 wt% is conducive to increasing mechanical properties, improving surface quality and reducing porosity of printed CF/GF-PEEK. GF/PEEK has better interfacial bonding than CF/PEEK due to the different surface treatments on fibers. Furthermore, microstructure observation suggests that fibers aligned along the printing orientation can strengthen the properties, while pores lead to performance degradation of 3D printed CF/GF-PEEK.
The objective of this study was to compare the physical and mechanical performance of poly(lactic acid) (PLA), acrylonitrile butadiene styrene (ABS), and nylon 6 fabricated using fused deposition ...modeling (FDM) and conventional injection molding. It is found that different processing methods did not affect the viscosity of the samples, and the percentage difference for the density measurement is less than 4%. Water absorption of FDM samples is approximately 108% higher compared to those fabricated using the injection molding. The results also revealed that the FDM method did not strongly affect the degree of crystallinity of ABS, but it increased the degree of crystallinity of PLA and nylon 6. The tensile strength, Young's modulus, elongation at break, and impact strength of FDM samples were approximately 48%, 50%, 48%, and 78%, lower compared with the injection molded samples. The results presented can provide a guide to manufacturing the final products using FDM with the desired performance.
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3D-printable, flexible, and conductive thermoplastic-based material was successfully developed for strain sensing applications. Thermoplastic polyurethane/multiwalled carbon nanotube (TPU/MWCNT) were ...compounded, their filaments were extruded, and the sensors 3D printed using fused deposition modeling. Mechanical, electrical, and piezoresistivity behaviors were investigated under monotonous and cyclic loadings. MWNCTs enhanced the printing capability of TPU by increasing its stiffness. Very modest decreases were observed in the elasticity modulus of printed nanocomposites (~14%, compared to that of bulk counterparts), indicating excellent interlayer adhesion and superior performance to those reported in literature. Consequently, the conductivity was largely preserved after printing, in both through-layer and cross-layer directions. The piezoresistivity gauge factors of as high as 176 were achieved under applied strains as large as 100%. A highly repeatable resistance-strain response was also obtained under cyclic loadings. The results demonstrate TPU/MWCNT as an excellent piezoresistive feedstock for 3D printing with potential applications in wearable electronics, soft robotics, and prosthetics, where complex design, multi-directionality, and customizability are demanded.
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•Flexible TPU/MWCNT was successfully 3D-printed as a sensing sensor.•The presence of MWCNT enhanced the printability of TPU.•Mechanical and electrical properties were highly preserved after 3D printing.•Printed sensors showed excellent cyclic piezoresistivity behavior.•Gauge factors as high as 176 were achieved.
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