جستجوی مقالات مرتبط با کلیدواژه « Fused deposition modelling » در نشریات گروه « مواد و متالورژی »

Several extensive researches are being carried out in the field of 3D printing. Polymer matrices, such as High-Density Polyethylene (HDPE), are less explored in particular on the microstructure and mechanical properties of HDPE composites developed via Fused Deposition Modelling (FDM) process. Very scarce amount of works is devoted to study HDPE’s reinforced with carbon nano-tubes (CNT’s) . In the present work, we report on the mechanical properties of  HDPE composites prepared via FDM process. Varying proportions of CNTs ( 0.5, 1, 1.5 and 2%) are used as reinforcements. It is found that increasing CNT content enhances impact and tensile strength, with HDPE/2.0%CNT outperforming pure HDPE by approximately 71.6% and 25.4%, respectively. HDPE/2.0%CNT composite also showed Young's modulus approximately 49.2% higher than pure HDPE. According to fracture analysis, pure HDPE failed near ductile, whereas composites failed brittle. CNTs occupy the free positions in the polymeric chains, and their tendency to restrict chain mobility causes HDPE to lose ductility and begin to behave brittle. The use of CNTs as reinforcement successfully improved the mechanical properties of HDPE.

Bone tissue engineering serves as a solution to repair and rebuild the damaged bone. In this study, first, the akermanite nanoparticles were synthesized by the sol-gel method; then the polylactic acid (PLA) scaffold was made using the fused deposition modelling (FDM), and the akermanite nanoparticle booster was used to improve its properties. The image of the electron microscopy (TEM) from akermanite particles showed that the size of these particles was 100 nm. The microstructure and phases of the scaffold was examined using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results of the field emission electron microscopy (FESEM) and energy dispersive spectroscopy (EDS, map) showed that the nanoparticles had a uniform distribution in the polymer matrix. The results of the compression test also revealed that the addition of akermanite nanoparticles improved the strength of the polymer scaffold. The bioactivity test was performed by immersing the scaffolds in the simulate body fluid (SBF) and then was examined using (SEM). Formation of the hydroxyapatite crystals on the surface of the scaffold containing akermanite nanoparticles, showing that the addition of akermanite particles improved the bioactivity and mechanical properties of the scaffold; therefore, this scaffold could be a good choice for use in bone tissue engineering.

Fused Deposition Modelling (FDM) is an additive manufacturing process to build 3D objects on a horizontal plane from bottom to top. In the conventional FDM process, the printing of curved objects causes the staircase effect and results in poor surface finish. In this work, the FDM process integrated with a 6-DOF Industrial robot is used to print the curved objects by generating non-linear tool paths to avoid the staircase effect. A standard NACA 0015 aircraft wing having curved surfaces is printed without staircase effect at a uniform deposition rate using an industrial robot. The wing is sliced into concentric curved layers either in the form of convex or a concave shape. A new methodology is developed by combining the non-linear toolpaths with the change in extruder orientation to print curved objects at a uniform deposition without any staircase effect. ABB Robotstudio simulation software is used for simulating the printing process and simulation results are validated by printing the portion of the wing using the Industrial robot with an FDM extruder as an end effector. The experimental results showed that the aircraft wing is printed successfully with uniform deposition at constant velocity without any staircase effect.