Display omitted
•Fused Filament Fabrication (FFF) 3D Printed artefacts were designed with different multi-scale configurations of the internal conductive pathways.•Electrothermal conduction paths ...through the sample were controlled by changing the printing parameters.•Tunneling Atomic Force Microscope (TUNA) provides direct information on the electrically conductive paths essentially composed of aligned Carbon Nanotubes.•The raster angle affects the electrical conductivity of the artefact printed parts and their heating.
This study proposes a simple method to produce three-dimensional (3D) manufacts with multiscale configurations and controlled electrical resistivity. 3D printed artefacts, based on acrylonitrile butadiene styrene and carbon nanotubes (CNTs), are obtained by fused filament fabrication. Highly orientated conductive pathways are achieved in the sample by selecting appropriate printing parameters. Scanning electron microscopy and tunnelling atomic force microscopy confirm that the conductive traces are essentially composed of aligned CNTs. The printing process determines an increase in the electrical conductivity from 6.88 × 10-2 (spooled filament) to 11.9 S/m (printed filament). The orientation of the spatial domains from the macro- to nanoscale is responsible for a decrease in the electrical resistance from 7782 (90° raster angle sample) tο 478 Ω (0° raster angle sample). Appropriate selection of the configuration and dimensions of electrical contacts confers the ability to selectively heat the part when subjected to an electric source. Temperature differences up to 55 °C were obtained in samples printed with a double-angle raster combination by changing the applied voltage from 20 to 40 V. This strategy can be used to fabricate electronic devices, thermistors capable of converting electrical energy to thermal energy, heat exchangers, and shielding for electromagnetic interference in a single step.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ
Display omitted
•An explicit method to convert stress field into toolpath for CFRPCs-AM considering manufacturing constraints.•The density of toolpath distribution is adaptively controlled by local ...principal stress value and geodesic distance.•The effectiveness of our method is verified on 2D and 3D structures subjected to a variety of loads and boundary conditions.•Experimental results show a significant improvement in stiffness and strength compared to conventional uniform toolpaths.
The infill toolpath utilized in continuous fiber reinforced polymer composites via additive manufacturing (CFRPCs-AM) significantly influences the mechanical performance of printed structures. However, existing infill toolpath for CFRPCs-AM are primarily designed for 2D planar structures and do not account for 3D shell structures with complex shapes or load path dependent characteristics. To address these limitations, this paper proposes an explicit streamline tracing method to convert the stress field into adaptive infill toolpaths for CFRPCs-AM. The method leverages principal stress direction and value fields to control toolpath density and distribution while considering the minimum allowable bead width constraint. Additionally, the geodesic distance is employed to precisely represent the distance between adjacent infill toolpaths on shell structures. Experimental validation on 2D and 3D complex structures under varying conditions demonstrates the effectiveness of the proposed method, which significantly improves stiffness and strength by 200–300% compared to traditional uniform toolpaths for CFRPCs-AM.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ
This paper aims to evaluate the elastic properties of fibre-reinforced polymer (FRP) structures printed by three-dimensional (3D) printing technology. Both experimental and theoretical approaches are ...adopted to investigate the performance of FRP 3D-printed structures and predict their elastic properties. Three types of FRP materials were considered in this study including Carbon, Kevlar and Glass printed in selected arrangements of fibre filaments and Nylon matrix. An analytical model was developed based on the Volume Average Stiffness (VAS) method to predict elastic properties of 3D printed coupons, while the numerical model was developed using Abaqus to predict the failure modes and damage in the FRP 3D-printed coupons tested in this study. A parametric study was carried out to develop the mathematical expressions for calculating elastic properties of FRP 3D-printed structures. The parametric study indicates that the level of fibre reinforcements and their orientation arrangement have significant effects on the structural performance of FRP 3D-printed composite sections.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•The chitosan solution/polyvinyl alcohol hydrogels with different contents of cobalt doped calcium silicate nanowires were prepared via 3D printing method for the repair of osteochondral defect ...induced by chondrosarcoma.•Attributing to the excellent photothermal performance, the prepared composite hydrogel scaffolds could effectively kill human chondrosarcoma cells.•The prepared composite hydrogel scaffolds could support the proliferation, adhesion and spread of rabbit bone mesenchymal stem cells and rabbit chondrocytes, and further promoted the formation of new bone and cartilage tissue in vivo.
Considering the difficulty in the treatment of chondrosarcoma in clinic, multifunctional composite hydrogel scaffolds were designed with excellent photothermal ability for the regeneration of damaged bone and cartilage tissue. The chitosan solution/polyvinyl alcohol (CP) hydrogels with different contents of cobalt doped calcium silicate (Co-CSH) nanowires were prepared via 3D printing method. Attributing to the excellent photothermal performance of Co-CSH nanowires, the average survival rate of human chondrosarcoma cells in the CP-5Co-13.4 % and CP-5Co-16.2 % scaffolds with near infrared laser irradiation was about 10.5 % and 9.9 %, respectively. At the same time, the prepared composite hydrogel scaffolds possessed satisfactory biocompatibility and could support the adhesion and spread of rabbit bone mesenchymal stem cells (rBMSCs) and rabbit chondrocytes in the hydrogel scaffolds, and further promoted the formation of new bone and cartilage tissue in vivo, on account of the stimulation effect of released bioactive ions. Therefore, the prepared composite hydrogel scaffolds is expected to provide a new therapeutic strategy for the postoperative adjuvant treatment of chondrosarcoma.
The diagram of 3D printing multifunctional hydrogel scaffolds for repairing tumor-induced osteochondral defects. Display omitted
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The performance enhancement of 3D‐printed electrode comprised of polylactic acid (PLA) and graphite (Gr) doped with graphene oxide (GO) was studied to detect five heavy metal ions in trace level. The ...pretreatment of PLA/Gr/GO electrode with potential cycling in H2SO4 solution achieved the most sensitive response. The characteristics of the composite electrodes were verified using XPS, FE‐SEM, EDXS, Raman, and impedance spectroscopy. The experimental variables affecting the response current were optimized with respect to pH, deposition time, ratio of PLA/Gr/GO, and supporting electrolytes. The pretreated 3D‐PLA/Gr/GO electrode showed a wide dynamic range from 0.5 ppb to 1.0 ppm with low detection limits of 0.039–0.13 ppb. The reliability of the PLA/Gr/GO electrode was evaluated by analyzing the reference samples of European Reference Materials.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The integration of endless fiber reinforced composites in additive manufacturing enables the automated production of materials with high mechanical properties such as strength. The current state of ...the art utilizing print heads with separate fiber and matrix feeds showed that, without active infiltration, the fiber infiltration is poor or not possible for thermoplastics with low flowability (high viscosity). In this work, the improvement of the print head technology and the investigated infiltration effect lead to a significantly higher infiltration. The material selection of thermoplastic matrix (PA6) and fiber reinforcement (carbon fiber) were adjusted for the new process parameters. The selection of the fiber matrix combination was conducted using the interfacial tension calculations at room temperature. The polar and dispersive surface energy of two different carbon fibers as well as the wetting of PA6 polymer melts on carbon fibers and on aluminum carriers were investigated. The calculation of composite properties using material data of the matrix and fiber was used to determine the process windows for specific parameters such as layer height, layer width and nozzle size. Furthermore, the mechanical properties and the cost of the composite can be determined in relationship with the materials used and the fiber volume content. The composition of the fiber sizing and the influence of high processing temperatures was characterized using TGA, FTIR spectroscopy and XPS analysis. The processing parameters and rheological behavior of PA6 thermoplastic resins and mixtures were investigated, and a mixture of 75 wt.% Ultramid B3k and wt.25% of Ultramid B50l from BASF was used for the composite fabrication by material extrusion. The optimization of the extrusion process enables the production of filaments with higher flowability (low zero viscosity), with the fiber infiltration improved by the adjusted rheological behavior. Samples for mechanical and optical analysis were fabricated using the self developed print head and three different types of carbon fibers. Three point bending properties were investigated as a function of layer height and printing temperature; tensile properties of single composite strands fabricated with different printing temperatures and multilayer composite were also characterized. The fiber volume content and the porosity were evaluated in crosssectional analyses. The investigated material combinations, optimization of process parameters and the fiber roving infiltration effect in the print head leads to higher mechanical properties and lower porosity in the composite.
Biological 3D printing composite forming process is combined with the 3D printing technology and electrospinning technology. The composite molding process is used for preparing 3D scaffolds for ...tissue engineering. Complex biological 3D printing composite forming process and unstable processing environment make it difficult to form better quality of composite scaffolds. Therefore, it is necessary to optimize the process parameters. In this paper, based on orthogonal experiment, signal-to-noise ratio (SNR) analytical technique, one of the parameter designing methods, is adopted to determine the degree of influence exerted by process parameters on the quality of composite scaffold and thus obtain the degree sequence of each process parameter on the evaluation criterion during biological 3D printing composite forming process. Moreover, under grey correlation theory, the multi-objective parameter optimization problem can be transformed into the single objective optimization one. A group of optimized process parameters under multiple process criterions is obtained. Through the forming experiment of composite scaffold, the results show that process parameters obtained by the above method can produce good quality scaffold.
Full text
Available for:
DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
PDF
