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•Design principles for 3D-printed accelerometer are derived using ana- lytical model.•By applying design principles, a small-sized showcase accelerometer was 3D-printed.•Accelerometer ...exhibited linear response up to-425 Hz, and a low cross- axis sensitivity.
Fused-filament fabrication, one of the most accessible additive manufacturing technology, has already been used to manufacture piezoresistive static/quasistatic strain sensors, force sensors and wind sensors. Recent research showed that fused-filament fabrication could also be used for the manufacturing of dynamic sensors. However, the anisotropic mechanical and piezoresistive behaviour, the heterogeneity, the large number of process parameters and the large number of possible geometrical designs open up numerous design options for manufacturing. Additionally, a small size is difficult to achieve due to the relatively low geometrical tolerances and the resolution of fused-filament fabrication. This paper is focused on the design principles of a single-process, fused-filament fabricated, uni-axial accelerometer with a piezoresistive sensing element. The anisotropic piezoresistive behaviour is researched for the maximum sensitivity in the measured acceleration direction and the minimal cross-axis sensitivity for the perpendicular axes. The analytical accelerometer model is based on a Bernoulli-Euler beam and is used to understand the frequency and the geometrical influences of the piezoresistive accelerometer with a beam-shaped sensing element and an attached intertial mass. Finally, a small-sized (22 × 22 × 15 mm3), single-axis, prototype accelerometer, with an approximately linear response up to-425 Hz and a low cross-axis sensitivity was manufactured. The derived principles can be used for further optimisation of the developed prototype sensor and as a foundation for the derivation of design principles for other types of fused-filament fabricated accelerometers, including 3-axis accelerometers. keyword: accelerometer; piezoresistivity; additive manufacturing; fused filament fabrication; dynamic sensor; 3D printing.
Abstract Acrylonitrile butadiene styrene (ABS) is the most common of engineering plastic materials; it is copolymer of Styrene-Acrylonitrile and butadiene styrene in special form. It is widely used ...in substantive and Additive Manufacturing (AM) applications. AM is a promising manufacturing technology that can fulfill future needs as products and their configurations are changing day by day. Fused Deposition Modeling FDM is an AM technique that fabricates parts layer upon layer. This paper analyses the effect of different process variables and orientations on the tensile properties of the FDM manufactured specimens. Standard specimens are printed using commercial ABS and manufactured ABS filaments for analysis of tensile properties. The ABS filament is fabricated using a mini filament extruder. After modeling, the specimens are printed using an FDM printer. The tensile testing of specimens is carried out on the Instron 3360 table frame UTM machine. Tensile properties obtained for different specimens are presented.
Fused filament fabrication is considered one of the most used processes in additive manufacturing rapid prototypes out of polymeric material. Poor strength of the deposited layers is still one of the ...main critical problems in this process, which affects the mechanical properties of the final parts. To improve the mechanical strength, investigation into various process parameters must be considered. In this article, the influence of different process parameters has been experimentally investigated by means of physicochemical and mechanical characterizations. Special attention was given to the thermal aspect. In that respect, the in situ measurement of temperature profile during deposition indicated that several parameters affect the cooling rate of material and consequently have an influence on the final parts. It was found that the influence of increasing the extruder temperature is more significant in comparison with other process parameters.
Purpose
The filament-based feeding mechanism employed by the majority of fused deposition modelling (FDM) 3D printers dictates that the materials must have very specific mechanical characteristics. ...Without a suitable mechanical profile, the filament can cause blockages in the printer. The purpose of this study was to develop a method to screen the mechanical properties of pharmaceutically-relevant, hot-melt extruded filaments to predetermine their suitability for FDM.
Methods
A texture analyzer was used to simulate the forces a filament is subjected to inside the printer. The texture analyzer produced a force-distance curve referred to as the flexibility profile. Principal Component Analysis and Correlation Analysis statistical methods were then used to compare the flexibility profiles of commercial filaments to in-house made filaments.
Results
Principal component analysis showed clearly separated clustering of filaments that suffer from mechanical defects
versus
filaments which are suitable for printing. Correlation scores likewise showed significantly greater values with feedable filaments than their mechanically deficient counterparts.
Conclusion
The screening method developed in this study showed, with statistical significance and reproducibility, the ability to predetermine the feedability of extruded filaments into an FDM printer.
Limited in their insolubility and non-melting properties, biomass materials are hard to be directly applied to the fabrication of triboelectric nanogenerator (TENG), especially lignin, chitosan (CTS) ...and cellulose. To tackle these challenges, a novel strategy is proposed for the rapid preparation of insoluble and infusible biomass material based triboelectric nanogenerator (IBTENG) using digital fabrication methods. Insoluble and infusible biomass materials and polydimethylsiloxane (PDMS) were carried by polyamide (PA) and polyethylene (PE) tubes, respectively, to fabricate the porous positive and negative electrodes using fused deposition modeling (FDM). The optimal output of the IBTENG reaches 308 V and 61.6 μA at the frequency of 30 Hz and the power of 3.5 W, while the energy conversion efficiency reaches 78% and the power density is 5.93 W/m2. Compared with TENG prepared by traditional materials, IBTENG with outstanding performance is an extremely competitive candidate for eco-friendly energy-conversion devices based on ubiquitous mechanical energy. Further, it can be utilized directly to light two series-connected LED bulbs rated at 85 V and 3 W. This detailed investigation presented herein is a simple and universal approach for the direct use of insoluble and infusible biomass powders in the field of high-performance triboelectric devices, eliminating the need for complicated dissolution and after processing, which enables rapid fabrication of individualized and materially diverse devices.
A novel strategy is proposed for the rapid fabrication of insoluble and infusible biomass material based triboelectric nanogenerators (IBTENG) with microstructure using digital preparation methods. The rapidly fabricated and eco-friendly IBTENG exhibits satisfactory performance (U = 308 V, I = 61.6 μA, ŋ = 78%, Q = 5.93 W/m2) and can directly illuminate two series-connected LED bulbs rated at 85 V and 3 W. Display omitted
•Insoluble and infusible biomass materials can be directly applied to rapidly prepare IBTENG with microstructure using FDM.•Microstructure was formed inside the friction layer, which effectively improved the triboelectric properties of IBTENG.•The rapidly fabricated and eco-friendly IBTENG exhibits satisfactory performance (U = 308 V, I = 61.6 μA, Q = 5.93 W/m2).•This IBTENG can directly illuminate two series-connected bulbs rated at 85 V and 3 W.
•Integrated microfluidic devices fabricated with FDM 3D printing technology.•FDM is used as an alternative technique for cost-effective device prototyping.•Different materials integrated within the ...microchannel during the printing process.•Fabrication of a 3D printed microfluidic e-tongue sensor.•Good distinction of basic tastes with concentrations below the human threshold.
Microfluidic devices based on polydimethylsiloxane shown a plethora of experimental possibilities due to good transparency, flexibility and ability to adhere reversibly and irreversibly to distinct materials. Though PDMS is a milestone in microfluidic developments, its cost and handling directed the field to search for new options. 3D printing technology nowadays starts a revolution offering materials and possibilities that can contribute positively to current methodologies. Here we explored the fused deposition modeling 3D printing technique to obtain integrated, transparent and sealed microchannels made with polylactic acid, a cheap alternative material to set up microfluidic systems. Using a home-made 3D printer, devices could be assembled in a simplified process, enabling the integration of different materials such as paper, glass, wire and polymers within the microchannel. To demonstrate the efficacy of this approach, a 3D-printed electronic tongue sensor was built, enabling the distinction of basic tastes below the human threshold.
Understanding the mechanical response of polymer components fabricated by fused deposition modeling (FDM) is an important issue. Therefore, the present study deals with the effects of raster angle ...and layer orientation on the tensile properties and fracture toughness of acrylonitrile butadiene styrene (ABS) specimens produced by the FDM method. Two groups of specimens are considered. The first group includes specimens with the same layer orientation and the four different raster angles 0°/90°, 15°/–75°, 30°/–60°, and 45°/–45°. Specimens in the second group have the fixed raster angle 45°/–45° and three different layer orientations. Tensile tests are performed using dumbbell specimens, and semicircular bending (SCB) specimens were used for fracture mechanics tests. The critical value of J-integral obtained from finite element simulations is used as a parameter to characterize fracture properties. In the first group of specimens, the critical value of J-integral for the 45°/–45° specimen is 4389 J/m
2
while it is about 1880 J/m
2
for the 0°/90° specimen. In the second group, the vertically printed specimens have the least fracture resistance 1004 J/m
2
, while this value reaches 5934 J/m
2
for the specimens in which the precrack is perpendicular to the printed layers. In addition, the fracture surface of tensile specimens is analyzed using scanning electron microscopy for the mesomechanical study of failure in the printed specimens. Lastly, the crack path in SCB specimens is explored experimentally to understand how the raster angle and layer orientation affect the fracture trajectory and to justify different values of fracture loads.
Nozzle condition monitoring in 3D printing Tlegenov, Yedige; Hong, Geok Soon; Lu, Wen Feng
Robotics and computer-integrated manufacturing,
12/2018, Volume:
54
Journal Article
Peer reviewed
Open access
•A theoretical model of FDM process with regards to nozzle condition is introduced.•Novel 3D printer based on Cartesian parallel manipulator was built.•A novel method of monitoring nozzle clogging ...using vibration sensing is proposed.
3D printing and particularly fused filament fabrication is widely used for prototyping and fabricating low-cost customized parts. However, current fused filament fabrication 3D printers have limited nozzle condition monitoring techniques to minimize nozzle clogging errors. Nozzle clogging is one of the most significant process errors in current fused filament fabrication 3D printers, and it affects the quality of the prototyped parts in terms of geometry tolerance, surface roughness, and mechanical properties. This paper proposes a nozzle condition monitoring technique in fused filament fabrication 3D printing using a vibration sensor, which is briefly described as follows. First, a bar mount that supports the liquefier in fused filament fabrication extruder was modeled as a beam excited by a system of process forces. The boundary conditions were identified, and the applied forces were analyzed for Direct and Bowden types of fused filament fabrication extruders. Second, a new 3D printer with a fixed extruder and a moving platform was designed and built for conducting nozzle condition monitoring experiments. Third, nozzle clogging was simulated by reducing the nozzle extrusion temperature, which caused partial solidification of the filament around inner walls of the nozzle. Fourth, sets of experiments were performed by measuring the vibrations of a bar mount during extrusion of polylactic acid, acrylonitrile butadiene styrene, and SemiFlex filaments via Direct and Bowden types of fused filament fabrication extruders. Findings of the current study show that nozzle clogging in fused filament fabrication 3D printers can be monitored using an accelerometer sensor by measuring extruder’s bar mount vibrations. The proposed technique can be used efficiently for monitoring nozzle clogging in fused filament fabrication 3D printers as it is based on the fundamental process modeling.
The 3D Concrete Printing (3DCP) process is rapidly developing worldwide, showing its ability to construct large-scale components or even a building. However, the current 3DCP process has found it ...hard to manufacture architectural components with detailed ornamentations and features on their surface due to the Fused Deposition Modelling (FDM) manner that generates fixed-width filaments. This paper introduces a novel Volume - Forming 3D Concrete Printing (VF3DCP) method applying a variable-size square nozzle to manufacture architectural ornaments. The VF3DCP process is described as to directly fabricate a variable cross-section volume during one-time work instead of an FDM accumulation process. A VF3DCP extrusion kit prototype featured by a steering module and a nozzle-varying module is developed. Functional relationships of four key process parameters for a trial material, including nozzle size, nozzle travel speed, material extrusion rate and toolpath curvature radius, are fitted by two process tests. Two case studies into the manufacture of an architectural carved pattern and a curved wall structure together validate a Voronoi Diagram-based skeleton line-segment algorithm for the single-path and multi-path toolpath planning of the VF3DCP process. The results show the potential of the proposed method in manufacturing architectural ornaments.
•A novel Volume - Forming 3D Concrete Printing (VF3DCP) method applying a variable-size square nozzle is introduced.•A VF3DCP extrusion kit prototype featured by a steering module and a nozzle-varying module is developed.•Functional relationships of key process parameters for a trial material are fitted through process tests as calibration.•Voronoi Diagram-based skeleton line-segment algorithms for VF3DCP toolpath planning are validated by two case studies.
•A spider web-like flexible strain sensor based on CNT/GNP/TPU CPCs was 3D printed.•The strain sensor shows high linearity and sensitivity, and large response range.•The customized structure endows ...the sensor with directional strain recognition.
Inspired by the unique structure of spider web, we designed and prepared a spider web-like strain sensor based on multi-walled carbon nanotubes (MWCNT)/graphene nanoplatelets (GNP)/thermoplastic polyurethane (TPU) conductive polymer composites. Fused filament fabrication (FFF) 3D printing was used to meet the growing demand for flexible electronic devices and overcome limitations with the directional sensitivity of traditional strain sensors. The sensor response exhibited high linearity (R2 = 0.98 at 50% strain), a large strain response range (0–300%), high sensitivity (GF > 10000 at 300% strain), short response time (40 ms), low hysteresis, and good stability (1000 cycles). In addition, due to the special structural design, the sensor identified external forces in different directions. This further expands the application range of the sensor. This work provides valuable guidance for the customized fabrication of flexible strain sensors.
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