We have developed a method for the three-dimensional (3D) printing of continuous fiber-reinforced thermoplastics based on fused-deposition modeling. The technique enables direct 3D fabrication without the use of molds and may become the standard next-generation composite fabrication methodology. A thermoplastic filament and continuous fibers were separately supplied to the 3D printer and the fibers were impregnated with the filament within the heated nozzle of the printer immediately before printing. Polylactic acid was used as the matrix while carbon fibers, or twisted yarns of natural jute fibers, were used as the reinforcements. The thermoplastics reinforced with unidirectional jute fibers were examples of plant-sourced composites; those reinforced with unidirectional carbon fiber showed mechanical properties superior to those of both the jute-reinforced and unreinforced thermoplastics. Continuous fiber reinforcement improved the tensile strength of the printed composites relative to the values shown by conventional 3D-printed polymer-based composites.

A study was conducted to evaluate the current production capabilities of the Mark One ® 3D printer in printing carbon fibre reinforced thermoplastic (CFRTP) tensile test specimens according to the JIS K 7073 by making use of fused deposition modelling. Several different types of CFRTP tensile test specimens are printed and are tensile tested in the longitudinal direction to obtain an overview of the mechanical properties of 3D printed CFRTP material. These properties are compared with the literature values known for composite materials to see if these agree. The main goal of this research is to increase the knowledge of the 3D printing process of CFRTP and to later use this knowledge to further improve the 3D printing process to obtain stronger 3D printed CFRTP materials.

wileyonlinelibrary.comembedded in the elastomer base. For example, stretchable electrodes utilizing carbon nanotubes (CNTs), [ 10,11 ] metal nanowires, [ 12 ] or metal ions [ 13 ] with an elastomer base have been proposed.As a stretchable electrode, liquid metals, which are in the liquid state at room temperature, are highly attractive materials. [ 14 ] For the liquid metals of a stretchable electrode, a eutectic galliumindium alloy (EGaIn) and GaInSn are often used because of their low toxicity and low melting point. [ 15,16 ] The composition of the constituent metals in EGaIn are 75% Ga and 25% In by weight and the melting point is 15.5 °C. For GaInSn, the composition is 68.5% Ga, 21.5% In, and 10% Sn by weight and the melting point is −19 °C. Because both of these materials are in the liquid state at room temperature, they have attracted attention as a replacement for highly toxic mercury. [ 15,16 ] Table 1 summarizes the melting points and electrical conductivities of EGaIn and GaInSn. [ 17 ] By comparing GaInSn and EGaIn, it is found that the electrical conductivity is almost the same, but GaInSn has a lower melting point; thus, it can be in the liquid state at a lower temperature. The liquid metals have almost limitless deformability compared with solid metals. By using a liquid metal as the electrodes of a stretchable device, its mechanical properties are governed by the mechanical properties of the elastomeric substrate. [ 14 ] Therefore, extremely stretchable electronic devices are possible by using a high failure-to-strain elastomer for sealing liquid metals for application to stretchable wires [ 18 ] and interconnections. [ 19 ] For the high failure-to-strain elastomer, polydimethylsiloxane (PDMS) is often used because PDMS is a biomaterial and is highly stretchable without structural damage over 100% strain, which enables curved surfaces to be followed; therefore, PDMS can be applied to human-body sensing. [ 20,21 ] Moreover, liquid metals are not just for stretchable electrodes or wiring; functional stretchable devices using changes in the electrical properties due to stretching have been developed, such as a stretchable antenna that tunes the resonance frequency, [ 14,17 ] a capacitor and inductor that sense the applied strain, [ 22 ] straincontrolled diffraction of light, [ 23 ] and a device that senses pressure and strain. [ 24,25 ] By using a combination of a low-toxicity and low-meltingpoint liquid metal and a biocompatible PDMS elastomer, various types of wearable electronics have been developed, such as sensor skin for intelligent robots [ 26 ] and a stretchable keyboard For identifying human or fi nger movement, it is necessary to sense subtle movements at multiple points, including the local strain and global deformation simultaneously; however, this has not yet been realized. Therefore, a highly stretchable, global, and distributed local strain sensing electrode made of GaInSn and polydimethylsiloxane is developed for wearable devices. To investigate the electrical properties of multiple se...

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This review discusses key technologies of intelligent tires focusing on sensors and wireless data transmission. Intelligent automobile tires, which monitor their pressure, deformation, wheel loading, friction, or tread wear, are expected to improve the reliability of tires and tire control systems. However, in installing sensors in a tire, many problems have to be considered, such as compatibility of the sensors with tire rubber, wireless transmission, and battery installments. As regards sensing, this review discusses indirect methods using existing sensors, such as that for wheel speed, and direct methods, such as surface acoustic wave sensors and piezoelectric sensors. For wireless transmission, passive wireless methods and energy harvesting are also discussed.

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