Wearable pressure sensors having versatile device structures have been extensively investigated to achieve high sensitivity under mechanical stimuli. Here, we introduce piezoelectric pressure sensors based on fabrics woven using polyvinylidene fluoride (PVDF) weft and polyethylene terephthalate (PET) warp yarns with different weave structures: 1/1 (plain), 2/2, and 3/3 weft rib patterns. The dependence of the pressure-sensing performance on the weave pattern is demonstrated with an actual large-scale fabric up to the ~2 m scale. An optimized pressure sensor with a 2/2 weft rib pattern produced a high sensitivity of 83 mV N−1, which was 245% higher than that of the 1/1 pattern. The detection performance of the optimal fabric was extensively evaluated with a variety of ambient input sources, such as pressing, bending, twisting, and crumpling, as well as various human motions. Further, a large all-fabric pressure sensor with arrayed touch pixel units demonstrated highly sensitive and stable sensing performance.
PVC coated fabric is a useful structural material mainly used as a roof material because of its lightweight, flexibility. However, the main issues of this PVC coated fabric product is that it is damaged such as tensile failure, peel, and tear when exposed to extreme environments such as strong rain and wind owing to its inferior mechanical properties. Various studies have been reported to improve the mechanical properties of PVC coated fabric, there have been no significant improvement. Therefore, in this study, to improve the mechanical properties of the PVC coated fabrics, applied the low viscosity PVC resin and 4 [Formula: see text] 4 matt weave structure polyester fabric. In addition, the mechanical properties of PVC coated fabrics with various viscosity PVC resins (D10, D8, D5, D2 and D0) were investigated and the mechanical properties of PVC coated fabrics with various weaving structure such as plain weave structure (1 [Formula: see text] 1), matt weave structure (2 [Formula: see text] 2, 3[Formula: see text] 3, and 4 [Formula: see text] 4) were studied. The PVC coated fabric fabricated by low viscosity PVC resin (D10), the tensile strength, tear load, and peel strength improved about 3%, 11%, and 29% compared to the PVC coated fabric fabricated by high viscosity PVC resin (D0). The mechanical properties of the PVC coated fabric fabricated by 4 × 4 matt weave structure polyester fabric was superior to the 1 × 1 plain weave structure polyester fabric and 2 × 2, 3 × 3 matt weave structure polyester fabrics because of the low crimp rate and low intersection point of the warp yarn and weft yarn of the fabric.
In this study, carbon/epoxy composites were manufactured by coating with a polyamide at different weight percentages (5 wt.%, 10 wt.%, 15 wt.%, and 20 wt.%) to improve their impact resistance and fracture toughness. The chemical reaction between the polyamide and epoxy resin were examined by fourier transform infrared spectroscopy, differential scanning calorimetry and X-ray photoelectron spectroscopy. The mechanical properties and fracture toughness of the carbon/epoxy composites were analyzed. The mechanical properties of the carbon/epoxy composites, such as transverse flexural tests, longitudinal flexural tests, and impact tests, were investigated. After the impact tests, an ultrasonic C-scan was performed to reveal the internal damage area. The interlaminar fracture toughness of the carbon/epoxy composites was measured using a mode I test. The critical energy release rates were increased by 77% compared to the virgin carbon/epoxy composites. The surface morphology of the fractured surface was observed. The toughening mechanism of the carbon/epoxy composites was suggested based on the confirmed experimental data.
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