Theoretical Investigation of a Long Period Grating Sensor Employing Multilayer Fiber Geometry

A theoretical formulation of the long-period grating sensor is implemented with respect to efficient refractive indices of core and cladding. The obtained result is utilized further for determination of ERIs of core and cladding using graphical analytical method and multilayer fiber geometry. ERI values of primary guided core, bi and tri layer fiber geometry using MATLAB software. In the present paper effective refractive index of core and cladding for the two and three layers have been investigated. The cladding modes have also been calculated using Erdogan’s proposed three-layer geometry as well as two-layer graphical solution method. We have compared both the techniques, discussed the limitations of graphical solution method and the benefits of three-layer geometry.

Mechanical properties of hybrid vetiver/banana fiber mat reinforced vinyl ester composites

Green sustainable life and biofibers play a vital role in achieving eco-friendly environment and great opportunities for fabricating the products. This work focused on the effect of the hybrid mat as reinforcement in vetiver/banana fiber mat reinforced vinyl ester composites. Composites plates were fabricated at 45° and 90° directions in ten different combinations by the compression molding machine. The mechanical properties of composites plates were tested as per ASTM standard. The morphological behaviour of tested specimens were evaluated by SEM. The hybrid double-layer fiber mat composites in longitudinal direction exhibit optimum results in tensile and flexural properties. However, it is found that vetiver double-layer fiber mat composites at 90° direction, indicating better impact strength than a banana and hybrid fiber mat composites. SEM images provided that composite properties are dependent on interface bonding between the fibers and matrix.

Performance of Short Fiber Interlayered Reinforcement Thermoplastic Resin in Additive Manufacturing

To further improve the mechanical properties of thermoplastic resin in additive manufacturing (AM), this paper presents a novel method to directly and quantitatively place the short fibers (SFs) between two printing process of resin layers. The printed composite parts with SFs between the layers was reinforced. The effects of single-layer fiber content, multi-layer fiber content and the length of fibers on the mechanical properties of printed specimens were studied. The distribution of fibers and quality of interlayer bonding were assessed using mechanical property testing and microstructure examination. The results showed that the tensile strength of the single-layered specimen with 0.5 wt% interlayered SFs increased by 18.82%. However, when the content of SFs continued to increase, the mechanical properties declined because of the increasing interlayered gap and the poor bonding quality. In addition, when the interlayered SFs length was 0.5–1 mm, the best reinforcement was obtained. To improve the interfacial bonding quality between the fiber and the resin, post-treatment and laser-assisted preheating printing was used. This method is effective for the enhancement of the interfacial bonding to obtain better mechanical properties. The research proves that adding SFs by placement can reduce the wear and breakage of the fibers compared to the conventional forming process. Therefore, the precise control of the length and content of SFs was realized in the specimen. In summary, SFs placement combined with post-treatment and laser-assisted preheating is a new method in AM to improve the performance of thermoplastic resin.

Recycling of denim fabric wastes into high-performance composites using the needle-punching nonwoven fabrication route

At present, a large number of waste textiles are disposed through incineration and burial, which cause serious environmental pollution. Therefore, recycling textile wastes into high mechanical products with eco-friendly method is an urgent issue. Based on the above status quo, three kinds of 3D waste denim fiber needled felts/epoxy composites (3DWECs) with different areal densities of the mono-layer fiber web were designed and fabricated, and the effect of the areal density of the mono-layer fiber web on its mechanical properties was studied in this work. The cross-section morphologies of 3DWECs were also examined. Tensile, bending and compressive test results revealed that 2# 3DWECs (the planar density of mono-layer fiber webs was 557 g/m2) possessed better mechanical properties than 1# 3DWECs and 3# 3DWECs. Both the static and dynamic mechanical testing results showed that 3D waste denim fiber needled felts acting as the reinforcement played an essential role in the bearing function. Moreover, the peel tests indicated that the peel strengths of the 3DWECs were above the limits of the Chinese National Standard for particle board. The composites have the potential as a substitute for some particle boards.