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This paper proposes a technique for detecting impact-induced surface and subsurface fractures in Glass Fibre Reinforced Composites (GFRPs) and hybrid composite materials. Various categories of composite samples, namely Unidirectional GFRP, Bidirectional GFRP, Woven mat GFRP and Carbon-flax hybrid composites are fabricated by the hand-layup process, and cracks are induced in the samples by three-point flexural bending test using a Universal Testing Machine. Near-field microwave Non-Destructive Testing (NDT) is employed in detecting the above cracks by recording the S11 parameter from the microwave transceiver probe throughout the sample. For image rendering the resulting outputs are passed as a 2-dimensional array to the image-rendering algorithms, namely Iterative Curve-Based Interpolation (ICBI), Improved New Edge-Directed Interpolation (INEDI) and the Lanczos algorithm. The most suitable algorithm to identify the clear picture and size of crack is identified, and the effectiveness of Microwave NDT for these composites is analysed. [ABSTRACT FROM AUTHOR]

Monitoring thrust during drilling operations is critical to optimizing drilling parameters and ensuring safe and efficient drilling. In this study, we will monitor variations in thrust force during the drilling process using a sensor coated with carbon black. These sensors measure changes in electrical resistance when the sensor is subjected to a mechanical load, such as drilling force. Carbon black at 5 wt% was used, which was embedded in a fiberglass composite. For this study, an orthogonal arrangement of Taguchi's L27 sequence was used, with drill diameter D, feed rate F, and spindle speed S as machining parameters. The thrust force was measured with a force dynamometer and the resistance change was measured simultaneously with the developed new system. Analysis of variance was used to find the optimal parameters, and in this study, a mathematical model was proposed to measure the thrust force directly using the electrical resistance detected. NSGA-II algorithm was used to predict solutions for the given parameters for comparison. A comprehensive way of drilling process and data-driven decisions to improve drilling performance and safety was studied, and a correlation between actual thrust and calculated thrust of 0.91 was found. The proposed system was able to monitor and continuously record thrust force in real time during drilling, with electrical resistance as the most important factor with an error percentage of less than 8% compared to the NSGA-II predictions of less than 5%. [ABSTRACT FROM AUTHOR]

In the work presented here, microwave non-destructive testing using a rectangular waveguide loaded with a novel planar unit cell filter for the inspection of defects in the composite is studied. The proposed planar filter is designed as a unit cell with a copper (annealed) microstrip component on an FR-4 substrate. The waveguide loaded with the planar filter exhibits a reflection coefficient of −35.919 dB at a frequency of 10.548 GHz. This planar filter waveguide is used as the sensor probe for the non-destructive testing method proposed here and is aimed to increase the sensitivity by measuring the differences in permittivity of materials. Computer simulation technology software (CST studio suite) is used for implementing the design, simulation, and material/defect evaluation. The defects studied are voids, cracks, and delamination in an epoxy-based natural flax fiber-reinforced composite material. The performance-improved microwave sensor probe is used to pick up permittivity variations in the presence of defects in lax-based natural fiber-reinforced composite material. [ABSTRACT FROM AUTHOR]

In this paper, a novel four-layered low-profile, textile antenna operating in the Industrial Scientific and Medical band (ISM) has been proposed for wearable applications. The proposed antenna was completely made from textile materials with the substrate being cotton and the conductive portions done by embroidering Zari threads to the substrate. The realized antenna has a compact profile of 51 mmx 45mmx 0.785 mm. To improve the return loss and gain, a rectangular slot of dimension 10mm x 10 mm was introduced. On-body analysis also shows that the antenna has powerful performance with specific absorption rates well below the threshold specified by International Electrotechnical Commission (IEC) for 1g and 10g tissue. In addition to validate the design, real-time deployment with a Particle Photon was done to continuously monitor the heart rate and upload it to the Particle app via cloud. The fabricated antenna was also evaluated under bent, crumpled, moisture absorbed and on-body conditions where the antenna performance was measured by Signal to Noise Ratio (SNR), Received Signal Strength Indicator (RSSI) of the network connected to and the round-trip time taken by the device to successfully respond to the Constrained Application Protocol (CoAP) message sent by the Particle Cloud. On analysis, it was seen that the performance of the antenna was unaffected by the deformations induced making it best suited for on-body applications. [ABSTRACT FROM AUTHOR]

A symmetric multilayered embroidered textile antenna is proposed in this article. The proposed antenna is designed at industrial, scientific, and medical band frequency of 2.45 GHz, to be used as a wearable made of Zari and cotton cloth. An end‐to‐end slot has been introduced to improve return loss and efficiency. The four‐layered antenna is fabricated using conventional embroidery and the layers are sewn together to form the entire structure. Measurements on the fabricated antenna are performed to validate the characteristics of the structure in bent, crumpled, and wet conditions. Results with regard to return loss, gain, bandwidth, and radiation pattern were presented to prove the usefulness of the structure. Furthermore, the antenna was integrated with Arduino Uno development board and tested for data transmission as a wearable system. [ABSTRACT FROM AUTHOR]