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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]

This article presents a conformal and on-body RF sensor with reduced wiring complexity for tremor detection in Parkinson's disease evaluation. RF sensor aids in detecting and extracting continuous finger movement that makes exact and repeated estimation of tremor feasible. The shift in frequency during finger motion is investigated to monitor tremor. The sensor is developed on a finger cap in such a way that it conforms to the shape of a human finger. The realized sensor can detect relative angle changes with an accuracy of 0.57o. The fabricated sensor is tested in real-time with variations in finger length, diameter, and skin thickness. The influence of these variations on the frequency shift is investigated using analysis of the variance and fuzzy method. The correlation value of 98% between experimental and predicted values is obtained using the fuzzy logic. [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]

In this paper, a portable system for noninvasive detection of fractures in human bones is presented. A planar microwave ring resonator is used as the sensor. The proposed planar microwave sensor is designed using the finite integration-based CST Microwave Studio and tested on a human bone covered by porcine tissues. Fracture induced in the bone was detected by monitoring the transmission characteristics of the sensor as it scans the affected region. The resonant frequency of the ring resonator has been observed at every scan point, and the values are plotted using iterative curvature-based interpolation, improved new edge directed interpolation, and Lanczos imaging technique. The extent of fracture is then derived from the image. The average accuracy of the detected fracture for Lanczos method of resampling was 98.86%. The specific absorption rate was below the minimum level of 1.6 W/Kg at every point of scanning. Portable noninvasive monitoring of fractures in the tibial bone will help in immobilizing the affected part at an earlier stage, thereby reducing the recovery time for patients. [ABSTRACT FROM AUTHOR]

In this paper, a novel planar microwave sensor for nondestructive measurement of strain during testing of printed circuit board (PCBs) is proposed. Planar microstrip patch bridged on both sides with squared split ring resonator is used to measure strain. Measurement of stress of isotropic dielectric materials in their linear elastic region that are uses as PCB substrates is also done using the proposed method. The designed microwave probe works at a frequency of 2.45 GHz. The feasibility of the use of time-domain reflectometry method to monitor strain in materials is presented here. The proposed sensor exhibits a sensitivity of about 333 ps for every 1% change in strain. Finite integration technique and real-time measurements have been done to corroborate the relation derived between the transmit time and the strain experienced by the material. The correlation between the simulated and measured strain is about 99.3%. The proposed sensor can be used for faster and accurate testing of PCB substrates without requiring complex calibrations. [ABSTRACT FROM PUBLISHER]

This paper proposes a unique, first of its kind fabrication technique for the making of textile antennas. A novel method that provides scope for automation in textile antenna production is presented here. A completely integrated textile antenna fabrication method that eliminates the tasks of positioning and fastening of the various components of a patch antenna is discussed. The technique employs multilayer weaving for the production of a wearable antenna on a cotton substrate. Silver yarn is used for the conductive regions of the textile antenna. Two layers of woven cotton serve to isolate the radiating patch from the ground plane of the antenna. The designed antenna was chosen to operate at the frequency of 2.45 GHz for Wireless Local Area Network. The built prototype resonated at 2.43 GHz with a |S11|of 218.62 dB. The integrated textile antenna exhibited a gain of 1.06 dBi at 2.43 GHz. [ABSTRACT FROM AUTHOR]

A novel dual frequency, wide band textile antenna has been proposed. A slot cut out of a regular rectangular patch revealing a vertical dumbbell-shaped conducting region resonates at global positioning system (L1 and L3) and time division duplex long term evolution fourth generation bands. The radiation efficiencies of the antenna at the lower and upper resonant frequencies are 96 and 88%, respectively. The antenna is fabricated using double side silver coated conductive fabric on a denim substrate and experimentally validated. The textile antenna resonates from 1.435 to 1.81 GHz and from 2.755 to 3.19 GHz. The antenna has a bandwidth of 375 and 435 MHz, that is, fractional bandwidth of 25.08 and 12.6% at the lower and upper bands, respectively. The fabricated antenna is then subjected to bending, shear, stretching deformations and their effects on the bandwidth of the antenna are analysed using analysis of variance method. The significant factors and their percentage contribution on the bandwidth are also determined using the F-test. Finally, an empirical equation is derived for the designed antenna to compute the bandwidth and the results are validated. [ABSTRACT FROM AUTHOR]

This letter proposes a novel method of noninvasive detection of voids in fiber reinforced plastics (FRPs). An ideal nondestructive evaluation method for the detection of subsurface defects that utilizes the capabilities of a magnetoinductive planar microstrip sensor is examined through a finite-integration-based model in this letter. A combination of magneto inductive waveguide as (MIW) and a patch radiator is used as the sensing element. The magnetoinductive waveguide increases the sensitivity of the patch to the presence of voids in the FRP. [ABSTRACT FROM PUBLISHER]