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This paper presents a module for monitoring the contact force between a probe for measuring vibration perception on the wrist and the skin. The module was designed for an original measuring stand for the automatic testing of the vibrotactile discrimination thresholds using the psychophysical adaptive method of 1 up–2 down with two or three interval forced choices (2IFC, 3IFC). Measurement methods were implemented in LabVIEW software. The inspiration for the project was the need to check the possibility of building a vibrating interface for transmitting information through vibrations delivered to the wrist via a bracelet. The test procedure on the wrist is not standardized; however, during its development, the recommendations of the Polish Norm–International Organization for Standardization PN-ISO 13091-1, 2006 were adopted. This standard contains methods for measuring vibration sensation thresholds on the fingertips for the assessment of neural dysfunction. The key to the repeatability of measurements seems to be the ability to continuously control the pressure of the measuring probe on the skin. This article compares two solutions for measuring the contact force along with an analysis of their accuracy and the impact of vibrations on the measured values. Moreover, the results of measurements of vibrotactile amplitude and frequency discrimination thresholds obtained on the ventral wrist at five frequencies (25, 32, 63, 125 and 250 Hz) are presented.

The main focus of this work was the design and development of a cross-beam force transducer for use in the construction of a tri-axial dynamometer. This dynamometer would be able to measure the cutting force along all three axes simultaneously during turning operations. The force transducer was built on the concept of the Maltese cross-beam, but it had been modified and improved so that it had a higher sensitivity and reduced the amount of interference error or cross-talk error that it produced. An investigation into the distribution of strain, as well as the determination of sensor locations within the transducer construction was carried out by means of finite element analysis. In order to develop a prototype of a turning dynamometer, a number of piezoresistive strain gauges were utilized in the transducer. In order to determine sensitivity, linearity, hysteresis, and repeatability, calibration tests were performed in three directions that were perpendicular to one another. To investigate the dynamic properties and capabilities of the dynamometer for use in turning applications, both modal analysis and actual turning tests were performed. The results of the experiments demonstrated that the newly developed turning dynamometer is a realistic approach for measuring cutting force in machining without reliability and accuracy.

Within these studies the piezoresistive effect was analyzed for 6H-SiC and 4H-SiC material doped with various elements: N, B, and Sc. Bulk SiC crystals with a specific concentration of dopants were fabricated by the Physical Vapor Transport (PVT) technique. For such materials, the structures and properties were analyzed using X-ray diffraction, SEM, and Hall measurements. The samples in the form of a beam were also prepared and strained (bent) to measure the resistance change (Gauge Factor). Based on the results obtained for bulk materials, piezoresistive thin films on 6H-SiC and 4H-SiC substrate were fabricated by Chemical Vapor Deposition (CVD). Such materials were shaped by Focus Ion Beam (FIB) into pressure sensors with a specific geometry. The characteristics of the sensors made from different materials under a range of pressures and temperatures were obtained and are presented herewith.

One of the most important parameters measured in the tests at laboratory–scale of reinforced concrete (RC) beams is the flexural strains required to investigate the behavior and develop a model. Flexural strains measured precisely are of great importance both in the correct interpretation of the behavior of RC beam tested and in the development of models close to the real behavior. Moment-curvature diagrams of RC beams are also created using flexural strains. The moment-curvature relationship, which is used to examine the behavior of RC beams under bending effect, is used to determine the bearing capacity of the beam and the failure modes in bending. Moment-curvature diagrams are also used to calculate the ductility of reinforced concrete beams. Therefore, it gives an idea about the amount of plastic energy that a RC beam can store. In the literature, it has been observed that there are a lot of problems encountered in the measurement of flexural strains. In this study, a flexural strain measurement setup (FSMS) is designed, manufactured, and tested on RC beam to eliminate these problems. In addition to being cost-effective and not labour intensive, FSMS developed can quickly, easily and more accurately measure the flexural strains of RC beams. It can also easily measure the flexure strains in RC beams with various cross-sectional shapes such as rectangular, triangular, trapezoidal, T, circular, etc. FSMS will certainly provide more accurate data to interpret the behavior of RC beams and to develop a model for RC beams or to check the accuracy of new strain measuring methods. As a result, the developed FSMS will provide great convenience to researchers interested in measuring flexural strains of RC beams in laboratory scale.

Monitoring the serviceability performance of reinforced concrete (RC) structures in the field provides critical data for informing RC modeling, analysis, and design. Currently, there is a lack of monitoring technology that can capture the complex behavior of RC elements in place, in detail, while also being feasible to implement. A technique of using fiber-optic sensors to simultaneously monitor both distributed RC beam deflections and crack widths is developed and described. Thirteen beam specimens with varying properties were tested in three-point bending to evaluate the technique against other sensor technologies. The results showed that distributed beam deflections can be accurately measured up until load levels approaching failure, while crack widths can be measured up until a width of 0.3 mm (0.0118 in.). The technique is practical to implement and provides robust data sets not achievable with other sensing technologies, making it an effective option for field-monitoring applications. Keywords: beams; crack widths; deflections; distributed fiber-optic sensors; monitoring; reinforced concrete; serviceability; strain.

This study explores the effectiveness of 3D Digital Image Correlation (DIC) for measuring displacement and strain of a propeller undergoing angular motion. Traditional methods, such as strain gauges, face limitations including physical interference, technical difficulties in sensor connections, and restricted measurement points, leading to inaccuracies in capturing true conditions. To overcome these challenges, this research utilizes non-contact 3D DIC technology, enabling measurement of surface displacements and deformations without interfering with the tested component. Experiments were conducted using the model aircraft propellers mounted on a custom-built test stand for partial angular motion. The 1 Mpx high-speed cameras captured strain and displacement data across the propeller blades during motion. The DIC strain measurements were then compared to strain gauge data to evaluate their accuracy and reliability. The results demonstrate that 3D DIC enables precise displacement measurements, while strain measurements are subject to certain limitations. Displacement measurements were achieved with a noise level of ±10 μm, while strain measurement noise ranged from 26 to 174 µm/m depending on direction. Strain gauge measurements were also performed for verification of the DIC measurements and calibration of the filtering procedure. Two types of non-metallic materials were used in the study: Nylon LGF60 PA6 for the propeller and 3D-printed PC ABS for the cantilever beam used in strain measurement validation. This study underscores the potential of DIC for monitoring rotating components, with a particular focus on measuring strains that are often overlooked in publications addressing similar topics. Additionally, it focuses on comparing DIC strain measurements with strain gauge data on rotating components, addressing a critical gap in existing literature, as strain measurement in rotating structures remains underexplored in current research.

Distributed reinforcement strain measurements could provide invaluable information for reinforced concrete (RC) model development and evaluation. A technique to measure distributed reinforcement strains using fiber optic sensors in RC elements is developed, which is more cost-effective and less time-consuming than existing methods. Nine RC beams were tested in three-point bending to evaluate the measurements, which were found to be accurate when compared to electrical strain gauges and theoretical predictions. This is the first instance where distributed fiber optic sensors have measured reinforcement strains accurately after cracking; however, strains well above yield were not reliably measured. Relating reinforcement strains with corresponding crack width measurements highlighted differences in how cracks initiate from crack to crack in a single specimen. Lastly, the experimental data were used to evaluate the potential for existing models to be used to predict reinforcement strains from external crack width measurements for RC assessment purposes. Keywords: assessment; cracking behavior; distributed fiber optic sensors; reinforced concrete; reinforcement strains.

The behavior of reinforced concrete beams strengthened with near-surface-mounted (NSM) iron-based shape memory alloy (Fe-SMA) bars was studied. Because there were no jacking tools used to apply the prestressing force, this technique was called self-prestressing. The prestrained Fe-SMA bar was anchored inside a precut groove at the tension side of the RC beam (2000 x 305 x 150 mm [78.7 x 12.0 x 5.9 in.]). The bar was then activated through heating above 300[degrees]C (572[degrees]F), causing a prestressing force in the bar. The beam was then tested under four-point bending setup to failure. The results revealed a significant increase in the yielding and ultimate load capacities. Unlike the prestressed FRP strengthening techniques, the ductility of the beam was significantly improved due to the yielding nature of the Fe-SMA material. Keywords: anchorage; fiber-reinforced polymers; flexural strengthening; iron-based shape memory alloys; near-surface-mounted.

Recent research has indicated that the implantation of a network of piezoelectric transducer patches in element regions of potential damage development, such as the beam–column joint (BCJ) area, substantially increases the efficacy and accuracy of the structural health monitoring (SHM) methods to identify damage level, providing a reliable diagnosis. The use of piezoelectric lead zirconate titanate (PZT) transducers for the examination of the efficiency of an innovative strengthening technique of reinforced concrete (RC) columns and BCJs is presented and commented on. Two real-scale RC BCJ subassemblages were constructed for this investigation. The columns and the joint panel of the second subassemblage were externally strengthened with carbon fiber-reinforced polymer (C-FRP) ropes. To examine the efficiency of this strengthening technique we used the following transducers: (a) PZT sensors on the ropes and the concrete; (b) tSring linear variable displacement transducers (SLVDTs), diagonally installed on the BCJ, to measure the shear deformations of the BCJ panel; (c) Strain gauges on the internal steel bars. From the experimental results, it became apparent that the PZT transducers successfully diagnosed the loading step at which the primary damage occurred in the first BCJ subassemblage and the damage state of the strengthened BCJ during the loading procedure. Further, data acquired from the diagonal SLVDTs and the strain gauges provided insight into the damage state of the two tested specimens at each step of the loading procedure and confirmed the diagnosis provided by the PZT transducers. Furthermore, data acquired by the PZT transducers, SLVDTs and strain gauges proved the effectiveness of the applied strengthening technique with C-FRP ropes externally mounted on the column and the conjunction area of the examined BCJ subassemblages.

Hydrogen fuel cell vehicles have gained more attention as future automobiles due to their environmental benefits and extended driving ranges. Concurrently, the global hydrogen sensor market is also experiencing substantial growth. These sensors are integrated into vehicles to detect hydrogen leakage and concentration, thereby ensuring the safety of hydrogen fuel cell vehicles. In particular, hydrogen pressure sensors, commonly installed on the manifold and regulator of vehicles, can measure hydrogen pressure and diagnose safety concerns caused by hydrogen leakage in advance. In this paper, we identify the vulnerable points of hydrogen pressure sensors when exposed to vehicle driving environments, investigate failure mechanisms, and provide process optimization techniques. Specifically, our reliability modeling verifies that the components of a printed circuit board (PCB) exposed to humid environments undergo corrosion due to ion migration, leading to the generation of extrinsic series or parallel resistances, which in turn cause fluctuations of output voltage. Through structural and elemental analysis, we pinpoint process-related factors that make components vulnerable to humidity, thereby suggesting recommendations for enhancing the manufacturing process. Based on this analysis in the development stage, we can proactively address and improve reliability and further safety-related issues for future automobiles, thus preventing real field issues.