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Purpose: To evaluate the effect of immersion in water on deforma8on of maxillary denture bases created with CAD/CAM and heat-polymerized resin fabrica8on techniques under loading condi8ons. Materials and Methods: 2-mm-thick denture bases were fabricated using four techniques: CAD/CAM milling (CCM; Polywax PMMA blank, Yamachi PMMA disk Yamahachi Dental); 3D prin8ng (3DP; BV005, NextDent Base); compression molding (CM; Luciton 199, Dentsply Sirona); and injec8on molding (IM; Ivobase, Ivoclar; n = 5 per group). Three sta8c 49-N loads were applied perpendicular to each denture base, and the mean strain value (MSV) was recorded with strain gauges a[ached to the denture surface. The denture bases were stored at 37°C in dis8lled water for 14 and 28 days, and the MSVs under the same sta8c load were recorded. Results: The highest MSVs were observed at the posterior palatal seal, tuberosity, and labial notches of the dentures. The lowest MSVs were recorded for the CCM group and then the CM and IM groups. The highest MSVs were recorded for the 3DP group. No significant differences in regional MSVs (P > .05) were observed among the CCM, CM, and IM aber 14 and 28 days in water. Large devia8ons in MSVs were recorded for the 3DP group across the measurement sites aber water exposure (P < .05). Conclusions: CCM had the lowest denture deforma8on under sta8c loading. Aber immersion in water, the deforma8on changes under sta8c loading were stable for CCM, CM, and IM. However, varia8ons among the materials used in 3DP group influenced the mechanical performance and presented larger deformations. [ABSTRACT FROM AUTHOR]

Robust adhesion is crucial for ionic hydrogels in flexible electronic pressure and strain sensors. Herein, we design a transparent and strong adhesion electronic pressure and strain sensor based on a multifunctional ionic hydrogel with double network using polyacrylamide (PAM) and gum arabic (GA). First, the effect of ionic type on the mechanical properties of hydrogels was measured. The GA/PAM–Fe3+ hydrogel with high extensibility (1835%) and toughness 1. 47 MJ / m 3 was selected as the best sensor material. Moreover, the GA/PAM–Fe3+ hydrogel has good adhesion property with various substrates, and the maximum peel strength of the hydrogel to skin could reach up to 123.9 N/m. Furthermore, the resistance of GA/PAM–Fe3+ hydrogel is sensitive to a wide strain window and the gauge factor shows stable and reliable change during deformation. Due to its compliant and excellent adhesive properties, strain sensors based on this hydrogel can be well fixed on the epidermis without adhesive tape, and can perceive large and gentle body movements. These characteristics demonstrate that GA/PAM–Fe3+ hydrogel is promising for a broad range of practical applications in wearable sensors. [ABSTRACT FROM AUTHOR]

State‐of‐the‐art biosignal monitoring systems strive to achieve a balance between biocompatibility, biodegradability, and miniaturized, unobtrusive signal acquisition, thus requiring further research for improved user safety, mobility, and comfort. Here, a fully wireless sensing system is presented for real‐time in vivo assessment of physiological vital signs, addressing these challenges to enhance performance and user experience. The system features a biodegradable passive tag with a nanoscale crack‐based strain gauge sensor connected to a coil antenna on a gelatin‐ionic liquid substrate (GIS). The thermal crosslinking in the GIS promotes adhesion, while the presence of ionic liquid decreases the self‐resonance frequency of the BCA to below 100 MHz, enabling the device to operate in detuned mode. A lightweight (1.547 g) wearable reader patch interrogates an implanted passive tag via near‐field inductive coupling and transmits sensory data to peripheral devices via Bluetooth. Thus, the system ensures minimal tissue absorption and extended transmission range while consuming ≈80 mW of power during operation. In vitro and in vivo studies, culminating in successful implementation within a rat model, validated the implanted tag's biocompatibility and the system's capability to wirelessly acquire and process superimposed physiological vital signs, highlighting its potential to enhance patient outcomes through improved diagnostic and monitoring practices. [ABSTRACT FROM AUTHOR]

Highlights Proper design and accurate mechanical assessment of composite C‐beam after opening are of great importance in structure engineering. This paper aims to experimentally and analytically investigate the postbuckling response of large‐size C‐beam with web opening under bending‐shear coupling load. New specimen with four different open shapes were designed and tested. Strain gauges and displacement measurements were applied to monitor its buckling behavior, strain field distribution and critical failure load. Four specimens with various openings were loaded until catastrophic failure occurred. Additionally, an analytical model was introduced to predict the residual strength of circular opening. The results indicate that while the presence of an opening significantly decreases the load carrying capacity, it has minimal effect on the bending stiffness. Compared with intact specimen, the initial delamination, buckling and ultimate strength of the circular opening decreases less than those of the rectangular opening. By altering the position of the rectangular opening, improvements can be made in terms of initial delamination resistance and buckling load; however, ultimate strength remains largely unaffected. Reinforcing the edge of an opening further reduces resistance to initial delamination but other two indicators are improved. Overall, from buckling to failure stages, post‐buckling bearing capacity after opening decreases by 40%. Moreover, the shear failure mode is observed during catastrophic failures. And the analysis method employed is relatively conservative. Ten large size composite C beams are conducted under coupling loads. Deformation, strain distribution and failure mode are presented. Influence of openings on postbuckling behavior of beam is analyzed. An analysis method is employed to predict the residual strength of beam. It could provide valuable insights for assisting in designing beam openings. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the degree of conversion (%), flexural strength (MPa), elastic modulus (GPa), compressive strength (MPa), Knoop microhardness (KHN), post-gel shrinkage (%) and prediction of ideal concentration of cholesteryl methacrylate (CM) in experimental resins. Four formulations were manipulated (F): F1, control group, (0 % CM); F2 (15 % CM); F3 (19.8 % CM) and F4 (30 % CM). Bis-GMA and CM percentages were determined using Statistica™ software. For the degree of conversion test, Raman spectroscopy was used. To testing flexural strength, elastic modulus and compressive strength, a universal testing machine was used. For the Knoop microhardness test five indentations were made in each sample. Post-gel shrinkage was determined using the strain gauge method. Statistica™ software processed all data obtained in this study. Results were submitted to one-way ANOVA and Tukey's post hoc tests (α = 0.05). Better performance was observed for F2 (15 % CM) and F3 (19,8 % CM) for degree of conversion, elastic modulus and post-gel shrinkage. For Knoop microhardness F2 (15 % CM), F3 (19,8 % CM) and F4 (30 % CM) showed higher values than F1 (0 % CM). For flexural strength F1 (0 % CM) and F3 (19,8 %) were similar and F4 showed the lowest values and for compressive strength F1 (0 % CM) showed the highest values. For mixture designs analysis data, concentrations ≤ 25 % of CM would provide better results. Addition of CM at concentrations lower than 30 % contributed to a significant increase in the degree of conversion, microhardness values, elastic modulus and reduction of post-gel shrinkage. • Cholesteryl methacrylate proved to be a promising polymer for improving composites. • An endocyclic double bond can be an additional site for photochemical cycloaddition. • Concentrations ≤ 25 % cholesteryl methacrylate enhance composite resins. • Post-gel shrinkage performed better with 15 %, 19.8 % and 30 % cholesteryl methacrylate. • Knoop microhardness was higher with 15 %, 19.8 %, and 30 % cholesteryl methacrylate. [ABSTRACT FROM AUTHOR]

D1244 in operation – first data and results on the way to controlled adaptation Global construction is responsible for about 50 % of the world's CO2‐emissions and resource consumption. For a sustainable future, a drastic reduction is required, which, however, is in contradiction to the worldwide demographics characterized by population increase and urbanization. One possible approach are adaptive load‐bearing structures equipped with distributed actuators and sensors that can manipulate deformations and stress distributions under loads through geometric adaptation. For high‐rise buildings, this technology enables a reduction of resource consumption by about 50 %, for example. The world's first prototype was inaugurated at the end of 2021 on the campus of the University of Stuttgart. With twelve floors on a base area of 5 m × 5 m, the D1244 is 36 m high and has 24 hydraulic actuators, 128 strain gauges, and an optical measurement system that uses two cameras to measure deformations at 16 points on the structure in a plane parallel to the camera sensor with submillimeter precision. This paper illustrates the steps within the model‐based development chain for automation and control of D1244 that have been accomplished and the results that have been achieved on this high‐rise building. The experimental model identification and the subsequent model‐based controller and observer design are discussed. Finally, the algorithms used for fault detection and diagnosis are presented and their basic functionality is demonstrated on the basis of initial validation measurements. [ABSTRACT FROM AUTHOR]

The basic measuring element of vibrating-wire strain gauges is a steel piano wire, functioning in the elastic range. This element is constantly under tension. Therefore, its material gradually deforms permanently. This deformation causes its stress to relax. This relaxation results in a measurement errors of the strain gauges. This error, as demonstrated by both in situ and laboratory tests, can reach values of even several percent of the strain gauge measuring range (FSR) over periods of 10 years. Therefore, a concept of a differential strain gauge was proposed, for the construction of which two measuring wires would be used. Changing the input value of the strain gauge, i.e. a displacement of one of its anchors in relation to the other one would cause one wire to lengthen while the other wire shortened identically. The measured displacement would be calculated on the basis of the difference in the frequency of the wires vibrations. In this way, the influence of the simultaneous relaxation of the wires on the measurement result would be greatly reduced. Based on this concept, a prototype differential strain gauge for measuring concrete deformation was realized. In addition to two wires, it also contains two electromagnets, placed together with the wires in a common body-housing. After the strain gauge was assembled, its first tests were carried out under laboratory conditions. [ABSTRACT FROM AUTHOR]

The loading system stiffness (LSS) of a rock mechanics testing machine is important in laboratory testing because it dictates whether the coal or rock failure process is stable or unstable. It is also critical to ejection kinetic energy after coal specimen failure. When unstable failure accidents such as rock burst occur in rock engineering, the speed of ejected coal or rock may reach or even exceed 10 m/s. Such unstable failures, if unplanned, can result in injuries of workers, damage to equipment and delays in production in underground mines. To systematically study the influence of the LSS on mechanical characteristics and kinetic energy of coal specimens, tests are first carried out using an LSS-variable testing system named BGYD-600. PCI-2 acoustic emission (AE) test system, acceleration sensor and dynamic strain gages are used to monitor the AE signals of coal and deformation, displacement of test machine. And the kinetic energy is calculated by energy analysis method. The test results show that the LSS has influence on the stress–strain curves of coal specimens after the peak strength. The smaller the LSS, the steeper the post-peak curves. In addition, as the LSS decreases, the spalling of coal blocks increases considerably, and the powdery phase begins to appear, and the coal specimen is destroyed at a shorter time with more coal blocks being ejected. Moreover, the maximum AE energy occurred not at the peak strength using the BGYD-600, which is different from the large stiffness testing machines. Finally, considering the impact of the elastic deformation energy release of the testing machine on the coal specimens, the kinetic energy calculation formula when the coal specimen failure is derived. And the influence of LSS on the kinetic energy, elastic deformation energy, dissipation energy and total input energy is analyzed. As the LSS increases, the kinetic energy of the coal specimen shows a decreasing trend. The quantitative relationship between mechanical characteristics, kinetic energy and LSS given in this paper has certain reference value for mining and civil engineering projects. Highlights: The loading system stiffness effects on mechanical characteristics of coal specimens were studied by indoor rock mechanics tests. The impact of the energy released by the testing machine on the coal specimen was first obtained from an experimental perspective. A quantitative calculation formula for the kinetic energy of coal specimen when it is destroyed under the loading system tiffness effects was obtained. [ABSTRACT FROM AUTHOR]

The digital image correlation (DIC) system is a powerful tool for measuring distributions of displacement and strain on the surface of a specimen. DIC systems are employed not only for homogeneous materials such as metals but also for heterogeneous materials such as wood. Although numerous validations of DIC system accuracy for metallic materials exist, the accuracy verification for wood, especially under multiaxial stress conditions, is less common. This study investigated the accuracy of a DIC system equipped with a bilateral telecentric lens on wood (Douglas fir). The accuracy verification in uniaxial stress fields was conducted through full compression testing, while verification in multiaxial stress fields was performed through partial compression testing. Additionally, compression tests on A6063 (aluminium alloy) were conducted to examine the differences in the DIC system accuracy between homogeneous and heterogeneous materials. The accuracy of the DIC system was assessed by comparing the results with those obtained from strain gauges. The results from the full compression tests indicate that the accuracy of axial strain measured by the DIC system was comparable for the specimens of A6063 and Douglas fir in the longitudinal (L) direction but was inferior for Douglas fir in the radial (R) direction. This is because the differences in the mechanical properties of earlywood and latewood produce high strain gradients. Furthermore, the differences in Young's modulus obtained from the DIC system and strain gauge for the specimens of A6063, Douglas fir (L), and Douglas fir (R) were − 1.23%, 2.26%, and − 12.5%, respectively. In the partial compression tests, the accuracy of strain components measured by the DIC system in the specimens of Douglas fir (R) was lower than that in A6063. In the partial compression tests, high strain gradients appear in multiple strain components, leading to a notable decrease in the accuracy of the DIC system compared to the full compression tests. [ABSTRACT FROM AUTHOR]

Background: Strain gauges commonly used in structural testing are manually pasted, usually with a 1–4 mm deviation between the actual pasted position and the theoretical position. The deviation leads to measurement errors, which are more pronounced in high strain gradient regions with stiffness discontinuities such as openings, reinforcements, and notches. Objective: This study aims to obtain the actual pasted position of strain gauges and thus improving the testing measurement accuracy. Methods: A non-contact strain gauge positioning method is proposed. Firstly, considering that the strain gauges have a regular shape, the irregular borderlines are filtered out based on the geometric features of a borderline image. Secondly, considering that the color of the strain gauge is significantly different from the test piece, and the color features within the borderline are extracted by clustering and compared with the strain gauges to complete the recognition. Finally, based on the epipolar geometry, the matching relationship of the strain gauges in different images is obtained, and the positioning is completed based on binocular vision according to the strain gauge recognition results. Results: For a simple plate, the average positional error of strain gauges is reduced by 71%. For a small square tube, the average error is reduced by 44%. For a large cylinder, the average error is reduced by 32.4%. Conclusion: The proposed non-contact strain gauge positioning method can obtain high precision strain gauge positions, which effectively improves the test measurement accuracy. [ABSTRACT FROM AUTHOR]

This article shows the strain analysis on two cantilever cast-in-place prestressed concrete bridges during construction. Strain gauges, measuring strain based on the change in electrical resistance, were installed on both structures in order to obtain strain results during and after construction. Nonlinear numerical models were made to simulate the realistic behaviour of the structure and show the effect of creep and shrinkage during the construction phases. The numerical model taking into account creep and shrinkage is validated and shows good overlap with the measured results. Relative compressive stresses as well as the necessary precamber are shown. The effects of creep and shrinkage are analysed. Finally, the data can be used to analyse and compare other similar bridges and validate different numerical models. A recommendation for the design of future prestressed concrete balanced cantilever bridges is given. [ABSTRACT FROM AUTHOR]

Introduction: This study aimed to evaluate the validity of the HandyGym portable flywheel device with an integrated rotary encoder in measuring force and power during iso-inertial exercises compared to a traditional reference system. Methods: In total, 10 trained volunteers (3 women, 7 men; age 25.2 ± 3.8 years) performed half-squats with five different load configurations using the HandyGym device. Concurrent measurements were obtained from HandyGym's rotary encoder and a criterion system (MuscleLab 6000 strain gauge and linear encoder). Five load configurations were tested, with 15 repetitions recorded per condition. The validity of the HandyGym measurements was assessed through mean bias, typical error of estimation (TEE), and Pearson correlation coefficients, with Bland–Altman plots used to analyze the agreement between the two systems. Results: The HandyGym showed high correlations with the reference system for both force (r = 0.76–0.90) and power (r = 0.60–0.94). However, systematic biases were observed, with the HandyGym consistently underestimating force and power at lower loads and overestimating power at higher loads. The TEE values indicated moderate to large errors, particularly in power measurements. Conclusion: The HandyGym provides valid force measurements with moderate bias, suitable for general monitoring. However, power measurements are less consistent, especially at higher loads, limiting the device's utility for precise assessments. Adjustments or corrections may be necessary for accurate application in professional contexts. [ABSTRACT FROM AUTHOR]

This study aimed to optimize the lower articulation of low-floor trams using a meta-model technique, followed by an experimental validation. The design variables were identified through structural analyses, and the optimization reduced the weight of the lower articulation by 20% while maintaining load-bearing performance. Strain gauges were attached to failure-prone areas for structural and fatigue testing. The results of the optimized design were compared with experimental data, confirming its validity. This method effectively reduces the cost and improves the performance of tram articulation devices. This study presents an effective approach for cost reduction and performance improvement in the lower articulation of low-floor trams. [ABSTRACT FROM AUTHOR]

Accurate identification of impact loads is vital for structural assessment and design. Traditional methods rely on complex equipment, such as accelerometers or strain gauge, which can be expensive and prone to failure. This study introduces a non-contact intelligent identification approach incorporating visual sensing technology, providing a convenient means to identify impact loads. Numerical simulations explore the differences in identifying impact forces through acceleration and displacement responses, particularly by considering such variables as measurement noise and number of measurement points. A meticulously designed experiment verified the feasibility of the proposed method for measuring the displacement and velocity of rapidly moving targets, and evaluated its performance in terms of accuracy. A series of impact loading experiments were conducted on a simply supported girder bridge model to validate the effectiveness of the proposed impact force identification method. Results indicate strong agreement between displacement response measurements and percentile meters. The proposed non-contact method accurately identifies single or continuous impact loads, with a minimum peak relative error of 0.2%. This study represents a pioneering application of intelligent visual sensing technology in the field of impact load identification. Moreover, the current research introduces a novel approach to address the challenges faced by conventional methods in identifying impact loads. Future research can leverage the groundwork laid by this study to further optimize and expand the proposed method, enhancing its capabilities and fully harnessing its potential to offer advanced solutions in structural health monitoring. [ABSTRACT FROM AUTHOR]

BACKGROUND RESULTS CONCLUSION Intelligent identification and precise plucking are the keys to intelligent tea harvesting robots, which are currently of increasing significance. Aiming at plucking tender leaves for high‐quality green tea production, in this study, a tender leaf identification algorithm and a mechanically perceptible plucking finger have been proposed.Based on the segmentation algorithm and color features, the tender leaf identification algorithm shows an average identification accuracy of over 92.8%. The mechanically perceptible plucking finger plucks tender leaves in a way that a human hand does, aiming to maintain the high quality of tea products. Though finite element analysis, we determine the ideal size of grippers and the location of strain gauge attachment on a gripper to enable the employment of feedback control of desired gripping force. As revealed in our experiments, the success rate of tender leaf plucking reaches 92.5%, demonstrating the effectiveness of our design.The results show that the tender leaf identification algorithm and the mechanically perceptible plucking finger are effective for identification of tender leaves and plucking, providing a foundation for the development of an intelligent tender leaf plucking robot. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

This study designs a blasting loading device capable of changing the utilization of explosive gas by modifying the constraint conditions. The propagation of crack and stress waves in red sandstone under different explosive gases is recorded using digital image correlation technology and ultra‐dynamic strain gauges. Both methods are effectively validated against each other. The results showed that as the utilization of explosive gas increases, the explosive stress wave induces layer cracking at the specimen's far end and tensile failure at its near end. In addition, the larger the stress wave's amplitude, the greater the spatial attenuation coefficients of the compression and tension waves. The study ultimately deduces the propagation process of the incident wave and analyzes the influence of stress wave propagation on the specimen's failure characteristics. [ABSTRACT FROM AUTHOR]

Monitoring stress and strain at the critical details of steel bridges is essential for ensuring structural integrity. This study introduces a three‐layer flexible strain sensor produced through a spraying process, using flake‐shaped silver‐coated copper powder as the conductive filler and modified acrylic emulsion as the matrix material. The study investigated the impact of size parameters on sensor sensitivity, determining optimal dimensions of 20 mm in length, 2 mm in width, and an initial resistance value ranging from 1.0 Ω to 1.8 Ω. Analysis of the optimized sensor's performance unveiled high sensitivity and linear response capabilities under low strain conditions with a gauge factor (GF) value of up to 25.6 and a linear correlation coefficient R2 ≥ 0.971 under 300 με. Notably, the sensor exhibits an extremely low strain detection limit of 0.005% and a broad response range spanning from 0.005% to 0.19% strain. It demonstrates swift response and recovery times of 500–800 ms, showcases directional strain response, exhibits good repeatability, and endures durability tests (withstanding 3000 cycles). Furthermore, a fitting formula is proposed to accurately depict the strain and relative resistance change relationship across a wide response range. The study and initial application of this sensor's sensing characteristics and performance signify its potential for practical engineering applications. [ABSTRACT FROM AUTHOR]

Monitoring soft-tissue biomechanics is of interest in biomedical research and clinical treatment of diseases. An important focus is biointegrated strain gauges that track time-dependent mechanics of targeted tissues with deforming surfaces over multidirections. Existing methods provide limited gauge factors, tailored for sensing within specific directions under quasi-static conditions. We present development and applicability of implantable/wearable strain gauges that integrate multiple ultrathin monocrystalline silicon-based sensors aligned with different directions, in stretchable formats for dynamically monitoring direction angle-sensitive strain. We experimentally and computationally establish operational principles, with theoretical systems that enable determination of intensities and direction of applied strains at an omnidirectional scale. Wearable evaluations range from cardiac pulse to intraocular pressure monitoring of eyeballs. The device can evaluate cardiac disorders of myocardial infarction and hypoxia of living rats and locate the pathological orientation associated with infarction, in designs with possibilities as biodegradable implants for stable operation. These findings create clinical significance of the devices for monitoring complex dynamic biomechanics. [ABSTRACT FROM AUTHOR]

The sense of touch and perception of hand motion form an essential part of the somatic sensory system. Although piezoelectric sensors demonstrate high sensitivity and linearity, they are traditionally not employed for electronic skins because of their limited stretchability. Here, a printed, skin‐conformal, electronic system consisting of stretchable piezoelectric pressure sensors and carbon nanotube strain gauges capable of identifying tactile sensations and joint movements on the hand is introduced. The pressure sensor demonstrates both high sensitivity (19.9 mV kPa−1) and linearity (0.1–1000 kPa) while being reliably stretchable to above 15%. To complement the pressure sensing functionality, a strain gauge is fabricated in a rapid stamp printing process and designed to demonstrate excellent mechanical reliability with up to 70% strain and high sensitivity (36.5‐gauge factor). These sensors can seamlessly conform to numerous anatomical regions and cover wide areas of the skin, making them ideal for deployment in an electronic skin. Finally, the sensors are integrated with a flexible microelectronic device to demonstrate their functionality in human touch and prosthetic hand applications. [ABSTRACT FROM AUTHOR]

In order to further understand the impact of tip air injection on compressor stability under circumferential pressure distortion, a series of experimental studies on tip air injection under uniform and circumferential distortion were conducted on a low-speed single rotor axial flow compressor. The unsteady measurements were carried out by use of microsensors and strain gauges bonded on the rotor blade surfaces, and a collection of dynamic pressure sensors installed on the casing wall. Results indicate that with the increase in the injected momentum ratio, the load at the leading edge near the rotor blade tip obviously decreases, thereby delaying the stall. By comparing the pressure distribution on the rotor blade surface under different injected momentum ratios, tip air injection can effectively suppress flow separation at the blade tip to enhance flow capability. In addition, it can also weaken the fluctuation of tip leakage flow and reduce the dynamic stress similar to natural vibration near the blade root both in stationary and rotating coordinate systems. Under the condition of inlet circumferential distortion, tip air injection can significantly reduce the load at the distorted region and suppress the low-frequency disturbances measured on the rotor blade surface caused by inlet distortion. In addition, the dynamic stress near the blade root can also be effectively reduced by tip air injection. It implies that tip air injection can both extend the stall margin and reduce blade vibration when suffering from circumferential distortion; thus, the compressor can safely operate. [ABSTRACT FROM AUTHOR]

The use of ultra-high strength steels (UHSS) is increasing in many industries. These steels are gaining importance in structural applications due to their advantageous properties of high strength and low weight. However, the reliability and durability of welded joints are often questioned due to uncertainties that may occur in the manufacturing process and the use of different modeling techniques. Therefore, it is important to conduct experimental and numerical studies to determine the performance of welded joints and to optimize weld design. In this study, two T weld joint specimens, 20 mm and 30 mm in length, were prepared using S960QL UHSS. Loading was carried out by attaching strain gauges to the samples, and normal stress values varying over time were measured. Different finite element analysis (FEA) modeling techniques were prepared, and numerical analyses were performed using Ansys software. The stress magnification factor (km) was determined for different models. As a result of the study, the average km was determined to be 1.05 for stresses above 500 MPa in the modelling technique closest to the experimental study. Error rates and km values were found to be high for values below 500 MPa stress. As a result of the results obtained, modeling techniques were determined to accurately determine the reliability and durability of welded joints in UHSS, Additionally, new km values have been suggested. [ABSTRACT FROM AUTHOR]

Measurement of the impact process is challenging due to its short duration and high frequency response. Due to the very small strain in low-velocity impacts, the requirements for the temporal and spatial resolution of test methods are extremely high. Traditionally, strain gauges or lasers are commonly used to measure the dynamic response of a single point, or quasi-static loading is used to achieve full-field response. To finely describe the transient full-field deformation process of low-velocity impacts, a high-speed imaging system combined with 3D digital image correlation (DIC) technique is set up to investigate the instantaneous responses of impact on a polyvinyl chloride (PVC) plate at the ms and με level. The full-field deformation of the contact surface and the whole process of elastic wave propagation are measured. The measurement by DIC closely matches the measurement by strain gauges and agrees well with the numerical simulation results. The measurement reveals that the "multi-micro-impacts" phenomenon may happen during a complete impact process due to the complex strain wave propagation. This work provides a benchmark case for low-velocity impact full-field testing, and the results show that 3D DIC can accurately evaluate dynamic behaviors of low-velocity impact between flexible bodies and can accurately describe the spatiotemporal propagation characteristics of strain waves. [ABSTRACT FROM AUTHOR]

This paper proposes a force-sensing wing, Senswing, to enhance the intelligence of flapping-wing aerial vehicles (FWAVs). Force perception is a crucial capability for robots to interact safely and effectively in unknown environments. However, FWAVs perform flapping motions with significant acceleration and deceleration, which can cause the flexure element inside force sensors to deteriorate due to repeated loading or even fail due to impulsive forces. To address this, we constructed a force measurement system by attaching 16 strain gauges directly to the wing root while maintaining high rigidity. We confirmed that the external force measurement capability closely matched the values obtained by a six-axis force sensor, with almost no error. Additionally, when measuring aerodynamic forces during wing flapping, the sensor could detect differences in wind speed even during flapping. With this sensor, FWAVs can achieve in-flight measurement of thrust and lift through a force-sensing system. [ABSTRACT FROM AUTHOR]

Residual stress is rarely considered as an initial condition for Finite Element Analysis (FEA), or used in the component design. A comprehensive numerical and experimental investigation into prestressed steel sheets is conducted. Residual stresses at specific locations were introduced into the steel sheets by dimple formation. FEA is used to simulate dynamic dimple forming of a mild steel disk due to a tool impact and detect the existence of prestress after dimple formation. A physical drop-hammer was used to form a range of dimple sizes in disks to experimentally validate the FEA predictions associated with dimple depth. Dimples were then created using a screw press and the prestress was measured by strain gauges beyond the zone of permanent out-of-plane deformation associated with a dimple. The experimental strain gauge measurements during dimple formation were found to be consistent with FEA predictions. The results demonstrated that the predicted and measured radial and tangentially projected stress components remain in steel sheets after forming a dimple. Furthermore, the predicted prestress was greater near to the dimple formation and occurred at higher magnitudes in the tangential direction than the radial direction. The highest prestress remaining in the disk was at the magnitude of the material's ultimate tensile stress, predicted in the tangential direction at the edge of the dimple. The numerical and experimental results showed the three stages of prestress formation: the development of stresses during dimple formation, the elastic recovery after the dimple forming, and the final prestressed equilibrium state of the rimmed disk. [ABSTRACT FROM AUTHOR]

Spacecraft recovery technology is crucial in the field of aerospace, in which the parachute plays a key role in slowing down the descent speed of the spacecraft and realizing a smooth landing. In order to construct a dynamically adjustable parachute deployment strategy, it is necessary to measure the parachute dynamic load accurately in real-time. However, the existing sensor measurement scheme makes it difficult to meet the measurement requirements due to its large structure and complex wiring. In order to meet the current demand for real-time measurement of parachute cords dynamic load, a miniature measuring instrument is designed. According to the function and technical requirements of the miniature measuring instrument, the hardware modules of the acquisition system are selected and designed, and the integration debugging and performance optimization of the microcontroller module, A/D sampling module, signal acquisition circuit, and power supply module are carried out. The software of the parachute cords tension acquisition system based on the miniature measuring instrument is developed. The Load Cell is modeled by using SolidWorks 2022 and statically analyzed by using Ansys 2022 R1 Workbench finite element analysis software. Then the final structure of the Load Cell and the pasting position of the strain gauge are determined through the results analysis as well as experimental verification. The hardware module of the signal acquisition system for the miniature measuring instrument is then encapsulated. The force value of the miniature measuring instrument is calibrated and tested many times by using the microcomputer-controlled electronic universal testing machine. The experimental results show that the designed miniature measuring instrument has accurate data, strong stability, and good real-time performance, which meets the demand for real-time accurate measurement of miniature measuring instruments, and can provide reliable data for parachute cords parameter validation and stepless unfolding design. [ABSTRACT FROM AUTHOR]

A multifunctional sensor comprising flexible and transparent ultraviolet (UV) photodetectors (PDs) with strain gauges based on Ag nanowire (AgNW)@ZnO nanorods (ZnONRs) was fabricated using a cost-effective, simple, and efficient method. High-aspect ratio silver nanowires were synthesized using the polyol method. An AgNW@ZnONR composite was formed via the hydrothermal method to ensure the multifunctional capability of the flexible sensors. After refining the process parameters, the size of the ZnO nanorods was decreased to fabricate pliable multifunctional sensors using AgNW@ZnONRs. At a deposition of 0.207 g of AgNW@ZnONRs, the sensor achieves its maximum switching ratio and fastest response time under conditions of 2000 μW/cm2 UV optical power density. With a ton (rise time) of 2.7 s and a toff (fall time) of 2.3 s, the ratio of Ion to Ioff current is 1151. Additionally, the sensor's maximum optical current value correlates linearly with UV light's power density. The maximum response current increased from 222.5 pA to 588.1 pA, an increase of 164.3%, when the bending angle was increased from 15° to 90° for the sensor with a deposition of 0.276 g of AgNW@ZnONRs. There was no degradation in the response of the sensors after 10,000 bending cycles, as they have excellent stability and repeatability, which means they can meet the requirements of wearable sensor applications. Therefore, there is great potential for the practical application of multifunctional AgNW@ZnONRs in flexible sensors. [ABSTRACT FROM AUTHOR]

To investigate the performance of in-service skewed bridges, two continuous two-span steel I-girder bridges, one skewed 45° with integral abutments and the other skewed 41° with stub abutments, were instrumented during construction for long-term field monitoring. The bridges are located near each other and experience similar traffic volume and thermal variation, from roughly −18°C to 38°C (0°F to 100°F). Critical girders and cross-frames were instrumented with strain gauges and/or tiltmeters, and temperature was recorded at each sensor. Superstructure response over more than 2 years of data collection was recorded and studied, including for the in-service first-stage half bridges (temporarily for 6 months) and the full bridges. Girder cross-sections and cross-frames were within the elastic range during field monitoring, so stress directly relates to measured strain. The bridge superstructures experienced cyclic stress variation under thermal loading—there was clear linear correlation between bridge response and seasonal temperature variation, especially for decomposed girder axial stress and strong-axis bending stress. Deviation from the correlation was observed due to changes in abutment restraint during seasonal temperature variation and thermal gradient under daily temperature changes. Exterior girders were frequently unevenly heated by direct sunlight, which induced a diverging daily stress–temperature relationship compared to long-term observations. Thermal response of exterior girders is more complex than interior girders regarding both strong-axis and lateral bending, which is often not incorporated in standard bridge design procedures. Several girder bottom flanges and cross-frame members exhibited atypical increasing stress that started during the first cold-weather period; some of the stress development continued over time, regardless of long-term thermal cycles. [ABSTRACT FROM AUTHOR]

PURPOSE. The aim of this study was to investigate microstrains around two non-parallel implant-supported prostheses and different abutment connections and positions under vertical static load using strain gauges. MATERIALS AND METHODS. 4 models simulating the mandibular unilateral free-end were fabricated. 8 implants (4.0 × 10 mm and 5.0 × 10 mm) were inserted in the second premolar, perpendicular to the occlusal plane, and the second molar, tilted at 15°. Four groups were analyzed: engaging and angled abutments (control group), both non-engaging abutments, both screw-and cement-retained prosthesis (SCRP) abutments, and engaging and non-engaging abutments. Strain gauges were placed buccally, lingually, mesially, and distally adjacent to each implant. The restoration was cement-retained in the control group and screw and cement-retained in the rest. Zirconia bridges were fixed on the abutment with NX3, and a 300 N vertical static load was applied. Microstrains were recorded and analyzed. RESULTS. Both non-engaging abutments showed the highest compressive microstrains (-52.975), followed by engaging, angled abutment (-25.239). SCRP-SCRP abutments had the lowest compressive microstrains (-14.505), while the engaging, non-engaging abutments showed tensile microstrains (0.418). Microstrains in SCRP-SCRP and engaging, non-engaging groups were significantly lower than in the control group (a = .05). Premolar areas showed compressive microstrains (-47.06), while molar sites had tensile microstrains (+0.91), with microstrains in premolars being significantly higher than in molar area (a = .05). CONCLUSION. The types of abutment connections and positions may have a potential effect on microstrains at the implant-bone interface. SCRP-SCRP abutments could be an alternative to use in non-parallel implant-supported prostheses when two implants make an angle of no more than 20 degrees. [ABSTRACT FROM AUTHOR]

Background: Leash pulling is a commonly reported problem behavior for dog owners, as a result, a variety of leash equipment types are offered to mitigate pulling force. We were particularly interested in prong collars as their inherently aversive design has made their use a subject of debate. Though banned in certain countries and widely available in others, to date, there is no research comparing them to other leash walking equipment. Methods: We compared four types of leash walking equipment: a martingale (flat collar as baseline measure), a front-connection harness, a polymer prong-style collar (Starmark), and a standard metal prong collar. Twenty-three dogs were walked on all four types of equipment for 5-min each. Equipment was attached to a leash which was connected to a battery-powered strain gauge to measure the dog's pulling force. All walks were video recorded for behavior analysis. Results: There were statistically significant differences among the leash equipment types in pulling impulse (Newtons × seconds), (χ2(2) = 30.6, p < 0.001). Post-hoc analysis revealed significant differences in impulse between the martingale and the other equipment: harness (Z = −3.69, p < 0.001), Starmark collar (Z = −3.62, p < 0.001) and prong collar (Z = −3.92, p < 0.001). No other differences among equipment types were significant. Fifteen behaviors were examined as welfare indicators but only three: looking at the handler, lip licking, and sniffing occurred across all dogs and all walks. There was a statistically significant difference in frequency of lip licking behavior across the four types of leash-equipment (χ2(2) = 8.17, p = 0.04) and post-hoc analysis showed a difference between the martingale and the harness (Z = −2.65, p = 0.008). While our research did not provide any clear evidence of poorer welfare due to equipment type, we caution the generalizability of these findings and recommend further assessment of these items of leash-walking equipment in real-life scenarios. [ABSTRACT FROM AUTHOR]

Piezoelectric inkjet printing technology, known for its high precision and cost-effectiveness, has found extensive applications in various fields. However, the issue of residual vibration significantly limits its printing quality and efficiency. This paper presents a method for suppressing residual vibration based on the particle swarm optimization (PSO) algorithm. Initially, an improved PI model considering the nonlinear hysteresis characteristics of piezoelectric ceramics is established, and the model is identified through a strain gauge circuit to ensure its accuracy in describing the nonlinear hysteresis characteristics. Subsequently, a dynamic model of the piezoelectric inkjet printing system is constructed, with precise parameter identification achieved using the self-induction principle. This enables precise simulation of residual vibration. Finally, the driving waveform is optimized based on the PSO algorithm, with iterative calculations employed to find the optimal combination of driving waveform parameters, effectively suppressing residual vibration while ensuring sufficient injection energy. The results indicate that this method significantly reduces the amplitude of residual vibration, thereby effectively enhancing printing quality and stability. This research offers a novel solution for residual vibration suppression in piezoelectric inkjet printing technology, potentially advancing its applications in printing and biofabrication. [ABSTRACT FROM AUTHOR]

Operational loads of an aircraft are the prerequisite for assessing its safety or fatigue life. Traditionally, numerous strain gauge sensors are installed to monitor the operational loads, which inevitably increase the weight and system complexity of the aircraft. Therefore, in order to decrease the maintenance costs and data redundancy, the number and location of strain sensors should be optimized for accurate and reliable operational load monitoring. In this paper, a novel two-stage strain gauge location optimization method is proposed to reduce the number of strain gauges while maintaining the operational load monitoring accuracy, which is validated by a numerical case study of an aircraft wing. In the first stage, the traditional Pearson correlation measure is harnessed to initially eliminate numerous correlated strain gauge monitoring points, reducing 996 original strain gauge measurement points to 13 for the aircraft wing box. In the second stage, an improved correlation measure method is proposed to further reduce the 13 strain gauge points to 2, which can evaluate the correlation degree of several variables and simultaneously determine the optimal strain monitoring locations for the two load actuators in this study. The relative errors between the predicted loads and the actual loads for both load actuators are less than 4% when only two optimized monitoring points are adopted. In addition, a comparison study with LASSO regression and principal component regression methods is conducted. The results demonstrate that the proposed method has the characteristics of less monitoring points and higher load prediction precision. [ABSTRACT FROM AUTHOR]

Corrosion is a major cause of deterioration in conventional steel-reinforced prestressed concrete (PC) piles installed in aggressive (marine) environments. As foundation members in bridges, deteriorated piles may result in failure or expensive repair or reconstruction. Corrosion resistant alternatives for reinforcing piles longitudinally and transversely include carbon fiber composite cables (CFCC) and stainless-steel (SS). However, the cost of these alternatives is prohibitive, which in turn increases the production cost of PC piles. To mitigate the high cost of CFCC and SS piles, the spirals in these corrosion resistant piles can be safely replaced by glass fiber–reinforced polymer (GFRP) bars in spiral form. In this research, the effectiveness of GFRP spirals in confining PC piles is presented by showing results of impact experiments conducted on full-size specimens. One control pile was reinforced with steel strands and spirals, while another pile was reinforced with steel strands and GFRP spirals. The spirals within the piles were instrumented at critical locations with strain gauges to record spiral responses. Externally, pile driving analyzer strain gauges and accelerometers were installed for pile response along loading direction. In addition, to further understand the spatial response of the piles tested, three-dimensional finite-element (FE) models were developed using a commercially available code to simulate the impact test. For the FE model, concrete behavior of was modeled using concrete damaged plasticity model, the behavior of steel strands was simulated using a bilinear elastoplastic material, and the GFRP spiral behavior was modeled using a linear elastic material. The results of the research show that PC piles can be confined with GFRP spirals, without decreasing the load-carrying capacity of the pile. Practical Applications: This research brought forth valuable insights with practical implications, particularly regarding the use of glass fiber–reinforced polymer (GFRP) spirals within prestressed concrete applications. The practical applications encompass several key points that stand to influence engineering practices. Notably, both experimental results and finite-element studies assert that prestressed concrete piles reinforced with GFRP spirals exhibit performance comparable to their traditional counterparts employing steel spirals. This similarity extends to a robust response under impact loads, indicating that prestressed concrete piles featuring GFRP spirals as lateral reinforcement can effectively withstand pile driving forces, rendering them suitable for practical applications. Furthermore, the study introduces the prospect of enhancing corrosion resistance in prestressed concrete piles by incorporating GFRP spirals in combination with corrosion-resistant strands. This development expands the feasibility of deploying corrosion resistant prestressed concrete piles for bridge foundations in marine environments. Engineers engaged in bridge construction projects are thus encouraged to explore the adoption of GFRP-reinforced prestressed concrete piles, anticipating enhanced durability and longevity for bridge structures, especially in regions subject to harsh environmental conditions. This plays a pivotal role in advancing resilient and sustainable infrastructure practices within the realm of civil engineering and construction. [ABSTRACT FROM AUTHOR]

This study thoroughly investigated the compressive and tensile strength characteristics of black shale using both experimental and analytical approaches. Uniaxial compression tests were conducted to determine the elastic constants of black shale modeled as idealized, linear elastic, homogeneous, and transversely isotropic. Additionally, Brazilian tests were carried out on shale, considering it a transversely isotropic material. Strain measurements were recorded at the center of disc specimens subjected to diametric loading. By placing strain gages at the disc centers, the five elastic constants were accurately estimated. The effects of experimental methods and diametric loading on the elastic constant determination were evaluated and analyzed, and the indirect shear strength of the black shale, considering anisotropy, was determined using the estimated stress concentration coefficient. This study revealed that the indirect tensile strength of black shale is significantly influenced by the angle between the anisotropic planes and the diametric loading direction. Moreover, it was revealed that the stress concentration coefficients for anisotropic rocks vary from those of isotropic rocks, depending on the inclination angle of the bedding planes. This study confirms that the shear (tensile) strength of anisotropic black shale is not constant but varies with the orientation of the anisotropic planes in relation to the applied load. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Strain gauge plays vital roles in various fields as structural health monitoring, aerospace engineering, and civil infrastructure. However, traditional flexible strain gauge inevitably brings the pseudo-signal caused by the substrate temperature effect and determines its accuracy. Here, we present an anisotropic composite substrate designed to modify the thermal expansion performance via Micro-electro-mechanical System (MEMS) technology, which facilitates the development of strain gauges that are minimally affected by substrate temperature-induced effect. Compared to the isotropic flexible substrate, the simulated expansion displacement in the thermal insensitive direction is reduced by 53.6% via introducing an anisotropic thermal expansion structure. The developed strain gauge exhibits significantly reduced sensitivity to temperature-induced effect, with a temperature coefficient of resistance decreasing from 87.3% to 10%, along with a notable 47.1% improvement in TCR stability. In addition, the strain gauge displays a sensitivity of 1.99 and boasts a wide strain operational range of 0–6000 µε, while maintaining excellent linearity. Furthermore, stress response conducted on a model of an aircraft wing illustrates the rapid monitoring of the strain gauge, which can detect strain as low as 100 µε. This study strongly highlights the potential applicability of the developed strain gauge in the aircraft, ships, and bridges for monitoring stress. [ABSTRACT FROM AUTHOR]

In wind turbines, to investigate the cause of failures and evaluate the remaining lifetime, it may be necessary to measure their loads. However, it is often difficult to do so with only strain gauges in terms of cost and time, so a method to evaluate loads by utilizing only simple measurements is quite useful. In this study, we investigated a method with machine learning to estimate hub center loads, which is important in terms of preventing damage to equipment inside the nacelle. Traditionally, measuring hub center loads requires performing complex strain measurements on rotating parts, such as the blades or the main shaft. On the other hand, the tower is a stationary body, so the strain measurement difficulty is relatively low. We tackled the problem as follows: First, machine learning models that predict the time history of hub center loads from the tower top loads and operating condition data were developed by using aeroelastic analysis. Next, the accuracy of the model was verified by using measurement data from an actual wind turbine. Finally, individual pitch control, which is one of the applications of the time history of hub center loads, was performed using aeroelastic analysis, and the load reduction effect with the model prediction values was equivalent to that of the conventional method. [ABSTRACT FROM AUTHOR]

Featured Application: The strengthening of the columns and the connections of the columns with the beams for reinforced concrete buildings designed and constructed according to older codes is crucial for regions prone to seismic activity. Herein, the application of the innovative C-FRP ropes for the strengthening of these structural elements is featured. The experimental results yielded from testing real-scale columns demonstrated that this strengthening technique is both highly effective and easy to implement. Moreover, it is emphasized that the C-FRP ropes technique can easily be applied by the practicing engineer in structures with complex configuration without any geometrical restraints. The application of the innovative C-FRP ropes for the strengthening of reinforced concrete columns is experimentally examined. Two real-scale specimens with the same geometrical characteristics and the same steel reinforcements were constructed for the needs of this investigation. The primary objective of the study is to investigate the efficacy of the use of C-FRP ropes as externally mounted reinforcement for the strengthening of deficient external columns. In this direction, (a) C-FRP ropes are applied as longitudinal reinforcement of the column for the increase in the flexural strength, (b) C-FRP ropes are applied as external confining stirrups in the critical end parts of the column for the improvement of the concrete strength and the development of local element ductility, and finally (c) C-FRP ropes are applied as external stirrups in the form of diagonal X-shaped reinforcement for the increase in the capacity of the part of the column connected with the beam (joint panel). Both specimens are tested under the same cyclic loading procedure that comprises seven steps and each step includes three full loading cycles. The maximum loads of the strengthened specimen at the three loading cycles of the seventh step were 40%, 72% and 87% higher than the corresponding ones of the unstrengthened specimen. On the other hand, the measured shear deformations of the joint panel of the pilot (unstrengthened) specimen at the sixth and the seventh steps were 43% and 44% higher than the corresponding ones of the strengthened specimen. In general, it is concluded that the strengthened column exhibited improved hysteretic response and the whole behavior was apparently improved compared to the pilot specimen without strengthening in terms of maximum loads per loading step, dissipated energy, and shear deformations of the joint panel. In particular, it is stressed that the measured shear deformations of the joint panel and strain gauge measurements have substantiated that the column and the connection panel of the strengthened specimen remain almost intact, whereas damage and eventually failure have been located in the column and the joint panel of the pilot specimen. Additionally, it is emphasized that the C-FRP ropes can easily be applied in structures with complex configuration without any geometrical restraints. [ABSTRACT FROM AUTHOR]

The locked segment is critical for determining the stability of locked segment-type landslides. Research indicates that the volume expansion point marks the transition from the secondary creep stage to the tertiary creep stage in a landslide's evolution, and also separates the stable crack growth stage from the unstable crack growth stage in the locked segment. Identifying the volume expansion point is essential for early warning and predicting locked segment-type landslides. A series of instruments (resistance strain gauges, acoustic emission system, piezoelectric acceleration sensors, etc.) were used to conduct physical model tests of the landslide with retaining-wall-like locked segment under external load on the landslide's trailing edge. The evolution process of this landslide was analyzed through changes in slope shape and stress response characteristics. The experimental results reveal the failure mechanism of the landslide with retaining-wall-like locked segment: the upper part of the landslide thrusts and slides, the middle part squeezes and uplifts, the retaining-wall-like locked segment produces a locking effect, and compression-shear fracture of the retaining-wall-like locked segment leads to landslide failure. Based on the deformation and acoustic emission characteristics of the locked segment, a method for identifying the volume expansion point was established. This point was used as the onset of acceleration point in the inverse velocity method to predict the failure time of the locked segment-type landslides, incorporating the three-stage creep model and Fukumoto's theory. [ABSTRACT FROM AUTHOR]

The economic impact of Structural Health Monitoring Systems based on optical fibre sensors is assessed in the development of composite helicopter rotor blades. Hence, the focus of this analysis is on the helicopter's Beginning Of Life stage. Two applications of the Structural Health Monitoring System are considered in the development of composite blades: curing cycle development and accomplishment of laboratory and flight certification tests. Optical fibre sensors measure the temperature field during the curing cycle and strain field during the laboratory tests and allow load identification during the load survey activity. It was found that Structural Health Monitoring Systems can potentially lead to economic benefits during the development of the blade provide that a reduction in the number of curing cycles and number of blades tested is achieved as a consequence of the improvement of the temperature and strain field quality. Moreover, an economic benefit could be achieved during the load survey activity, needed to complete the certification of the composite blade, avoiding the periodical maintenance of the applied strain gauges acquiring the strains during the flight. [ABSTRACT FROM AUTHOR]

A novel laser thermal printing technique toward the fabrication of all‐in‐one flexible intelligent devices is presented in this work, addressing the existing challenges in their scalable manufacturing and multifunctional performance. The first‐ever application of this technique for the synthesis of a multifunctional intelligent cobweb structure is presented. The resultant cobweb integrates a conductive network of multi‐walled carbon nanotubes (MWCNTs) and NdFeB magnetic microparticles within a polydimethylsiloxane (PDMS) matrix, enabling seamless incorporation of sensing, stimulus response, and actuation functionalities. The cobweb exhibits multifunctional sensing characteristics, including a 2.37 strain gauge factor and a 0.312%·mT−1 magnetic field sensitivity, excellent stability exceeding 3500 cycles. Furthermore, the cobweb achieves accurate capture of a beetle on the basis of real‐time sensing of the beetle, verifying its rapid stimulus response characteristics. Meanwhile, the cobweb exhibits an electromagnetic ejection performance with an ejection height of over 33.5 times the size of the projectile, verifying its powerful actuating ability. These results demonstrate the successful integration of multifunctional sensing, stimulus response, and actuation within the cobweb structure, facilitated by the innovative laser thermal printing process. The laser thermal printing technique marks a significant advancement in the efficient fabrication of miniaturized and multifunctional flexible intelligent devices based on thermosetting materials. [ABSTRACT FROM AUTHOR]

Pile-supported embankments have been recognized as long-standing solutions for construction in compressible soft soils. Instead of improving the physical and mechanical properties of the soft soil, this method emphasizes efforts to transfer the embankment load to a competent layer below the compressible layer. Mortar column inclusion (inklusi kolom mortar or IKM) is recognized as one of the rigid inclusions in a pile-supported embankment. The IKM combined with a load transfer platform (LTP) has been widely utilized to support embankments. Studies on pile-supported embankments have generally focused on the arching mechanisms and geotextile tensile force evaluations; however, most of these investigations were conducted on soft cohesive soils. The application of pile-supported embankment on peat has rarely been studied comprehensively. This study presents a full-scale trial embankment on peat in West Sumatra, Indonesia. The 8-m-high trial embankment was supported by a series of IKM piles and a geotextile-reinforced LTP layer; instruments were then installed in the embankment, ground, LTP, geotextile, and IKM. These instruments included a series of vibrating wire earth pressure cells, vibrating wire strain gages, fiber optic sensors, vibrating wire piezometers, settlement profilers, settlement plates, and inclinometers. The instruments provided observations on the ground movements, IKM displacements, and stresses in the materials. Comprehensive evaluations from field monitoring allowed study of load transfer via the arching mechanism, deformation pattern, and IKM performance in peat. Finite element analyses (FEAs) were also conducted for comparison and verification. The field monitoring results and FEAs showed good agreement, thereby demonstrating the potential of the proposed ground improvement method for embankment construction on peat. [ABSTRACT FROM AUTHOR]

Plantar shear stress may have an important role in the formation of a Diabetic Foot Ulcer, but its measurement is regarded as challenging and has limited research. This paper highlights the importance of anatomical specific shear sensor calibration and presents a feasibility study of a novel shear sensing system which has measured in-shoe shear stress from gait activity on both healthy and diabetic subjects. The sensing insole was based on a strain gauge array embedded in a silicone insole backed with a commercial normal pressure sensor. Sensor calibration factors were investigated using a custom mechanical test rig with indenter to exert both normal and shear forces. Indenter size and location were varied to investigate the importance of both loading area and position on measurement accuracy. The sensing insole, coupled with the calibration procedure, was tested one participant with diabetes and one healthy participant during two sessions of 15 minutes of treadmill walking. Calibration with different indenter areas (from 78.5 mm2 to 707 mm2) and different positions (up to 40 mm from sensor centre) showed variation in measurements of up to 80% and 90% respectively. Shear sensing results demonstrated high repeatability (>97%) and good accuracy (mean absolute error < ±18 kPa) in bench top mechanical tests and less than 21% variability within walking of 15-minutes duration. The results indicate the importance of mechanical coupling between embedded shear sensors and insole materials. It also highlights the importance of using an appropriate calibration method to ensure accurate shear stress measurement. The novel shear stress measurement system presented in this paper, demonstrates a viable method to measure accurate and repeatable in-shoe shear stress using the calibration procedure described. The validation and calibration methods outlined in this paper could be utilised as a standardised approach for the research community to develop and validate similar measurement technologies. [ABSTRACT FROM AUTHOR]

Copyright of Technisches Messen is the property of De Gruyter and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Technisches Messen is the property of De Gruyter and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A cleanroom free optimized fabrication of a low-cost facile tungsten diselenide (WSe2) combined with chitosan-based hydrogel device is reported for multifunctional applications including tactile sensing, pulse rate monitoring, respiratory rate monitoring, human body movements detection, and human electrophysiological signal detection. Chitosan being a natural biodegradable, non-toxic compound serves as a substrate to the semiconducting WSe2 electrode which is synthesized using a single step hydrothermal technique. Elaborate characterization studies are performed to confirm the morphological, structural, and electrical properties of the fabricated chitosan/WSe2 device. Chitosan/WSe2 sensor with copper contacts on each side is put directly on skin to capture human body motions. The resistivity of the sample was calculated as 26 kΩ m−1. The device behaves as an ultrasensitive pressure sensor for tactile and arterial pulse sensing with response time of 0.9 s and sensitivity of around 0.02 kPa−1. It is also capable for strain sensing with a gauge factor of 54 which is significantly higher than similar other reported electrodes. The human body movements sensing can be attributed to the piezoresistive character of WSe2 that originates from its non-centrosymmetric structure. Further, the sensor is employed for monitoring respiratory rate which measures to 13 counts/min for healthy individual and electrophysiological signals like ECG and EOG which can be used later for detecting numerous pathological conditions in humans. Electrophysiological signal sensing is carried out using a bio-signal amplifier (Bio-Amp EXG Pill) connected to Arduino. The skin-friendly, low toxic WSe2/chitosan dry electrodes pave the way for replacing wet electrodes and find numerous applications in personalized healthcare. [ABSTRACT FROM AUTHOR]

Digital Image Correlation (DIC) often encounters challenges with variability and consistency in traditional speckle pattern application techniques, such as spray-painting, affecting measurement accuracy and reliability. This study evaluates a film-free water decal method as an alternative for applying speckle patterns in DIC. SS275 structural steel specimens were prepared with speckle patterns using both the film-free water decal method and traditional spray-painting. The quality of the speckle patterns was assessed, and their effectiveness for DIC was evaluated through tensile testing and a comparison with strain gauge measurements. The film-free water decal method provided enhanced control over speckle pattern application, resulting in high-quality, consistent patterns. Strain measurements obtained using this method closely matched those from traditional methods, confirming its reliability. The film-free water decal method offers a practical and reliable alternative to spray-painting, improving the consistency and accuracy of DIC experiments, with potential applications in various engineering and scientific fields. [ABSTRACT FROM AUTHOR]

Sensor-based monitoring of process and tool condition in milling is a key technology for improving productivity and workpiece quality, as well as enabling automation of machine tools. However, industrial implementation of such monitoring systems remains a difficult task, since they require high sensitivity and minimal impact on CNC machines and cutting conditions. This paper presents a novel multi-sensory tool holder for measurement of process forces and vibrations in direct proximity to the cutting tool. In particular, the sensor system has an integrated temperature sensor, a triaxial accelerometer and strain gauges for measurement of axial force and bending moment. It is equipped with a self-sufficient electric generator and wireless data transmission, allowing for a tool holder design without interfering contours. Milling and drilling experiments with varying cutting parameters are conducted. The measurement data are analyzed, pre-processed and verified with reference signals. Furthermore, the suitability of all integrated sensors for detection of dynamic instabilities (chatter) is investigated, showing that bending moment and tangential acceleration signals are the most sensitive regarding this monitoring task. [ABSTRACT FROM AUTHOR]

In this paper, the suitability of digital image correlation (DIC) technology in evaluating the flexural behaviour of as-built and carbon-fiber-reinforced polymer (CFRP) strengthened reinforced concrete beams was verified by conducting a four-point bending test on four large-size beams. The DIC data obtained during the tests were compared to the results measured using traditional techniques such as displacement sensors and electrical strain gauges, as well as the findings derived from finite element (FE) numerical simulations. A good agreement was achieved between the local displacement and strain measurements and the data from DIC as a function of the applied load. Moreover, the crack patterns generated by the FE modelling were validated by the corresponding patterns derived from DIC. This suitability study is expected to contribute to the future field implementation of DIC technology to monitor the CFRP-strengthened members of critical structures such as bridges. [ABSTRACT FROM AUTHOR]

Benign, locally aggressive tumors of the distal femur are typically treated with intralesional curettage and polymethylmethacrylate (PMMA) cementation. However, it is not known whether plate fixation should be added to biomechanically augment these PMMA‐filled defects. The purpose of this study was to evaluate the performance of two competing techniques for reconstruction of a distal femoral defect. For this biomechanical study, we used 12 composite femurs with properties comparable to bone. In nine femurs, identical contained medial distal femoral defects were created using a robotic arm. Group A contained three intact femurs, Group B three femurs with an unfilled defect, Group C three femurs reconstructed with PMMA alone, and Group D three femurs reconstructed with PMMA plus a medial locking plate. Locations of greatest stress concentration were determined by PhotoStress analysis, then three strain gauges were applied to each specimen at these high‐stress locations. Specimens were loaded within a physiologic range followed by loading to failure. Outcome measures included construct stiffness, strain along the distal femur, and load at failure. Results showed that stiffness and strain were not significantly different between reconstructive techniques; however, both techniques reduced tensile strain along the popliteal surface by approximately 40% compared to non‐reconstructed specimens. All specimens failed at the femoral neck before failing at the distal femur. These findings suggest that plate augmentation of PMMA‐filled distal femoral defects like the one in this study offers insignificant biomechanical benefit within physiologic loads and therefore may be unnecessary. [ABSTRACT FROM AUTHOR]

The role of steel connections is essential in structural fire design and analysis for steel-framed composite structures. The current structural design provisions provide strength reduction factors of load-carrying members and their end-connection elements at elevated temperatures, based on small-scale experiments under uniform heating conditions. The realistic thermal and structural evolution in member connections, especially as part of full-scale floor assemblies exposed to a large compartment fire, has not been well characterized. A large compartment fire experiment was recently conducted on a 9.1 m by 6.1 m composite floor assembly as part of a two-story steel-framed building. The test assembly had a total of ten shear-tab (fin-plate) connections subjected to combined fire and mechanical loading. This paper presents the measured thermal response of these connections to fire and comparison with the corresponding Eurocode 3 predictions with two methods (1) incorporating the beam bottom flange temperature at midspan and (2) the section factor method. The results show that the Eurocode 3 methods conservatively predict the maximum temperature during heating and the cooling rate but overestimate the high-temperature strength of connections when estimated using the section factor method, showing that the Eurocode 3 simplified approaches are not meant to provide the details of the failure mode for connections. This study suggests that estimating the strength of connections using strength reduction factors may not guarantee a safe structural fire design. In addition, this paper estimated the total axial force (from slab and beam) at the composite connection via using the strain gauge measurements close to the column bases which were not exposed to fire. It suggests realistic axial load and rotational demand on the shear connection due to restraints to thermal elongation or contraction of supported members should be considered in future design guidance as should designing and detailing the connections for ductility to withstand the inelastic deformation demands during the heating and the cooling phases. [ABSTRACT FROM AUTHOR]