Semiconductor Strain Gauges Research Articles

Measurements of the Effective Stress Coefficient for Elastic Moduli of Sandstone in Quasi-Static Regime Using Semiconductor Strain Gauges.

Numerous experimental and theoretical studies undertaken to determine the effective stress coefficient for seismic velocities in rocks stem from the importance of this geomechanical parameter both for monitoring changes in rock saturation and pore pressure distribution in connection with reservoir production, and for overpressure prediction in reservoirs and formations from seismic data. The present work pursues a task to determine, in the framework of a low-frequency laboratory study, the dependence of the elastic moduli of n-decane-saturated sandstone on the relationship between pore and confining pressures. The study was conducted on a sandstone sample with high quartz and notable clay content in a quasi-static regime when a 100 mL tank filled with n-decane was directly connected to the pore space of the sample. The measurements were carried out at a seismic frequency of 2 Hz and strains, controlled by semiconductor strain gauges, not exceeding 10-6. The study was performed using a forced-oscillation laboratory apparatus utilizing the stress-strain relationship. The dynamic elastic moduli were measured in two sets of experiments: at constant pore pressures of 0, 1, and 5 MPa and differential pressure (defined as a difference between confining and pore pressures) that varied from 3 to 19 MPa; and at a constant confining pressure of 20 MPa and pore pressure that varied from 1 to 17 MP. It was shown that the elastic moduli obtained in the measurements were in good agreement with the Gassmann moduli calculated for the range of differential pressures used in our experiments, which corresponds to the effective stress coefficient equal to unity.

A piezoelectric-driven nanoindentation system for scanning electron microscope with improved analog compensation method.

This paper presents a novel piezoelectric-driven nanoindentation system for a scanning electron microscope (SEM) with an improved analog compensation (IAC) method. This system mainly consists of a piezoelectric-driven indenter head, a rectangle-shaped transducer, and a nanopositioner module. Compared with the state-of-the-art piezoelectric-driven nanoindentation system with a circle-shaped transducer, the proposed nanoindentation system is capable of multi-direction operation inside a SEM with a rectangle-shaped transducer. Self-matched semiconductor strain gauges are selected as the position sensor for the piezoelectric-actuator. The Wheatstone bridge output voltage cannot achieve a zero temperature coefficient because the temperature coefficients of self-matched semiconductor strain gauge pairs become significantly different from each other after installation in practice. An IAC method is proposed to compensate the temperature coefficients further. Compared with the existing analog compensation method, the IAC method solves the problem of amplifier saturation and improves the sensitivity of the self-matched semiconductor strain gauge pairs position sensor by 27%. The multi-direction operation results inside a standard SEM HITACHI SU5000 validate the advantage of the developed nanoindentation system.

Damping oscillations of a cylinder with a coaxial disc and a stabilizer

The damped rotational oscillations of the cylinder, which is equipped with a coaxial disk in the head part, and has a stabilizer in the tail part, are studied. The elongation of the cylinder (the ratio of length to diameter) is nine. The cylinder is mounted in the test section of the low velocities wind tunnel with a wire suspension containing steel springs. In the equilibrium position, the axis of the cylinder is horizontal and parallel to the velocity vector of the incoming flow. Under the action of the air flow, the attenuation of rotational oscillations of the cylinder changes. A semiconductor strain gauge is attached to one of the suspension springs, which measures the dependence of spring tension on time during oscillations. The voltage at the output of the strain gauge is transmitted to the PC oscilloscope. The digital signal of the oscilloscope is transmitted to the computer. After calibration of the device, the frequency and amplitude of damped rotational oscillations around a horizontal axis passing through the center of the cylinder and perpendicular to the velocity vector of the incoming flow are determined. The effect of the air flow is described by analogues of rotational derivatives, which in the case of bluff bodies depend on the amplitude of the oscillations of the angle of inclination of the body and on the amplitude of the angular velocity. A simple model of the stabilizer’s effect on rotational derivatives is proposed.

Hypersonic aerodynamic force balance using temperature compensated semiconductor strain gauges

Metal foil strain gauges remain the state-of-the-art transducers for wind tunnel balances. While strain gauge technology is very mature, piezoresistive semiconductor sensors offer alternatives that are worth exploring to assess their unique benefits, such as better strain resolution and accuracy, which would enable balances to be designed with higher factors to safety and hence longer fatigue lifetimes. A new three-component balance, based on temperature compensated semiconductor strain gauges, is designed, calibrated and tested in a hypersonic low density wind tunnel. The static accuracy of the semiconductor balance is calibrated better than 0.3% FS, and the dynamic accuracy of the balance is established using a HB-2 standard model in a Mach 12 hypersonic flow. Good experimental repeatability is confirmed to be better than 2.5% FS, and the effectiveness of the balance is demonstrated by comparing the forces and moments of measured data with computational fluid dynamics simulations, as well as reference wind tunnel results under similar conditions.

Low-frequency laboratory measurements of the elastic properties of solids using a distributed acoustic sensing system

In recent decades, low-frequency (LF) experiments based on the forced-oscillation (FO) method have become common practice in many rock physics laboratories for measuring the elastic and anelastic properties of rocks. However, the use of the electronic displacement sensors in traditional acquisition systems of FO devices such as conventional capacitive transducers or strain gauges seriously limits both the efficiency and productivity of LF measurements, and, due to the limited contact area of the displacement sensors with a sample under test, increases the requirements for sample homogeneity. In this paper, we present the first results obtained in the development of a new laboratory method elaborated to measure the elastic properties of solids. The method is a further development of the FO method where traditional data acquisition is replaced by acquisition based on fiber-optic distributed acoustic sensing (DAS) technology. The new method was tested in a laboratory study using two FO setups designed for measurements under uniaxial and confining pressures. The study was carried out on a sample made from polymethyl methacrylate (PMMA) and an aluminium standard, first under uniaxial pressure at FO frequencies of 1, 10, 30, 60 and 100 Hz, and then under confining pressure at an FO frequency of 1 Hz. Both uniaxial and confining pressures were equal to 10 MPa, and the strain in the PMMA sample in all measurements did not exceed 4 × 10-8. The performance of DAS acquisition was compared with the measurements conducted at a strain of 1 × 10-6 using the traditional FO method based on the use of semiconductor strain gauges and the ultrasonic method. The results of the DAS measurements are in good agreement with the FO measurements carried out using semiconductor strain gauges and with the literature data.

Water-soluble pristine C60 fullerenes attenuate isometric muscle force reduction in a rat acute inflammatory pain model

BackgroundBeing a scavenger of free radicals, C60 fullerenes can influence on the physiological processes in skeletal muscles, however, the effect of such carbon nanoparticles on muscle contractility under acute muscle inflammation remains unclear. Thus, the aim of the study was to reveal the effect of the C60 fullerene aqueous solution (C60FAS) on the muscle contractile properties under acute inflammatory pain.MethodsTo induce inflammation a 2.5% formalin solution was injected into the rat triceps surae (TS) muscle. High-frequency electrical stimulation has been used to induce tetanic muscle contraction. A linear motor under servo-control with embedded semi-conductor strain gauge resistors was used to measure the muscle tension.ResultsIn response to formalin administration, the strength of TS muscle contractions in untreated animals was recorded at 23% of control values, whereas the muscle tension in the C60FAS-treated rats reached 48%. Thus, the treated muscle could generate 2-fold more muscle strength than the muscle in untreated rats.ConclusionsThe attenuation of muscle contraction force reduction caused by preliminary injection of C60FAS is presumably associated with a decrease in the concentration of free radicals in the inflamed muscle tissue, which leads to a decrease in the intensity of nociceptive information transmission from the inflamed muscle to the CNS and thereby promotes the improvement of the functional state of the skeletal muscle.

Development of High Dynamic Range Six-Axis Force Sensor with Simple Structure

We propose a six-axis force sensor with a simple structure that can measure small forces while affording a high load capacity. For a robot to perform complex motions in an unknown environment, the force sensor used must exhibit a high resolution and high load rating. Various studies have been conducted to simultaneously satisfy these two requirements. However, the high processing cost due to the complicated sensor structure is problematic. Therefore, we develop a column-type high dynamic range (HDR) six-axis force sensor using two types of strain gauges. The sensor was composed of a drawn pipe to solve structural problems that arise during manufacturing. By attaching strain gauges to the surface of the drawn pipe, the forces and torques in the six axes can be measured. HDR measurement was realizable using a semiconductor strain gauge for small loads and a metallic foil strain gauge for large loads. Based on the simulation results, the rated loads of the sensor were 1400 N in the Fx and Fy directions, 9000 N in the Fz direction, and 120 Nm in the Mx, My, and Mz directions. The performance of the fabricated force sensor was evaluated. The maximum nonlinearity errors of the semiconductor strain gauge and the metallic foil strain gauges were 1.21% and 1.81%, respectively. In addition, when comparing the S/N ratios, the minimum measurable values were 0.035 N and 0.13 N for Fy and Fz, respectively.

Accurate Cutting-Force Measurement with Smart Tool Holder in Lathe.

Cutting force in lathe work is closely related to tool wear and affects the turning quality. Direct measurement of the cutting force by measuring the strain of the tool holder is challenging because the tool holder design aims to be highly rigid in order to undertake large cutting forces. Accordingly, the most popular dynamometer designs modify the standard tool holder by decreasing the structural rigidity of the holder, which reduces the machining precision and is not widely accepted. In order to solve the issue of the low stiffness of the dynamometer reducing the machining precision, in this paper, the ultra-low strain on the tool holder was successfully detected by the highly sensitive semiconductor strain gauges (SCSG) adjacent to the blade cutting insert. However, the cutting process would generate much heat, which increases the force measuring area temperature of the tool holder by about 30 °C. As a result, the readout drifted significantly with the temperature changes due to the high temperature coefficient of SCSG. To solve this problem, the temperature on the tool holder was monitored and a BP neural network was proposed to compensate for temperature drift errors. Our methods improved the sensitivity (1.14 × 10-2 mV/N) and the average relative error of the BP neural network prediction (≤1.48%) while maintaining the original stiffness of the tool holder. The smart tool holder developed possesses high natural frequency (≥6 kHz), it is very suitable for dynamic cutting-force measurement. The cutting experiment data in the lathe work show comparable performance with the traditional dynamometers and the resolution of the smart tool holder is 2 N (0.25% of total range).

A novel smart toolholder with embedded force sensors for milling operations

In the era of intelligent manufacturing and big data, cutting force has become one of the most important data sources for the machining process, which is not only of significance for offline analysis, but also crucial for online monitoring and control. However, the current table and rotating dynamometers for cutting force sensing meet the problems of cumbersome installation and low integration, which make them still limited to laboratory applications. In this paper, a novel integral smart toolholder with unique on-toolholder force sensing units has been proposed, whereby a measuring part (i.e. the thin-walled beam) has been designed as a separated agent from the supporting part (i.e. the thick beam) by four double T-slots. Moreover, to achieve the high sensitivity, self-compensating semiconductor strain gages were embedded into a standard toolholder with a data acquisition unit as an integrated solution. A mechanistic model has also been developed to decouple the four-component milling force thus to optimise the sensing structure to allow the high-sensitivity while not to reduce the stiffness significantly. To improve integration while allow machining continuously without interruption, a slip ring was utilized to supply power and data transfer with low latency. Owing to the split structure design, the proposed smart toolholder possessed improved flexibility and reconfigurability, and it could be used in the assembly of multi-type machining spindles and multi-size tools. Various tests were also performed to determine the static and dynamic characteristics of the proposed smart toolholder. The results showed that the proposed smart toolholder has high sensitivity, linearity, repeatability, and hysteresis. A further cutting experiment demonstrated that the proposed smart toolholder can measure the four-components milling force accurately and its relative deviation is less than 10% with the comparison of off-the-shelf dynamometer, which provides a smart solution for monitoring the cutting tool condition.

Rotational and translational oscillations of cylinders of small aspect ratio in the air flow

Rotational and translational oscillations of three cylinders differing in the ratio of length to cylinder diameter (elongation) are considered. The cylinders were suspended in the test section of the low velocity wind tunnel on a wire suspension containing steel springs. In the equilibrium position, the axis of the cylinders is directed horizontally and parallel to the velocity vector of the incoming flow. Under the influence of the air flow, the cylinders could make rotational or translational oscillations. Semiconductor strain gauges are attached to the two suspension springs, measuring the periodically changing tension of the springs during oscillations. The analog signal from the strain gauges was transmitted to a PC oscilloscope, which transmitted it in digital form to a computer. After calibration of the device and decoding of the signal, the frequencies and amplitudes of translational oscillations in the vertical direction and rotational oscillations around the horizontal axis passing through the center of the cylinder and perpendicular to the velocity vector of the incoming flow were determined. It turned out that in the studied range of cylinder elongations there is a transition from rotational to translational oscillations. A cylinder with elongation 1.9 performs steady rotational oscillations under the influence of wind, the amplitude of which increases with increasing air flow velocity. The previously proposed mathematical model correctly predicts rotational oscillations. The square of the amplitude of rotational oscillations is a linear function of the Strouhal number if the velocity of the air flow is sufficiently large. Translational oscillations of the cylinder with elongation 1.9 are damped. A decrease in the elongation of the cylinder to 1.5 is accompanied by a decrease in the amplitudes of rotational vibrations. At low air flow velocities, translational oscillations with a small amplitude are registered. Further reduction of the elongation to 1.0 leads to the complete absence of rotational oscillations. The amplitude of translational oscillations is growing. Translational oscillations are realized in a limited range of air flow velocities.

遠心圧縮機インペラに発生する衝撃波形成角度の計測

In a compressor, shock waves are generated when the impeller blade velocity reaches supersonic speed relative to the air drawn in from the air inlet. The shock interacts with the tip-leakage vortex and the boundary layer on the impeller blade surface. The interaction causes the pressure rise and the reverse flow. Thus, it is important to predict the formation of shock on the blades in compressor design. This study focused on a position of the shock in a centrifugal compressor. In general, simultaneous measurement by multiple pressure sensors is necessary to measure the angle of the shock formed near the leading edge of the impeller blade. In this study, a pressure history was measured at a single point near the leading edge of the blade using a semiconductor pressure transducer. The semiconductor pressure transducer has a diaphragm onto which a semiconductor strain gauge is glued. The pressure acting on the diaphragm is proportional to the strain at the center of the diaphragm. The direction of maximum principal strain of the diaphragm corresponds to the shock direction or its perpendicular direction. The strains in three different directions on the diaphragm were obtained and the direction of maximum principal strain was calculated using Rosette analysis. As a result, the angle of formation of the shock wave generated in the centrifugal compressor impeller was estimated.

High Dynamic Range 6-Axis Force Sensor Employing a Semiconductor–Metallic Foil Strain Gauge Combination

This letter proposes a force sensor that combines semiconductor strain gauges and metallic foil strain gauges to present force information of a higher dynamic range to robots. The strain gauges have different sensitivities, with semiconductor strain gauge sensitivity being approximately 90-fold than that of the metallic foil strain gauges. Using this difference in sensitivity, large forces and small forces are both detected through the two types of strain gauges and high dynamic range force detection is achieved by combining the output signals of these two. It was confirmed from the SN ratio test that the proposed sensor has a measurement range from 0.005 N to 1000 N, the maximum load. The dynamic range is 2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\times 10^5$</tex-math></inline-formula> , extending the dynamic range of the 6-axis force sensor with the highest range in previous studies two-fold.

Laboratory measurements with DAS: A fast and sensitive tool to obtain elastic properties at seismic frequencies

Forced-oscillation stress-strain laboratory measurements are increasingly employed to obtain elastic and viscoelastic properties of rocks at seismic frequencies. Yet these measurements are time-consuming and expensive, due in part to the use of metal or semiconductor strain gauges, which need to be glued to the sample. Such gauges are fragile, have relatively low sensitivity, and measure very local strain only so the measurements can be affected by a slight misalignment of the system assembly and local heterogeneity of the rock. The emergence of fiber-optic distributed acoustic sensing (DAS) technology provides an alternative means of measuring strain. Strain measurements with DAS involve winding an optical fiber around the sample multiple times and connecting it to a DAS recording unit. Pilot experiments performed using this setup on a range of rocks and materials show good agreement with strain gauge measurements. Advantages of DAS over strain gauges include much higher strain sensitivity (down to 10−11) and signal-to-noise ratio (and hence, shorter time required for measurements), larger dynamic range, ability to measure average (rather than local) strain in the sample, and robustness at elevated temperatures. Although the pilot experiments demonstrate the potential of DAS for rock physics measurements, further research and improvement of the proposed methodology are required to obtain independent estimates of Young's modulus and Poisson's ratio and to port the system into a pressure vessel to obtain rock properties under in-situ conditions.

High Dynamic Range Uniaxial Force/Torque Sensor Using Metal Foil and Semiconductor Strain Gauge

High Dynamic Range Uniaxial Force/Torque Sensor Using Metal Foil and Semiconductor Strain Gauge

Bending moment distribution estimation of an actual steel building structure by microstrain measurement under small earthquakes

Most structural health monitoring systems estimate the overall behavior by measuring the acceleration response, which cannot directly measure the stress or damage state of individual structural members. An alternative approach is to use strain measurements; however, methods for analyzing and utilizing strain data for actual steel buildings have not been established. In this study, highly precise semiconductor strain gauges were applied to an actual building. The accelerations and strains measured during earthquake loading were used to calculate the ratio of the bending moment at the beam or column sections to the displacement at the top of the building, which was defined as the “local stiffness.” This physical index represents the stiffness of structural elements near the measurement location and can be easily predicted through simple static frame analysis. The measured local stiffness was comparable to the analytical local stiffness values for the beams but was larger than that for the columns. This indicates that nonstructural members may exhibit a certain degree of restoring force and that the measured local stiffness may be strongly affected by nonstructural elements that are not considered during the structural design stage. Conversely, the measured local stiffness can be used to estimate the behavior of nonstructural components. The measured dominant frequency and local stiffness of the beams and columns showed a dependency on amplitude, but opposite trends were observed for the beams and columns. This indicates that the amplitude dependency of the dominant frequency is not due to the behavior of the beams and columns but to other reasons such as nonstructural components or changes in mass.

High-Rate In-Plane Shear Testing of IM7/8552 Using the Split Hopkinson Tension Bar

The high-rate in-plane shear properties of IM7/8552 carbon/epoxy composite material were investigated using a split Hopkinson tension bar featuring constant impedance mountings and semiconductor strain gauges in order to maximize the quality of the load signal. The in-plane shear response up to failure was evaluated using digital image correlation and correction terms for fiber rotation. The data confirmed previously determined experimental data reporting an increase of in-plane shear strength with increasing loading rate: In-plane shear strengths of 135 and 175 MPa were measured for strain rates of 320 and , respectively. The results indicate that a Johnson–Cook-type semilogarithmic scaling law can be used to describe the evolution of in-plane shear strength with increasing loading rate.

Analysis of high velocity impacts of quasibrittle material fragments with a Hopkinson bar

In this work it has been characterized the impact behaviour of quasibrittle fragments against a Hopkinson bar in a wide range of impact velocities (70-180 m/s). Hopkinson bar is designed to measure the impact forces thanks to a proper instrumentation. In this case, semiconductor strain gauges, which sensibility is higher than common strain gauges, are used. Two material are studied to widen the range of applicability of the experimental facility: PMMA and a woven composite material. Moreover, two high speed cameras (Photron SA-Z) have been used to obtain the displacement and strain field of the fragment impactor using 3D Digital Image Correlation (DIC). A special technique has been used to print the speckle in the fragment based on previous works. The developed experimental methodology has shown the different failure modes that may happen in the fracture process when the quasibrittle fragments acts as the impactor providing a better understanding of its physical behaviour.

Soft projectile impact forces measurement using Hopkinson bars: application to ice, artificial bird and rubber

This work presents an experimental campaign of impacts of soft projectiles to measure the induced force during the impact. Three different materials acting as soft impactors that could strike against a aeronautical structural component: ice, artificial bird and rubber have been impacted at several velocities against an aluminium Hopkinson bar. This device has been instrumented with semiconductor strain gauges that allow to obtain the induced compression strain. Additionally, all the impacts were recorded using high-speed video cameras, allowing the kinematic analysis of the projectile during the impact. After the results study, it has been concluded that there is a linear dependency between the kinetic energy and the peak force for all three materials. Added to that, it has been proved that the higher peak force corresponds to ice, despite the kinetic energy, followed by rubber and finally the artificial bird. In addition, while ice and artificial bird projectiles get radially dispersed after the impact, rubber spheres rebound due to its different behaviour. The obtained data is of great interest to design structures which could be subjected to impacts of soft materials such as aeronautic structures

Mechanical response of porcine hind leg muscles under dynamic tensile loading

A modified split Hopkinson tension bar (SHTB) apparatus was used to investigate the dynamic tensile mechanical response of porcine muscles. A hollow aluminum alloy transmission bar and a semiconductor strain gauge were used to enhance the weak signal from porcine muscles. A ring-shaped copper pulse shaper was used to achieve stress equilibrium and constant approximate strain rates in the specimens. The thin muscle specimen, fixed by 3D-printed clamps, was warped around the bar ends to minimize the radial inertial effect during tensile loading. The quasi-static tests at strain rates of 0.1 s∧-1 were also conducted on a universal material testing machine to investigate the strain rate dependence. The true stress-strain curves of porcine muscle tissues along the fiber direction were determined at approximate strain rates of 800 s∧-1, 2000 s∧-1, and 3000 s∧-1. The experimental results show that the porcine muscle exhibits nonlinear, rate-sensitive, and orthotropic behavior. The Mooney–Rivlin model with two material constants was sufficient to represent the tensile response of porcine muscles at each strain rate. The rate-dependent Fields–Backofen model can describe the high strain rate response of the porcine muscles.

Modeling frequency integrating unfolding converter with a semiconductor strain gauge bridge taking into account temperature effect

The article considers development of an algorithm and construction of a simulation model of frequency integrating unfolding converter characteristics for a bridge circuit with semiconductor strain gauges, using the MathCAD software as simulation environment. Construction of a simulation model gives the possibility of joint application of bridge circuits with semiconductor strain gauges and frequency integrating unfolding converters in the development of sensitive elements of sensors for mechanical quantities that able to function at high temperatures. An algorithm for determining components of the output signal frequency error is proposed, taking into account variation in parameters of strain gauges and the effect of high temperature, which will allow revealing influence of the error components on the output signal frequency. As a result, the above mentioned can be used in the development of additional methods and means for temperature compensation, taking into account features of semiconductor strain gauges, and to increase objectivity in the analysis of calculation results applied to converters of mechanical values into frequency.