Strain Gauge System Research Articles

Modulation of force and velocity for accurate tasks by a startle

Background Some skilfulfast activities require control of trajectory and force to fulfill the task. It is known that voluntary reactions can be speeded up by a startling auditory stimulus (SAS) delivered at the same time as the imperative signal (IS), a phenomenon termed Start-React (Valls-Sole et al., 1999). The aim of the present study was to examine how the performance of a task that demands accuracy, mainly in terms of velocity during the trajectory or force control when holding an object, is changed by a SAS timed to occur either at the time of IS or at a pre-determined time interval when movement has already begun and motor control of accurate reaching is expected. Methods Nine subjects performed an accurate elbow extension between two spots placed at an angular distance of 30° when holding with their right hand a pen that monitored, through two strain gauge systems, the force of the subject’s fingers during the hold, and the force at which pen-tip was exposed with table contact. According to block of trials, this end spot had three possible diameters: 5, 10, and 20 mm. Kinematic and force parameters were measured for three conditions, control, with SAS at IS or SAS delivered when movement has already started. Results In SAS trials, there were no evident differences with respect to control trials in the general outline but there were differences in the timing of the events. In SAS-IS trials time to peak velocity was 166 ms (SD = 41 ms), time to peak force was 95 ms (SD = 43 ms) both shorter than in control or SAS delivered when movement began. Peak velocity (315 ± 56 o/s) and peak force (8 ± 2 arbitr. units) were larger for SAS-IS trials than for control or SAS delivered when movement started. Conclusions Startle can advance a task that requires accuracy with velocity and force modulations, but when task onset is already launched there are not evident changes in velocity or force parameters, that seem already prepared.

The effects of noise on speech movements in young, middle-aged, and older adults

People often talk in noisy environments, which can influence the effectiveness of communication. This study examined the impact of several types of noise on speech production by measuring lip movements during a sentence repetition task. Sixty participants in three age groups ranging from 20 to 70 repeated a sentence under five noise conditions (silence, one person reading aloud, two readers, six readers, and pink noise). A head-mounted strain gauge system tracked vertical lip movements. With the presentation of noise during a speaking task, the intensity increased due to the Lombard effect in all of the noise conditions. The utterance duration for the 1-talker condition was significantly shorter when compared to the silent condition. The peak velocity of a selected lip-closing gesture increased in all of the noise conditions compared to silence. Speech movement variability in the pink noise and 6-talker conditions was lower than in the silent condition. The repetitive nature of the sentence repetition task may not have required a high level of self-monitoring, resulting in speech output that was more automatic in the noise conditions. Speech movement differences as a function of the type of noise suggest that hearing speech while talking may be more distracting than speaking in the presence of continuous (e.g., pink) noise. Because people communicate in noisy environments every day, an increased understanding of the effects of noise on speech may have value from both theoretical and clinical perspectives.

Universal digital strain gauge measurement system of aeroelastic deformation development

This article presents description of the universal digital strain gauge system developed to measure the static and dynamic aeroelastic deformations of elasticity-scale models during the tests in aerodynamic tube and during in-flight tests of an experimental air vehicles. The main requirements for such devices are small size and possibility of operation in a wide temperature range. The article considers the dependence of zero offset from temperature. Functional diagram block and logic diagram of the build system are shown.

Development of the information technology for processing anomalous measurements of strain-gauge systems

The aim of the research is the development of the information technology for processing anomalous measurements of strain-gauge systems to improve the accuracy of estimating the mass of an object with a limited time of weighing. With this, the main problem is the need to describe anomalous situations that may occur on a variety of sensors under uncertainty. This task required the development of an appropriate mathematical approach based on the theory of fuzzy time series, as well as new approaches in determining the degree of comparison of fuzzy situations. In practice, the search for anomalies is proposed to carry out with the help of the algorithms using the specially-designed standard bases, describing the fuzzy situations. It is assumed that the standard bases are formed of a large set of real situations. Experimental results show that using this information technology in processing the signals from a plurality of strain gauges increases the estimation accuracy of the sensor readings by several times.

Finite Element Modeling of Effect of Adhesive Layer and Carrier Thickness Used for Strain Gauge Mounting

Metal foil strain gauges are most widely used for the stress analysis in engineering structures. Typical strain gauge system includes strain sensitive grid, carrier material, and adhesive layer. Strain measurement from the strain gauge is partially affected by carrier and adhesive materials and their thickness. In the present work, a Finite Element Model is developed in order to study the effect of both adhesive layer and carrier thickness on strain measurements while using strain gauges. To understand the behavior of the adhesive material, mechanical characterization is done on bulk adhesive specimen. Finite Element Analysis (FEA) is carried out with different materials namely epoxy and polyurethane. Initially a single element foil loop is considered for the analysis and further this is extended to metal foil strain gauge with nine end-loops. Finally, the strain variation through thickness of adhesive layer, carrier and strain sensitive grid is obtained from FEA. The results thus obtained are compared with analytical results from Basic Strength of Materials approach.

Formulation of multi-criteria optimization problem for process a set of signals of strain gauge systems

The study defines a set of linguistic variables allowing carrying out a classification of fuzzy signals. Using fuzzy classification signals it is constructed approximating relation that connected the maximum value of a signal received from one source to different systems of primary processing. The proposed algorithm allows narrowing down the set of solutions of formulated multi-criteria optimization problem, the use of which solves the problem of removing anomalies in the current set of signals. We solve the practical problem of building information model estimating the mass of an object with a limited time of weighing, when the objects are moving at high speed. In practical observations it is revealed that in some cases, high-frequency stochastic noise formed dynamic phenomena occurring in the process of weighing, can strongly reject the measured time series of the real signal. It is the cause of abnormal situations occurring in the measurement of strain signals. The developed algorithm allows handling certain abnormal situations arising in the measurement of strain gauge signal. This, in turn, improves the accuracy of estimating the mass of the object with a limited weighing time when objects moving with high speed processing.

Selected problems concerning determination of the buckling load of channel section beams and columns

The issue of buckling load determination in composite channel section beams subjected to pure bending and channel section columns subjected to uniform compression is considered. Some selected problems with determination of buckling load on the basis of the collected and processed experimental data are discussed. The data necessary to determine buckling load (applied load and the corresponding displacement, strains at chosen points of beam-columns and displacements in three perpendicular directions of all visible points of the considered beam-columns) were collected with a strain gauge system, an Aramis® 3D optical system and a universal testing machine. Buckling load was determined by means of the following well-known methods: the mean strain method, the method of straight-lines intersection on the graph of load vs. mean strains, the curve inflection point method, the load-square of deflection curve method and Koiter’s method. All results were obtained during the experimental investigations and the numerical FEM analysis of the channel section profile made of a GFRP laminate with the symmetrical eight-layer arrangement [45/-45/90/0]s. The profiles under consideration were subjected to compression or pure bending (four-point bending test). The rules for each methods of buckling load determination are proposed on the basis of the obtained results.

Increasing the reliability of quality control of the wheels of freight cars in motion using digital data processing

An analysis of the pattern of rail deformation under a passing train using a rapid-response strain-gauge system is described. Digital signal processing algorithms are created, which involve filtration and regression analysis for minimizing the effects of continuous noise and an uninformative low-frequency component on the reliability of identifying the wheel pair and the assessment of forces in the wheel-and-rail system. A method for assessing the force impact of rolling surface defects on the dynamics of the interaction of rails with wheels is tested.

Space-compatible strain gauges as an integration aid for the James Webb Space Telescope Mid-Infrared Instrument

Space instruments are designed to be highly optimised, mass efficient hardware required to operate in extreme environments. Building and testing is extremely costly, and damage that appears to have no impact on performance at normal ambient conditions can have disastrous implications when in operation. The Mid-Infrared Instrument is one of four instruments to be used on the James Webb Space Telescope which is due for launch in 2018. This telescope will be successor to the Hubble Space Telescope and is the largest space-based astronomy project ever to be conceived. Critical to operation of the Mid-Infrared Instrument is its primary structure, which provides both a stable platform and thermal isolation for the scientific instruments. The primary structure contains strain-absorbing flexures and this article summarises how these have been instrumented with a novel strain gauge system designed to protect the structure from damage. Compatible with space flight requirements, the gauges have been used in both ambient and cryogenic environments and were successfully used to support various tasks including integration to the spacecraft. The article also discusses limitations to using the strain gauge instrumentation and other implications that should be considered if such a system is to be used for similar applications in future.

Suitable design of mouthguard for sports-active person with spaced dentition.

Custom-made mouthguard (MG) is popularly used by sports-active persons or athletes having either normo-occlussion or malocclusion to prevent dental injury. For sports-active person with malocclusion, specially designed mouthguard is often required. The purpose of this study was to make a suitable design custom-made mouthguard for sports-active person with spaced dentition by the shock absorption capability. Two different types of double layered mouthguards were made from a model of a sports-active person having spaced dentition with polyolefin sheets. One type was made by filling the interproximal spaces of the spaced dentition and the other type, which was devoid of interproximal space covering, without mouthguard materials (keeping space). The impact tests were carried out by a free-falling object via testing machine and a vertical rod. The strains of the dentition with mouthguard were measured by means of strain gage system to compare between two different designs of mouthguard. Unpaired t-test was carried out as statistical analysis. The strains of the dentition with mouthguard by filling the interproximal spaces were significantly low compared with the mouthguard by keeping spaces (P<0.05). For sports-active person with spaced dentition, it is important for reducing injury risks that the mouthguard covered the teeth and filled or embedded interproximal space certainly.

Morphological Considerations of Fish Fin Shape on Thrust Generation

In this study, we aimed to determine the relationship between thrust generation and fish fin shape. To compare the effect fin shape had on thrust generation, we categorized the morphological shapes of fish fins into equilateral polygonal shapes. Polygonal fins were used to generate thrust that depended only on shape. These fins were constructed of a hard elastic material to eliminate any influence of shape deformation. A servomotor with a reciprocal rotation moved a fin cyclically, and thrust was experimentally measured using a strain gage system. Thrust tended to be proportional to the inertia moment of a fin, which indicated difficulty with rotation. Moreover, this trend for thrust generation was directly related to the number of apexes of a polygonal fin. The force translated ratio, which was thrust divided by the force required for fin rotation, was evaluated to determine the hydrodynamic characteristics of fins. This finding showed that the force translated ratio of a fin increased with increased movable perimeter length. The greatest thrust was generated by a triangular fin rotated at its apex, which is often seen in general fish tail fins, whereas the hydrodynamic characteristics were the worst in polygonal fins.

EVALUATION THE PATTERN AND MAGNITUDE OF THE LOADS APPLIED ON MTKRGO ORTHOSIS DURING WALKING OF PARAPLEGIC SUBJECTS

Various kinds of orthosis have been designed for paraplegic subjects to stand and walk. They have been designed based on this assumption that most of the loads applied on the orthosis (OR) and body complex is transmitted by OR. In this study, it was aimed to determine the role of OR to transmit the loads by use of strain gauge system. Three spinal cord injury subjects, with lesion between T12 and L1, were recruited in this study. A motion analysis system with a Kistler force plate was used to collect the kinetic and kinematic parameters. Moreover, the loads applied on the OR were determined by use of strain gauges attached on the lateral bar of OR. The pattern of the loads applied on the complex, OR and body, differed from that of OR. Nearly 43% of adduction moment was transmitted by OR. In contrast the role of OR to transmit the flexing/extending moments and vertical force is negligible. The results of strain gauge and motion analysis systems differed completely from each other's. As the strain gauge show the absolute values of the loads applied on OR, it is recommended using its result in order to design an OR for paraplegic subjects.

Effects of castration method and frequency of intramuscular injections of ketoprofen on behavioral and physiological indicators of pain in beef cattle1

Two experiments were conducted to determine the effect of a single or multiple intramuscular (i.m.) injection of ketoprofen and castration technique on physiological and behavioral indicators of pain in beef calves. A total of 150 bull calves (284.8 ± 22.7 kg BW) were used in both experiments, each 1 conducted as a 3 × 2 factorial design, where main factors included castration technique--no castration (CT), surgical (SU), or band (BA)--and drug administration--physiological solution (PS) or i.m. injection of ketoprofen (KP; 3 mg Anafen/kg BW) in the neck of calves. Animals were weighed weekly during the experiment to calculate ADG. Behavioral responses indicative of pain and discomfort during the castration procedure were documented using a visual analog score (VAS) by an experienced observer who was blind to the treatments. Movements of the animals in the chute during castration were quantified using a strain gauge system mounted on the head gate to evaluate the escape response of the cattle. Pens were equipped with an automated feed bunk monitoring system enabling feed intake and feeding behavior to be continuously monitored for each individual. Thermographic images of the scrotal area were evaluated 24 and 0.5 h before castration, 0.5, 1, 24, 48, and 270 h postcastration, and weekly thereafter until the end of the trial. Blood samples were obtained postcastration to evaluate changes in total white blood cell (WBC) count and neutrophil-to-lymphocyte (N:L) ratio. Saliva samples were taken 24 and 0.5 h before castration, immediately after castration, and 0.5, 1, 2, 5, 24, and 48 h and then 5, 7, and 14 d after castration to determine cortisol concentration. Scrotal temperature, VAS, total WBC, N:L ratio, salivary cortisol, mobility, and pressure exerted in the chute were greater (P < 0.05) and ADG and feed intake were lower (P < 0.05) in SU than in CT animals within the first week after castration. Also, BA calves had a greater (P < 0.05) scrotal temperature around wk 4 after castration and a lower feed intake and ADG at wk 2 and 3 and wk 6 and 7 after castration, respectively, compared to CT. Treatment KP had limited effects on reducing the indicators of pain associated with SU or BA, suggesting that further studies will be needed to assess the posology of the i.m. administration of ketoprofen to improve the consistency of its effects as a pain mitigation strategy after castration.

Serration Phenomena Occurring During Tensile Tests of Three High-Manganese Twinning-Induced Plasticity (TWIP) Steels

In this study, the serration phenomena of two high-Mn TWIP steels and an Al-added TWIP steel were examined by tensile tests, and were explained by the microstructural evolution including formation of localized Portevin–Le Chatelier deformation bands and twins. In stress–strain curves of the high-Mn steels, serrations started in a fine and short shape, and their height and periodic interval increased with increasing strain, whereas the Al-added steel did not show any serrations. According to digital images of strain rate and strain obtained from a vision strain gage system, deformation bands were initially formed at the upper region of the gage section, and moved downward along the tensile loading direction. The time when the band formation started was matched with the time when one serration occurred in the stress–time curve. This serration behavior was generally explained by dynamic strain aging, which was closely related with the formation of deformation bands.

Microprocessor multi-channel strain-gauge systems for dynamic tests of structures

In this paper we consider design principles for three high-performance microprocessor multi-channel strain-gauge systems used in dynamic tests of different structures (endurance tests of alighting gears, mobile control of wagon wheels, etc.). It is underlined that, in contrast to well-known systems, strain gauges power supply is performed by direct current. To avoid the impact of self-heating temperature errors on measurement results, strain gauges power supply is activated for short periods to measure the deformations of a structure.

Presentation, Diagnosis, and Management of Achalasia

Presentation, Diagnosis, and Management of Achalasia

Force Sensor of a Climbing Robot Derived from Its Own Flexible Structure

One of the most important design constraints of a climbing robot is its own weight. When links or legs are used as a locomotion system they tend to be composed of special lightweight materials, or four-bars-linkage mechanisms are designed to reduce the weight with small rigidity looses. In these cases, flexibility appears and undesirable effects, such as dynamics vibrations, must be avoided at least when the robot moves at low speeds. The knowledge of the real tip position requires the computation of its compliance or stiffness matrix and the external forces applied to the structure. Gravitational forces can be estimated, but external tip forces need to be measured. This paper proposes a strain gauge system which achieves the following tasks: (i) measurement of the external tip forces, and (ii) estimation of the real tip position (including flexibility effects). The main advantages of the proposed system are: (a) the use of external force sensors is avoided, and (b) a substantial reduction of the robot weight is achieved in comparison with other external force measurement systems. The proposed method is applied to a real symmetric climbing robot and experimental results are presented.

Studying the deformation and temperature distributions in a specimen during acoustic-emission testing of the weld-seam welding and cooling process

The results of experimental studies of the weld-seam welding and cooling process in steel specimens using acoustic emission (AE) and strain gauging are presented. Deformation was measured by high-temperature strain gauges welded to specimens using spot welding. Temperature was measured by chromel-alumel thermocouples. Measurements were performed with measured with an MMTC-64.01 microprocessor strain-gauging system and a CЦaД −16.10 AE system. Computers of these two systems exchanged information. Residual strain deformations were recorded on a specimen after cooling of a weld seam. Metallographic studies of transverse sections, which were were cut out from the clusterization zones of a weld seam, confirmed the presence of cracks, pores, and faulty fusions.

Flow regimes and surface air entrainment in partially filled stirred vessels for different fill ratios

In many industrial applications, stirred vessels have a liquid height-to-tank diameter ratio (fill ratio), H/T, equal to, or larger than, 1. However, there are many instances when H/T<1, as when a vessel is emptied or filled. When the impeller submergence is reduced as a result of lowering the liquid level, the fluid dynamics of even a single-phase stirred liquid can become quite complex. The objective of this work was to study the hydrodynamic changes that occur when H/T is decreased, and to determine the conditions for which adequate mixing can still be achieved. A baffled vessel equipped with a disk turbine was used. Particle Image Velocimetry (PIV) was used for the experimental determination of the velocity profiles, impeller pumping capacities and Pumping Numbers. A strain gage system was used to measure power dissipation. Computational Fluid Dynamics (CFD) was used to predict velocity profiles, Power Numbers, and Pumping Numbers using a multiple reference frame (MRF) model coupled, when needed, with a Volume of Fluid (VOF) model. Results show that a critical impeller submergence ratio, Sbcr/D, exists below which: (1) the macroscopic flow pattern generated by the impeller changes substantially, transitioning from a “double-loop” recirculation flow to a "single-loop up-pumping" recirculation flow; (2) the Power Number and radial Pumping Number drop significantly; (3) vortex formation occurs, air entrainment is greatly facilitated, and impeller flooding typically results. The critical Sbcr/D ratio was not affected by agitation speed. Impeller flooding was observed only when the new regime was established and the vortex depth reached the impeller disk. This phenomenon was correlated to a critical value of the Froude Number, Frcr. These results show that stirred vessels can be effectively operated only within certain ranges of the operating variables without compromising their mixing effectiveness. This knowledge can help practitioners avoid operating their equipment in regions where the desired mixing effects are not achievable.

SU-E-J-158: A Prototype of a Real-Time Respiratory Motion Monitoring System Using Microsoft Kinect Sensor.

To investigate the feasibility of a low-cost respiratory motion monitoring system based on the Microsoft Xbox Kinect sensor. We improved Kinect's inherent depth resolution from 1 cm to 1 mm via a motion magnification system. Using the Kinect software development kit, we programmed the Kinect to capture depth images and determine the average depth over a thoracic region of interest, viewed almost parallel to the subject's surface. Kinect respiratory traces (average depth vs time at a rate of 30 Hz) were acquired from four volunteers and compared with those simultaneously acquired using a commercially available strain gauge respiratory gating system. The correlation coefficient (CC) between Kinect and strain gauge traces varied from 0.958 to 0.978, with a mean CC of 0.969. This strong correlation was also demonstrated by the joint probability distribution and visual inspection. This work demonstrates the feasibility of using the Kinect for respiratory motion tracking. Traces are similar to those of a clinically used strain gauge system. The Kinect-based system provides a new and economical way to monitor respiratory motion.