Inductive Displacement Transducer Research Articles

The Effect of Frequency on Double-Coil Inductive Displacement Transducer

The Effect of Frequency on Double-Coil Inductive Displacement Transducer

Optimization of an Inductive Displacement Transducer.

This paper presents the optimization of an inductive displacement transducer or linear variable differential transformer (LVDT). The method integrates design software (SolidWorks 2023), simulation tools (COMSOL Multiphysics), and MATLAB. The optimization phase utilizes the non-dominated sorting genetic algorithm (NSGA)-II and -III to fine-tune the geometry configuration by adjusting six inner parameters corresponding to the dimension of the interior components of the LVDT, thus aiming to improve the overall performance of the device. The outcomes of this study reveal a significant achievement in LVDT enhancement. By employing the proposed methodology, the operational range of the LVDT was effectively doubled, extending it from its initial 8 (mm) to 16 (mm). This expansion in the operational range was achieved without compromising measurement accuracy, as all error values for the working range of 0-16 (mm) (NSGA-II with a maximum final relative error of 2.22% and NSGA-III with 2.44%) remained below the imposed 3% limit. This research introduces a new concept in LVDT optimization, capitalizing on the combined power of NSGA-II and NSGA-III algorithms. The integration of these advanced algorithms, along with the interconnection between design, simulation, and programming tools, distinguishes this work from conventional approaches. This study fulfilled its initial objectives and generated quantifiable results. It introduced novel internal configurations that substantially improved the LVDT's performance. These achievements underscore the validity and potential of the proposed methodology in advancing LVDT technology, with promising implications for a wide range of engineering applications.

Effect of Excitation Signal on Double-Coil Inductive Displacement Transducer.

A double-coil inductive displacement transducer is a non-contact element for measuring displacement and is widely used in large power equipment systems such as construction machinery and agricultural machinery equipment. The type of coil excitation signal has an impact on the performance of the transducer, but there is little research on this. Therefore, the influence of the coil excitation signal on transducer performance is investigated. The working principle and characteristics of the double-coil inductive displacement transducer are analyzed, and the circuit simulation model of the transducer is established. From the aspects of phase shift, linearity, and sensitivity, the effects of a sine signal, a triangle signal, and a pulse signal on the transducer are compared and analyzed. The results show that the average phase shift, linearity, and sensitivity of the sine signal were 11.53°, 1.61%, and 0.372 V/mm, respectively; the average phase shift, linearity and sensitivity of the triangular signal were 1.38°, 1.56%, and 0.300 V/mm, respectively; and the average phase shift, linearity, and sensitivity of the pulse signal were 0.73°, 1.95%, and 0.621 V/mm, respectively. It can be seen that the phase shift of a triangle signal and a pulse signal is smaller than that of a sine signal, which can result in better signal phase-locked processing. The linearity of the triangle signal is better than the sine signal, and the sensitivity of the pulse signal is better than that of the sine signal.

Effect of the Coil Excitation Method on the Performance of a Dual-Coil Inductive Displacement Transducer.

A dual-coil inductive displacement transducer is a non-contact type measuring element for measuring displacement and is widely used in large power equipment systems such as construction machinery and agricultural equipment. However, the effect of the coil excitation method on the performance of dual-coil inductive displacement sensors has not been studied. This paper investigates the impact of different coil excitation methods on the operating performance of displacement transducers. The working principle, electromagnetic characteristics, and electrical characteristics were analyzed by building a mathematical model. A transducer measurement device was used to determine the relationship between core displacement and coil inductance. Three coil excitation methods were proposed, and the effects of the three coil excitation methods on the amplitude variation, phase shift, linearity, and sensitivity of the output signal were studied by simulation based on the AD630 chip as the core of the conditioning circuit. Finally, the study's feasibility was demonstrated by comparing the experiment to the simulation. The results show that, under the uniform magnetic field strength distribution in the coil, the coil voltage variation is proportional to the inductive core displacement. The amplitude variation is the largest for the dual-coil series three-wire (DCSTW) and is the same for the dual-coil series four-wire (DCSFW) and dual-coil parallel differential (DCPD). DCSFW has an enormous phase shift. DCSTW has the best linearity. The research in this paper provides a theoretical basis for selecting a suitable coil excitation, which is conducive to further improving the operating performance of dual-coil inductive displacement transducers.

Quasi-static cyclic tests on a half-scaled two-storey steel frame equipped with Crescent Shaped Braces at both storeys: Experimental vs. numerical response

This paper discusses the results of quasi-static cyclic tests performed on a half-scaled two-storey one-bay steel pendular frame equipped with Crescent Shaped Braces (CSBs) at both storeys. The same steel pendular frame was previously tested with only one CSB device located at the first storey to validate the structural response of a single device when inserted into a realistic frame. The CSB seismic design procedure and the experimental results of this first configuration were presented and discussed in a companion paper which proved that the experimental behaviour of the single CSB matched the theoretical predictions and that the effect of connection plates was not negligible. Here the attention is focused, for the first time, on a structure fully braced along the height by CSBs as in a realistic building configuration. During the tests, the global and local responses of the structure were monitored by means of inductive displacement transducers, strain gauges and Digital Image Correlation technique. Non-linear Finite Element models were also developed to provide an in-depth interpretation of the experimental results. The objective is twofold: (i) the experimental assessment of the global performances of the braced structure in terms of stiffness, strength, ductility and energy dissipation, and (ii) the comparison between the experimental and the numerically-simulated response of the structure, with specific focus on the response of the two CSBs and on the effects of realistic connections (parasitic bending moments and bolt slippage). In conclusion, the results of the experimental test carried out on a two-storey building structure fully braced with CSBs proved that the CSB seismic design procedure is effective and the use of CSBs as diagonal braces could represent a feasible solution for buildings to achieve multiple seismic performance objectives.

Assay of Direct Digital Output Floating-Wiper Inductive Displacement Sensor

A direct digital output non-contact inductive type displacement sensor whose principle of operation alone was presented earlier, is analyzed to ascertain parameters that influence the errors in the output. Further, its efficacy is established through results obtained from a prototype unit built and tested. The proposed direct digital output non-contact inductive displacement transducer employs the popular successive approximation register (SAR) method of conversion. The digital output is proportional to the displacement of the contactless (floating) wiper and is unaffected by the variations in the coupling capacitor that is formed between the wiper and the inductive element. Test results on a prototype transducer indicated a worst-case error of 0.9 %.

Test of the tensile load capacity of a timber structure joint with an inserted nail plate

The aim of this paper was to determine the axial tensile load capacity of timber structure elements with inserted metal plates with welded nails. The tests were performed on three specimens in the laboratory of the AdMaS centre of the Faculty of Civil Engineering, Brno University of Technology. The tensile force was applied on the specimen by increasing the force up to the specimen failure. The inductive displacement transducers continuously measured the displacement of the inserted joint plates with regard to timber prisms. The tensile load-bearing capacity of the tested joint was determined at 205.0 kN. Due to the advantages, the tested joints with inserted nail plates seem to be appropriate for joining suitable timber elements.

Proof Load Test on Bridges and Viaducts: A Bibliography Analysis

This article aims at the study of proof load tests on bridges and viaducts, presenting the definitions and methods related to this test, in addition to describing the first load tests ever performed in Brazil. It evaluates the procedures of the Brazilian standards (NBR 9607:2013), comparing with the international regulations. The following topics present the importance and the way in which the load test is carried out, showing the risks of this test. Finally, this article explains the relevance of instrumentation and describes the most commonly used equipment: extensometer, inductive displacement transducer, deflectometer, clinometer, topography instruments, single-cell cell for measuring stationary forces and hydrostatic leveling system with pressure cell.

Design of an inductive pickup type displacement transducer using an electro‐optic effect of lithium‐niobate‐based Mach–Zehnder interferometers

In this study, an improved inductive pickup coil and an electro-optic type displacement transmitter has been proposed. A modified differential inductance bridge network has been used to generate electrical signals and Mach–Zehnder interferometer (MZI) converts an electrical signal into an optical signal. The sensitivity of the sensor part of the transducer is very good because of two parallel magnetic paths for the inductive pickup. The theoretical equations explaining the operation of the transducer are derived. The proposed transducer is tested experimentally to obtain the static characteristics. The characteristics of the MZI-based displacement transmitter have been observed by using PC-based Opt wave Opti-BPM.v.9 simulation software in the linear zone. The experimental and simulated results are reported in this study. Very good linear characteristics of the transducer with adjustable sensitivity have been observed. The transmitter output in the form of normalised intensity of light is also found to be linearly related with displacement. The theoretical equations derived in this are found to support the experimental characteristics to a very good extent.

ASSESSMENT OF MECHANICAL CHARACTERISTICS OF VASCULAR ENDO-PROSTHESES

Titanium nickelide (nitinol) is one of prospective materials for production of special endo-prostheses and other parts and characterized with effect of shape memory. A specific feature of vascular endo-prostheses is the necessity to provide the required rigidity within the temperature interval from 15 to 42 оС. It has been established that titanium nickelide is able to provide the required rigidity but it depends on preliminary heat treatment parameters. So, it is important to determine rela-tions between rigidity of titanium nickelide wire and its preliminary heat treatment parameters for the given temperature in-terval. The aim of the work is to create devices that allow to estimate radial and flexural rigidity of elements made of flexible nitinol wire for manufacturing various medical products, including endo-prostheses of vessels – stents and stent grafts, filter traps. Laboratory digital scales and a specially developed dynamometer based on a cylindrical slotted spring and inductive displacement transducer have been used for measuring a load. The paper proposes possible variants of device designs used to monitor radial rigidity of blood vessel endo-prostheses, as well as to control flexural rigidity of endo-prosthesis elements and wire for their manufacture. The developed devices allow us to evaluate mechanical characteristics of samples under the desired temperature conditions. An introduction of the developed devices has permitted to carry out an operative control on radial and flexural stiffness of intravascular endo-prostheses elements both under conditions of research investigations and during technological process of their manufacture. Currently, the devices are used to specify heat treatment regimes for nitin-ol wire from various manufacturers while manufacturing vascular endo-prostheses.

Accurate LVDT Signal Converter

A novel technique to implement a signal converter for an inductive displacement transducer, a linear variable differential transformer (LVDT), is proposed in this paper. The technique is based on the use of the proposed peak-amplitude finder and the zero-order sample and hold circuit (ZSH) instead of the synchronous demodulator used in traditional approach. The advantage of this technique is that the phase shift due to the dominant pole of the low-pass filter used in the traditional synchronous demodulator is avoided. Therefore, the fast response time of the proposed LVDT signal converter is achieved. The core displacement signal, which is varied in proportion to the position of the moving core of the LVDT, is accurately extracted to direct-current (DC) voltage signal. The reference signal used to generate the control signal for the ZSH is directly provided by the output signal of the LVDT to prevent the phase shift caused by the LVDT structure. Performances of the proposed technique are discussed in detail and confirmed by the experimental demonstration using commercial devices. The purpose of the proposed technique is emphasized in terms of high accuracy, fast response, simple configuration and low cost.

Calibration Characteristic of an Inductive Displacement Transducer

A primary measuring inductive transducer of solenoid type is considered. The equation of its transformation function is derived using the Umov–Poynting theorem. We estimate the influence of the basic design parameters of the transducer on its metrological characteristics.

INFLUENCE OF CYCLIC LOADING ON THE DEFLECTION DEVELOPMENT OF CONCRETE SPECIMENS

Durability of the structures is one of the most discussed issues of last decades. It is one of the most easily measured properties for analysis during the structural lifetime. Concrete deflections increase over time due to rheological effects (creep and shrinkage) in addition cyclic creep can be observed on the cyclically loaded structures. The deflection increase due to the cyclic creep is not properly quantified. The fatigue damage function presented in this paper provides an analytical solution for the deflection development due to cyclic loading. The evaluation of the deflection is based on the reduction of the initial modulus of elasticity.Main principles of the function are discussed and compared with the standardized approaches for the fatigue assessment. Experimental verification of the fatigue damage function was carried out on reinforced concrete specimens and on prestressed concrete slab. To improve the standardized approaches, the real stress distribution was considered with the use of newly-developed method of partial integration over the height of the specimen compressive zone.The deflection increase due to cyclic loading was measured regularly with inductive displacement transducer. Comparison of the measured values and the values calculated using the presented function shows good agreement. The fatigue damage function can be used easily in “in-hand” calculations, or can be inserted into FEM-based software and used in practical applications for assessing the increase in the deformations of concrete structural elements caused by cyclic loading.

Simulation Analysis of Output Characteristic of the Inductive Displacement Transducer

Aiming at the structure and electromagnetic induction characteristics of inductive displacement transducers, it is inevitable to appear the problem between nonlinearity output and temperature drift, by which it’s testing accuracy is affected, on the basis of analysis of structural characteristics and working principle of the inductive displacement sensor, mathematical model of the relationship between input and output has been constructed, which can be simulated and analyzed by MATLAB software. The results indicate that the inductive displacement transducer has an proximately linear extent ( ) and the linearity errors are influenced by the coils number and the semidiameter;In the case of relatively constant of other parameters, when the coil of radius and the number of coil turns are fixed ,there will be the core displacement x and , the sensor output characteristic has an favorable linearity under the circumstances of changing the coil radius and the number of turns in proper sequence; When ,the output property of the sensor appears worse linearity.

Primary stability and strain distribution of cementless hip stems as a function of implant design

BackgroundShort stem prostheses have been developed to preserve the femoral bone stock. The purpose of this study was to evaluate the stress-shielding effect in the proximal femur as well as the micromotion between bone and implant as a measure of primary stability for a new short stem in comparison to a clinically successful short stem and a straight stem. MethodsUsing paired fresh human femurs, stress shielding was examined by using tri-axial strain gage rosettes. The strain distribution of the proximal femur was measured before and after implantation of three cementless prostheses of different design concepts and stem lengths. Furthermore, interface motion and rotational stability were investigated under dynamic loading (100–1600N) after 100,000 load cycles using inductive miniature displacement transducers. FindingsA reduction of longitudinal cortical strains in the proximal femur was displayed for all three implants. The reduction was less pronounced for the shorter stem implants, however.Interface motion was below the critical threshold of 150μm at almost all measuring points for all three stems, with a tendency for greater rotational stability in the shorter stem implants. InterpretationThe new short stem prosthesis displayed reduced stress shielding and comparable primary stability to an established short stem and a conventional shaft design. Shortening the stem did not negatively influence primary stability. The clinical implications of these findings remain to be proven.

Editorial

Editorial

On the Shear Behaviour of Concrete Beams Reinforced by Carbon Fibre‐Reinforced Polymer Bars: An Experimental Investigation by Means of Acoustic Emission Technique

Abstract: This paper reports test results of 20 concrete beams reinforced by carbon fibre‐reinforced polymer (CFRP) bars, without any shear reinforcement, subjected to three‐point bending tests. The tests were conducted at the Official Laboratory of the Department of Structural Engineering of the University of Calabria with the aim of both analysing and improving the knowledge of the mechanical behaviour of these new structural elements and to validate, from an experimental point of view, some theoretical relationships suggested in the recent Italian Guidelines CNR‐DT 203/2006. All tested specimens were classified into four groups according to the different concrete compressive strength and to CFRP‐bar reinforcement. Mid‐span deflection, moment‐curvature and bar strains were investigated by means of linear inductive displacement transducers, centesimal dial gauges and strain gauges directly applied onto CFRP bars. In almost all cases, shear failure mode was observed. A major diagonal crack within the beam shear span extended horizontally at the level of the CFRP bars indicating bond failure. During the experimental study, the acoustic emission technique was used to find out the beams cracking moment and to investigate the damage phenomena occurred inside the beams during the experimental tests, by means of a monitoring system set up.

The ability of different materials to reproduce accurate records of interocclusal relationships in the vertical dimension

Restorations made on incorrectly mounted casts might require considerable intra-oral adjustments to correct the occlusion or might even necessitate a remake of the restoration. The aim of this study was to evaluate interocclusal recording materials for their ability to reproduce accurate vertical interocclusal relationships after a storage time of 1 and 48 h, respectively. A custom-made apparatus was used to simulate the maxilla and mandible. Eight interocclusal records were made in each of the following groups: G1: Aluwax (aluminium wax), G2: Beauty Pink wax (hydrocarbon wax compound), G3: Futar D, G4: Futar D Fast, G5: Futar Scan (G3-G5: vinyl polysiloxane), G6: Ramitec (polyether). The vertical discrepancies were measured by an inductive displacement transducer connected to a carrier frequency amplifier after storage of the records for two periods of 1 and 48 h. Two-way anova was used for statistical analysis. The mean vertical discrepancies in mum (1/48 h) for G1 (31/35) and G2 (35/38) were statistically significantly higher than for the other groups G3 (8/10), G4 (11/12), G5 (6/8) and G6 (5/8) (P < or = 0.05). There were no statistically significant differences between the elastomers tested. The effect of storage on the vertical discrepancies was statistically significant (P < 0.001). Vinyl polysiloxane and polyether interocclusal records can be used to relate working casts during mounting procedures without significant vertical displacement of the casts.

Experimentelle Untersuchungen zum Einfluß operationstechnischer Fehler auf die Primärstabilität zementloser Hüftendoprothesenschäfte

For quantified evaluation of the primary stability of cementless femoral stem prostheses the operative faults: too low sized stem, distally short-lined anchoring with proximally surpassing stem and fissure or fracture of the femur shaft were simulated in autoptical test series. By inductive displacement transducers the micromotion between stem and proximal bone layer were measured in medio-lateral and ventro-dorsal direction under static load conditions before and after a dynamic loading of 50,000 cycles. The underdimensioned stem showed its instable anchoring by obviously increased micromotions in all measure plains. The proximally excelling only distally anchored prosthesis demonstrated immense amounts of motion. The fissure doesn't seem to decrease the primary stability of the stems too much. These results of the autoptical test series can only be directly transferred to the conditions of the first weeks after implantation, because the influence of later bone integration could not be considered.

Multidimensional Tests of Superelastic, Polycristalline NiTi under Isothermal Conditions

AbstractDifferent isothermal and non‐isothermal tension/torsion tests are conducted on hourglass‐shaped, superelastic NiTi specimens. A new measurement device based on inductive displacement transducers is presented allowing for a directly decoupled measurement of twist and elongation at the same measuring points within the gage length. Thus, not only measuring but also controlling the deformation of the specimen is possible. The specimen temperature is actively controlled to keep the temperature deviation as low as possible and to be able to react immediately to sudden changes in the temperature field due to latent heat generation/absorption during phase transitions. (© 2006 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)