A novel ultrasonic waveguide based technique for measuring the moduli of elastic isotropic material as a function of temperature using ultrasonic guided wave modes is presented here. This technique can be utilized for measuring Young’s modulus (E) and Shear Modulus (G) of multiple material using the guided ultrasonic L(0, 1) and T(0, 1) wave modes respectively over a wide range of temperatures (demonstrated here from room temperature to 1200 °C). The specimens used in the experiments here have special embodiments (for instance, a bend) at one end of the waveguide and an ultrasonic guided wave generator (transducer) at the other end for obtaining reflected signals in a pulse-echo mode. The far end of the waveguides with the embodiment is kept inside a heating device such as a temperature-controlled furnace. The time of flight difference (δTOF) were used to measure the moduli at different temperatures. Several materials were tested and the comparison between literature values and measured values were found to be in agreement, for both elastic moduli (E and G) measurements, as a function of temperature. This technique provides significant reduction in time, effort and cost over conventional means of measurement of temperature dependence of elastic moduli. © 2016, Society for Experimental Mechanics.

Krishnan Balasubramaniam

Department of Mechanical Engineering

Suresh Periyannan

Elastic moduli

Guided electromagnetic wave propagation

Mechanical properties

Sensors

Shear flow

Temperature distribution

Ultrasonic waves

Ultrasonics

Waveguides

ELASTIC ISOTROPIC MATERIALS

High temperature

Measurement of temperature

Multiple materials

PULSE-ECHO MODE

REFLECTED SIGNAL

TEMPERATURE-DEPENDENT ELASTIC MODULUS

ultrasonic guided wave

Ultrasonic applications

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Experimental Mechanics

This paper reports on an ultrasonic waveguide sensor for liquid level measurements using three guided wave modes simultaneously. The fundamental wave modes longitudinal L(0,1), torsional T(0,1), and flexural F(1,1) were simultaneously transmitted/received in a thin stainless steel wire-like waveguide using a standard shear wave transducer when oriented at an angle of 45° to the axis of the waveguide. Experiments were conducted in non-viscous fluid (water) and viscous fluid (castor oil). It was observed that the flexural F(1,1) wave mode showed a change in both time of flight (due to the change in velocity and dispersion effects) and amplitude (due to leakage) for different levels (0-9 cm) of immersion of the waveguide in a fluid medium. For the same level of immersion in the fluid, the L(0,1) and the T(0,1) modes show only a relatively smaller change in amplitude and no change in time of flight. The experimental results were validated using finite element model studies. The measured change in time of flight and/or the shift in central frequency of F(1,1) was related to the liquid level measurements. Multiple trials show repeatability with a maximum error of 2.5% in level measurement. Also, by monitoring all three wave modes simultaneously, a more versatile and redundancy in measurements of the fluid level inside critical enclosures of processing industries can be achieved by compensating for changes in the fluid temperature using one mode, while the level is measured using another. This ultrasonic waveguide technique will be helpful for remote measurements in physically inaccessible areas in hostile environments. © 2019 Author(s).

Fulltext

Review of Scientific Instruments

Ultrasonic waveguide based level measurement using flexural mode F(1,1) in addition to the fundamental modes

This paper reports the feasibility of using an ultrasonic waveguide sensor for distributed temperature measurement in two different case studies, that is: 1) skin temperature of a solid structure (pipe) and 2) fluid (water). This technique improves upon the conventional multiple thermocouples approach for multi-level temperature measurements. The range of temperatures is from room temperature to maximum utility temperature for the two case studies (85 °C for water and 200 °C for pipe). Using the interaction of the propagating ultrasonic waves in a thin rodlike waveguide with intentionally designed geometric discontinuities (bends, axisymmetric, non-axisymmetric notches, and so on), the localized information on the temperature is extracted. An ultrasonic technique for accurate temperature measurement by tracking the time-of-flight of reflected guided wave modes from appropriately spaced notch reflectors is therefore proposed here, while using the reflection from a bend is used as a reference. Using a finite element model approach, the notch size and/or the bend radius were selected in order to reduce mode conversion effects as well as to obtain uniform amplitudes of the reflected signals from these designed discontinuities. The numerical results were experimentally validated for the L(0,1) wave mode using a stainless steel waveguide sensor. This paper is of interest to industrial applications including mould cooling jacket temperature monitoring during the steel manufacturing process as well as for furnace wall temperature measurements in petrochemical industries. © 2001-2012 IEEE.

IEEE Sensors Journal

Ultrasonic waveguide-based multi-level temperature sensor for confined space measurements

This paper studies the propagation of ultrasound in spiral waveguides, towards distributed temperature measurements on a plane. Finite Element (FE) approach was used for understanding the velocity behaviour and consequently designing the spiral waveguide. Temperature measurements were experimentally carried out on planar surface inside a hot chamber. Transduction was performed using a piezo-electric crystal that is attached to one end of the waveguide. Lower order axisymmetric guided ultrasonic modes L(0,1) and T(0,1) were employed. Notches were introduced along the waveguide to obtain ultrasonic wave reflections. Time of fight (TOF) differences between the pre-defined reflectors (notches) located on the waveguides were used to infer local temperatures. The ultrasonic temperature measurements were compared with commercially available thermocouples. © 2017 Author(s).

AIP Advances

Multiple temperature sensors embedded in an ultrasonic “spiral-like” waveguide

This paper describes novel techniques for simultaneous measurement of temperatures at multiple locations using two configurations (a) a single transducer attached to multiple waveguides of different lengths (each with a single bend) and (b) single waveguide with multiple bends connected to single transducer. These techniques improve upon the earlier reported studies using straight waveguides, where the non-consideration of the effect of temperature gradients was found to be a major limitation. The range of temperature measurement is from room temperature to maximum utility temperature of the waveguide material. The time of flight difference of reflected ultrasonic longitudinal guided wave modes (L(0, 1)) from the bend, which is the reference signal, and another signal from the end of the waveguide, is utilized to measure the local temperature of the surrounding media. Finite element simulations were employed to obtain the appropriate dimensions and other design features of the multiple bent waveguide. This work is of interest to several industrial applications involving melters and furnaces. © 2016

Ultrasonic bent waveguides approach for distributed temperature measurement

Distributed temperature sensing has important applications in the long term monitoring of critical enclosures such as containment vessels, flue gas stacks, furnaces, underground storage tanks and buildings for fire risk. This paper presents novel techniques for such measurements, using wire in a spiral configuration and having special embodiments such a notch for obtaining wave reflections from desired locations. Transduction is performed using commercially available Piezo-electric crystal that is bonded to one end of the waveguide. Lower order axisymmetric guided ultrasonic modes were employed. Time of fight (TOF) differences between predefined reflectors located on the waveguides are used to infer temperature profile in a chamber with different temperatures. The L(0,1) wave mode (pulse echo approach) was generated/received in a spiral waveguide at different temperatures for this work. The ultrasonic measurements were compared with commercially available thermocouples. © 2017 Author(s).

AIP Conference Proceedings

Distributed temperature sensing using a SPIRAL configuration ultrasonic waveguide

A novel technique for simultaneously measuring the moduli of elastic isotropic material, as a function of temperature, using two ultrasonic guided wave modes that are co-generated using a single probe is presented here. This technique can be used for simultaneously measuring Young's modulus (E) and shear modulus (G) of different materials over a wide range of temperatures (35°C-1200°C). The specimens used in the experiments have special embodiments (for instance, a bend) at one end of the waveguide and an ultrasonic guided wave generator/detector (transducer) at the other end for obtaining reflected signals in a pulse-echo mode. The orientation of the transducer can be used for simultaneously generating/receiving the L(0,1) and/or T(0,1) using a single transducer in a waveguide on one end. The far end of the waveguides with the embodiment is kept inside a heating device such as a temperature-controlled furnace. The time of flight difference, as a function of uniform temperature distribution region (horizontal portion) of bend waveguides was measured and used to determine the material properties. Several materials were tested and the comparison between values reported in the literature and measured values were found to be in agreement, for both elastic moduli (E and G) measurements, as a function of temperature. This technique provides significant reduction in time and effort over conventional means of measurement of temperature dependence of elastic moduli. © 2015 AIP Publishing LLC.

Simultaneous moduli measurement of elastic materials at elevated temperatures using an ultrasonic waveguide method

This paper reports on a robust technique for the measurement of temperature at multiple heights (levels). This technique uses a bank of straight ultrasonic waveguide temperature sensors attached to a single ultrasonic pulser-receiver instrument. Since the ultrasonic waveguide does not use a junction, the robustness of the sensor is expected to be more for field applications. The measurements have been made by using the L(0,1) ultrasonic guided wave mode end reflection as the signal of interest. The changes in the time-of-flight (DTOF) of this signal as the measurement were related to the local changes temperature of the surrounding medium. Several waveguide configurations were studied and the thickness of the waveguide was optimized to provide a reliable calibration curve. Data was collected and analyzed in a laboratory furnace from 45°C to 1100°C, and the multi-level temperature measurement was demonstrated both in the laboratory as well as in a waste treatment vitrification facility. © 2014 Elsevier Ltd. All rights reserved.

Measurement: Journal of the International Measurement Confederation

Multi-level temperature measurements using ultrasonic waveguides

A novel technique for measuring the moduli of elastic isotropic material as a function of temperature, using ultrasonic guided wave modes is presented here. These techniques can be used for measure the Young's modulus (E) and Shear Modulus (G) of material. Here, the L (0, 1) wave mode is used for measuring E and T(0,1) mode for G. The scope of measurement is made from room temperature to maximum utility temperature of material. In this work, the material is required in the form of a waveguide with an ultrasonic guided wave generator at one end and an embodiment (such as a notch or a bend) at the other end for obtaining reflected signals. The transducer is kept at room temperature while the end (along with the embodiment) is kept inside a heating device such as a temperature controlled furnace. The time of flight difference (δTOF), as a function of temperature, between the guided wave reflections from the embodiment and the end of the waveguide, is used to measure the material properties. The technique is based on the fact that, in addition to elongation of the waveguide, the sound speed in the materials also varies with temperature and is measurable from changes in the time of flight of signals. In addition, the ambient temperature of the waveguide end is measured using a calibrated thermocouple. Several materials were tested and the data was compared with values obtained from literature. For instance, Inconel -690 waveguide with embodiment of a 'L' bend was evaluated from 45°C to 1100°C at a frequency of 0.5 MHz L(0, 1) and T(0, 1) modes. The comparison between the literature values and the measured values were found to be in agreement with a regression correlation factor R=0.999 or better, for both E and G measurements. Advantages of the method over conventional methods of such measurements will also be discussed. © 2014 AIP Publishing LLC.

Temperature dependent e and G measurement of materials using ultrasonic guided waves

The paper presents an attempt to find the possibility of measuring high temperature properties of mould powder slags such as viscosity, break temperature, liquidus temperature during heating as well as solidification start and solidification end temperatures during cooing using ultrasonics. These powders are used in continuous casting of steel and the abnormality in their properties can impact the productivity and quality of the steel products. These properties are in general measured by high temperature rotational viscometers, hot stage microscopes and DTA instruments. Here, the fundamental flexural guided wave mode F(1,1) in a ceramic buffer rod was employed in experiments. The results show the possibility of measuring all the above properties in single experiment by measuring ultrasonic reflection factors during continuous heating and cooling of the mould powders. The advantage of the ultrasonic system is that it can be installed in the plant for online monitoring of these properties. The ultrasonically measured properties of the mould powders supplied by five different suppliers were compared with those measured by rotational viscometers and estimated by mathematical models. © 2011.

Ironmaking and Steelmaking

Measurement of viscosity and melting characteristics of mould powder slags by ultrasonics

This paper describes an experimental procedure using ultrasonic waves propagating in a rod to simultaneously measure the viscosity and temperature of melts at high temperatures using a very small amount of sample and without any mechanical rotating equipment. This method has applications in laboratory tests as well as for process monitoring in industries. A refractory material is used as buffer rod in the experiment to transfer the ultrasonic vibrations from a piezoelectric transducer into the melt, which is water cooled to protect the transducer from high temperatures. The sensor is based on the effect of melt viscosity on ultrasonic guided wave reflections from the solid-fluid interface. The difference in the time of flight of the ultrasonic wave in the buffer rod at two different temperatures is used to measure the temperature. The results from the measurement of melt viscosity using the proposed method, on three different glass samples, are in agreement with the values provided by the National Institute of Standards and Technology, USA. This method offers advantages in reduction in the amount of sample, cost, complexity in experiments, experimental time. © 2008 Elsevier B.V. All rights reserved.

Journal	Data powered by TypesetExperimental Mechanics
Publisher	Data powered by TypesetSpringer New York LLC
ISSN	00144851
Open Access	No