WAVEGUIDE TECHNIQUE FOR THE SIMULTANEOUS MEASUREMENT OF TEMPERATURE DEPENDENT PROPERTIES OF MATERIALS

[0001] This technology comes in the area of sensors and sensing techniques for material properly and process conditions measurement. This has specific applications in the measurement of material properties that are temperature dependent and particularly at high temperatures.

[0002] Some of the prior arts that are relevant in the field of invention are given below

• • [0003] 2001 Apparatus and method for high temperature viscosity and temperature measurements U.S. Pat. No. 6,296,385 B1
  • [0004] 1999 Ultrasonic buffer/waveguide EP 0935798 A1 (text from WO1998019296A1)
  • [0005] 1989-Ultrasonic temperature sensors, and ultrasonic waveguide connectors for use therewith, EP 0351050 B1
  • [0006] 2009-Remote ultrasonic transducer system EP 2091669 A1 (text from WO2008060153A1)
  • [0007] 1992-Distributed temperature sensor EP 0465029 A2
  • [0008] 2012-Differential ultrasonic waveguide cure monitoring probe U.S. Pat. No. 8,291,744 B2
  • [0009] 2010-Ultrasonic sensor for measuring flow rates in liquid melts EP 2158456 A2 (text from WO2008152031A2
  • [0010] 1998 U.S. Pat. No. 5,828,274
  • [0011] 2010 Ultrasonic non-destructive testing EP 2266714 A1
  • [0012] 2006 device and method for ultrasonically determining the dynamic elastic modulus of a material EP 1726947 A1
  • [0013] 2008 Device and method for ultrasonically determining the dynamic elastic modulus of a material EP 1875223 A1 (text from WO2006111559A1)
  • [0014] [1] Balasubramaniam, K, V. V. Shah, D. Costley, G. Bourdeaux, and J. P. Singh, “High Temperature Ultrasonic Sensor for the Simultaneous Measurement of Viscosity and Temperature of Melts” Review of Scientific Instruments, Vol.70 (12), pp. 1-6, (1999).
  • [0015] [2] Balasubramaniam, K., V. V. Shah, D. Costley, G. Bourdeaux, and J. P. Singh, “Viscosity and Temperature Measurements at very High Temperature by Ultrasound Reflection” U.S. Pat. No. 6,296,385, (2001).
  • [0016] [3] Balasubramaniam, K., V. V. Shah, G. Boudreaux, R. D. Costley, C. Menezes, and J. P. Singh, “Temperature and Viscosity in-situ Sensor for Hostile Processes” Review of Progress in Quantitative Nondestructive Evaluation, Vol. 18B, pp.1163-1170, (1999).
  • [0017] [4] Faber, A. J., F. Simonis, R. Breeuwer and Henk de wall. “Application of ultrasonic measuring techniques in industrial glass melting” Glastech. Ber. 64Nr. 5, (1991).
  • [0018] [5] Shah, V. V., K. Balasubramaniam, “Measuring Newtonian Viscosity from the Phase of Reflected Ultrasonic Shear wave”, Ultrasonics, Vol. 38, pp.921-927(2000).
  • [0019] [6] Shah, V. V., K. Balasubramaniam, R. D. Costley, and J. P. Singh, “Sensor Development for High Temperature Viscosity Measurement” Review of Progress in Quantitative Non-destructive Evaluation, Vol.17A, pp.859-866.(1998).
  • [0020] [7] Shah, V. V., and K. Balasubramaniam, “Effect of viscosity on ultrasound wave reflection from a solid/liquid interface,” Ultrasonics, Vol. 34, No. 8, pp. 817-24, (1996), Plenum Press, N.Y., Vol. 17A, pp. 859-866, (1996).
  • [0021] [8] Sheen, S. H.,H,-T. Chien, and A. C. Raptis, “An In-Line Ultrasonic Viscometer”, Review of Progress in Quantitative Nondestructive Evaluation, Vol. 14A, pp.1151-57, (1995).
  • [0022] [9] Sheen, S. H., H. T. Chien and A. C. Raptis, “Measurement of shear impedances of viscoelastic fluids”, IEEE Ultrasonics Symposium Proceedings, (IEEE, New York) Vol.1, pp. 453, (1996).
  • [0023] [10] T. K. Vogt, M. J. S. Lowe, and P. Cawley, “Measurement of the Material Properties of Viscous Liquid using Ultrasonic Guided Waves” IEEE Transaction on Ultrasonics, Ferroelectrics, and Frequency Control, Vol. 51, No. 6, pp 737-747, (2004).

[0024] The measurement of temperature dependent properties of material is critical This is required for both solid and fluid materials. The invention describes here uses unique embodiments to an ultrasonic waveguide to determine the following properties of a solid material that forms the waveguide that is encased in a fluid media with known properties:

• • [0025] 1. Moduli (both Normal and Shear moduli) as a function of temperatures.
  • [0026] 2. Density as a function of temperature.

[0027] Further, once the solid media is characterized, the temperature dependent properties of the fluid is measured that includes the following properties:

• • [0028] 1. Viscosity of the fluid
  • [0029] 2. Density of the fluid
  • [0030] 3. Temperature of the fluid
  • [0031] 4. Surface level of the fluid.

[0032] Further, using multiple waveguides, the gradients in the above properties can be measured.

[0033] This invention describes a waveguide based technique with special modifications to the end of the waveguide to obtain reliable reflected ultrasonic signals from the end of the wave guide, that is inside a heating chamber (such as controlled furnace), and the interpretation of the reflected signals leading to a quantitative measurement of mechanical properties of the waveguide material i.e. Young's and Shear Moduli, Density and the properties of the fluid surrounding the waveguide i.e. viscosity, density, level and temperature of the fluid.

[0034] Ultrasonic waveguides, with unique embodiments to the end of the waveguides, have been used here for accomplishing multiple measurements as described below:

• • [0035] When the end of the waveguide is in a known media (for instance Air or Vacuum) the technique is capable of measuring the mechanical properties of the waveguide, including the Young and Shear moduli and density.
  • [0036] When the end of the waveguide is in an unknown fluid media, the technique is capable of measuring the mechanical properties of the fluid, including viscosity, density, and temperature.
  • [0037] When the sensor is used in conjunction with a temperature controlled chamber, the dependencies of these measured properties to temperature can be obtained.
  • [0038] The technique uses guided ultrasonic wave modes that are generated using an ultrasonic transducer at one end of the wave guide, travel along the length of the waveguide, interacts with the end of the waveguides, and is reflected back to from this end. The end of the waveguides has unique embodiments that permit a multiple interactions between the ultrasonic wave and the embodiment. The reflected signal from are detected and recorded using an ultrasonic transducer and associated instrumentation. The necessary ultrasonic amplitudes and time of flights are obtained from the reflected signal and the properties of the waveguide material and the surrounding fluid is calculated.

[0039] The system in one aspect is novel in the configuration which includes plurality of bends and/or notches at one end and thereby the method is novel in the path being created including a plurality of bends and/or notches at one end. The feature including the designing in the end, for example in a very simple case it will be one bend or a one notch which provides a reference signal that allows the user to improve the measurement and makes the system and method robust. In a more sophisticated measurement, it can be designed either with multiple notches/bends, or any other non-linear turns/paths/features or other forms of features that can be machined/modified in the measurement end of the waveguide to provide either improved measurement capability, or capability to measure many properties simultaneously, or improve the robustness or the measurements, or use these features to make measurements at multiple positions using the same waveguide. This is the key feature in the disclosure which includes the system and the method.

[0040] FIG. 1A to 1D: Some of the typical embodiments to the end of the waveguide is shown in FIGS. 1A, 1B, 1C and 1D.

[0041] FIG. 2: A typical instrumentation for the data collection is shown in the figure. However, microprocessor and FPGA based hardware can be used to replace many of the instrumentation functionalities. Typical instrumentation block diagram for the sensor data collection.

[0042] One of the typical modes of excitation of the guided wave modes in the waveguide is through using a Piezoelectric Crystal based transduction. The excitation of the desired wave-modes will depend on the relative position of the crystal, the orientation of the piezoelectric domain coordinates (which influences the surface tractions provided by the transduction). The generation of several guided wave modes is feasible including T(0,1), L(0,1), L(0,2), F(1,1), etc. all of which can be used in the sensing. While, piezo-electric method is a typical method of generation, other modes such as electromagnetic, laser based, thermo-electric, etc. are also equality applicable. The FIG. 3 shows some typical positioning of the piezo-electric based transducers on the waveguide. The vibration of the piezo crystal is shown.

[0043] FIG. 3: Some of the typical combinations of the Piezo-crystal vibrations and position of the crystal with respect to the waveguide orientation.

[0044] The experiments have been conducted for the determination of (a) Normal Moduli (E), (b) Shear Moduli (G) and temperature and temperature gradients using the sensor made of a rod made of a high temperature material. The time of flight of the signal of the ultrasonic guided wave that travels along the length of the waveguide, reflects due to the features at the end of the waveguide and returns back to the transducer was employed in the sensing. The sensor was placed inside a furnace and thermocouples were used for verification of temperature measurement purposes.

[0045] FIG. 4: The waveguide embodiment using an L bend was employed in the study reported here. The sensor along with a holder for the piezo-crystal transducer for the generation of the ultrasonic wave modes is shown in the FIG. 4: A typical time domain signal (also called as the A-scan signal) is shown in the FIG. 4. The two signals, one reflected from the bend region and the other reflected from the end of the waveguide is observed in the A Scan signal at times of flight that represents the duration of travel to and fro from the transducers to the region of reelection.

[0046] A typical L bent waveguide with the probe and waveguide holder. Typical ultrasonic RF signal obtained by the transducer showing the reflected signal from the bend and the end of the waveguide.

[0047] The time of fligh will depend on the velocity of the wave mode and coefficient of expension. If the wave guide is surrounded by a fluid that has a gradient in the temperature, the difference in the time of flight between the end of the waveguide signal and the bend reflected signal will be invarient to temperature gradients (since the bend region is in a uniform temperature region).

[0048] The difference in the time of fight (DTOF) measurement is used for the calculation of E or G. The L(0,2) mode of guided wave is used for the calculation of E and the T(0,1) is used for the measurement of G and a standard thermocouple is used for measureme to temperature by calculating the thermocouple near to the bend waveguide. Once, the E and the G values as a function of temperature, the waveguide can be used for the measurement of the properties of the fluid such as temperature, viscosity and density.

[0049] A typical result obtained using a waveguide of circular crossection (rod,wire) of 2.3 mm diameter made from Inconel-690 (a high temperature material commonly used in making up of thermocouples) was employed for the measurement. A furnace was employed with temperature controller. Measurements were taken and the DTOF was calculated from the signals during both the heating and the cooling cycle of the furnace. The data in the temperature range of 30 to 1100° C. is shown in the figure below for the L(0,2) wave mode.

[0050] FIG. 5 The δTOF for the L (0,1) mode vs temperature as measured using thermocouples and the polynomial fit curve.

[0051] Using this information, thr E vs Temperature for the material is derived as shown in the Plot marked as FIG. 6. The DTOFs measured in the previous plot is used here to derive the E moduli values. The experimentally derived values for E were then compared with the values available in the literature (Table 4, page 2 from Publication Number SMC-079, Copyright© Special Metals Corporation, 2009 (Oct 09)) and was found to be in excellent agreement.

[0052] FIG. 6 The E vs Temp for Inconel-690 as measured using the L(0,1) waveguide sensor made from Inconel-690. Two separate experimental measurements are shown here and compared with data obtained from literature (Table 4, page 2 from Publication Number SMC-079, Copyright© Special Metals Corporation, 2009 (Oct 09)).

[0053] The δtof's using the T(0,1) for the same material is shown in the figure below for the heating and the cooling cycles in the same temperature range. Due to the slower velocity of the T(0,1) mode, the δtof's values are relatively higher (as anticipated).

[0054] FIG. 7 The δtof for the T(0,1) mode vs temperature as measured using thermocouples and the polynomial fit curve.

[0055] The G vs. Temp curve for the material Inconel-690 and a comparison between the measurements and data from Literature is shown on the FIG. 8.

[0056] FIG. 8 The G vs Temp for Inconel-690 as measured using the T(0,1) waveguide sensor made from Inconel-690. Two separate experimental measurements are shown here and compared with data obtained from literature (Table 4, page 2 from Publication Number SMC-079, Copyright© Special Metals Corporation, 2009 (Oct 09)).

[0057] Once the Local material properties such as Temperature, Viscosity, Density, etc of the surrounding fluid can be measured using measurements of a single waveguide and Gradients in the properties of the fluid can be ascertained using multiple waveguides as shown in the figure below. The bend regions are located are appropriate heights in order to measure local material properties. Bother DTOF and Amplitude ratio (amplitude of the signal from the bend region divided by the amplitude from the waveguide end) will be use in the measurement of the fluid properties.

[0058] FIG. 9 Diagram showing the multiple L bend waveguides same material (Chromel) for measurement the properties of the fluids. Another diagram shows the different high temperature materials A-B-C.

[0059] FIG. 10 The DTOF for the L (0,1) mode vs temperature are measured at heating (H) and cooling (C) cycle, using multiple Chromel wave guides, then polynomial fit curve.

[0060] The invention discloses a method for measuring mechanical properties of a solid material using guided ultrasonic wave modes. The method is novel in using the solid material which itself forms the wave guide encased in a fluid media. The method shall include the first step of generating plurality guided ultrasonic wave modes using an ultrasonic transducer at one end of the wave guide, which plurality of waves travel in different path along the length of waveguide to interact with a corresponding end of the wave guide and gets reflected there from. Thereafter plurality of ultrasonic amplitudes and time of flights from the plurality of reflected signals is detected and analyzed for calculating a plurality of properties of the waveguide material and the surrounding fluid using detected plurality of ultrasonic amplitudes and time of flights.

[0061] In another aspect the material may be a solid or a fluid.

[0062] In another aspect, the properties that are identified shall be many which include at least physical properties such as elastic properties, viscoelastic properties of the material, density, viscosity and temperature over a range of temperatures. In fact the system works on a very wide range of temperature.

[0063] In another aspect the invention discloses arranging plurality of the process occurring in sequence which will provide gradients of properties of material means at least physical/elastic/viscoelastic properties of the material, density, viscosity and temperature over a range of temperatures.

[0064] In another aspect the invention includes a system for operating a novel method for measuring mechanical properties of a solid material using standard ultrasonic wave modes characterized in the solid material which forms the wave guide encased in a fluid media. It comprises of positioning an ultrasonic transducer at one end of the wave guide to generate a plurality of ultrasonic wave modes each of which waves travel in different path along the length of wave guide and gets reflected there from. The system also includes a plurality of sensors for detecting plurality of ultrasonic amplitude and time of flights from the plurality of reflected signals. There is a processor means for analyzing and calculating a plurality of properties of the wave guide material and the surrounding fluid. As in the method the other aspects of the invention are equally applicable as the material maybe a solid or a fluid and a range of mechanical properties can be identified with the system. The system works over a wide range of temperature and number of systems can be arranged. The system may comprise of plurality of systems which will provide gradients of properties of material means at least physical/elastic/viscoelastic properties of the material, density, viscosity and temperature over a range of temperatures.

[0065] Some of the sailent features that have been acquired in the product are the following

• • [0066] The sensor will quantitatively measure the elastic properties including the Young's moduli, Shear Moduli, Poisson's Ratio, Bulk Moduli of the material as a function of temperature.
  • [0067] The sensor will quantitatively measure the density of the material as a function of temperature.
  • [0068] The sensor will measure the properties of the inviscid and viscous fluids in contact with the outside surface or the inside surface of waveguide including viscosity, temperature, density,
  • [0069] The sensor, when used in multiple numbers, will measure the gradients/profiles of the properties of the waveguide material and the fluid.
  • [0070] More than one of these properties can be obtained simultaneously from the same experiment.
  • [0071] The wave guide may be in the form of a solid rod, wire, plate, sheet, etc., or hollow tube, pipe, shell, etc.
  • [0072] The guided wave modes employed can be of the Longitudinal (L(m,n)), Torsional (T(m,n), Flexural (F(m,n)), Anti-Symmetric (A(m)), Symmetric (S(m)), Shear Horizontal (SH(m)), etc.
  • [0073] The guided waves may be generated and received using one or more of the different mechanisms of guided wave generations including Piezo-electricity (longitudinal and shear modes), Electro-Magnetic transduction (Magnetostriction, Lorentz Force, EMF, etc.), Thermal mechanisms (e.g. pulser laser), Microwave, etc.

[0074] The temperature dependent property measurements are currently obtained using very sophisticated, time consuming, and expensive methods. The currently sensor design allows for these measurement to be made in relatively in expensive and short time duration without the development of an sophisticated experimental apparatus.

[0075] This technology can prove to be very critical to process industries and industries involved in high temperature processes. Industries could include power plants, refineries, chemical and fertilizer industries, etc. The technology can provide the industry with a rapid and low cost approach for measuring vital material properties of metals/ceramics/etc. as a function of temperature. This will allow the industry to improve the design process of their components and plants. Additionally, manufacturing industries that mold, form, forge materials will also have interest in this technology.

[0076] The disclosure is to the extent as possible by the inventors in terms of descriptions and embodiments for the purpose of easy understanding when read by the skilled persons in the art. None of the embodiments/illustrations/examples shall be limiting on the scope of invention. The scope of invention is as per the descriptions and the claims annexed to this application.