An ultrasonic measurement method for the internal temperature field of a metal matrix composite structure

Abstract

The present invention discloses an ultrasonic measurement method for the internal temperature field of a metal-based composite material structure, which belongs to the field of ultrasonic non-destructive detection, and includes the steps of exciting ultrasonic waves on the surface of the metal-based composite material structure and detecting the characteristics of its echo signal; if the echo signal has the characteristics of the first echo and the second echo, firstly using an equivalent homogenization processing method to homogenize the inhomogeneous material, and then using ultrasonic measurement of the transit sound to measure the internal temperature field of the metal-based composite material; if the echo signal does not have the characteristics of the first echo and the second echo, then ending. The present invention overcomes the complex problems caused by the diverse material component structures of traditional composite materials, has a good measurement result accuracy, and is suitable for ultrasonic temperature measurement of various metal-based composite materials.

Description

Technical Field

[0001] The present invention relates to the field of ultrasonic nondestructive detection, and more specifically, to an ultrasonic measurement method for the internal temperature field of a metal matrix composite material structure. Background Art

[0002] Metal matrix composites are composite materials that are artificially combined with metal or alloy as the matrix and one or more metal or non-metal reinforcements. They have the advantages of high strength, high modulus, and high temperature resistance, and are eye-catching high-temperature materials for aerospace. The temperature variation characteristics inside the material structure are very important for the thermal safety assessment of the structure. Ultrasonic temperature measurement can achieve non-destructive and online measurement of the temperature field inside the material structure.

[0003] Traditional ultrasonic temperature measurement methods are only applicable to the measurement of internal temperature fields of homogeneous materials (pure metals, stainless steel, etc.). They require direct provision of parameters such as thermal conductivity, density, and specific heat of homogeneous materials. However, for heterogeneous metal-based composite materials, since they are composed of a variety of metal and non-metal materials and have complex internal material composition and structure, it is impossible to directly provide relevant physical property parameters. Therefore, traditional methods cannot be used to achieve internal temperature measurement. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an ultrasonic measurement method for the internal temperature field of a metal-based composite material structure. By performing equivalent homogenization processing on the material parameters of non-homogeneous materials and combining a temperature field reconstruction method based on ultrasonic transit sound, the measurement and reconstruction of the internal temperature field of the metal-based composite material can be achieved. The complex problems caused by the diverse material component structures of traditional composite materials in temperature field measurement are overcome, the measurement results have good accuracy, and the method is suitable for ultrasonic temperature measurement of a variety of metal-based composite materials.

[0005] The object of the present invention is achieved through the following solutions:

[0006] A method for ultrasonically measuring the internal temperature field of a metal matrix composite material structure comprises the following steps:

[0007] Excite ultrasonic waves on the surface of the metal matrix composite structure and detect the characteristics of its echo signal;

[0008] If the echo signal has the characteristics of the first echo and the second echo, the inhomogeneous material is first homogenized by an equivalent homogenization processing method, and then the internal temperature field of the metal-based composite material is measured by ultrasonic measurement of the transit sound; if the echo signal does not have the characteristics of the first echo and the second echo, the process ends.

[0009] Furthermore, the method of homogenizing the inhomogeneous material by using an equivalent homogenization method and then measuring the internal temperature field of the metal matrix composite material by ultrasonic measurement of the transit sound specifically includes the following sub-steps:

[0010] Step S1, equivalence of physical parameters: The metal matrix composite material consists of two parts: the matrix and the reinforcement particles. The changes in the thermal physical parameters of the matrix material and the reinforcement phase material with temperature, the changes in the mechanical parameters with temperature, and the proportions of the matrix and the reinforcement phase material in the entire material are known respectively. The thermal physical parameters and mechanical parameters of the composite material as a whole are obtained by equivalent homogenization:

[0011] (1)

[0012] Among them, the parameters of the matrix material are , the volume occupied is , the parameters of the reinforcement phase material are , the volume occupied is , is the total volume, and the final equivalent parameters are ;

[0013] According to the relationship between ultrasonic wave velocity and its material parameters:

[0014] (2)

[0015] (3)

[0016] The longitudinal wave velocity is , the shear wave speed is , E is the elastic modulus, ρ is the material density obtained after equivalent homogenization, is the Poisson's ratio of the material;

[0017] Combined with the relationship between each material parameter and temperature, the ultrasonic propagation velocity and temperature of the three conditions of the matrix material, the reinforcement phase material and the equivalent homogenization were fitted respectively. relation;

[0018] Step S2, ultrasonic temperature measurement process: Construct a mathematical model of ultrasonic temperature measurement under one-dimensional heat transfer conditions: one end of the material structure is a heating boundary, and the other end is an adiabatic end. The ultrasonic probe excites ultrasonic waves at the adiabatic end and receives echo information. When the pulse echo method is used for measurement, the propagation time of ultrasonic waves in the solid under non-uniform temperature distribution, i.e., the transit time Through formula (4), we can get:

[0019] (4)

[0020] in, L As the material thickness, under one-dimensional heat transfer conditions, the temperature distribution state of each point inside the structure is only x The function of x is the distance between each point inside the structure and the heating end; V (T) represents the propagation speed of ultrasound in solid media, which is related to the internal temperature and physical parameters of the solid medium. Within a certain temperature range, it is expressed as a linear relationship with temperature:

[0021] (5)

[0022] Where a and b are constants obtained through calibration experiments or theoretical fitting, and T is the node temperature;

[0023] For the one-dimensional heat conduction problem, the governing equation is expressed as:

[0024] (6)

[0025] in, k , , ρ are the thermal conductivity, specific heat and material density of the material obtained after equivalent homogenization, and t represents the time;

[0026] Boundary conditions:

[0027] (7)

[0028] in, is the heating boundary, is to be measured;

[0029] Initial conditions:

[0030] (8)

[0031] Among them, the material thickness L and initial temperature known;

[0032] In terms of the temperature field measurement inside the structure, it is transformed into an optimization problem of inverting the thermal boundary. The optimization goal is to minimize the difference between the measured ultrasonic propagation time and the propagation time obtained by numerical calculation. The following objective function is constructed:

[0033] (9)

[0034] in, Represents the actual measured ultrasonic sound time data, represents the calculated ultrasonic sound time data, m Represents the total number of measurement points, Jrepresents the objective function, represents the iterative convergence criterion; combining equations (1)-(9) and the relationship between ultrasonic velocity and temperature, the equivalent heating boundary is inverted Finally, the one-dimensional temperature distribution inside the structure is obtained by solving the direct problem of heat conduction.

[0035] Furthermore, the thermophysical parameters include thermal conductivity, specific heat and density.

[0036] Furthermore, the mechanical parameters include elastic modulus and Poisson's ratio.

[0037] Furthermore, the transition sound time Specifically, it is the echo time difference between the first ultrasonic echo signal and the second ultrasonic echo signal.

[0038] Furthermore, the material thickness is specifically a one-way propagation distance of the ultrasonic wave along the thickness direction.

[0039] Furthermore, the metal-based composite material includes a TaWNbC composite material.

[0040] Furthermore, in the TaWNbC composite material, the matrix is ​​TaW and the reinforcement material is NbC.

[0041] Furthermore, the diameter of NbC particles is 0.06 mm.

[0042] Further, the NbC particles are evenly distributed in the set area.

[0043] The beneficial effects of the present invention include:

[0044] This method adopts an equivalent homogenization processing method, so that metal-based composite materials can also be used to measure their internal temperature field based on ultrasonic propagation time (transit time), overcoming the complex problems of temperature field measurement caused by the diverse material component structures of traditional composite materials. The method has good measurement accuracy and is suitable for ultrasonic temperature measurement of various metal-based composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0046] Figure 1 Schematic diagram of ultrasonic echo signal (experiment) in metal matrix composite materials;

[0047] Figure 2is a schematic diagram of a metal matrix composite material;

[0048] Figure 3 Schematic diagram of equivalent homogenization; (a) is before equivalent homogenization; (b) is after equivalent homogenization;

[0049] Figure 4 It is a schematic diagram of the mathematical model of ultrasonic temperature measurement;

[0050] Figure 5 This is a flow chart of ultrasonic temperature measurement of metal matrix composite materials;

[0051] Figure 6 Schematic diagram of the relationship between ultrasonic shear wave velocity and temperature in TaW;

[0052] Figure 7 Schematic diagram of the relationship between ultrasonic shear wave velocity and temperature in NbC;

[0053] Figure 8 Schematic diagram of the relationship between ultrasonic shear wave velocity and temperature in the metal matrix composite material TaWNbC;

[0054] Fig. 9 Schematic diagram of ultrasonic echo signal (before equivalent homogenization treatment of metal matrix composite material TaWNbC);

[0055] Fig.10 Schematic diagram of ultrasonic echo signal (after equivalent homogenization treatment of metal matrix composite material TaWNbC);

[0056] Fig.11 Schematic diagram for comparison between the reconstruction results and the true results. DETAILED DESCRIPTION

[0057] All features disclosed in all embodiments in this specification, or steps in all methods or processes implicitly disclosed, except for mutually exclusive features and / or steps, can be combined and / or expanded or replaced in any manner.

[0058] In view of the problems in the background, the present invention aims at the demand for measuring the internal temperature of the structure of metal matrix composite materials, and proposes an ultrasonic measurement method for the internal temperature of the metal matrix composite material structure based on ultrasonic shear wave detection. This method has a good measurement effect on the internal temperature of the metal matrix composite material structure.

[0059] Specifically, in the embodiment, the purpose of the present invention is to achieve the measurement of the internal temperature field of the metal matrix composite structure by designing a new ultrasonic temperature measurement method inside the composite material, so as to provide the most accurate benchmark data and evaluation basis for the safety assessment of the composite material structure. The specific technical solution is as follows:

[0060] (1) If Figure 1As shown in the test results of ultrasonic detection experiment, when ultrasonic waves are excited on the surface of metal matrix composite materials, the echo signal has an obvious first echo. and the second echo , it is believed that the method proposed by the present invention can be used to ultrasonically measure the internal temperature field, the transit time (acoustic time difference) .

[0061] (2) Equivalence of physical parameters

[0062] like Figure 2 and Figure 3 As shown in the figure, the metal matrix composite material consists of two parts: the matrix and the reinforced particles. The changes in the thermophysical parameters (thermal conductivity, specific heat, density, etc.) of the matrix material and the reinforced phase material with temperature, the changes in the mechanical parameters (elastic modulus, Poisson's ratio, etc.) with temperature, and the respective proportions of the matrix and reinforced phase materials in the entire material are known. The thermophysical parameters and mechanical parameters of the composite material as a whole are obtained by equivalent homogenization:

[0063] (1)

[0064] Among them, the parameters of the matrix material are , the volume (area) occupied is , the parameters of the reinforcement phase material are , the volume (area) occupied is , is the total volume (total area), and the final equivalent parameters are .

[0065] According to the ultrasonic wave velocity (longitudinal wave , transverse wave ) and its material parameters:

[0066] (2)

[0067] (3)

[0068] Combining the relationship between each material parameter and temperature, the ultrasonic propagation velocity and temperature of the three conditions of the matrix material, the reinforcement phase material and the equivalent homogenization can be fitted respectively. relation.

[0069] (3) Ultrasonic temperature measurement process

[0070] Build as Figure 4The mathematical model of ultrasonic temperature measurement under one-dimensional heat transfer conditions is shown in the figure: one end of the material structure is the heating boundary, and the other end is the adiabatic end. The ultrasonic probe excites ultrasonic waves at the adiabatic end and receives echo information. When the pulse echo method is used for measurement, the propagation time of ultrasonic waves in the solid under the non-uniform temperature distribution state is the transit time. (The echo time difference between the first ultrasonic echo signal and the second ultrasonic echo signal) can be obtained by formula (4):

[0071] (4)

[0072] in, L As the material thickness (the one-way propagation distance of ultrasonic waves along the thickness direction), under one-dimensional heat transfer conditions, the temperature distribution state of each point inside the structure is only x function. V (T) represents the propagation speed of ultrasound in solid media, which is related to factors such as the internal temperature and physical properties of the solid medium. Within a certain temperature range, it can usually be expressed as a linear relationship with temperature:

[0073] (5)

[0074] For one-dimensional heat conduction problems, the governing equation can be expressed as:

[0075] (6)

[0076] Boundary conditions:

[0077] (7)

[0078] Initial conditions:

[0079] (8)

[0080] in, T is the node temperature, x is the node position, t For time, k , , ρ They are the thermal conductivity, specific heat and material density of the material obtained after equivalent homogenization, and the thickness of the structure L and the initial temperature is known, is the heating boundary and is to be measured.

[0081] In terms of the temperature field measurement inside the structure, the problem is transformed into an optimization problem of the inversion boundary. The optimization goal is to minimize the difference between the measured ultrasonic propagation time and the propagation time obtained by numerical calculation. The following objective function is constructed:

[0082] (9)

[0083] Represents the actual measured ultrasonic sound time data, represents the calculated ultrasonic sound time data, and m represents the total number of data points. Combining equations (1)-(9) and the relationship between ultrasonic velocity and temperature, the equivalent thermal boundary is inverted Finally, the one-dimensional temperature distribution inside the structure is obtained by solving the direct problem of heat conduction. The temperature field reconstruction flow chart is as follows: Figure 5 shown.

[0084] Different from the previous ultrasonic temperature measurement method which can only directly carry out temperature measurement on homogeneous materials such as pure metals and stainless steel, this method uses an equivalent homogenization method to scientifically "homogenize" the non-homogeneous metal-based composite materials, thereby realizing the measurement of the internal temperature of the composite structure by using the ultrasonic propagation time, and expanding the original ultrasonic temperature measurement principle method from the field of homogeneous materials to the field of composite materials.

[0085] The present invention provides the following specific implementation case to verify the technical effect: a refractory metal-based ceramic reinforced composite material TaWNbC is selected as the research object, the matrix is ​​TaW, the reinforcing material is NbC, and a two-dimensional model with a length of 10 mm and a width of 10 mm is established in the COMSOL multi-physics field simulation platform. The diameter of the NbC particles is 0.06 mm, which is evenly distributed in a 10×10 mm area, and the number is 100. The other areas are TaW materials.

[0086] The temperature variations of thermal conductivity, specific heat, density, elastic modulus, and Poisson's ratio of TaW and NbC are known. Ultrasonic shear waves are excited above a 10×10 mm area. Combining equation (3), the relationship between the ultrasonic shear wave velocity and temperature when the ultrasonic shear wave propagates in TaW and NbC can be fitted respectively. The fitting results are shown in the figure below. Figure 6 and Figure 7 As shown, according to the proportion of TaW and NbC in the whole material, combined with (1) (3) and Figure 6 , Figure 7 The fitting results can be used to fit the material parameters of the composite material TaWNbC after equivalent homogenization, as well as the relationship between the ultrasonic shear wave velocity and temperature after equivalent homogenization, such as Figure 8 shown.

[0087] First, the TaWNbC model material is numerically simulated with an initial temperature of 25 °C. The lower boundary is set as a steady-state thermal boundary for heating, and the two sides are adiabatic boundaries. After the temperature distribution inside the material reaches a steady state, ultrasonic shear waves are excited at the upper boundary of the model, such as Fig. 9 As shown, when the transition sound is obtained .

[0088] Secondly, the model numerical simulation of TaWNbC material after equivalent homogenization was carried out. The initial temperature was 25℃, the lower boundary was set as a steady-state thermal boundary for heating, and the two sides were adiabatic boundaries. After the temperature distribution inside the material reached a steady state, ultrasonic shear waves were excited at the upper boundary of the model to obtain the transit time. ,like Fig.10 As shown, according to the ultrasonic transit time ,as well as Figure 8 The relationship between the shear wave velocity and temperature in the sample is combined with the above-mentioned ultrasonic temperature measurement method to reconstruct the internal steady-state temperature field of the refractory metal-based ceramic reinforced composite material TaWNbC after equivalent homogenization treatment.

[0089] After being processed by an equivalent method, the internal temperature distribution of the material reconstructed by ultrasonic temperature measurement is compared with the true value. Fig.11 As shown, the overall reconstruction deviation compared with the true value is about 1.9°C, which shows that the method is effective and has good accuracy.

[0090] The units involved in the embodiments of the present invention may be implemented by software or hardware, and the units described may also be arranged in a processor. The names of these units do not, in some cases, limit the units themselves.

[0091] According to one aspect of an embodiment of the present invention, a computer program product or a computer program is provided, the computer program product or the computer program includes a computer instruction, and the computer instruction is stored in a computer-readable storage medium. A processor of a computer device reads the computer instruction from the computer-readable storage medium, and the processor executes the computer instruction, so that the computer device executes the method provided in the above various optional implementations.

[0092] As another aspect, an embodiment of the present invention further provides a computer-readable medium, which may be included in the electronic device described in the above embodiment; or may exist independently without being assembled into the electronic device. The above computer-readable medium carries one or more programs, and when the above one or more programs are executed by an electronic device, the electronic device implements the method described in the above embodiment.

Claims

1. A method for ultrasonically measuring the internal temperature field of a metal matrix composite material structure, characterized in that: The following steps are involved: Excite ultrasonic waves on the surface of the metal matrix composite structure and detect the characteristics of its echo signal; If the echo signal has the characteristics of the first echo and the second echo, the inhomogeneous material is firstly homogenized by using an equivalent homogenization processing method, and then the internal temperature field of the metal matrix composite material is measured by ultrasonic measurement of transit sound; if the echo signal does not have the characteristics of the first echo and the second echo, the process ends; The method of homogenizing the inhomogeneous material by using an equivalent homogenization method and then measuring the internal temperature field of the metal matrix composite material by using ultrasonic measurement of transit sound specifically includes the following sub-steps: Step S1, equivalence of physical parameters: The metal matrix composite material consists of two parts: the matrix and the reinforcement particles. The changes in the thermal physical parameters of the matrix material and the reinforcement phase material with temperature, the changes in the mechanical parameters with temperature, and the proportions of the matrix and the reinforcement phase material in the entire material are known respectively. The thermal physical parameters and mechanical parameters of the composite material as a whole are obtained by equivalent homogenization: （1） Among them, the parameters of the matrix material are , the volume occupied is , the parameters of the reinforcement phase material are , the volume occupied is , is the total volume, and the final equivalent parameters are ; According to the relationship between ultrasonic wave velocity and its material parameters: (2) (3) The longitudinal wave velocity is , the shear wave speed is , E is the elastic modulus, ρ is the material density obtained after equivalent homogenization, is the Poisson's ratio of the material; Combining the relationship between each material parameter and temperature, the ultrasonic propagation velocity and temperature of the three cases of the matrix material, the reinforcement phase material and the equivalent homogenization are fitted as follows: relation; Step S2, ultrasonic temperature measurement process: Construct a mathematical model of ultrasonic temperature measurement under one-dimensional heat transfer conditions: one end of the material structure is a heating boundary, and the other end is an adiabatic end. The ultrasonic probe excites ultrasonic waves at the adiabatic end and receives echo information. When the pulse echo method is used for measurement, the propagation time of ultrasonic waves in the solid under non-uniform temperature distribution, i.e., the transit time Through formula (4), we can get: (4) in, L As the material thickness, under one-dimensional heat transfer conditions, the temperature distribution state of each point inside the structure is only x The function of x is the distance between each point inside the structure and the heating end; V (T) represents the propagation speed of ultrasound in solid media, which is related to the internal temperature and physical parameters of the solid medium. Within a certain temperature range, it is expressed as a linear relationship with temperature: (5) Where a and b are constants obtained through calibration experiments or theoretical fitting, and T is the node temperature; For the one-dimensional heat conduction problem, the governing equation is expressed as: (6) in, k , , ρ are the thermal conductivity, specific heat and material density of the material obtained after equivalent homogenization, and t represents the time; Boundary conditions: (7) in, is the heating boundary, is to be measured; Initial conditions: (8) Among them, the material thickness L and initial temperature known; In terms of the temperature field measurement inside the structure, it is transformed into an optimization problem of inverting the thermal boundary. The optimization goal is to minimize the difference between the measured ultrasonic propagation time and the propagation time obtained by numerical calculation. The following objective function is constructed: (9) in, Represents the actual measured ultrasonic sound time data, represents the calculated ultrasonic sound time data, m Represents the total number of measurement points, J represents the objective function, represents the iterative convergence criterion; combining equations (1)-(9) and the relationship between ultrasonic velocity and temperature, the equivalent heating boundary is inverted Finally, the one-dimensional temperature distribution inside the structure is obtained by solving the direct problem of heat conduction.

2. The ultrasonic measurement method of the internal temperature field of the metal matrix composite material structure according to claim 1 is characterized in that: The thermophysical parameters include thermal conductivity, specific heat and density.

3. The ultrasonic measurement method of the internal temperature field of the metal matrix composite material structure according to claim 1, characterized in that: The mechanical parameters include elastic modulus and Poisson's ratio.

4. The ultrasonic measurement method of the internal temperature field of the metal matrix composite material structure according to claim 1, characterized in that: The transit time Specifically, it is the echo time difference between the first ultrasonic echo signal and the second ultrasonic echo signal.

5. The ultrasonic measurement method of the internal temperature field of the metal matrix composite material structure according to claim 1, characterized in that: The material thickness is specifically the one-way propagation distance of the ultrasonic wave along the thickness direction.

6. The ultrasonic measurement method of the internal temperature field of the metal matrix composite material structure according to claim 1, characterized in that: The metal-based composite material includes a TaWNbC composite material.

7. The ultrasonic measurement method of the internal temperature field of the metal matrix composite material structure according to claim 6, characterized in that: The TaWNbC composite material comprises TaW as the matrix and NbC as the reinforcing material.

8. The ultrasonic measurement method of the internal temperature field of a metal matrix composite material structure according to claim 7, characterized in that: The diameter of NbC particles is 0.06 mm.

9. The ultrasonic measurement method of the internal temperature field of a metal matrix composite material structure according to claim 7, characterized in that: The NbC particles are evenly distributed in the set area.

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