High-temperature strain sensor calibration device and calibration method

Abstract

The invention relates to the technical field of sensor calibration, in particular to a high-temperature strain sensor calibration device and calibration method. A high-temperature strain sensor calibration device comprises a bottom frame, a first equal-strength cantilever beam, a second equal-strength cantilever beam, a heat conduction sleeve, a heat preservation sleeve, an induction coil, a top frame and two micrometer calipers. The lower surface of the left end of the first equal-strength cantilever beam is fixed with the upper end surface of the left side of the underframe; the lower surface of the right end of the second equal-strength cantilever beam is fixed with the upper end surface of the right side of the underframe; the heat conduction sleeve sleeves the outer side of the first equal-strength cantilever beam; the heat preservation sleeve sleeves the outer side face of the heat conduction sleeve. The induction coil is wound on the outer side surface of the heat-insulating sleeve; the two micrometer calipers are fixed to the lower end faces of the two side edges of the top frame respectively. The calibration device solves the problem that the reliability and consistency of the calibration result are poor when an existing calibration device calibrates the surface acoustic wave strain sensor, and is suitable for calibration of the surface acoustic wave strain sensor.

Description

Technical Field

[0001] The invention relates to the technical field of sensor calibration, and in particular to a high-temperature strain sensor calibration device and a calibration method. Background Art

[0002] Surface acoustic wave (SAW) strain sensors are widely used in aerospace, industrial manufacturing, consumer electronics and other fields due to their small size, high quality factor and long-distance monitoring. In practical applications, in order to ensure the measurement accuracy of the surface acoustic wave strain sensor, a calibration device is required to calibrate the surface acoustic wave strain sensor. However, due to the use of a single cantilever beam structure, the existing calibration device cannot decouple the influence of stress on the surface acoustic wave strain sensor and the influence of temperature on the surface acoustic wave strain sensor, resulting in poor reliability and consistency of the calibration results. Based on this, it is necessary to invent a high-temperature strain sensor calibration device and calibration method to solve the problem of poor reliability and consistency of the calibration results of the existing calibration device when calibrating the surface acoustic wave strain sensor. Summary of the invention

[0003] In order to solve the problem that the reliability and consistency of calibration results of existing calibration devices when calibrating surface acoustic wave strain sensors are poor, the present invention provides a high temperature strain sensor calibration device and a calibration method.

[0004] The present invention is achieved by adopting the following technical solutions: A high temperature strain sensor calibration device comprises a base frame, a first-level strength cantilever beam, a second-level strength cantilever beam, a heat-conducting sleeve, a heat-insulating sleeve, an induction coil, a top frame, and two screw micrometers; The base frame is a mountain-shaped structure; the first-level strength cantilever beam and the second-level strength cantilever beam are symmetrically distributed on the left and right sides; the lower surface of the left end of the first-level strength cantilever beam is fixed to the upper end surface of the left side of the base frame; the lower surface of the right end of the second-level strength cantilever beam is fixed to the upper end surface of the right side of the base frame; The heat-conducting sleeve is sleeved on the outside of the first-level strength cantilever beam; the heat-insulating sleeve is sleeved on the outer side of the heat-conducting sleeve; an assembly notch is provided between the left end of the inner side of the heat-conducting sleeve and the left end of the outer side of the heat-insulating sleeve, and the upper end of the left side of the bottom frame is fixedly embedded in the assembly notch; the induction coil is wound on the outer side of the heat-insulating sleeve; The top frame is an inverted mountain-shaped structure, and the lower end surface of the middle vertical rod of the top frame is fixed to the upper end surface of the middle vertical rod of the bottom frame; the two micrometers are symmetrically distributed on the left and right sides, and the two micrometers are respectively fixed on the lower end surfaces of the two sides of the top frame; the measuring heads of the two micrometers are both facing downward, and the measuring heads of the two micrometers are respectively in contact with the upper surface of the right end of the first equal-strength cantilever beam and the upper surface of the left end of the second equal-strength cantilever beam.

[0005] The first-level strength cantilever beam and the second-level strength cantilever beam are both made of nickel-based alloy; the heat-conducting sleeve is made of graphite; and the heat-insulating sleeve is made of mullite.

[0006] The first equal strength cantilever beam comprises a first left beam section, a first middle beam section, and a first right beam section; the first left beam section is a rectangular sheet structure; the first middle beam section is an isosceles trapezoidal sheet structure with a wide left end and a narrow right end, and the left end width of the first middle beam section is equal to the width of the first left beam section; the first right beam section is a rectangular sheet structure, and the width of the first right beam section is equal to the right end width of the first middle beam section; the thickness of the first left beam section, the thickness of the first middle beam section, and the thickness of the first right beam section are all the same; The second equal-strength cantilever beam includes a second left beam section, a second middle beam section, and a second right beam section; the second left beam section is a rectangular sheet structure; the second middle beam section is an isosceles trapezoidal sheet structure with a narrow left end and a wide right end, and the left end width of the second middle beam section is equal to the width of the second left beam section; the second right beam section is a rectangular sheet structure, and the width of the second right beam section is equal to the right end width of the second middle beam section; the thickness of the second left beam section, the thickness of the second middle beam section, and the thickness of the second right beam section are all consistent.

[0007] A high temperature strain sensor calibration method is implemented based on a high temperature strain sensor calibration device according to the present invention. The method is implemented by the following steps: Step 1: Select a strain gauge, a first surface acoustic wave strain sensor, and a second surface acoustic wave strain sensor respectively; paste the strain gauge at the maximum stress point of the second equal-strength cantilever beam; paste the first surface acoustic wave strain sensor at the maximum stress point of the first equal-strength cantilever beam; paste the second surface acoustic wave strain sensor on the upper surface of the left end of the first equal-strength cantilever beam; Step 2: Select a dynamic strain tester, a first RF transceiver, a second RF transceiver, a network analyzer, a host computer, and a high-frequency power supply respectively; connect the strain gauge to the dynamic strain tester; connect the first surface acoustic wave strain sensor and the second surface acoustic wave strain sensor to the first RF transceiver; fix the first RF transceiver to the upper end surface of the left side of the chassis; wirelessly connect the first RF transceiver to the second RF transceiver; connect the second RF transceiver to the network analyzer; connect the dynamic strain tester and the network analyzer to the host computer; connect the high-frequency power supply to the induction coil; Step 3: Calibrate the relationship between the resonant frequency and stress, and the relationship between the resonant frequency and temperature respectively; the specific steps are as follows: Step a: placing the second equal strength cantilever beam under normal temperature; then, adjusting the right micrometer screw so that the measuring head of the micrometer screw moves downward for a certain distance, thereby applying stress to the second equal strength cantilever beam, causing the second equal strength cantilever beam to deflect; During the stress application process, the stress output by the strain gauge changes; the stress change output by the strain gauge is transmitted to the dynamic strain tester, which records it on the one hand and transmits it to the host computer on the other hand; Step b: start the high-frequency power supply, and the high-frequency current output by the high-frequency power supply is converted into a high-frequency electromagnetic field through the induction coil; under the action of the high-frequency electromagnetic field, the heat-conducting sleeve generates eddy current and generates heat, thereby heating the first surface acoustic wave strain sensor and the second surface acoustic wave strain sensor; then, the network analyzer sends an excitation signal, and the excitation signal is transmitted to the first surface acoustic wave strain sensor and the second surface acoustic wave strain sensor through the second radio frequency transceiver and the first radio frequency transceiver in sequence, so that the first surface acoustic wave strain sensor and the second surface acoustic wave strain sensor start to work; then, adjust the left-hand micrometer so that the measuring head of the micrometer moves downward by a distance equal to the distance moved by the measuring head of the right-hand micrometer in step a, thereby applying stress to the first equal-strength cantilever beam, so that the first equal-strength cantilever beam generates a deflection, and the deflection is equal to the deflection generated by the second equal-strength cantilever beam in step a; During the heating and stress application process, the resonant frequencies output by the first surface acoustic wave strain sensor and the second surface acoustic wave strain sensor both change. The change in the resonant frequency output by the first surface acoustic wave strain sensor is caused by both the temperature change and the stress change, while the change in the resonant frequency output by the second surface acoustic wave strain sensor is only caused by the temperature change. The changes in the resonant frequencies output by the first surface acoustic wave strain sensor and the second surface acoustic wave strain sensor are sequentially transmitted to the network analyzer via the first RF transceiver and the second RF transceiver. The network analyzer records the changes and transmits them to the host computer. Step c: the host computer makes a difference between the resonant frequency change output by the first surface acoustic wave strain sensor and the second surface acoustic wave strain sensor, thereby obtaining the resonant frequency change caused only by the stress change; then, the host computer calibrates the relationship between the resonant frequency and the stress according to the resonant frequency change caused only by the stress change; Step d: The host computer calibrates the relationship between the resonant frequency and the temperature according to the resonant frequency variation output by the second surface acoustic wave strain sensor, that is, the resonant frequency variation caused only by the temperature variation.

[0008] Compared with the existing calibration device, the present invention no longer adopts a single cantilever beam structure, but a double cantilever beam structure, and combines it with a new calibration method to achieve the decoupling of the influence of stress on the surface acoustic wave strain sensor and the influence of temperature on the surface acoustic wave strain sensor, thereby effectively ensuring the reliability and consistency of the calibration results.

[0009] The present invention effectively solves the problem of poor reliability and consistency of calibration results when the existing calibration device calibrates the surface acoustic wave strain sensor, and is suitable for the calibration of the surface acoustic wave strain sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a structural schematic diagram of the present invention.

[0011] Figure 2 yes Figure 1 Schematic diagram of part of the structure.

[0012] Figure 3 It is a structural schematic diagram of a cantilever beam of first-class strength in the present invention.

[0013] Figure 4 yes Figure 3 Top view of the .

[0014] Figure 5 It is a structural schematic diagram of the second equal strength cantilever beam in the present invention.

[0015] Figure 6 yes Figure 5 Top view of the .

[0016] Figure 7 It is a structural schematic diagram of the heat-insulating sleeve in the present invention.

[0017] Figure 8 yes Figure 7 AA section view.

[0018] Fig. 9 yes Figure 7 BB cross-sectional view.

[0019] Fig.10 It is a schematic diagram of step one and step two in the present invention.

[0020] Fig.11 yes Fig.10 Partial schematic diagram.

[0021] In the figure: 1-base frame, 2.1-first equal-strength cantilever beam, 2.2-second equal-strength cantilever beam, 3-heat-conducting sleeve, 4-insulating sleeve, 5-induction coil, 6-top frame, 7-screw micrometer, 8-strain gauge, 9.1-first surface acoustic wave strain sensor, 9.2-second surface acoustic wave strain sensor, 10-dynamic strain tester, 11.1-first RF transceiver, 11.2-second RF transceiver, 12-network analyzer, 13-host computer, 14-high-frequency power supply; dotted lines represent wireless connections. DETAILED DESCRIPTION

[0022] A high temperature strain sensor calibration device comprises a base frame 1, a first-level strength cantilever beam 2.1, a second-level strength cantilever beam 2.2, a heat-conducting sleeve 3, a heat-insulating sleeve 4, an induction coil 5, a top frame 6, and two screw micrometers 7; The chassis 1 is a mountain-shaped structure; the first-level strength cantilever beam 2.1 and the second-level strength cantilever beam 2.2 are symmetrically distributed on the left and right sides; the lower surface of the left end of the first-level strength cantilever beam 2.1 is fixed to the upper end surface of the left side of the chassis 1; the lower surface of the right end of the second-level strength cantilever beam 2.2 is fixed to the upper end surface of the right side of the chassis 1; The heat-conducting sleeve 3 is sleeved on the outside of the first-level strength cantilever beam 2.1; the heat-insulating sleeve 4 is sleeved on the outer side of the heat-conducting sleeve 3; an assembly notch is provided between the left end of the inner side of the heat-conducting sleeve 3 and the left end of the outer side of the heat-insulating sleeve 4, and the upper end of the left side of the bottom frame 1 is fixedly embedded in the assembly notch; the induction coil 5 is wound around the outer side of the heat-insulating sleeve 4; The top frame 6 is an inverted mountain-shaped structure, and the lower end surface of the middle vertical rod of the top frame 6 is fixed to the upper end surface of the middle vertical rod of the bottom frame 1; the two micrometers 7 are symmetrically distributed on the left and right sides, and the two micrometers 7 are respectively fixed to the lower end surfaces of the two sides of the top frame 6; the measuring heads of the two micrometers 7 are both facing downward, and the measuring heads of the two micrometers 7 are respectively in contact with the upper surface of the right end of the first equal-strength cantilever beam 2.1 and the upper surface of the left end of the second equal-strength cantilever beam 2.2.

[0023] The first-level strength cantilever beam 2.1 and the second-level strength cantilever beam 2.2 are both made of nickel-based alloy; the heat-conducting sleeve 3 is made of graphite; and the heat-insulating sleeve 4 is made of mullite.

[0024] The first equal strength cantilever beam 2.1 comprises a first left beam section, a first middle beam section, and a first right beam section; the first left beam section is a rectangular sheet structure; the first middle beam section is an isosceles trapezoidal sheet structure with a wide left end and a narrow right end, and the left end width of the first middle beam section is equal to the width of the first left beam section; the first right beam section is a rectangular sheet structure, and the width of the first right beam section is equal to the right end width of the first middle beam section; the thickness of the first left beam section, the thickness of the first middle beam section, and the thickness of the first right beam section are all the same; The second equal-strength cantilever beam 2.2 includes a second left beam section, a second middle beam section, and a second right beam section; the second left beam section is a rectangular sheet structure; the second middle beam section is an isosceles trapezoidal sheet structure with a narrow left end and a wide right end, and the left end width of the second middle beam section is equal to the width of the second left beam section; the second right beam section is a rectangular sheet structure, and the width of the second right beam section is equal to the right end width of the second middle beam section; the thickness of the second left beam section, the thickness of the second middle beam section, and the thickness of the second right beam section are all consistent.

[0025] A high temperature strain sensor calibration method is implemented based on a high temperature strain sensor calibration device according to the present invention. The method is implemented by the following steps: Step 1: Select the strain gauge 8, the first surface acoustic wave strain sensor 9.1, and the second surface acoustic wave strain sensor 9.2 respectively; paste the strain gauge 8 to the maximum stress point of the second equal strength cantilever beam 2.2; paste the first surface acoustic wave strain sensor 9.1 to the maximum stress point of the first equal strength cantilever beam 2.1; paste the second surface acoustic wave strain sensor 9.2 to the upper surface of the left end of the first equal strength cantilever beam 2.1; Step 2: Select the dynamic strain tester 10, the first RF transceiver 11.1, the second RF transceiver 11.2, the network analyzer 12, the host computer 13, and the high-frequency power supply 14 respectively; connect the strain gauge 8 to the dynamic strain tester 10; connect the first surface acoustic wave strain sensor 9.1 and the second surface acoustic wave strain sensor 9.2 to the first RF transceiver 11.1; fix the first RF transceiver 11.1 to the upper end surface of the left side of the chassis 1; wirelessly connect the first RF transceiver 11.1 to the second RF transceiver 11.2; connect the second RF transceiver 11.2 to the network analyzer 12; connect the dynamic strain tester 10 and the network analyzer 12 to the host computer 13; connect the high-frequency power supply 14 to the induction coil 5; Step 3: Calibrate the relationship between the resonant frequency and stress, and the relationship between the resonant frequency and temperature respectively; the specific steps are as follows: Step a: placing the second equal strength cantilever beam 2.2 under normal temperature; then, adjusting the right micrometer screw 7 so that the measuring head of the micrometer screw 7 moves downward for a certain distance, thereby applying stress to the second equal strength cantilever beam 2.2, so that the second equal strength cantilever beam 2.2 generates deflection; During the stress application process, the stress output by the strain gauge 8 changes; the stress change output by the strain gauge 8 is transmitted to the dynamic strain tester 10, which records it on the one hand and transmits it to the host computer 13 on the other hand; Step b: start the high-frequency power supply 14, and the high-frequency current output by the high-frequency power supply 14 is converted into a high-frequency electromagnetic field through the induction coil 5; under the action of the high-frequency electromagnetic field, the heat-conducting sleeve 3 generates eddy current and generates heat, thereby heating the first surface acoustic wave strain sensor 9.1 and the second surface acoustic wave strain sensor 9.2; then, the network analyzer 12 sends out an excitation signal, and the excitation signal is transmitted to the first surface acoustic wave strain sensor 9.1 and the second surface acoustic wave strain sensor 9.2 through the second RF transceiver 11.2 and the first RF transceiver 11.1 in sequence, so that the first surface acoustic wave strain sensor 9.1 and the second surface acoustic wave strain sensor 9.2 start to work; then, adjust the left-hand micrometer 7 so that the measuring head of the micrometer 7 moves downward by a distance equal to the distance moved by the measuring head of the right-hand micrometer 7 in step a, thereby applying stress to the first equal-strength cantilever beam 2.1, so that the first equal-strength cantilever beam 2.1 generates a deflection, which is equal to the deflection generated by the second equal-strength cantilever beam 2.2 in step a; During the heating and stress application process, the resonant frequencies output by the first surface acoustic wave strain sensor 9.1 and the second surface acoustic wave strain sensor 9.2 both change. The change in the resonant frequency output by the first surface acoustic wave strain sensor 9.1 is caused by both the temperature change and the stress change, while the change in the resonant frequency output by the second surface acoustic wave strain sensor 9.2 is only caused by the temperature change. The changes in the resonant frequencies output by the first surface acoustic wave strain sensor 9.1 and the second surface acoustic wave strain sensor 9.2 are transmitted to the network analyzer 12 via the first RF transceiver 11.1 and the second RF transceiver 11.2 in sequence. The network analyzer 12 records the changes and transmits them to the host computer 13. Step c: the host computer 13 makes a difference between the resonant frequency variation output by the first surface acoustic wave strain sensor 9.1 and the second surface acoustic wave strain sensor 9.2, thereby obtaining the resonant frequency variation caused only by the stress variation; then, the host computer 13 calibrates the relationship between the resonant frequency and the stress according to the resonant frequency variation caused only by the stress variation; Step d: The host computer 13 calibrates the relationship between the resonant frequency and the temperature according to the resonant frequency variation output by the second surface acoustic wave strain sensor 9.2, that is, the resonant frequency variation caused only by the temperature variation.

[0026] During specific implementation, the width of the first left beam section is 60mm and the length is 60mm; the length of the first middle beam section is 225mm; the width of the first right beam section is 10mm and the length is 15mm; the width of the second left beam section is 10mm and the length is 15mm; the length of the second middle beam section is 225mm; the width of the second right beam section is 60mm and the length is 60mm.

[0027] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that these are only examples, and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A high temperature strain sensor calibration device, characterized in that: It comprises a base frame (1), a cantilever beam of the first-class strength (2.1), a cantilever beam of the second-class strength (2.2), a heat-conducting sleeve (3), a heat-insulating sleeve (4), an induction coil (5), a top frame (6), and two screw micrometers (7); The base frame (1) is a mountain-shaped structure; the first-level strength cantilever beam (2.1) and the second-level strength cantilever beam (2.2) are symmetrically distributed on the left and right sides; the lower surface of the left end of the first-level strength cantilever beam (2.1) is fixed to the upper end surface of the left side of the base frame (1); the lower surface of the right end of the second-level strength cantilever beam (2.2) is fixed to the upper end surface of the right side of the base frame (1); The heat-conducting sleeve (3) is sleeved on the outside of the first-level strength cantilever beam (2.1); the heat-insulating sleeve (4) is sleeved on the outer side of the heat-conducting sleeve (3); an assembly notch is provided between the left end of the inner side of the heat-conducting sleeve (3) and the left end of the outer side of the heat-insulating sleeve (4), and the upper end of the left side of the bottom frame (1) is fixedly embedded in the assembly notch; the induction coil (5) is wound around the outer side of the heat-insulating sleeve (4); The top frame (6) is an inverted mountain-shaped structure, and the lower end surface of the middle vertical rod of the top frame (6) is fixed to the upper end surface of the middle vertical rod of the bottom frame (1); the two micrometer screws (7) are symmetrically distributed, and the two micrometer screws (7) are respectively fixed to the lower end surfaces of the two side edges of the top frame (6); the measuring heads of the two micrometer screws (7) are both downward, and the measuring heads of the two micrometer screws (7) are respectively in contact with the upper surface of the right end of the first equal strength cantilever beam (2.1) and the upper surface of the left end of the second equal strength cantilever beam (2.2).

2. A high temperature strain sensor calibration device according to claim 1, characterized in that: The first-level strength cantilever beam (2.1) and the second-level strength cantilever beam (2.2) are both made of nickel-based alloy; the heat-conducting sleeve (3) is made of graphite; and the heat-insulating sleeve (4) is made of mullite.

3. A high temperature strain sensor calibration device according to claim 1, characterized in that: The first equal strength cantilever beam (2.1) comprises a first left beam section, a first middle beam section, and a first right beam section; the first left beam section is a rectangular sheet structure; the first middle beam section is an isosceles trapezoidal sheet structure with a wide left end and a narrow right end, and the left end width of the first middle beam section is equal to the width of the first left beam section; the first right beam section is a rectangular sheet structure, and the width of the first right beam section is equal to the right end width of the first middle beam section; the thickness of the first left beam section, the thickness of the first middle beam section, and the thickness of the first right beam section are all the same; The second equal-strength cantilever beam (2.2) comprises a second left beam section, a second middle beam section, and a second right beam section; the second left beam section is a rectangular sheet-like structure; the second middle beam section is an isosceles trapezoidal sheet-like structure with a narrow left end and a wide right end, and the width of the left end of the second middle beam section is equal to the width of the second left beam section; the second right beam section is a rectangular sheet-like structure, and the width of the second right beam section is equal to the width of the right end of the second middle beam section; the thickness of the second left beam section, the thickness of the second middle beam section, and the thickness of the second right beam section are all consistent.

4. A high temperature strain sensor calibration method, the method is implemented based on the high temperature strain sensor calibration device according to claim 1, characterized in that: This method is implemented by the following steps: Step 1: Select a strain gauge (8), a first surface acoustic wave strain sensor (9.1), and a second surface acoustic wave strain sensor (9.2) respectively; paste the strain gauge (8) to the maximum stress point of the second equal strength cantilever beam (2.2); paste the first surface acoustic wave strain sensor (9.1) to the maximum stress point of the first equal strength cantilever beam (2.1); paste the second surface acoustic wave strain sensor (9.2) to the upper surface of the left end of the first equal strength cantilever beam (2.1); Step 2: Select a dynamic strain tester (10), a first radio frequency transceiver (11.1), a second radio frequency transceiver (11.2), a network analyzer (12), a host computer (13), and a high-frequency power supply (14) respectively; connect the strain gauge (8) to the dynamic strain tester (10); connect the first surface acoustic wave strain sensor (9.1) and the second surface acoustic wave strain sensor (9.2) to the first radio frequency transceiver (11.1); fix the first radio frequency transceiver (11.1) to the upper end surface of the left side of the base frame (1); wirelessly connect the first radio frequency transceiver (11.1) to the second radio frequency transceiver (11.2); connect the second radio frequency transceiver (11.2) to the network analyzer (12); connect the dynamic strain tester (10) and the network analyzer (12) to the host computer (13); and connect the high-frequency power supply (14) to the induction coil (5); Step 3: Calibrate the relationship between the resonant frequency and stress, and the relationship between the resonant frequency and temperature respectively; the specific steps are as follows: Step a: placing the second equal-strength cantilever beam (2.2) in a room temperature environment; then, adjusting the right-hand micrometer (7) so that the measuring head of the micrometer (7) moves downward by a certain distance, thereby applying stress to the second equal-strength cantilever beam (2.2), causing the second equal-strength cantilever beam (2.2) to generate deflection; During the stress application process, the stress output by the strain gauge (8) changes; the stress change output by the strain gauge (8) is transmitted to the dynamic strain tester (10), and the dynamic strain tester (10) records the stress change and transmits the stress change to the host computer (13); Step b: starting the high-frequency power supply (14), and converting the high-frequency current output by the high-frequency power supply (14) into a high-frequency electromagnetic field through the induction coil (5); under the action of the high-frequency electromagnetic field, the heat-conducting sleeve (3) generates eddy current and generates heat, thereby heating the first surface acoustic wave strain sensor (9.1) and the second surface acoustic wave strain sensor (9.2); then, the network analyzer (12) sends an excitation signal, and the excitation signal is transmitted to the first surface acoustic wave strain sensor (9.1) and the second surface acoustic wave strain sensor (9.2) in sequence through the second radio frequency transceiver (11.2) and the first radio frequency transceiver (11.1). The sensor (9.2) causes the first surface acoustic wave strain sensor (9.1) and the second surface acoustic wave strain sensor (9.2) to start working; then, the left-positioned micrometer (7) is adjusted so that the measuring head of the micrometer (7) moves downward by a distance equal to the distance moved by the measuring head of the right-positioned micrometer (7) in step a, thereby applying stress to the first equal-strength cantilever beam (2.1), causing the first equal-strength cantilever beam (2.1) to generate a deflection equal to the deflection generated by the second equal-strength cantilever beam (2.2) in step a; During the heating and stress application process, the resonant frequencies output by the first surface acoustic wave strain sensor (9.1) and the second surface acoustic wave strain sensor (9.2) both change, the resonant frequency change output by the first surface acoustic wave strain sensor (9.1) is caused by both temperature change and stress change, and the resonant frequency change output by the second surface acoustic wave strain sensor (9.2) is caused only by temperature change; the resonant frequency changes output by the first surface acoustic wave strain sensor (9.1) and the second surface acoustic wave strain sensor (9.2) are transmitted to the network analyzer (12) via the first radio frequency transceiver (11.1) and the second radio frequency transceiver (11.2) in sequence, and the network analyzer (12) records the changes and transmits the changes to the host computer (13); Step c: the host computer (13) subtracts the resonant frequency variation output by the first surface acoustic wave strain sensor (9.1) and the second surface acoustic wave strain sensor (9.2), thereby obtaining the resonant frequency variation caused only by the stress variation; then, the host computer (13) calibrates the relationship between the resonant frequency and the stress according to the resonant frequency variation caused only by the stress variation; Step d: The host computer (13) calibrates the relationship between the resonant frequency and the temperature according to the resonant frequency change output by the second surface acoustic wave strain sensor (9.2), that is, the resonant frequency change caused only by the temperature change.

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