A high-temperature strain sensor calibration device and calibration method

Abstract

The application relates to the technical field of sensor calibration, in particular to a high-temperature strain sensor calibration device and a calibration method. The high-temperature strain sensor calibration device comprises a chassis, a first equal-strength cantilever beam, a second equal-strength cantilever beam, a heat-conducting sleeve, a heat-preservation sleeve, an induction coil, a top frame and two screw micrometers; the left end lower surface of the first equal-strength cantilever beam is fixed to the left side edge upper end surface of the chassis; the right end lower surface of the second equal-strength cantilever beam is fixed to the right side edge upper end surface of the chassis; the heat-conducting sleeve is sleeved outside the first equal-strength cantilever beam; the heat-preservation sleeve is sleeved outside the heat-conducting sleeve; the induction coil is wound outside the heat-preservation sleeve; and the two screw micrometers are respectively fixed to the lower end surfaces of the two side edges of the top frame. The application solves the problem that the reliability and consistency of the calibration result of the existing calibration device are poor when the surface acoustic wave strain sensor is calibrated, and is suitable for the calibration of the surface acoustic wave strain sensor.

Description

TECHNICAL FIELD

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

[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 advantages. In practical applications, in order to ensure the measurement accuracy of the surface acoustic wave strain sensor, a calibration device is needed to calibrate the surface acoustic wave strain sensor. However, the existing calibration device adopts a single cantilever beam structure, which 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, thereby 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 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

[0003] The present application provides a high-temperature strain sensor calibration device and 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.

[0004] The present application is implemented by using the following technical solutions:

[0005] A high-temperature strain sensor calibration device, comprising a chassis, a first equal-strength cantilever beam, a second equal-strength cantilever beam, a heat-conducting sleeve, a heat-insulating sleeve, an induction coil, a top frame, and two screw micrometers.

[0006] The chassis has a mountain-shaped structure. The first equal-strength cantilever beam and the second equal-strength cantilever beam are symmetrically distributed left and right. The left end of the first equal-strength cantilever beam is fixed to the left side of the chassis. The right end of the second equal-strength cantilever beam is fixed to the right side of the chassis.

[0007] The heat-conducting sleeve is sleeved on the outside of the first equal-strength cantilever beam. The heat-insulating sleeve is sleeved on the outside of the heat-conducting sleeve. A fitting gap is formed between the left end of the inside of the heat-conducting sleeve and the left end of the outside of the heat-insulating sleeve. The left side of the chassis is embedded in the fitting gap. The induction coil is wound around the outside of the heat-insulating sleeve.

[0008] 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 with the upper end surface of the middle vertical rod of the bottom frame; the two screw micrometers are symmetrically distributed left and right, and the two screw micrometers are respectively fixed on the lower end surfaces of the two side edges of the top frame; the measuring heads of the two screw micrometers are both downward, and the measuring heads of the two screw 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.

[0009] The first equal-strength cantilever beam and the second equal-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.

[0010] The first equal-strength cantilever beam comprises a first left beam segment, a first middle beam segment and a first right beam segment; the first left beam segment is in a rectangular sheet structure; the first middle beam segment is in a left-wide-right-narrow isosceles trapezoidal sheet structure, and the left end width of the first middle beam segment is equal to the width of the first left beam segment; the first right beam segment is in a rectangular sheet structure, and the width of the first right beam segment is equal to the right end width of the first middle beam segment; the thickness of the first left beam segment, the thickness of the first middle beam segment and the thickness of the first right beam segment are consistent; the second equal-strength cantilever beam comprises a second left beam segment, a second middle beam segment and a second right beam segment; the second left beam segment is in a rectangular sheet structure; the second middle beam segment is in a left-narrow-right-wide isosceles trapezoidal sheet structure, and the left end width of the second middle beam segment is equal to the width of the second left beam segment; the second right beam segment is in a rectangular sheet structure, and the width of the second right beam segment is equal to the right end width of the second middle beam segment; the thickness of the second left beam segment, the thickness of the second middle beam segment and the thickness of the second right beam segment are consistent.

[0011] A high-temperature strain sensor calibration method is realized based on the high-temperature strain sensor calibration device, and the method is realized by the following steps:

[0012] Step one: respectively selecting a strain gauge, a first surface acoustic wave strain sensor and a second surface acoustic wave strain sensor; the strain gauge is pasted at the maximum stress position of the second equal-strength cantilever beam; the first surface acoustic wave strain sensor is pasted at the maximum stress position of the first equal-strength cantilever beam; and the second surface acoustic wave strain sensor is pasted on the upper surface of the left end of the first equal-strength cantilever beam;

[0013] Step two: select a dynamic strain tester, a first radio frequency transceiver, a second radio frequency transceiver, a network analyzer, a host computer, a high-frequency power supply respectively; connect the strain gauge with the dynamic strain tester; connect the first and second surface acoustic wave strain sensors with the first radio frequency transceiver; fix the first radio frequency transceiver on the left end face of the chassis; wirelessly connect the first and second radio frequency transceivers; connect the second radio frequency transceiver with the network analyzer; connect the dynamic strain tester and the network analyzer with the host computer; connect the high-frequency power supply with the induction coil;

[0014] Step three: calibrate the relationship between the resonance frequency and the stress, and the relationship between the resonance frequency and the temperature; the specific steps are as follows:

[0015] Step a: place the second equal strength cantilever beam in a normal temperature environment; then, adjust the position of the right screw micrometer so that the measuring head of the screw micrometer moves downward by a distance, thereby applying stress to the second equal strength cantilever beam to make it produce deflection;

[0016] During the stress application process, the stress output by the strain gauge changes; the stress change amount output by the strain gauge is transmitted to the dynamic strain tester, which records it on one hand and transmits it to the host computer on the other hand;

[0017] 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 by the induction coil; under the action of the high-frequency electromagnetic field, the heat sleeve generates eddy current and heats up, thereby heating the first and second surface acoustic wave strain sensors; then, the network analyzer sends an excitation signal, which is transmitted to the first and second surface acoustic wave strain sensors in turn through the second and first radio frequency transceivers, so that the first and second surface acoustic wave strain sensors start working; then, adjust the position of the left screw micrometer so that the measuring head of the screw micrometer moves downward by a distance, which is equal to the distance moved by the measuring head of the right screw micrometer in step a, thereby applying stress to the first equal strength cantilever beam to make it produce deflection, which is equal to the deflection of the second equal strength cantilever beam in step a;

[0018] During the heating and stress applying processes, the resonance frequencies outputted by the first and second SAW strain sensors are changed, the resonance frequency change amount outputted by the first SAW strain sensor is caused by the temperature change and the stress change together, and the resonance frequency change amount outputted by the second SAW strain sensor is caused by the temperature change only; the resonance frequency change amounts outputted by the first and second SAW strain sensors are transmitted to the network analyzer through the first and second RF transceivers in sequence, the network analyzer records the resonance frequency change amounts on one hand and transmits the resonance frequency change amounts to the upper computer on the other hand;

[0019] Step c: the upper computer makes a difference between the resonance frequency change amounts outputted by the first and second SAW strain sensors, thereby obtaining the resonance frequency change amount caused by the stress change only; then, the upper computer calibrates the relationship between the resonance frequency and the stress according to the resonance frequency change amount caused by the stress change only;

[0020] Step d: the upper computer calibrates the relationship between the resonance frequency and the temperature according to the resonance frequency change amount outputted by the second SAW strain sensor, i.e. the resonance frequency change amount caused by the temperature change only.

[0021] Compared with the prior calibration device, the present application adopts the double-cantilever beam structure instead of the single-cantilever beam structure, and combines with the new calibration method, thereby realizing the decoupling of the influence of the stress on the SAW strain sensor and the influence of the temperature on the SAW strain sensor, and effectively ensuring the reliability and consistency of the calibration results.

[0022] The present application effectively solves the problem of poor reliability and consistency of the calibration results of the prior calibration device when calibrating the SAW strain sensor, and is suitable for the calibration of the SAW strain sensor. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a structural schematic diagram of the present application.

[0024] Figure 2 is a partial structural schematic diagram of Figure 1 .

[0025] Figure 3 is a structural schematic diagram of the first equal-strength cantilever beam in the present application.

[0026] Figure 4 is a top view of Figure 3 .

[0027] Figure 5 is a structural schematic diagram of the second equal-strength cantilever beam in the present application.

[0028] Figure 6 isFigure 5 Top view.

[0029] Figure 7 This is a schematic diagram of the structure of the thermal insulation sleeve in this invention.

[0030] Figure 8 yes Figure 7 AA sectional view.

[0031] Figure 9 yes Figure 7 BB cross-sectional view.

[0032] Figure 10 This is a schematic diagram of steps one and two in this invention.

[0033] Figure 11 yes Figure 10 A partial schematic diagram.

[0034] In the diagram: 1-Base frame, 2.1-First equal-strength cantilever beam, 2.2-Second equal-strength cantilever beam, 3-Heat-conducting sleeve, 4-Insulation sleeve, 5-Induction coil, 6-Top frame, 7-Micrometer screw gauge, 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; Dashed lines indicate wireless connection. Detailed Implementation

[0035] A high-temperature strain sensor calibration device includes a base frame 1, a first equal-strength cantilever beam 2.1, a second equal-strength cantilever beam 2.2, a heat-conducting sleeve 3, an insulation sleeve 4, an induction coil 5, a top frame 6, and two micrometer screw gauges 7.

[0036] Among them, the base frame 1 has a mountain-shaped structure; the first equal strength cantilever beam 2.1 and the second equal strength cantilever beam 2.2 are symmetrically distributed from left to right; the lower surface of the left end of the first equal strength cantilever beam 2.1 is fixed to the upper surface of the left side of the base frame 1; the lower surface of the right end of the second equal strength cantilever beam 2.2 is fixed to the upper surface of the right side of the base frame 1.

[0037] The heat-conducting sleeve 3 is fitted on the outside of the first equal-strength cantilever beam 2.1; the heat-insulating sleeve 4 is fitted 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 base 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.

[0038] The top frame 6 is inverted mountain-shaped structure, and the middle vertical rod lower end surface of the top frame 6 is fixed with the middle vertical rod upper end surface of the bottom frame 1; two screw micrometers 7 are symmetrically distributed left and right, and the two screw micrometers 7 are respectively fixed on the two side lower end surfaces of the top frame 6; the measuring heads of the two screw micrometers 7 are all downward, and the measuring heads of the two screw micrometers 7 are respectively in contact with the right end upper surface of the first equal strength cantilever beam 2.1 and the left end upper surface of the second equal strength cantilever beam 2.2.

[0039] The first equal strength cantilever beam 2.1 and the second equal strength cantilever beam 2.2 are both made of nickel-based alloy; the heat conduction sleeve 3 is made of graphite; and the heat preservation sleeve 4 is made of mullite.

[0040] The first equal strength cantilever beam 2.1 comprises a first left beam segment, a first middle beam segment and a first right beam segment; the first left beam segment is in rectangular sheet structure; the first middle beam segment is in left-narrow-right-wide isosceles trapezoidal sheet structure, and the left end width of the first middle beam segment is equal to the width of the first left beam segment; the first right beam segment is in rectangular sheet structure, and the width of the first right beam segment is equal to the right end width of the first middle beam segment; the thickness of the first left beam segment, the thickness of the first middle beam segment and the thickness of the first right beam segment are consistent; the second equal strength cantilever beam 2.2 comprises a second left beam segment, a second middle beam segment and a second right beam segment; the second left beam segment is in rectangular sheet structure; the second middle beam segment is in left-wide-right-narrow isosceles trapezoidal sheet structure, and the left end width of the second middle beam segment is equal to the width of the second left beam segment; the second right beam segment is in rectangular sheet structure, and the width of the second right beam segment is equal to the right end width of the second middle beam segment; the thickness of the second left beam segment, the thickness of the second middle beam segment and the thickness of the second right beam segment are consistent.

[0041] A high-temperature strain sensor calibration method is realized based on the high-temperature strain sensor calibration device, and the method is realized by the following steps:

[0042] Step one: respectively select the strain gauge 8, the first surface acoustic wave strain sensor 9.1 and the second surface acoustic wave strain sensor 9.2; paste the strain gauge 8 at the maximum stress position of the second equal strength cantilever beam 2.2; paste the first surface acoustic wave strain sensor 9.1 at the maximum stress position of the first equal strength cantilever beam 2.1; and paste the second surface acoustic wave strain sensor 9.2 on the left end upper surface of the first equal strength cantilever beam 2.1;

[0043] Step two: select the dynamic strain tester 10, the first radio frequency transceiver 11.1, the second radio frequency transceiver 11.2, the network analyzer 12, the upper computer 13, the high-frequency power supply 14 respectively; connect the strain gauge 8 with 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 with the first radio frequency transceiver 11.1; fix the first radio frequency transceiver 11.1 on the left side of the end surface of the chassis 1; wirelessly connect the first radio frequency transceiver 11.1 with the second radio frequency transceiver 11.2; connect the second radio frequency transceiver 11.2 with the network analyzer 12; connect the dynamic strain tester 10 and the network analyzer 12 with the upper computer 13; connect the high-frequency power supply 14 with the induction coil 5;

[0044] Step three: calibrate the relationship between the resonance frequency and the stress, and the relationship between the resonance frequency and the temperature; the specific steps are as follows:

[0045] Step a: place the second equal strength cantilever beam 2.2 in a normal temperature environment; then, adjust the position of the right screw micrometer 7 to move the measuring head of the screw micrometer 7 downward by a distance, thereby exerting stress on the second equal strength cantilever beam 2.2 to make the second equal strength cantilever beam 2.2 produce deflection;

[0046] In the process of applying stress, 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 one hand and transmits it to the upper computer 13 on the other hand;

[0047] 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 by the induction coil 5; under the action of the high-frequency electromagnetic field, the heat conduction sleeve 3 generates eddy current and heats up, 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, which is transmitted to the first surface acoustic wave strain sensor 9.1 and the second surface acoustic wave strain sensor 9.2 in turn through the second radio frequency transceiver 11.2 and the first radio frequency transceiver 11.1, so that the first surface acoustic wave strain sensor 9.1 and the second surface acoustic wave strain sensor 9.2 start working; then, adjust the position of the left screw micrometer 7 to move the measuring head of the screw micrometer 7 downward by a distance, which is equal to the distance moved by the measuring head of the right screw micrometer 7 in step a, thereby exerting stress on the first equal strength cantilever beam 2.1 to make the first equal strength cantilever beam 2.1 produce deflection, and the deflection is equal to the deflection produced by the second equal strength cantilever beam 2.2 in step a;

[0048] During the heating and stress applying process, the resonance frequencies outputted by the first SAW strain sensor 9.1 and the second SAW strain sensor 9.2 are changed, the resonance frequency change amount outputted by the first SAW strain sensor 9.1 is caused by both temperature change and stress change, and the resonance frequency change amount outputted by the second SAW strain sensor 9.2 is caused by temperature change only; the resonance frequency change amounts outputted by the first SAW strain sensor 9.1 and the second SAW strain sensor 9.2 are transmitted to the network analyzer 12 through the first RF transceiver 11.1 and the second RF transceiver 11.2 in sequence, the network analyzer 12 records the resonance frequency change amounts on one hand and transmits the resonance frequency change amounts to the host computer 13 on the other hand;

[0049] Step c: the host computer 13 subtracts the resonance frequency change amounts outputted by the first SAW strain sensor 9.1 and the second SAW strain sensor 9.2, thereby obtaining the resonance frequency change amount caused by stress change only; then, the host computer 13 calibrates the relationship between the resonance frequency and stress according to the resonance frequency change amount caused by stress change only;

[0050] Step d: the host computer 13 calibrates the relationship between the resonance frequency and temperature according to the resonance frequency change amount outputted by the second SAW strain sensor 9.2, i.e. the resonance frequency change amount caused by temperature change only.

[0051] In a specific implementation, the width of the first left beam segment is 60 mm, and the length thereof is 60 mm; the length of the first middle beam segment is 225 mm; the width of the first right beam segment is 10 mm, and the length thereof is 15 mm; the width of the second left beam segment is 10 mm, and the length thereof is 15 mm; the length of the second middle beam segment is 225 mm; and the width of the second right beam segment is 60 mm, and the length thereof is 60 mm.

[0052] Although the specific embodiments of the present application are described above, those skilled in the art should understand that these are only illustrative, and the protection scope of the present application is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present application, and these changes and modifications all fall within the protection scope of the present application.

Claims

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

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

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

4. A high-temperature strain sensor calibration method, which is realized based on the high-temperature strain sensor calibration device according to claim 1, characterized in that: The method is realized by the following steps: Step one: select strain gauge (8), first surface acoustic wave strain sensor (9.1), second surface acoustic wave strain sensor (9.2) respectively; the strain gauge (8) is pasted at the maximum stress of the second equal strength cantilever beam (2.2); the first surface acoustic wave strain sensor (9.1) is pasted at the maximum stress of the first equal strength cantilever beam (2.1); the second surface acoustic wave strain sensor (9.2) is pasted on the upper surface of the left end of the first equal strength cantilever beam (2.1); Step two: select dynamic strain tester (10), first radio frequency transceiver (11.1), second radio frequency transceiver (11.2), network analyzer (12), host computer (13), high frequency power supply (14) respectively; the strain gauge (8) is connected with the dynamic strain tester (10); the first surface acoustic wave strain sensor (9.1) and the second surface acoustic wave strain sensor (9.2) are connected with the first radio frequency transceiver (11.1); the first radio frequency transceiver (11.1) is fixed on the left side of the bottom frame (1); the first radio frequency transceiver (11.1) is wirelessly connected with the second radio frequency transceiver (11.2); the second radio frequency transceiver (11.2) is connected with the network analyzer (12); the dynamic strain tester (10) and the network analyzer (12) are connected with the host computer (13); the high frequency power supply (14) is connected with the induction coil (5); Step three: the relationship between resonance frequency and stress, the relationship between resonance frequency and temperature are calibrated respectively; the specific steps are as follows: Step a: the second equal strength cantilever beam (2.2) is placed in a constant temperature environment; then, adjust the right spiral micrometer (7) to move the measuring head of the spiral micrometer (7) downward by a distance, thereby applying stress to the second equal strength cantilever beam (2.2), so that the second equal strength cantilever beam (2.2) produces deflection; In the process of applying stress, 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 one hand and transmits it to the host computer (13) on the other hand; Step b: start the high-frequency power supply (14), 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 conduction sleeve (3) generates eddy current and heats up, thereby heating the first and second surface acoustic wave strain sensors (9.1 and 9.2); then, the network analyzer (12) sends an excitation signal, which is transmitted to the first and second surface acoustic wave strain sensors (9.1 and 9.2) through the second and first radio frequency transceivers (11.2 and 11.1) in turn, so that the first and second surface acoustic wave strain sensors (9.1 and 9.2) start working; then, adjust the left spiral micrometer (7) so that the measuring head of the spiral micrometer (7) moves downward by a distance equal to the distance moved by the measuring head of the right spiral micrometer (7) in step a, thereby applying stress to the first uniform strength cantilever beam (2.1) to make it produce deflection, which is equal to the deflection produced by the second uniform strength cantilever beam (2.2) in step a; During the heating and stress application process, the resonance frequencies output by the first and second surface acoustic wave strain sensors (9.1 and 9.2) change, the resonance frequency change of the first surface acoustic wave strain sensor (9.1) is caused by both temperature change and stress change, and the resonance frequency change of the second surface acoustic wave strain sensor (9.2) is caused only by temperature change; the resonance frequency changes output by the first and second surface acoustic wave strain sensors (9.1 and 9.2) are transmitted to the network analyzer (12) through the first and second radio frequency transceivers (11.1 and 11.2) in turn, which is recorded by the network analyzer (12) on one hand and transmitted to the host computer (13) on the other hand; Step c: the host computer (13) subtracts the resonance frequency changes output by the first and second surface acoustic wave strain sensors (9.1 and 9.2), thereby obtaining the resonance frequency change caused only by stress change; then, the host computer (13) calibrates the relationship between resonance frequency and stress according to the resonance frequency change caused only by stress change; Step d: the host computer (13) calibrates the relationship between resonance frequency and temperature according to the resonance frequency change output by the second surface acoustic wave strain sensor (9.2), i.e. the resonance frequency change caused only by temperature change.

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