Strain structure for measuring large strain and measuring method

Abstract

The invention discloses a strain structure for measuring large strain and a measuring method, and relates to the field of dependent variable measurement, the strain structure comprises an elastic body connected with a measured piece, the elastic body comprises a patch part, two connecting parts and a mounting part, the two connecting parts are symmetrically arranged on the patch part, the mounting part is connected with one side, far away from the patch part, of each connecting part, and the two connecting parts are symmetrically arranged on the mounting part. The mounting part is arranged on the elastic body, the included angle between the connecting part and the patch part is larger than 90 degrees, and the included angle between the connecting part and the mounting part is larger than 90 degrees; a measuring strain gauge is arranged on the patch part, and a standard strain gauge is arranged on the measured piece. Large strain measurement is carried out through cooperation of the measurement strain gauge at the patch beam on the elastic piece and the standard strain gauge, the limitation of a traditional strain gauge in the high strain field can be effectively broken through, a wider measurement range is provided, the reliability and accuracy of measurement are enhanced, and the measurement accuracy can be guaranteed while the measurement precision is guaranteed. And the measuring requirements of various different materials and components are met.

Description

Technical Field

[0001] The present invention relates to the field of strain measurement, and in particular to a strain structure for measuring large strain and a measurement method. Background Art

[0002] In the design and evaluation of engineering structures, strain is a key parameter for determining material strength and structural safety, and structural performance analysis is usually performed through strain measurement. In traditional steel and metal structures, strain measurement using standard strain gauges has been widely used. However, in some special materials (such as composite materials and non-metallic materials) or structures (such as large-scale components and flexible structures), the strain may far exceed the measurement capability of conventional strain gauges, which brings measurement difficulties. For conventional strain gauges, their measurement range is usually limited, generally not exceeding 2000 microstrains. In large strain areas, the sensitivity and accuracy of traditional strain gauges are greatly reduced.

[0003] In the design and fatigue assessment of engineering structures, strain measurement is an important basis for evaluating stress deformation and material response. However, conventional strain measurement methods are usually only applicable to low strain ranges and cannot cope with high strain scenarios. In some non-metallic materials, composite materials, or structures with flexible properties, the strain may exceed 2000 microstrains, which is usually impossible for traditional strain gauges to accurately measure and may even lead to measurement errors and equipment damage.

[0004] Therefore, a strain gauge structure and a measurement method for measuring large strain are proposed to solve the problem that the conventional strain gauge cannot measure strains exceeding 2000 microstrains. Summary of the Invention

[0005] The purpose of the present invention is to provide a strain structure and a measurement method for measuring large strains, so as to solve the problem that conventional strain gauges cannot measure strains exceeding 2000 microstrains.

[0006] To achieve this object, the present invention adopts the following technical solutions: A strain structure and measurement method for measuring large strains, including an elastomer connected to a measured object, the elastomer including a patch portion and two connecting portions and a mounting portion, the two connecting portions being symmetrically arranged on the patch portion, the mounting portion being connected to a side of the connecting portion away from the patch portion, the mounting portion being arranged on the elastomer, the angle between the connecting portion and the patch portion being greater than 90°, and the angle between the connecting portion and the mounting portion being greater than 90°; a measuring strain gauge is provided on the patch portion, and a standard strain gauge is provided on the measured object.

[0007] A connecting hole is provided on the mounting portion, a connecting piece is provided in the connecting hole, and the mounting portion is connected to the measured component through the connecting piece and the connecting hole.

[0008] The connecting part includes a stud and a locking sleeve. The stud is arranged in the locking sleeve. One end of the stud passes through and extends to the side of the mounting part away from the measured object. The locking sleeve is arranged in the connecting hole. The end of the locking sleeve away from the mounting part is formed with a plurality of tightening parts, and a plurality of teeth are formed on the tightening part. The screw rotates and moves toward the locking sleeve, and the tightening piece drives the teeth to move toward the inner wall of the connecting hole.

[0009] A square thermal insulation gasket is sleeved on the stud, and the thermal insulation gasket is located between the mounting portion and the locking sleeve. The mounting portion is provided with a through hole for the thermal insulation gasket to pass through. When the thermal insulation gasket is in contact between the mounting portion and the test piece, the thermal insulation gasket is inclined, and the mounting portion and the vertical projection of the thermal insulation gasket partially overlap.

[0010] A protective piece is provided on the outer side of the measuring strain gauge. The protective piece is provided on the patch portion and is a vulcanized rubber piece.

[0011] The standard strain gauge is connected to the standard strain gauge, the measuring strain gauge is connected to the measuring strain gauge, and the standard strain gauge is signal-connected to the measuring strain gauge.

[0012] A strain measurement method for measuring large strains is applied to the strain structure for measuring large strains as described above, and the measurement method comprises the following steps: Step S1, installing a measuring strain gauge on an elastic body, placing the elastic body and the standard strain gauge on a test piece respectively, and then placing the test piece on a dynamometer; Step S2: applying multiple sets of loading forces to the test piece through a force measuring machine to obtain measured strains and measured voltages, and obtaining a strain mapping function based on the multiple sets of loading forces, measured strains, and measured voltages; Step S3, obtaining the drift voltage of the strain gauge of the measured object in an unloaded state under different temperature environments; Step S4: Apply actual loading force to the test piece through the dynamometer to obtain actual strain, actual voltage and corresponding temperature, then obtain corresponding correction voltage through drift voltage, and then obtain final strain value based on correction voltage and strain mapping function.

[0013] The strain mapping function in step S2 is obtained according to the following steps: Multiple sets of loading forces are applied to the workpiece in sequence through a dynamometer, and the standard strain gauge and the measuring strain gauge are used to provide the measured strain and the measuring voltage of the measuring strain gauge corresponding to each set of loading forces. Then, the strain mapping function is obtained by fitting the multiple sets of loading forces, the corresponding measured strain and the measuring voltage using the least squares method. The strain mapping function for: ; Where: is the strain value measured by the strain gauge; is the fitting coefficient; Measure voltage for multiple groups.

[0014] The drift voltage in step S3 is obtained according to the following steps: The DUT is heated to gradually increase its temperature, and the strain gauge is operated at different temperatures. The measured voltage of the DUT at different temperatures is then obtained, and the drift voltage is obtained by fitting multiple sets of measured voltages at different temperatures and the corresponding temperatures. The drift voltage for: ; Where: is the fitting coefficient; For multiple sets of temperatures.

[0015] The final strain value in step S4 is obtained according to the following steps: Apply actual loading force to the test piece through the dynamometer to obtain the actual strain, actual voltage and corresponding temperature. Then, obtain the corresponding correction voltage through the drift voltage, and then obtain the final strain value based on the correction voltage and strain mapping function. The final strain value for: ; ; Where: To correct the voltage; is the actual voltage.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a strain structure and measurement method for measuring large strains. By cooperating with a standard strain gauge and a measuring strain gauge arranged at a patch beam on an elastic member to perform large strain measurements, the present invention can effectively overcome the limitations of traditional strain gauges in the high strain field, provide a wider measurement range, and enhance the reliability and accuracy of the measurement. By utilizing the physical properties of the elastomer and the three-section structure formed by the patch beam, the connecting portion, and the mounting portion, the present invention can adapt to the measurement requirements of a variety of different materials and components while ensuring measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

[0018] The structures, proportions, sizes, etc. depicted in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not intended to limit the conditions under which the present invention can be implemented and therefore have no substantive technical significance. Any structural modifications, changes in proportional relationships, or adjustments in size should still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and objectives that can be achieved by the present invention.

[0019] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 Schematic diagram of the connection structure between the bypass stress elastic body and the tested object in the present invention; Figure 3 Schematic diagram of the connection structure between the bypass stress elastic body and the strain gauge in the present invention; Figure 4 Schematic diagram of the left side structure of the bypass stress elastic body of the present invention; Figure 5 Schematic diagram of the connection structure between the locking sleeve and the connecting hole in the present invention; Figure 6 It is a flowchart of the measurement method in the present invention.

[0020] Illustrations: 1. Elastomer; 11. Patch beam; 12. Connection part; 13. Mounting part; 14. Connection hole; 15. Connector; 151. Locking sleeve; 152. Stud; 153. Teeth; 154. Thermal insulation gasket; 2. Measuring strain gauge; 21. Protective part; 22. Measuring strain gauge; 3. Measured part; 4. Standard strain gauge; 5. Standard strain gauge; 6. Dynamometer. DETAILED DESCRIPTION

[0021] In order to make the purpose, features, and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0022] In the description of the present invention, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present invention and simplify the description. They are not intended to indicate or imply that the devices or elements referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. It should be noted that when a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be a centrally located component.

[0023] Example 1: See also Figure 1-5 In this embodiment, a strain structure for measuring large strain includes an elastic body 1 connected to a measured object 3. The elastic body 1 includes a patch portion 11 and two connecting portions 12 and a mounting portion 13. The two connecting portions 12 are symmetrically arranged on the patch portion 11. The mounting portion 13 is connected to a side of the connecting portion 12 away from the patch portion 11. The mounting portion 13 is arranged on the elastic body 1. The angle between the connecting portion 12 and the patch portion 11 is greater than 90°, and the angle between the connecting portion 12 and the mounting portion 13 is greater than 90°. A measuring strain gauge 2 is provided on the patch portion 11, and a standard strain gauge 4 is provided on the measured object 3.

[0024] It should be noted that measuring the strain amount of the test piece 3 after the loading force is applied by the measuring strain gauge 2 on the elastic body 1 and the standard strain gauge 4 can supplement the shortcomings of the standard strain gauge 4 to meet the measurement requirements higher than 2000 microstrain and achieve high-precision measurement of a large strain range.

[0025] It should also be noted that the three-section structure of the elastic body 1 can effectively disperse the stress concentration on the mounting surface. Figure 3-4 As shown, the symmetrical bending structure of the three-section elastic body 1 can guide the strain of the measured object 3 to the measuring strain gauge 2 without destroying the measuring point structure, thereby deriving the strain signal. At the same time, the connecting portion 12 located between the patch portion 11 and the mounting portion 13 can filter out local noise or error, and only retain the strain caused by the real structural load, so as to improve the measurement accuracy.

[0026] In a specific embodiment, the angle between the connecting portion 12 and the patch portion 11 is 90-120°, and the angle between the connecting portion 12 and the mounting portion 13 is 90-120°.

[0027] It can be known that the angles between the connecting portion 12 and the patch portion 11, and between the connecting portion 12 and the mounting portion 13 are 90-120°, ensuring that the patch portion 11 can better fit the curved surfaces or non-standard plane structures of different measured components, thereby improving the scope of application; it can be understood that the elastomer is made of a material with a high elastic modulus. The elastomer can ensure that it can still stably transmit strain signals without excessive deformation when subjected to large strains through its high elastic modulus. This not only provides a linear strain response, but also ensures measurement stability during long-term use.

[0028] It should be emphasized that, unlike traditional strain gauges that mainly measure strain through changes in resistance, elastomers use their geometric structure to enable them to withstand and respond to a wider range of strains. Through their elastic structure, elastomers can maintain a linear or stable response within a larger deformation range, thereby avoiding the problem of measurement distortion or saturation of traditional strain gauges under high strain. The elastomer adopts a bypass structure, which means that the strain measurement does not directly act on the surface of the test piece. The bypass structure allows the strain gauge to maintain a stable strain output when a large range of strain occurs, so that even when the surface of the test piece undergoes large deformation, the strain transfer of the elastomer can still maintain accurate measurement. In addition, in traditional strain gauges, directly installing strain gauges on the surface of the test piece will cause the strain gauge to be unable to cope with nonlinear changes in large deformation areas. The elastomer gradually transfers and amplifies the strain through its elastic deformation to a range suitable for accurate measurement by the strain gauge, thereby effectively measuring large strain areas that traditional methods cannot cover.

[0029] It is worth noting that compared with traditional high-precision strain gauges, the preparation process of the elastomer structure is relatively simple and can be manufactured through standard plastic, metal or composite material molding processes. Using methods such as hot pressing, injection molding or machining, the production process is relatively convenient and easy to mass-produce. Especially in terms of installation, the elastomer does not require a complicated curing process, reducing process requirements such as high-temperature curing and pressurization, which is extremely advantageous for large-scale engineering applications; at the same time, the raw materials of the elastomer can be more common synthetic polymers, rubber or metal materials, and their production costs are relatively low. Compared with traditional strain gauges that require high-precision and high-cost manufacturing of resistance strain gauges, the elastomer has more relaxed requirements in terms of materials and processing, so it can significantly reduce the overall production cost; in addition, the installation and maintenance process of the elastomer is very simple, and does not require additional complex heating, curing or high-temperature operations, reducing on-site construction and equipment requirements.

[0030] Furthermore, a connecting hole 14 is formed on the mounting portion 13 , a connecting piece is provided in the connecting hole 14 , and the mounting portion 13 is connected to the device under test 3 via the connecting piece and the connecting hole 14 .

[0031] It should be noted that the elastomer 1 can be threadedly connected to the piece under test 3 through the connection hole 14 on the mounting portion 13, so as to ensure a strong connection between the elastomer 1 and the piece under test 3 during the measurement process, prevent loosening or displacement during the strain change process, and allow the elastomer 1 to be firmly installed on the piece under test 3 of different materials and different strength grades. By rigidly mounting the elastomer 1 and the piece under test 3, the patch can be effectively prevented from falling off or slipping due to vibration and temperature changes during long-term operation.

[0032] It should also be noted that if Figure 3-4 As shown, the contact area between the mounting portion 13 and the test piece 3 allows the mounting portion 13 to be glued to the test piece 3 and ensures the bonding stability. In addition, by gluing the mounting portion 13 to the test piece 3, the elastomer 1 can also adapt to the indestructible test piece 3.

[0033] Furthermore, the connecting member 15 includes a stud 152 and a locking sleeve 151. The stud 152 is arranged in the locking sleeve 151. One end of the stud 152 passes through and extends to the side of the mounting portion 13 away from the measured object 3. The locking sleeve 151 is arranged in the connecting hole 14. The end of the locking sleeve 151 away from the mounting portion 13 is formed with a plurality of tightening portions, and a plurality of teeth 153 are formed on the tightening portions. The screw rotates and moves toward the locking sleeve 151, and the tightening piece drives the teeth 153 to move toward the inner wall of the connecting hole 14.

[0034] It should be noted that when the mounting plate is connected to the test piece 3 through the connecting piece 15, the locking sleeve 151 is passed through the mounting portion 13 and the locking sleeve 151 is inserted into the connecting hole 14, and then the stud 152 is rotated and pressed against the mounting portion 13. After the stud 152 is pressed against the mounting portion 13, the stud 152 moves the pressing plate toward the inner wall of the connecting hole 14 and presses against it. At the same time, the teeth 153 also move toward the inner wall of the connecting hole 14 and press tightly against the inner wall of the connecting hole 14.

[0035] It can be known that double tightening can be formed by the cooperation between the clamping piece and the teeth 153, thereby improving the tightness of the connection between the locking sleeve 151 and the measured piece 3, and then making the connection between the mounting portion 13 and the measured piece 3 more stable and tight, thereby improving the accuracy during measurement; it can be understood that after the stud 152 rotates and moves toward the mounting portion 13, the clamping piece and the teeth 153 are tightened against the inner wall of the connecting hole 14, which is well known to the staff in this field and will not be explained in this embodiment.

[0036] In more detail, a square thermal insulation gasket 154 is sleeved on the stud 152, and the thermal insulation gasket 154 is located between the mounting portion 13 and the cylinder. A through hole is provided on the mounting portion 13 for the thermal insulation gasket 154 to pass through. When the thermal insulation gasket 154 is in contact between the mounting portion 13 and the test piece 3, the thermal insulation gasket 154 is inclined, and the vertical projection of the mounting portion 13 and the thermal insulation gasket 154 partially overlap.

[0037] It should be noted that when connecting the locking sleeve 151 to the connecting hole 14, the locking sleeve 151 and the thermal insulation gasket 154 need to pass through the through hole. At the same time, after the thermal insulation gasket 154 passes through the through hole, the thermal insulation gasket 154 is tilted, and then the stud 152 is rotated to make the stud 152 and the mounting part 13 tightly. At this time, the mounting part 13 can make the thermal insulation gasket 154 abut against the test piece 3.

[0038] It can be known that by isolating the mounting portion 13 from the device under test 3 through the thermal insulation gasket 154, the heat on the device under test 3 can be prevented from being transferred to the elastic part during the measurement process, thereby preventing the heat from affecting the measurement results of the strain gauge 2 on the patch beam 11 during measurement, thereby improving the measurement accuracy.

[0039] It is understandable that the thermal insulation gasket 154 is made of a highly thermally insulating material. The thermal insulation gasket 154 made of a highly thermally insulating material can effectively block the heat transferred from the test piece 3 to the elastomer 1, thereby reducing the impact of the heat on the test piece 3 on the elastic member 1.

[0040] In a specific embodiment, the portion where the connecting portion 12 is connected to the patch portion 11 is configured to be arc-shaped, and the portion where the connecting portion 12 is connected to the mounting portion 13 is configured to be arc-shaped.

[0041] It should be noted that the connection between the connecting portion 12 and the patch portion 11 and the connection between the connecting portion 12 and the mounting portion 13 are both arc-shaped structures, which can make the stress in the elastomer 1 more smoothly transmitted, reduce stress concentration, thereby improving the durability and reliability of the elastomer 1, and help to improve the stability of strain measurement.

[0042] It should also be noted that in a large strain environment, linear connections or sharp corners can easily cause microcracks or local deformations. The elastomer 1 can maintain a uniform strain transfer path through an arc connection, improve signal stability, and avoid stress concentration, effectively extending the service life of the elastomer 1. It is particularly suitable for fatigue load scenarios. At the same time, the arc connection can increase the yield limit and shear resistance of the elastomer 1, reducing the probability of fracture.

[0043] Furthermore, a protective member 21 is provided on the outer side of the measuring strain gauge 2 . The protective member 21 is provided on the patch portion 11 , and the protective member 21 is a vulcanized rubber member.

[0044] It should be noted that the protective member 21 can protect the measuring strain gauge 2 from external environmental factors such as dust, moisture, chemicals, etc., ensuring the accuracy and long-term stability of the measurement; specifically, the protective member 21 made of vulcanized rubber provides high-strength physical protection, ensuring that the measuring strain gauge 2 can work stably for a long time in harsh environments, so that the protection level reaches the IP68 standard, effectively preventing the influence of environmental factors on the measuring strain gauge 2, and extending the service life of the measuring strain gauge 2, which is particularly suitable for applications in outdoor, industrial and high-temperature environments.

[0045] It should also be noted that the protective member 21 effectively prevents oxidation, corrosion or mechanical damage to the solder joints of the measuring strain gauge 2, ensures long-term measurement stability, and increases the life of the measuring strain gauge 2, making it suitable for unmanned remote monitoring projects.

[0046] It should be emphasized that vulcanized rubber has excellent sealing properties and is suitable for high-humidity, high-dust, and highly corrosive environments. Compared with ordinary sealants, the protective member 21 made of vulcanized rubber can maintain stable performance in the range of -40°C to 120°C and is suitable for various complex working conditions.

[0047] Furthermore, the standard strain gauge 4 is connected to the standard strain gauge 5 , the force-measuring strain gauge is connected to the force-measuring strain gauge, and the standard strain gauge 5 is signal-connected to the force-measuring strain gauge.

[0048] It should be noted that the above connection method ensures that strain data can be read accurately and in real time, and data storage and analysis are achieved through the signal transmission system, so as to facilitate real-time transmission and recording of strain data, facilitate subsequent data analysis and monitoring, and provide technical support for long-term use and remote monitoring.

[0049] Example 2: Referring to the figure, a strain measurement method for measuring large strain in this embodiment is applied to the strain structure for measuring large strain in Example 1. The measurement method includes the following steps: Step S1, installing the measuring strain gauge 2 on the elastic body 1, placing the elastic body 1 and the standard strain gauge 4 on the test piece 3 respectively, and then placing the test piece 3 on the dynamometer 6; Step S2: applying multiple sets of loading forces to the test piece 3 by the force measuring machine 6 to obtain measured strains and measured voltages, and obtaining a strain mapping function based on the multiple sets of loading forces, measured strains, and measured voltages; The strain mapping function in step S2 is obtained according to the following steps: Multiple sets of loading forces are sequentially applied to the test piece 3 by the force measuring machine 6, and the measured strain values ​​measured by the standard strain gauge 4 and the measured voltage of the measuring strain gauge 2 corresponding to each set of loading forces are provided respectively by the standard strain gauge 5 and the measuring strain gauge 22. Then, a strain mapping function is obtained by fitting the multiple sets of loading forces and the corresponding measured strain values ​​and measured voltages using the least squares method. Strain mapping function for: ; Where: is the strain value measured by strain gauge 2; is the fitting coefficient; Measure voltage for multiple groups.

[0050] Specifically, the multinomial fitting coefficients It is obtained by least squares method, which is well known to those skilled in the art and will not be described in this embodiment.

[0051] It should be noted that there is no linear relationship between the voltage output by the measuring strain gauge 2 and the strain of the standard strain gauge 4. Therefore, the strain mapping function is fitted by multiple sets of measurement data so that the output of the measuring strain gauge 2 can accurately reflect the actual strain. Therefore, the relationship between multiple sets of loading forces and voltages is fitted by the least squares method to obtain the strain mapping function.

[0052] It can be seen that the strain mapping function can convert the corresponding voltage value of the strain gauge 2 into the corresponding strain value, avoiding the error caused by nonlinearity. Moreover, the strain mapping function can expand the measurement range, so that the strain measurement can cover a large strain range that cannot be measured by traditional strain gauges. In addition, the fitting coefficient Obtained by the least squares method.

[0053] It should be emphasized that the strain mapping function can reduce the measurement error from ±10% of traditional single-point calibration to ±2-3%, thereby avoiding a sharp increase in strain ratio error when measuring large strains, and can also realize large-scale strain measurement suitable for nonlinear structural materials.

[0054] Step S3, obtaining the drift voltage of the strain gauge 2 of the test piece 3 in an unloaded state under different temperature environments; The drift voltage in step S3 is obtained according to the following steps: The test piece 3 is heated to gradually increase its temperature, and the measuring strain gauge 2 is operated at different temperatures. Then, the measured voltages of the test piece 3 at different temperatures are obtained, and the drift voltage is obtained by fitting multiple sets of measured voltages at different temperatures and the corresponding temperatures. Drift voltage for: ; Where: is the fitting coefficient; For multiple sets of temperatures.

[0055] Specifically, the multinomial fitting coefficients It is obtained by least squares method, which is well known to those skilled in the art and will not be described in this embodiment.

[0056] It should be noted that during the measurement process, due to different measurement environments, changes in ambient temperature will cause the zero point drift of the measuring strain gauge 2, thereby affecting the measurement accuracy. By obtaining the drift voltage to obtain the correction voltage, the error caused by the ambient temperature change can be eliminated, ensuring the accuracy of the measurement results, so that the measuring strain gauge 2 can still provide stable and reliable strain measurement results even in different temperature environments.

[0057] It should also be noted that during the measurement process, the heat insulation gasket 154 located between the mounting portion 13 and the piece under test 3 can reduce the heat transfer from the piece under test 3 to the elastic part 1, thereby reducing the fluctuation of the measurement voltage of the measuring strain gauge 2 at different temperatures, thereby improving the accuracy of subsequent measurements.

[0058] Step S4: Apply actual loading force to the test piece 3 through the dynamometer 6 to obtain actual strain, actual voltage and corresponding temperature, then obtain corresponding correction voltage through drift voltage, and then obtain final strain value according to correction voltage and strain mapping function.

[0059] The final strain value in step S4 is obtained according to the following steps S: Applying actual loading force to the test piece 3 through the dynamometer 6 to obtain actual strain, actual voltage and corresponding temperature, then obtaining corresponding correction voltage through drift voltage, and finally obtaining final strain value based on correction voltage and strain mapping function; Final strain value for: ; ; Where: To correct the voltage; is the actual voltage.

[0060] It should be noted that in actual applications, the output of the measuring strain gauge 2 will be affected by factors such as temperature changes and environmental interference. By correcting the voltage, an accurate final strain value can be obtained, so that the final strain value can accurately reflect the actual deformation of the measured object 3, which is suitable for high-precision and large strain scenarios.

[0061] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features thereof can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A strain gauge structure for measuring large strains, characterized in that: The invention comprises an elastic body (1) connected to a test piece (3), wherein the elastic body (1) comprises a patch portion (11) and two connecting portions (12) and a mounting portion (13), wherein the two connecting portions (12) are symmetrically arranged on the patch portion (11), the mounting portion (13) is connected to a side of the connecting portion (12) away from the patch portion (11), the mounting portion (13) is arranged on the elastic body (1), the angle between the connecting portion (12) and the patch portion (11) is greater than 90°, and the angle between the connecting portion (12) and the mounting portion (13) is greater than 90°; a measuring strain gauge (2) is arranged on the patch portion (11), and a standard strain gauge (4) is arranged on the test piece (3).

2. The strain structure for measuring large strain according to claim 1, characterized in that: A connecting hole (14) is provided on the mounting portion (13), a connecting piece is provided in the connecting hole (14), and the mounting portion (13) is connected to the measured component (3) via the connecting piece and the connecting hole (14).

3. The strain structure for measuring large strain according to claim 2, characterized in that: The connecting member (15) includes a stud (152) and a locking sleeve (151), wherein the stud (152) is arranged in the locking sleeve (151), and one end of the stud (152) passes through and extends to the side of the mounting portion (13) away from the measured object (3), and the locking sleeve (151) is arranged in the connecting hole (14), and a plurality of abutting portions are formed on the end of the locking sleeve (151) away from the mounting portion (13), and a plurality of teeth (153) are formed on the abutting portions. The screw is rotated to move toward the locking sleeve (151), and the abutting piece drives the teeth (153) to move toward the inner wall of the connecting hole (14).

4. The strain structure for measuring large strain according to claim 3, characterized in that: A square heat-insulating gasket (154) is sleeved on the stud (152), and the heat-insulating gasket (154) is located between the mounting portion (13) and the locking sleeve (151). The mounting portion (13) is provided with a through hole for the heat-insulating gasket (154) to pass through. When the heat-insulating gasket (154) is in contact between the mounting portion (13) and the test piece (3), the heat-insulating gasket (154) is inclined, and the vertical projections of the mounting portion (13) and the heat-insulating gasket (154) partially overlap.

5. The strain structure for measuring large strain according to claim 1, characterized in that: A protective member (21) is provided on the outside of the measuring strain gauge (2); the protective member (21) is provided on the patch portion (11); and the protective member (21) is a vulcanized rubber member.

6. The strain structure for measuring large strain according to claim 1, characterized in that: The standard strain gauge (4) is connected to the standard strain gauge (5), the measuring strain gauge (2) is connected to the measuring strain gauge (22), and the standard strain gauge (5) is signal-connected to the measuring strain gauge (22).

7. A strain measurement method for measuring large strain, characterized in that: Applied to a strain structure for measuring large strain according to any one of claims 1 to 6, the measurement method comprises the following steps: Step S1, installing a measuring strain gauge on an elastic body, placing the elastic body and the standard strain gauge on a test piece respectively, and then placing the test piece on a dynamometer; Step S2: applying multiple sets of loading forces to the test piece through a force measuring machine to obtain measured strains and measured voltages, and obtaining a strain mapping function based on the multiple sets of loading forces, measured strains, and measured voltages; Step S3, obtaining the drift voltage of the strain gauge of the measured object in an unloaded state under different temperature environments; Step S4: Apply actual loading force to the test piece through the dynamometer to obtain actual strain, actual voltage and corresponding temperature, then obtain corresponding correction voltage through drift voltage, and then obtain final strain value based on correction voltage and strain mapping function.

8. The strain measurement method for measuring large strain according to claim 7, characterized in that: The strain mapping function in step S2 is obtained according to the following steps: Multiple sets of loading forces are applied to the workpiece in sequence through a dynamometer, and the standard strain gauge and the measuring strain gauge are used to provide the measured strain and the measuring voltage of the measuring strain gauge corresponding to each set of loading forces. Then, the strain mapping function is obtained by fitting the multiple sets of loading forces, the corresponding measured strain and the measuring voltage using the least squares method. The strain mapping function for: ； Where: is the strain value measured by the strain gauge; is the fitting coefficient; Measure voltage for multiple groups.

9. The strain measurement method for measuring large strain according to claim 7, characterized in that: The drift voltage in step S3 is obtained according to the following steps: The DUT is heated to gradually increase its temperature, and the strain gauge is operated at different temperatures. The measured voltage of the DUT at different temperatures is then obtained, and the drift voltage is obtained by fitting multiple sets of measured voltages at different temperatures and the corresponding temperatures. The drift voltage for: ； Where: is the fitting coefficient; For multiple sets of temperatures.

10. The strain measurement method for measuring large strain according to claim 7, characterized in that: The final strain value in step S4 is obtained according to the following steps: Apply actual loading force to the test piece through the dynamometer to obtain the actual strain, actual voltage and corresponding temperature. Then, obtain the corresponding correction voltage through the drift voltage, and then obtain the final strain value based on the correction voltage and strain mapping function. The final strain value for: ； ； Where: To correct the voltage; is the actual voltage.

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