Dynamic strain testing method for surface of rotating body in electromagnetic environment

Abstract

The invention provides a method for testing the dynamic strain of the surface of a rotating body in an electromagnetic environment. The method comprises the following steps: constructing a bridge by using strain gauges and acquiring dynamic characteristic data of the rotating part under actual constraint conditions; performing simulation calculation according to the dynamic characteristic data, and determining the optimal pasting position of the strain gauge; pasting a strain gauge and formulating a wiring scheme of a strain gauge wire; the strain gauge is connected with a voltage signal amplifier, the amplified signal is connected with a data acquisition system through a conductive slip ring, and the amplified strain signal is recorded and processed; acquiring strain signals in real time and taking the strain signals as test data, and performing whole-course test in a full-rotating-speed range to complete dynamic strain test on the surface of the rotating body. The system has high sensitivity, the sensitivity and the measurement precision of the system are improved through full-bridge configuration, larger output signals are provided, the full bridge can achieve temperature compensation through symmetrical circuit design, and the system has good linear output characteristics and facilitates signal processing and analysis within the strain range.

Description

Technical Field

[0001] The invention relates to a method for testing dynamic strain on the surface of a rotating body under an electromagnetic environment, and belongs to the technical field of testing dynamic strain on the surface of a rotating body. Background Art

[0002] With the continuous development of modern science and technology, rotating machinery and equipment have been widely used in the fields of industry, aerospace and national defense. These rotating machinery and equipment are often in a complex electromagnetic environment during operation, such as motors, generators, radars and communication equipment. In order to ensure the safety and reliability of these equipment, it is particularly important to monitor and evaluate their operating status in real time. As a key monitoring method, dynamic strain testing can provide stress and strain information on the surface of the rotating body during operation, helping engineers to detect potential problems in a timely manner and take corresponding measures.

[0003] At present, dynamic strain testing mainly relies on sensor technologies such as strain gauges. These sensors can convert mechanical strain into electrical or optical signals, and record and analyze them through data acquisition systems. However, the test environment of rotating bodies in wind tunnels or driven by motors has strong electromagnetic interference, which seriously affects the accurate measurement of dynamic strain. At present, some strain testing methods for electromagnetic environments have been proposed, but most of these methods have problems such as complex technology, high cost or limited scope of application. Therefore, there is an urgent need for a method that can efficiently and reliably test the dynamic strain on the surface of a rotating body in an electromagnetic environment to meet the needs of high-precision strain measurement in industries such as industry, aerospace, and defense.

[0004] In summary, the present invention aims to provide a method for testing the dynamic strain on the surface of a rotating body under an electromagnetic environment, so as to overcome the shortcomings of the prior art and realize accurate testing of the dynamic strain on the surface of a rotating body under an electromagnetic environment. Summary of the invention

[0005] The present invention aims to solve the technical problems of complex technology, high cost and limited application scope in the existing strain testing methods for electromagnetic environment, and further proposes a dynamic strain testing method for the surface of a rotating body under electromagnetic environment.

[0006] The technical solution adopted by the present invention to solve the above problems is: the present invention proposes a method for testing the dynamic strain on the surface of a rotating body under an electromagnetic environment, comprising:

[0007] Step 1: Use strain gauges to build a bridge and obtain dynamic characteristic data of the rotating part under actual constraint conditions;

[0008] Step 2: Perform simulation calculation based on dynamic characteristic data to determine the best sticking position of the strain gauge;

[0009] Step 3: Paste the strain gauge and make a routing plan for the strain gauge wire;

[0010] Step 4: Connect the strain gauge and the voltage signal amplifier, connect the amplified signal to the data acquisition system through the conductive slip ring, and record and process the amplified strain signal;

[0011] Step 5: Collect strain signals in real time and use them as test data. Perform full-range testing within the full speed range to complete the dynamic strain test on the rotating body surface.

[0012] Optionally, in step 1, the bridge includes: a strain gauge R1, a precision resistor R2, a precision resistor R3 and a precision resistor R4;

[0013] The resistance values ​​of the precision resistors R2, R3 and R4 are all equal to the resistance value of the strain gauge, and the precision of the precision resistors R2, R3 and R4 is one thousandth.

[0014] Optionally, the strain gauge R1 is connected to the precision resistor R2, the precision resistor R3, and the precision resistor R4 respectively using twisted pair cables.

[0015] Optionally, obtaining the dynamic characteristic data of the rotating part under actual constraint conditions in step 1 specifically includes:

[0016] The output voltage of the bridge is calculated by the resistance change of the strain gauge R1 under stress and the resistance values ​​of the precision resistors R2, R3 and R4, and the output voltage is converted into strain, which is used as dynamic characteristic data. The output voltage of the bridge is proportional to the resistance change.

[0017] Optionally, the step of determining the optimal sticking position of the strain gauge in step 2 includes:

[0018] Step 2.1: Calibrate and validate the simulation model based on dynamic characteristic data;

[0019] Step 2.2: Use the finite element method to perform simulation calculations in combination with the calibrated and verified simulation model to generate a stress distribution cloud diagram of the rotating part under actual constraint conditions;

[0020] Step 2.3: Analyze the stress distribution cloud map and identify the area with the largest stress distribution;

[0021] Step 2.4: Select the area with the largest stress distribution and determine the best bonding position of the strain gauge based on actual engineering elements, where the actual engineering elements include but are not limited to the geometric shape of the structure, load conditions and operating environment.

[0022] Optionally, the step of pasting the strain gauge in step 3 specifically includes:

[0023] Use glue to stick the strain gauge to the best pasting position, use reinforcing glue to fix the strain gauge, and apply a thin layer of epoxy adhesive on the surface of the strain gauge. After pasting, perform electrical performance testing and measure the resistance and insulation resistance of the strain gauge. If the resistance value of the strain gauge does not match the nominal value and the insulation resistance does not meet the set standard requirements, immediately remove the original strain gauge and re-paste and fix it until the resistance value and insulation resistance of the strain gauge are qualified.

[0024] Optionally, the routing scheme for the strain gauge wires in step 3 specifically includes:

[0025] Step 3.1: Select a lightweight wire as the strain gauge wire, and stick the strain gauge on one side of the rotating part. The strain gauge wire is arranged and fixed on the surface of the rotating part according to the shortest path. The method of fixing the strain gauge wire is the same as the method of sticking the strain gauge.

[0026] Step 3.2: Drill holes at the propeller handle of the rotating part and at the upper and lower connections of the propeller hub. Use heat shrink tubing to protect the strain gauge wires when they pass through the small holes at the propeller handle. The wire routing direction is arranged according to the lead-out direction of the strain gauge.

[0027] Step 3.3: Conduct electrical performance tests on the routing and routing connections of all wires until the routing and routing connections of all wires pass the test, completing the routing of the strain gauge wires.

[0028] Optionally, the step of recording and processing the amplified signal in step 4 includes:

[0029] Step 4.1: Connect the bridge to a voltage amplifier, amplify the weak voltage signal output by the bridge and output it, so that the voltage signal reaches the level required for data acquisition, wherein the gain and noise characteristics of the voltage amplifier match the accuracy requirements of strain measurement;

[0030] Step 4.2: The output signal of the voltage amplifier is transmitted to the data acquisition system through the conductive slip ring, and the data acquisition system records and processes the amplified strain signal.

[0031] The voltage amplifier and the resistance strain gauge in the bridge are both grounded and connected using shielded cables.

[0032] The beneficial effects of the present invention are:

[0033] 1. The dynamic strain testing method for the surface of a rotating body under an electromagnetic environment proposed by the present invention has high sensitivity. The full-bridge configuration improves the sensitivity and measurement accuracy of the system and provides a larger output signal. For temperature compensation, the full-bridge can achieve temperature compensation through a symmetrical circuit design to reduce the impact of temperature changes on the measurement results. For linear output, within the strain range, the full-bridge configuration usually has good linear output characteristics, which is convenient for signal processing and analysis.

[0034] 2. Twisted pair cables can effectively offset external electromagnetic interference and reduce crosstalk, ensuring signal integrity and reliability; compared with shielded cables, twisted pair cables have lower manufacturing and installation costs and do not require complex shielding layers; twisted pair cables are relatively soft, easy to bend and install, and suitable for various wiring needs; twisted pair cables can be made of lightweight materials, such as enameled wire, which can minimize the impact on the dynamic balance of rotating parts when wiring on the surface of rotating parts.

[0035] 3. Voltage signal amplifiers can significantly increase the strength of weak signals, making them easier to measure and analyze; voltage signal amplifiers can provide high gain and low noise amplification, thereby improving measurement accuracy and signal quality; they can also adapt to the strength of different strain signals by adjusting the amplifier gain, and have strong flexibility; modern integrated circuit technology allows the amplifier to be miniaturized, making it easy to integrate with other circuits to amplify weak strain signals.

[0036] 4. The effective grounding of the present invention can significantly reduce electromagnetic interference and improve signal quality; grounding can protect equipment from damage caused by electrostatic discharge and electrical overload; grounding can also improve the safety of the system and prevent electric shock. The shielded cable can effectively shield external electromagnetic interference and protect signal integrity; it is also suitable for various complex electromagnetic environments, such as industrial sites, communication systems, etc.; and in high-noise environments, the shielded cable can significantly improve signal quality and reliability.

[0037] 5. Conductive slip rings allow power or signals to be continuously transmitted between rotating parts and fixed parts; they can be designed as multi-channel slip rings, allowing multiple power or signals to be transmitted simultaneously, improving the functionality of the system, and can test the surface dynamic strain of multiple test points at the same time; conductive slip rings have a compact structure and are easy to integrate into existing systems; slip ring systems can provide stable and reliable connections to meet the needs of long-term continuous operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A flow chart of a method for testing dynamic strain on the surface of a rotating body under an electromagnetic environment provided by the present invention;

[0039] Figure 2 A schematic diagram of the structure of a rotating body in the dynamic strain test of the rotating body surface provided by the present invention;

[0040] Figure 2 Among them, 1-strain gauge, 2-rotating part, 3-voltage signal amplifier, 4-rotation drive system, 5-propeller hub;

[0041] Figure 3 A connection circuit diagram of the full-bridge circuit provided by the present invention. DETAILED DESCRIPTION

[0042] Combination Figure 1-3This embodiment is described as follows. Figure 1 As shown, the steps of a method for testing dynamic strain on the surface of a rotating body under an electromagnetic environment described in this embodiment include:

[0043] S1: Determine the location of the strain gauge;

[0044] S101: Use strain gauges to build a bridge;

[0045] The bridge includes: strain gauge R1, precision resistor R2, precision resistor R3 and precision resistor R4;

[0046] The resistance values ​​of the precision resistors R2, R3 and R4 are all equal to the resistance value of the strain gauge, and the precision of the precision resistors R2, R3 and R4 is one thousandth;

[0047] The strain gauge R1 is connected to the precision resistor R2, the precision resistor R3, and the precision resistor R4 respectively using twisted pair wires;

[0048] The design of twisted pair cables reduces interference through physical structure. The two wires are twisted around each other at a certain pitch. This structure can make the induced voltages on the two wires caused by external electromagnetic interference cancel each other out, because the induced voltages generated by each wire under the influence of the same electromagnetic wave are equal and opposite in phase. The twisting of twisted pair cables also helps to reduce electromagnetic interference between adjacent pairs of wires, that is, crosstalk. Since the twisting pitch of each pair of twisted pair cables is different, the induction effect of the interference signal between adjacent pairs can be made inconsistent, thereby reducing crosstalk.

[0049] The present invention has high sensitivity. The full-bridge configuration improves the sensitivity and measurement accuracy of the system and provides a larger output signal. The full-bridge can achieve temperature compensation through a symmetrical circuit design to reduce the impact of temperature changes on the measurement results. The linear output, within the strain range, the full-bridge configuration usually has good linear output characteristics, which is convenient for signal processing and analysis.

[0050] S102: Acquiring dynamic characteristic data of the rotating part under actual constraint conditions;

[0051] The Wheatstone bridge infers the magnitude of strain by measuring the change in resistance. When a strain gauge is subjected to force, its resistance changes. By connecting the strain gauge to the Wheatstone bridge, this change can be measured and the strain can be calculated. A standard Wheatstone full bridge circuit contains four resistor elements: R1, R2, R3 and R4. The present invention replaces one of the resistor elements with a strain gauge so that its resistance changes with strain; the other three resistor elements use precision resistors with the same resistance as the strain gauge, with an accuracy of one thousandth. The output voltage of the bridge is proportional to the change in resistance. Through proper circuit design and calibration, the output voltage can be converted into strain.

[0052] S103: Calibrate and verify the simulation model based on dynamic characteristic data to ensure that the model accurately reflects the actual working state. Then, use the finite element method to perform simulation calculations to generate a stress distribution cloud map of the rotating part under actual constraint conditions. By analyzing the stress distribution cloud map, identify the stress concentration area, that is, the area with the largest stress distribution. After selecting the stress concentration area, it is necessary to consider the specific requirements of the actual engineering problem, such as the geometric shape of the structure, load conditions, operating environment and other factors, and further determine the specific pasting position of the strain gauge. In addition, the relationship between the sensitive direction of the strain gauge and the stress direction should be combined to ensure that the strain gauge can accurately measure the target stress component. Finally, combine the simulation calculation results with the actual engineering needs to reasonably determine the optimal pasting position of the strain gauge to achieve accuracy and reliability of strain measurement;

[0053] S2: Pasting and curing of strain gauges;

[0054] The pasting and curing of strain gauges are important steps to ensure the accuracy of strain measurement. Select the appropriate strain gauge model according to the specific measurement requirements and application environment;

[0055] S201: Use glue to precisely stick the strain gauge at the predetermined position and ensure that it is firmly attached to the substrate surface. To further enhance the bonding strength, use reinforcing glue for reinforcement. Apply a thin layer of epoxy adhesive on the surface of the strain gauge to provide additional mechanical strength and environmental protection.

[0056] S202: After the pasting and curing process is completed, a strict electrical performance inspection is required, including measuring the resistance value and insulation resistance of the strain gauge. The resistance value of the strain gauge should be consistent with the nominal value, and the insulation resistance should meet the set standard requirements. If the measurement result does not meet the requirements, the original strain gauge should be removed immediately, and the pasting and curing operations should be performed again until the electrical performance inspection is qualified. These steps ensure the reliability and measurement accuracy of the strain gauge at work.

[0057] S3: Develop a routing plan for the strain gauge wires;

[0058] S301: In order to ensure the transmission quality of the strain measurement signal and the reliability of the wire, the following wire routing plan is formulated: Select lightweight wires as the wires of the strain gauge. The strain gauge is pasted on the surface of one side of the rotating part, and the wires need to be arranged in the shortest path to reduce the resistance and inductance on the signal transmission path. The wires should be neatly arranged and fixed on the surface of the rotating part. The fixing method is the same as the pasting and curing method of the strain gauge to ensure the stability of the wires in the operating environment;

[0059] S302: Drill holes at the propeller handle of the rotating part and at the upper and lower connections of the propeller hub. The hole diameter should be large enough to lead out the enameled wire while minimizing the impact on the structural integrity. When the wire passes through the small hole at the propeller handle, it is necessary to use a heat shrink tube for protection to prevent the wire from being damaged by friction or external force and to increase the mechanical strength and toughness of the wire. The routing direction of the wire should be arranged according to the lead-out direction of the strain gauge to avoid wire crossing and complex routing paths;

[0060] S303: All wiring and connections must be checked for electrical performance to ensure that the resistance and insulation resistance of the wires meet standard requirements. In addition, to prevent environmental factors from affecting the wires, additional protection measures should be considered at the corresponding locations, such as insulation coating or waterproof packaging.

[0061] S4: Connect the bridge to the voltage amplifier;

[0062] The voltage signal amplifier receives the output voltage signal of the Wheatstone bridge, makes it reach the level required by the data acquisition system, and outputs it to the data acquisition system. The gain and noise characteristics of the amplifier should match the accuracy requirements of strain measurement. By amplifying the signal level and improving the ratio of signal to noise, subsequent data processing is more accurate. The instrument amplifier has a differential input and can eliminate common-mode noise. The signal output by the bridge is a differential signal. The amplifier can amplify the differential signal and suppress common-mode noise, which helps to eliminate the noise interference introduced on the transmission line. The amplifier integrates a low-pass filter to filter out high-frequency noise. This can effectively reduce the impact of electromagnetic interference and radio frequency interference in the environment, thereby improving the purity of the measurement signal.

[0063] Voltage signal amplifiers can significantly increase the strength of weak signals, making them easier to measure and analyze; voltage signal amplifiers can provide high gain and low noise amplification, thereby improving measurement accuracy and signal quality; they can also adapt to the strength of different strain signals by adjusting the amplifier gain, with strong flexibility; modern integrated circuit technology allows the amplifier to be miniaturized, making it easy to integrate with other circuits to amplify weak strain signals.

[0064] Both the amplifier and the resistance strain gauge in the bridge need good shielding and grounding measures to reduce the interference of external electromagnetic fields. Grounding is a basic electromagnetic compatibility measure that eliminates or reduces electromagnetic interference by connecting the metal casing or shielding layer of the system to the ground. Grounding can provide a low-impedance path for unwanted currents to quickly leave the system, thereby reducing noise and interference. Use shielded cables to connect the strain gauge and amplifier, and ensure that the shielding layer is grounded. Shielded cables are wrapped with a metal shielding layer outside the conductor, which can reflect or absorb external electromagnetic interference, thereby protecting the internal signal line. The shielding layer is usually grounded to provide a low-impedance interference path.

[0065] S5: Use conductive slip ring to transmit the amplifier output signal;

[0066] The output signal of the amplifier is transmitted through a conductive slip ring. The conductive slip ring is used to transmit signals between rotating parts and fixed parts to ensure the continuity and stability of the measurement signal in the rotating system.

[0067] Conductive slip rings allow continuous transmission of power or signals between rotating parts and fixed parts; they can be designed as multi-channel slip rings, allowing multiple power or signals to be transmitted simultaneously, improving the functionality of the system, and can test the surface dynamic strain of multiple test points at the same time; conductive slip rings have a compact structure and are easy to integrate into existing systems; slip ring systems can provide stable and reliable connections to meet the needs of long-term continuous operation.

[0068] S6: Connect the output end of the conductive slip ring to the data acquisition system;

[0069] The output of the conductive slip ring is connected to the data acquisition system, which records and processes the amplified strain signal and performs subsequent analysis and processing.

[0070] After completing the above preparations, the dynamic strain measurement test can be carried out. During the test, the system needs to perform full-range testing within the full speed range and collect strain data in real time. The present invention realizes the dynamic strain measurement of the surface of the rotating part under the electromagnetic environment. The obtained test data is true and reliable, and can truly reflect the distribution and changes of the stress on the surface of the rotating part. Through these data, the load distribution on the surface of the rotating part can be further understood, providing an important reference for structural optimization design and fatigue life prediction.

[0071] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for testing dynamic strain on the surface of a rotating body under an electromagnetic environment, characterized in that: The method for testing the dynamic strain on the surface of a rotating body under an electromagnetic environment comprises the following steps: Step 1: Use strain gauges to build a bridge and obtain dynamic characteristic data of the rotating part under actual constraint conditions; Step 2: Perform simulation calculation based on the dynamic characteristic data to determine the optimal sticking position of the strain gauge; Step 3: Paste the strain gauge and make a routing plan for the strain gauge wire; Step 4: connecting the strain gauge to a voltage signal amplifier, connecting the amplified signal to a data acquisition system through a conductive slip ring, and recording and processing the amplified strain signal; Step 5: The strain signal is collected in real time and used as test data, and a full-range test is performed within the full speed range to complete the dynamic strain test on the rotating body surface.

2. The method for testing dynamic strain on the surface of a rotating body under an electromagnetic environment according to claim 1, characterized in that: The bridge described in step 1 includes: a strain gauge R1, a precision resistor R2, a precision resistor R3 and a precision resistor R4; The resistance values ​​of the precision resistors R2 , R3 and R4 are all equal to the resistance value of the strain gauge, and the precision of the precision resistors R2 , R3 and R4 is one thousandth.

3. The method for testing dynamic strain on the surface of a rotating body under an electromagnetic environment according to claim 2, characterized in that: The strain gauge R1 is connected to the precision resistor R2, the precision resistor R3 and the precision resistor R4 respectively using twisted pair wires.

4. The method for testing dynamic strain on the surface of a rotating body under an electromagnetic environment according to claim 1, characterized in that: The dynamic characteristic data of the rotating part under the actual constraint conditions obtained in step 1 specifically include: The output voltage of the bridge resistance strain gauge is calculated by combining the resistance change of the strain gauge R1 under stress with the resistance values ​​of the precision resistors R2, R3 and R4, and the output voltage is converted into strain, which is used as dynamic characteristic data, wherein the output voltage of the bridge is proportional to the resistance change.

5. The method for testing dynamic strain on the surface of a rotating body under an electromagnetic environment according to claim 1, characterized in that: The steps for determining the optimal gage attachment position in step 2 include: Step 2.1: calibrating and validating the simulation model based on the dynamic characteristic data; Step 2.2: Use the finite element method to perform simulation calculations in combination with the calibrated and verified simulation model to generate a stress distribution cloud diagram of the rotating part under actual constraint conditions; Step 2.3: Analyze the stress distribution cloud map to identify the area with the largest stress distribution; Step 2.4: Select the area with the largest stress distribution, and determine the best sticking position of the strain gauge in combination with actual engineering elements, wherein the actual engineering elements include but are not limited to the geometric shape of the structure, the load conditions and the operating environment.

6. The method for testing dynamic strain on the surface of a rotating body under an electromagnetic environment according to claim 1, characterized in that: The specific steps of pasting the strain gauge in step 3 include: Use glue to stick the strain gauge at the best sticking position, use reinforcing glue to fix the strain gauge, and apply a thin layer of epoxy adhesive on the surface of the strain gauge. After sticking, perform electrical performance testing and measure the resistance value and insulation resistance of the strain gauge. If the resistance value of the strain gauge does not match the nominal value and the insulation resistance does not meet the set standard requirements, immediately remove the original strain gauge and re-stick and fix the strain gauge until the resistance value and insulation resistance of the strain gauge are qualified.

7. The method for testing dynamic strain on the surface of a rotating body under an electromagnetic environment according to claim 1, characterized in that: The routing plan for the strain gauge wires in step 3 specifically includes: Step 3.1: Select a lightweight wire as a strain gauge wire, the strain gauge is pasted on one side of the rotating part, the strain gauge wire is arranged and fixed on the surface of the rotating part according to the shortest path, and the strain gauge wire fixing method is the same as the method of pasting the strain gauge; Step 3.2: Drill holes at the propeller handle of the rotating part and the upper and lower connections of the propeller hub. Use heat shrink tubing to protect the strain gauge wires when passing through the small holes at the propeller handle. The wire routing direction is arranged according to the lead-out direction of the strain gauge. Step 3.3: Conduct electrical performance tests on the routing and routing connections of all wires until the routing and routing connections of all wires pass the test, completing the routing of the strain gauge wires.

8. The method for testing dynamic strain on the surface of a rotating body under an electromagnetic environment according to claim 1, characterized in that: The steps of recording and processing the amplified strain signal in step 4 include: Step 4.1: Connect the bridge to a voltage amplifier, amplify the weak voltage signal output by the bridge and output it, so that the voltage signal reaches the level required for data acquisition, wherein the gain and noise characteristics of the voltage amplifier match the accuracy requirements of strain measurement; Step 4.2: The output signal of the voltage amplifier is transmitted to a data acquisition system through a conductive slip ring, and the data acquisition system records and processes the amplified strain signal.

9. The method for testing dynamic strain on the surface of a rotating body under an electromagnetic environment according to claim 1, characterized in that: The voltage amplifier and the resistance strain gauge in the bridge are both grounded and connected using shielded cables.

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