Residual stress distribution detection method of epoxy insulation parts based on infrared

Abstract

The present invention provides an infrared-based residual stress distribution detection method for epoxy insulation parts, constructs a relative temperature difference response model when the insulation parts are subjected to different uniaxial stresses under the condition of being irradiated by an external excitation source, and can realize more efficient and accurate real-time monitoring of the residual stress of the insulation parts. The method includes: step 1) preparing a standard sample of epoxy insulation parts; step 2) constructing a relative temperature difference response model of epoxy insulation parts under different stresses; step 3) measuring the overall residual stress distribution of epoxy insulation parts. The present invention constructs a relative temperature rise model that describes the epoxy insulation parts when they are irradiated by an excitation source under different uniaxial stresses, and based on the model, measures the residual force distribution of the three-pillar insulator.

Description

Technical Field

[0001] The present invention belongs to the technical field of insulator mechanical testing, and specifically relates to an infrared-based epoxy insulation residual stress distribution detection method, which constructs a relative temperature difference response model when the insulation is subjected to different uniaxial stresses under the condition of being irradiated by an external excitation source, and can achieve more efficient and accurate real-time monitoring of the residual stress of the insulation component. Background Art

[0002] Gas insulated transmission line (GIL) is a metal-encapsulated transmission equipment, which is widely used in power systems due to its high reliability, strong environmental adaptability, and no secondary pollution. The three-pillar insulator widely used in GIL mainly plays the role of insulation and support, and its insulation performance largely determines the safety and stability of GIL. However, with the widespread application of GIL in power transmission and transformation projects, the failure rate of GIL equipment has far exceeded expectations, and the failure caused by insulation is particularly prominent. Stress concentration and internal defects are important causes of GIL insulator failure. Stress concentration is an important factor in the formation of defects, and defects promote stress concentration. The two affect each other, directly inducing partial discharge and abnormal heating of insulators, accelerating material degradation, and affecting the normal operation of insulators. At present, mechanical tests are generally used to test the mechanical properties of insulators, but mechanical tests can only assess whether the insulators pass a certain limit value, and cannot measure the internal stress under any load, and cannot judge whether the stress is concentrated. Therefore, exploring effective insulator stress detection methods and realizing efficient and accurate detection of insulator stress are of great significance for preventing insulator mechanical failure, avoiding insulation failures, and ensuring the safe and reliable operation of GIL equipment. The present invention applies infrared detection technology in the field of material mechanics to the electrical field, constructs a relative temperature rise model that can describe the epoxy insulation when it is heated by an external excitation source under different uniaxial stresses, and based on the model, measures the residual stress distribution of the three-pillar insulator. Summary of the invention

[0003] The present invention aims to provide a detection method for measuring residual stress distribution of epoxy insulating parts, which can realize more efficient and accurate real-time monitoring of residual stress of insulating parts.

[0004] Based on the theory that stress changes the specific heat capacity of materials, the present invention constructs a temperature response model when an insulating component is subjected to different uniaxial stresses under the condition of being heated by an external excitation source, and finally realizes the measurement of the residual stress distribution of the entire insulator.

[0005] The technical solution of the present invention is an infrared-based residual stress distribution detection method for epoxy insulation parts. By recording the temperature changes of standard samples of epoxy insulation parts under different uniaxial stresses when irradiated by an external laser source, a relative temperature difference response model of epoxy insulation parts under different stresses is constructed, which can realize more efficient and accurate real-time monitoring of the residual stress of insulation parts.

[0006] The specific steps include:

[0007] S1 Preparation of standard specimens of epoxy insulation parts;

[0008] S2 builds the relative temperature difference response model of epoxy insulation under different stresses:

[0009] Firstly, the prepared epoxy insulation standard specimens were placed in a uniaxial stress test system and uniaxial stresses of different magnitudes were uniformly applied;

[0010] Secondly, infrared rays are used as the excitation source to irradiate the standard specimens under different uniaxial stress conditions. The center point of the standard specimen is selected as the irradiated point, and the starting temperature of the point is recorded. The temperature change at the irradiated point of the specimen is recorded. The irradiation is continued until the temperature at the irradiated point of the insulating standard specimen reaches a steady-state value. At this time, the temperature of the point is recorded. The difference between the two recorded temperature values ​​is calculated to obtain the temperature difference of the standard specimen under different uniaxial stresses, which is recorded as ΔT.

[0011] Finally, the temperature difference of the standard sample of the insulation component under zero stress is measured according to the same steps as in (2), recorded as ΔT0. The relative temperature difference of the standard sample under different stresses, namely ΔT / ΔT0, is calculated based on ΔT0. The relationship curve between the relative temperature difference and the stress of the standard sample is fitted. The vertical axis is the relative temperature difference ΔT / ΔT0, with a unit of 1; the horizontal axis is the mechanical stress, with a unit of MPa. The positive value of mechanical stress represents tension, and the negative value represents pressure. Based on this, the epoxy insulation

[0012] Relative temperature difference response model of edge parts under different stresses;

[0013] S3 measures the overall residual stress distribution of epoxy insulation parts:

[0014] Firstly, 350 measuring points were selected on the epoxy resin / alumina composite insulator, and the temperature changes of each measuring point after five minutes of irradiation were recorded by infrared laser instrument and infrared thermometer, and the relative temperature difference of each measuring point was calculated;

[0015] Secondly, the calculation results are substituted into the relative temperature difference response model in step 2) to obtain the residual stress distribution of the entire insulator.

[0016] In the present invention, the epoxy insulating part in step 2) is any insulating part made of insulating material epoxy resin / alumina composite material according to the material ratio of step 1), and its structure includes: pot insulator, three-pillar insulator, and truncated cone insulator.

[0017] In the present invention, the uniaxial stress in step 2) includes uniaxial compressive stress and uniaxial tensile stress.

[0018] In the present invention, the relative temperature difference response model established in step 2) includes other forms.

[0019] In the present invention, the number of measuring points of the residual stress distribution measurement method established in step 3) is appropriately adjusted according to the different structures of the insulating parts.

[0020] In the present invention, the step 1) comprises the following steps:

[0021] First, the curing agent, epoxy resin solution and alumina powder are mixed to prepare an epoxy resin / alumina composite material.

[0022] Then add the mixed solution into the storage bottle;

[0023] Secondly, the standard sample mold is heated to 140-150°C, and the solution in the storage bottle is evacuated to remove bubbles, and then the solution is poured into the mold and cured. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the present invention;

[0025] Figure 2 is a relative temperature difference response curve diagram of the present invention;

[0026] Figure 3 This is a physical picture of the three-pillar insulator detection of the present invention;

[0027] Figure 4 , Figure 5 This is a diagram showing the residual stress distribution test results of the three-pillar insulator of the present invention. DETAILED DESCRIPTION

[0028] The present invention will be further described below by way of examples and drawings.

[0029] S1 Preparation of standard specimens of epoxy insulation parts: First, the curing agent, epoxy resin solution, and alumina powder are mixed in a mass ratio of 0.44:1:3.2, or other suitable mass ratios, to prepare an epoxy resin / alumina composite material, and then the mixed solution is added to a storage bottle; secondly, the standard specimen mold is first heated to 140-150°C, and the solution in the storage bottle is vacuumed to remove bubbles, and then the solution is poured into the mold for curing and molding;

[0030] S2 builds the relative temperature difference response model of epoxy insulation under different stresses:

[0031] Firstly, the prepared epoxy resin / alumina composite standard samples were placed in a uniaxial stress test system and uniaxial stresses of different magnitudes were uniformly applied;

[0032] Secondly, the infrared laser instrument is used as an excitation source to irradiate the standard specimens under different uniaxial stress conditions. The center point of the standard specimen is selected as the irradiated point, and the starting temperature of the point is recorded. The temperature change at the irradiated point of the specimen is recorded by an infrared thermometer. After five minutes of irradiation, the temperature at the irradiated point of the standard specimen of the insulating part almost reaches the steady-state value. At this time, the temperature of the point is recorded, and the difference between the two recorded temperature values ​​is obtained to obtain the temperature difference of the standard specimen under different stresses, which is recorded as ΔT.

[0033] Finally, according to the above steps, the temperature difference of the standard sample of the insulating component under zero stress is measured and recorded as ΔT0. According to ΔT0, the relative temperature difference of the standard sample under different stresses, namely ΔT / ΔT0, is calculated, and the relationship curve between the relative temperature difference and the stress magnitude of the standard sample is fitted. The vertical axis is the relative temperature difference ΔT / ΔT0, with a unit of 1; the horizontal axis is the mechanical stress, with a unit of MPa, where the positive value of the mechanical stress represents tension and the negative value represents pressure. Based on this, a relative temperature difference response model of epoxy insulating components under different stresses is constructed;

[0034] S3 measures the overall residual stress distribution of epoxy insulation parts:

[0035] Firstly, 350 measuring points were selected on the epoxy resin / alumina composite three-pillar insulator, and the temperature changes of each measuring point after five minutes of irradiation were recorded by infrared laser instrument and infrared thermometer, and the relative temperature difference of each measuring point was calculated;

[0036] Secondly, the calculation results are substituted into the relative temperature difference response model in step S2 to obtain the residual stress distribution of the entire insulator.

[0037] The steps of the embodiments of the pot-type insulator and the truncated cone insulator are the same as above.

[0038] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive. Therefore, the present invention includes but is not limited to the embodiments described in the specific implementation manner. Any other implementation manners derived by those skilled in the art based on the technical solution of the present invention also fall within the scope of protection of the present invention.

Claims

1. An infrared-based detection method for residual stress distribution of epoxy insulation parts, characterized in that: By recording the temperature changes of standard samples of epoxy insulation parts under different uniaxial stresses when irradiated by an external laser source, a relative temperature difference response model of epoxy insulation parts under different stresses is constructed to monitor the residual stress of insulation parts in real time. The specific steps include: S1 Preparation of standard specimens of epoxy insulation parts; S2 builds the relative temperature difference response model of epoxy insulation under different stresses: Firstly, the prepared epoxy insulation standard samples were placed in a uniaxial stress test system, and uniaxial stresses of different magnitudes were uniformly applied, including uniaxial compressive stress and uniaxial tensile stress; Secondly, infrared rays are used as the excitation source to irradiate the standard specimens under different uniaxial stress conditions. The center point of the standard specimen is selected as the irradiated point, and the starting temperature of the point is recorded. The temperature change at the irradiated point of the specimen is recorded. The irradiation is continued until the temperature at the irradiated point of the insulating standard specimen reaches a steady-state value. At this time, the temperature of the point is recorded. The difference between the two recorded temperature values ​​is calculated to obtain the temperature difference of the standard specimen under different uniaxial stresses, which is recorded as ΔT. Finally, according to the above steps, the temperature difference of the standard sample of the insulating part under zero stress is measured and recorded as ΔT0. According to ΔT0, the relative temperature difference of the standard sample under different stresses, namely ΔT / ΔT0, is calculated, and the relationship curve between the relative temperature difference and the stress magnitude of the standard sample is fitted. Based on this, a relative temperature difference response model of the epoxy insulating part under different stresses is constructed; S3 measures the overall residual stress distribution of the epoxy insulating part: First, select several measuring points on the epoxy insulation, record the temperature changes of each measuring point after irradiation, and calculate the relative temperature difference of each measuring point; Secondly, the calculation results are substituted into the relative temperature difference response model in step S2 to obtain the residual stress distribution of the entire insulator.

2. The method according to claim 1, characterized in that The epoxy insulation structure in S2 includes: a pot-type insulator, a three-pillar insulator, and a truncated cone insulator.

3. The method according to claim 1, characterized in that The number of measuring points of the residual stress distribution measurement method established in S3 is appropriately adjusted according to the different structures of the insulating parts.

4. The method according to claim 1, characterized in that: The S1 comprises the following steps: First, a curing agent, an epoxy resin solution, and an alumina powder are mixed to prepare an epoxy resin / alumina composite material, and then the mixed solution is added into a storage bottle; Secondly, the standard sample mold is heated to 140-150°C, and the solution in the storage bottle is evacuated to remove bubbles, and then the solution is poured into the mold and cured.

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