Method and device for testing ablation performance of thermal protection material in variable-angle tensile state

Abstract

The invention discloses a method and a device for testing the ablation performance of a thermal protection material in a variable-angle tensile state, the method utilizes a rotating device and a tensile device to realize the tensile of a test piece and test the ablation angle, and the ablation performance of the test piece is tested at a certain ablation angle, ablation angle change rate, tensile state or tensile rate. Related devices comprise a rotating device and a stretching device. The testing method is simple and easy to implement, the testing device is simple and easy to manufacture, and the influence of the elongation deformation rate, the elongation deformation amplitude and the ablation angle on the ablation performance of the material can be finely researched.

Description

Technical Field

[0001] This invention relates to the field of ablation of polymer thermal insulation materials and the field of ablation experiments, and more specifically to a method and apparatus for testing the ablation performance of thermal protection materials under varying angle tensile conditions. Background Technology

[0002] Hypersonic vehicles often deform to mitigate aerodynamic drag and aerodynamic heating caused by high-speed flight, or to perform maneuvers, by altering their wings or servos. As vehicle components rotate and elongate, the thermal protection material on the vehicle's surface is also stretched and elongated. However, deformation of the material at high temperatures can easily lead to accelerated ablation; in severe cases, the thermal protection material may be ablated through, causing the shell material to fail due to high temperatures. Currently, however, research on the ablation characteristics of thermal protection materials under deformation conditions is lacking. Summary of the Invention

[0003] To address the shortcomings or deficiencies of existing technologies, this invention provides a method for testing the ablation performance of thermal protection materials under varying angle tensile conditions.

[0004] Therefore, the ablation performance testing method for thermal protective materials under variable-angle tensile conditions provided by the present invention employs a variable-angle tensile device, which includes a tensile device and a rotating platform, wherein the tensile device is disposed on the rotating platform, and the method includes: Prepare a test specimen, the specimen being rectangular or square in shape; then mount both ends of the test specimen onto a tensile device, with the center of the test specimen passing through the axis of the rotating platform; place the ablation gun beside the test specimen, with the nozzle of the ablation gun horizontally facing the center of the test specimen, and set the initial distance between the center of the test specimen and the nozzle of the ablation gun; then perform one of the following tests on the test specimen: (1) The test piece is stretched at both ends by a stretching device to make it at the first tensile deformation rate. The first ablation angle is set by a rotating platform. Then the ablation gun is turned on to ablate the test piece for the first fixed duration. After the ablation is completed, the linear ablation rate and carbonization ablation rate of the test piece are detected. (2) Set the second ablation angle by rotating the platform; then drive the stretching device to stretch the two ends of the test piece at a certain speed so that the test piece is at the first stretching deformation rate. At the same time as the stretching device starts to move, open the ablation gun to perform the second fixed-time ablation on the test piece. When the ablation is completed, the stretching device stops moving. Then detect the linear ablation rate and carbonization ablation rate of the test piece. (3) The test specimen is stretched at both ends by the stretching device so that the test specimen is at the third tensile deformation rate; then the rotating platform is driven to rotate at the first rotation speed. At the same time as the rotating platform starts to rotate, the ablation gun is opened to ablate the specimen for the third fixed time. When the ablation is completed, the rotating platform stops moving. Then the linear ablation rate and carbonization ablation rate of the test specimen are detected. (4) Drive the tensile device to stretch both ends of the test piece so that the test piece is at the fourth tensile deformation rate. At the same time as the tensile device starts to stretch, drive the rotating platform to rotate at the second rotation speed. At the same time as the rotating platform and the tensile device start to rotate, open the ablation gun to ablate the test piece for the fourth fixed duration. At the same time as the ablation is completed, the tensile device and the rotating platform stop moving. Then, detect the linear ablation rate and carbonization ablation rate of the test piece. When testing and comparing multiple test pieces, the shape and size of each test piece and the test parameters are the same. The test parameters include: the initial distance between the center of the test piece and the nozzle of the ablation gun, and the tensile deformation rate, tensile deformation speed, ablation angle and rotation speed in each test. The tensile deformation rate Δ = (D1 - D0) / D0, where D0 is the initial length of the test piece along the tensile direction, and D1 is the length of the test piece after stretching; the tensile deformation rate is the tensile deformation rate that occurs per unit ablation time. The ablation angle is the angle between the direction of the ablation flame airflow ejected from the ablation gun and the surface of the test piece, and the ablation angle ranges from 0 to 90°. The rotation speed is taken as the rate of change of the ablation angle, which is the change value of the ablation angle per unit ablation time.

[0005] An alternative approach is to set the initial effective dimensions of the test piece as follows: the distance between the two ends of the stretched piece is 100mm in length, 50mm in width, and 10mm in thickness.

[0006] An alternative is to ablation time of 20 seconds.

[0007] Alternatively, a strain gauge or thermocouple is provided at the center of the surface of the test piece facing away from the ablation gun. The strain gauge is used to monitor the tensile state of the test piece, and the thermocouple is used to monitor the back temperature of the test piece.

[0008] The present invention also provides a testing apparatus for implementing the above method, the apparatus comprising a rotating platform and a tensile device; the tensile device comprising a hydraulic drive device, a hydraulic rod 1, a hydraulic rod 2, a slide rail and two mounting bases; The mounting base includes a base and a clamping plate, the clamping plate is disposed on the base, and the clamping plate is provided with a fixing through hole; The slide rail and hydraulic drive device are mounted on a rotating platform. Two bases are slidably mounted on the slide rail. The hydraulic drive device is connected to the rotating platform's pivot. Hydraulic rod 1 and hydraulic rod 2 are both connected to the hydraulic drive device, and the hydraulic drive device is located between the two hydraulic rods. At the same time, the hydraulic drive device and the two hydraulic rods are located between the two bases. The hydraulic drive device drives the two hydraulic rods to extend and retract. The two hydraulic rods respectively drive the two bases to move along the slide rail. Meanwhile, the extension directions of the two hydraulic rods are opposite to each other, and their retraction directions are opposite to each other.

[0009] Alternatively, the rotating platform is mounted on a slide rail. Two hydraulic rods push two bases away from the hydraulic drive device. The bases have alignment holes at their bottoms to accommodate the ends of the hydraulic rods.

[0010] This invention allows for precise study of the effects of elongation deformation rate and elongation deformation amplitude on the ablation properties of materials. The related testing equipment is simple to manufacture and the testing methods are easy to implement. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of the testing device of the present invention. Figure 2 This is a schematic diagram of the structure on which the test specimen is installed. Detailed Implementation

[0012] Unless otherwise specified, the scientific and technical terms used in this article are intended for understanding by those skilled in the art.

[0013] The tensile state, tensile process, or deflection of the equivalent heat source in the test method of this invention are used to simulate the usage state of the material under test in the actual use environment, such as simulating the usage environment of protective materials on devices such as aircraft wings, movable parts in the combustion chamber of ramjet engines, etc.; the correlation rate is the rate of change of the corresponding state.

[0014] Specifically, in the testing method, the ablation angle can be used to simulate the change in angle between the movable parts of an aircraft wing or ramjet engine combustion chamber and the direction of the high-temperature gas flow during the ablation process. The ablation angle change rate is used to simulate the rate of angle change caused by this action. The reasonable range of the ablation angle is 0-90°, and the angle change rate is ≤10° / s. The heat source in this invention's test is an ablation gun. During the ablation process, the direction of the hot airflow from the ablation gun always passes through the center of the test piece. The angle between the hot airflow direction and the surface of the test piece is adjusted by rotating the platform according to the testing requirements; this is the ablation angle, which is the angle between the direction of the ablation flame airflow and the surface of the test piece, ranging from 0 to 90°. The ablation angle change rate is the change in the ablation angle per unit time within the ablation duration. Wherein, 90° is perpendicular to the material surface, and 0° is parallel to the material surface.

[0015] Tensile deformation can be used to simulate the elongation and deformation of moving parts in aircraft wings, ramjet engine combustion chambers, and other devices. Tensile deformation rate is used to simulate the tensile deformation rate of such devices. For actual scenarios, the tensile deformation rate of the material is controlled to be ≤20% and the tensile deformation rate is controlled to be ≤500mm / min during testing.

[0016] In the specific plan, a unified measurement standard is required to objectively compare the ablation performance of each sample under rotational tensile conditions. This is achieved by standardizing the measurement standards for various relevant parameters in the unified measurement method. These parameters include the shape and size of the sample, the initial distance from the center of the sample to the ablation gun nozzle, the ablation time, the rotational tensile evaluation method and related indicators, and the ablation apparatus. Unless otherwise specified, the units for dimensional parameters in the plan can be mm, and the units for time can be seconds.

[0017] The ablation-related parameters, such as the size of the test specimen, the initial distance between the center of the sample and the ablation gun nozzle, and the ablation time, can be determined with reference to GJB 323A-1996 "Test Method for Ablation of Ablation Materials". The effective dimensions are 100mm in length, 50mm in width, and 10mm in thickness (the thickness can be appropriately reduced if the specimen has high hardness and is not easily deformed; for specimens with other special requirements, the specimen size can be changed according to actual needs). The initial distance between the center of the sample and the ablation gun nozzle is 20mm, and the ablation time is 20s. Other uniform values ​​can also be set according to actual needs. In addition, the tensile state of the specimen and / or the deflection angle relative to the heat source (ablation gun) should be selected according to the material's application scenario.

[0018] The calculation methods for the linear ablation rate and carbonization ablation rate in the method of this invention are as follows: Linear ablation rate = (overall thickness of the specimen material after ablation - original thickness of the material) / ablation time; Carbonization ablation rate = (thickness of the specimen material after ablation with the carbonized layer removed - original thickness of the material) / ablation time.

[0019] The apparatus for implementing the testing method of the present invention can realize the rotation (relative to the heat source) and stretching degree of the test piece according to the testing requirements, and the rotation and stretching rate of the test piece are controllable.

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1: This embodiment is a specific testing apparatus for implementing the testing method of the present invention, and includes participants. Figure 1 and2 As shown, the device includes a rotating platform 1 and a tensioning device. The tensioning device includes a hydraulic drive device 6, two hydraulic rods 5 (i.e., hydraulic rod 1 and hydraulic rod 2), a slide rail 2, and two mounting seats (3,4). The mounting seat includes a base 31 and a clamping plate 32 set on the base. The clamping plate is provided with a fixing through hole 33. In this embodiment, the slide rail 2 is mounted on the rotating platform 1, and the hydraulic drive device 6 is fixedly mounted in the middle of the slide rail. Two bases are slidably mounted on the slide rail and located on both sides of the hydraulic drive device. The hydraulic drive device passes through the rotating platform's axis, and two hydraulic rods 5 are connected to the hydraulic drive device, with the hydraulic drive device positioned between the two hydraulic rods. The hydraulic drive device and the two hydraulic rods are located between the two bases. The hydraulic drive device drives the two hydraulic rods to extend and retract, and the two hydraulic rods respectively drive the two bases to move along the slide rail. Simultaneously, the extension directions of the two hydraulic rods are opposite, and their retraction directions are opposite. In this embodiment, the two hydraulic rods respectively push the two bases away from the hydraulic drive device. To ensure reliable contact between the hydraulic rods and the bases, the bottom of the base is provided with alignment holes 34 to accommodate the ends of the hydraulic rods.

[0022] Before testing, ensure that the end of the hydraulic rod is aligned and in contact with the alignment hole. Adjust the base to be symmetrically distributed on both sides of the hydraulic drive device, with the end of the hydraulic rod in contact with the alignment hole 34. Place both ends of the test piece 7 in the clamping plate and tighten it with bolts installed in the fixing through holes. At this time, the test piece is in an unstressed and undeformed state, and the center of the test piece passes through the rotating device's axis. The ablation gun is placed directly in front of the test piece, and the direction of the hot airflow passes through the center of the test piece. During testing, set the rotation parameters of the drive motor of the rotating platform to control the ablation angle of the test piece during the ablation process; control the extension length and speed of the hydraulic rod to control the degree and rate of elongation and deformation of the test piece.

[0023] In some other schemes, strain gauges can be attached to the back of the specimen to measure the degree of deformation, or thermocouples can be attached to the back of the specimen to measure the back temperature over time, thus examining changes in the material's thermal protection performance.

[0024] The following embodiments use the above-mentioned device to conduct ablation tests on specific protective materials. The material being tested is ethylene propylene diene insulation material. The thickness of the test piece is 10 mm and the width is 50 mm. After the test piece is installed, the effective length of the test piece between the two mounting bases is 100 mm. The ablation experiment is carried out based on the oxyacetylene ablation device according to the national military standard GJB 323A-1996. The ablation time is 20 s. Initially, the center of the test piece is moved to 20 mm away from the nozzle of the ablation gun.

[0025] Example 2: This embodiment studies the ablation performance of materials under the conditions of a fixed ablation angle of 90° and a fixed tensile deformation rate of 10%.

[0026] The rotating platform was rotated to the test angle and fixed. Next, the hydraulic drive device was used to stretch the material to the test deformation length and then fixed. After setting the ablation gun, ablation began for 20 seconds. After the test, the linear ablation rate of the material was measured to be 0.514 mm / s, and the carbonization ablation rate was 0.671 mm / s.

[0027] Example 3: This embodiment studies the ablation performance of materials under the conditions of a fixed ablation angle of 90° and a tensile deformation rate of 60 mm / min.

[0028] First, the center of the specimen was moved to a position 20 mm from the nozzle of the ablation gun. Then, the hydraulic press was controlled to stretch the material at a constant rate, and the ablation time was calculated. After the test, the linear ablation rate of the material was found to be 0.373 mm / s, and the carbonization ablation rate was 0.426 mm / s.

[0029] Example 4: This embodiment studies the ablation performance of thermal insulation materials under the conditions of a fixed tensile deformation rate of 10% and a rotational angular velocity of 2.25° / s (starting position of 90°).

[0030] First, the center of the specimen was moved to a position 20 mm from the nozzle of the ablation gun. The platform was then rotated at a certain angular velocity by a motor, the ablation gun was ignited, and the ablation time was calculated. After the test, the linear ablation rate of the material was found to be 0.442 mm / s, and the carbonization ablation rate was 0.546 mm / s.

[0031] Example 5: This example studies the ablation performance of the thermal insulation material under the conditions of a tensile deformation rate of 60 mm / min and a certain rotational angular velocity of 2.25° / s (starting position of 90°): First, the center of the specimen was moved to a position 20 mm away from the nozzle of the ablation gun. At the same time, the hydraulic press was controlled to stretch the material at a constant rate, and the motor was controlled to rotate the platform at a certain angular velocity. Meanwhile, the spray gun was ignited, and the ablation time was calculated. The ablation time was 20 seconds. After the test, the linear ablation rate of the material was found to be 0.407 mm / s, and the carbonization ablation rate was 0.527 mm / s.

[0032] It can be seen that under tensile deformation ablation environment, the deformation of the material has a greater impact on its ablation resistance than the angle change. However, under the complex conditions where tension and angle change coexist, the ablation rate is affected by multiple coupled factors, resulting in a large variation in the ablation rate.

[0033] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for testing the ablative performance of a thermal protection material in an angled tensile state, characterized in that, The method is performed by using a variable angle stretching device, the variable angle stretching device comprises a stretching device and a rotating platform, the stretching device is arranged on the rotating platform, and the method comprises the following steps: A test piece is prepared, the test piece is in a rectangular or square shape; then the two ends of the test piece are installed on the stretching device, and the center of the test piece passes through the rotating shaft of the rotating platform; an ablation gun is arranged beside the test piece, the nozzle of the ablation gun is horizontally opposite to the center of the test piece, and the initial distance between the center of the test piece and the nozzle of the ablation gun is set; then the test piece is tested in one of the following manners: (1) the two ends of the test piece are stretched by the stretching device so that the test piece is in a first stretching deformation rate, and a first ablation angle is set by the rotating platform; then the ablation gun is turned on to ablate the test piece for a first fixed time; after the ablation is completed, the linear ablation rate and the carbonization ablation rate of the test piece are detected; (2) a second ablation angle is set by the rotating platform; then the two ends of the test piece are stretched by the stretching device at a certain movement rate so that the test piece is in a first stretching deformation rate, the stretching device starts to move at the same time that the ablation gun is turned on to ablate the test piece for a second fixed time, the stretching device stops moving at the same time that the ablation is completed, and then the linear ablation rate and the carbonization ablation rate of the test piece are detected; (3) the two ends of the test piece are stretched by the stretching device so that the test piece is in a third stretching deformation rate; then the rotating platform is driven to rotate at a first rotating speed, the ablation gun is turned on to ablate the test piece for a third fixed time at the same time that the rotating platform starts to rotate, the rotating platform stops moving at the same time that the ablation is completed, and then the linear ablation rate and the carbonization ablation rate of the test piece are detected; (4) the two ends of the test piece are stretched by the stretching device so that the test piece is in a fourth stretching deformation rate, the stretching device starts to move at the same time that the rotating platform is driven to rotate at a second rotating speed, the ablation gun is turned on to ablate the test piece for a fourth fixed time at the same time that the rotating platform and the stretching device start to rotate, the stretching device and the rotating platform stop moving at the same time that the ablation is completed, and then the linear ablation rate and the carbonization ablation rate of the test piece are detected; When a plurality of test pieces are tested and compared, the shapes and sizes of the test pieces and the test parameter conditions of the test pieces are the same, and the test parameter conditions comprise the initial distance between the center of the test piece and the nozzle of the ablation gun and the stretching deformation rate, the stretching deformation rate, the ablation angle and the rotating speed in each test; The stretching deformation rate Δ=(D1-D0) / D0, D0 is the length of the test piece in the stretching direction at the initial stage, and D1 is the length of the test piece after stretching; the stretching deformation rate is the stretching deformation rate per unit ablation time; The ablation angle is the angle between the direction of the ablation flame jet of the ablation gun and the surface of the test piece, and the ablation angle is 0-90°; The rotating speed is the ablation angle change rate, and the ablation angle change rate is the change value of the ablation angle per unit ablation time.

2. The method of claim 1, wherein the method is a method of testing the ablative performance of a thermal protection material in an angled tensile state, characterized in that, The distance between the two ends of the test piece is 100 mm, the width is 50 mm, and the thickness is 10 mm.

3. The method of claim 1, wherein the method is a method of testing the ablative performance of a thermal protection material in an angled tensile state, characterized in that, The ablation time is 20 s.

4. The method of claim 1, wherein, The surface center of the to-be-tested piece opposite to the ablation gun is provided with a strain gauge for monitoring the tensile state of the to-be-tested piece and a thermocouple for monitoring the back temperature of the to-be-tested piece.

5. A test device for implementing the method of claim 1, characterized in that, The device comprises a rotating platform and a stretching device; the stretching device comprises a hydraulic driving device, a hydraulic rod 1, a hydraulic rod 2, a slide rail and two mounting seats; The mounting seat comprises a base and a clamping plate, the clamping plate is arranged on the base, and a fixing through hole is arranged on the clamping plate; The slide rail and the hydraulic driving device are mounted on the rotating platform, the two bases are slidably mounted on the slide rail, the hydraulic driving device passes through the rotating platform rotating shaft, the hydraulic rod 1 and the hydraulic rod 2 are connected with the hydraulic driving device, the hydraulic driving device is located between the two hydraulic rods, the hydraulic driving device and the two hydraulic rods are located between the two bases, the hydraulic driving device drives the two hydraulic rods to extend and retract, the two hydraulic rods drive the two bases to move along the slide rail respectively, and the extension directions of the two hydraulic rods are opposite and the retraction directions are opposite.

6. The test device of claim 5, wherein, The rotating platform is mounted on the slide rail.

7. The test device of claim 5, wherein, The two hydraulic rods respectively push the two bases to move away from the hydraulic driving device.

8. The test device of claim 5, wherein, The base bottom is provided with an alignment hole for accommodating the end of the hydraulic rod.

Images