A low-cycle fatigue test device and test method for composite blades at low temperature

Abstract

The present invention discloses a low-cycle fatigue test device and test method for composite blades at low temperature in the field of blade test technology, comprising a test box installed on a test bracket, and also comprising: a hub simulation fixture for fixing the blade root, which is arranged in the test box and is fixed to the bottom of the test bracket through the test box; a blade fixture for clamping the blade, which is arranged in the test box and is connected to a centrifugal fatigue test component and a pneumatic fatigue test component through the test box; the centrifugal fatigue test component comprises a first actuator, the piston end of the first actuator is connected to an upper pulley via a first tension sensor, the upper pulley is connected to a lower pulley via a first steel wire rope, and the lower pulley is connected to the blade fixture; the pneumatic fatigue test component comprises a second actuator, the piston end of the second actuator is connected to a second tension sensor, and the second tension sensor is connected to the blade fixture via a second steel wire rope. The present invention solves the problem of a single fatigue test scenario of existing test devices.

Description

Technical Field

[0001] The invention relates to the technical field of compressor blade testing, and in particular to a low-cycle fatigue testing device and a testing method for composite blades at low temperatures. Background Art

[0002] The main purpose of fatigue testing on carbon fiber blades of compressors is: 1. To verify the fatigue performance of blades and obtain fatigue limit and life according to damage theory; 2. To obtain fatigue failure mode of blades to improve structure and detail design. The load on carbon fiber blades is generated by work done on air during rotation. This load acts on the surface of the blade and is a flexible load. The load direction is sometimes positive and sometimes negative, and the blade deforms greatly under the load. It is very difficult to simulate the actual working condition in reality.

[0003] When the low-cycle fatigue performance of existing compressor blades needs to be verified, the material-level low-cycle fatigue test method is mainly used for evaluation. The material level is based on the low-cycle test of the test plate using the material. For the low-temperature low-cycle fatigue test of the product level, there are multi-section loaded test benches in the industry. For example, the prior art discloses a low-temperature fatigue test device for carbon fiber blades, and its publication number is: CN 114509360 A, and the publication date is: 2022.05.17. The test device assesses the bending moment of the blade, but does not assess the condition where the compressor blade is subjected to a large centrifugal force during rotation. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a low-cycle fatigue test device and test method for composite blades under low temperature, which solves the problem of single fatigue test scenario in the existing test device and realizes fatigue testing that truly simulates on-site working conditions.

[0005] The object of the present invention is achieved by: a low-cycle fatigue test device for composite blades at low temperature, comprising a test box installed on a test bracket, and also comprising:

[0006] The hub simulation fixture is used to fix the blade root, which is arranged in the test box and passes through the test box and is fixed to the bottom of the test bracket;

[0007] A blade clamp is used to clamp the blade, is arranged in the test box, and passes through the test box to connect the centrifugal fatigue test assembly and the pneumatic fatigue test assembly;

[0008] A fatigue test assembly includes a centrifugal fatigue test assembly and a pneumatic fatigue test assembly. The centrifugal fatigue test assembly includes a first actuator, a piston end of the first actuator is connected to an upper pulley via a first tension sensor, the upper pulley is connected to a lower pulley via a first steel wire rope, and the lower pulley is connected to a blade clamp; the pneumatic fatigue test assembly includes a second actuator, a piston end of the second actuator is connected to a second tension sensor, and the second tension sensor is connected to the blade clamp via a second steel wire rope.

[0009] As a preferred technical solution of a low-cycle fatigue test device for composite blades at low temperatures described in the present invention, the hub simulation fixture includes a fixed seat fixed in the test box, the upper end of the fixed seat is a pair of L-shaped claws, the bottom of the fixed seat is fixedly connected to the upper end of the pull rod, and the lower end of the pull rod is fixed to the bottom of the test bracket.

[0010] As a preferred technical solution of a low-cycle fatigue test device for composite blades at low temperature described in the present invention, the blade clamp includes a pair of clamping plates for clamping the blades, the space between the clamping plates and the blades is filled with short glass fibers, through-pin holes are provided on the clamping plates, the short glass fibers and the blades, and bolts are provided in the through-pin holes for fixing the clamping plates, the short glass fibers and the blades in series; a connecting head is also provided between the clamping plates, the connecting head is hinged in the clamping plates via a connecting pin, and the connecting head passes through the test box to connect the centrifugal fatigue test assembly and the pneumatic fatigue test assembly.

[0011] As a preferred technical solution of a low-cycle fatigue test device for composite blades at low temperature described in the present invention, a first support assembly and a second support assembly are also provided in the test box, the first support assembly includes a first set of plates installed on a first slide, and the second support assembly includes a second set of plates installed on a second slide.

[0012] As a preferred technical solution of a low-cycle fatigue test device for composite blades at low temperature described in the present invention, the test box includes a box body with one side open, the other side of the box body is fixed on the test bracket, the upper part of the box body is provided with an input pipe connecting the inside and outside of the box body, the bottom of the box body is provided with an output pipe connecting the inside and outside, and the open side of the box body is sealed by a box door.

[0013] As a preferred technical solution of the low-cycle fatigue test device for composite blades at low temperature described in the present invention, the outer periphery of the test box is wrapped with a thermal insulation layer.

[0014] As a preferred technical solution of the low-cycle fatigue test device for composite blades at low temperature described in the present invention, a temperature sensor is installed on the top of the test box.

[0015] A low-cycle fatigue test method for composite blades at low temperature, using the test device described above, comprises the following steps:

[0016] Step 1) After assembling the blade to be tested and the blade fixture, put them into the test box, fix the root end of the blade on the hub simulation fixture, and sleeve the petiole section in the first support assembly and the second support assembly. Adjust the positions of the first set of plates and the second set of plates so that the first set of plates is sleeved near the blade and the second set of plates is sleeved near the blade root, and close the box door;

[0017] Step 2) Connect the centrifugal fatigue test assembly and the pneumatic fatigue test assembly to the blade fixture, adjust the test state, and then introduce cold and hot media into the test box as needed. When the temperature in the test box reaches the preset value, turn on the centrifugal fatigue test assembly and the pneumatic fatigue test assembly, and pull the blade fixture from two directions at the same time to perform a bidirectional test.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention has multiple uses and is easy to install and process. It is more optimized than a single-channel blade fatigue test bench, has more test types than a single-direction load fatigue test bench, and can meet more stringent use environments. It can save costs and realize multiple uses of one test tool. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0021] Figure 1 It is a front view of the structure of the present invention.

[0022] Figure 2 It is a schematic diagram of the structure of the centrifugal fatigue test assembly in the present invention.

[0023] Figure 3 It is a schematic diagram of the wheel hub simulation fixture structure in the present invention.

[0024] Figure 4 It is a side view of the structure of the present invention.

[0025] Figure 5 It is a schematic diagram of the structure of the pneumatic fatigue test assembly in the present invention.

[0026] Figure 6 It is a schematic diagram of the internal structure of the test box in the present invention.

[0027] Figure 7 A schematic structural diagram of the first slide.

[0028] Figure 8It is a top view of the structure of the present invention.

[0029] Fig. 9 It is a schematic diagram of the blade clamp structure in the present invention.

[0030] Fig.10 Schematic diagram of compressor blade application scenarios.

[0031] Among them, 100, hub simulation fixture; 101, fixed seat; 101a, claw; 102, pull rod; 200, blade fixture; 201, clamp; 202, glass short fiber; 203, bolt; 204, connector; 205, connecting pin; 206, dynamic seal; 300, centrifugal fatigue test assembly; 301, first actuator; 302, first tension sensor; 303, upper pulley; 303a, upper pulley seat; 304, first steel wire rope; 305, lower pulley; 305a, lower pulley seat; 400, pneumatic fatigue test assembly; 401, second actuator; 402, second tension sensor; 403, The second steel wire rope; 500, test bracket; 501, side bracket; 502, mounting bracket; 600, test box; 601, first support assembly; 601a, first slide; 601b, first set of plates; 602, second support assembly; 602a, second slide; 602b, second set of plates; 603, box body; 604, box door; 605, input pipe; 606, output pipe; 607, slide; 608, slider; 609, support plate; 700, insulation layer; 701, box body; 702, top cover; 703, pressure rod; 800, temperature sensor; 901, blade; 902, petiole; 903, leaf root. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments 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 creative work are within the scope of protection of the present invention.

[0033] like Fig.10 As shown, it is an application scenario of a composite blade 901 for a compressor. The blade root 903 and the blade stalk 902 of the composite blade 901 are fixed in the hub, and the hub is installed on the main shaft. During the rotation of the hub, the blade root 903 of the blade 901 will be subjected to centrifugal force. At the same time, it will also be subjected to circumferential resistance and axial thrust. Since the resistance and thrust can be combined into a thrust in a certain direction close to the surface of the blade 901 (the thrust can be achieved by tension during the test), it is only necessary to simulate the centrifugal force and thrust during the test. The main detections are the end of the blade root 903 (centrifugal force) and the blade body of the blade 901 (thrust).

[0034] like Figure 1-9 A low-cycle fatigue test device for composite blades at low temperatures is shown, comprising a test box 600 mounted on a test bracket 500, and further comprising:

[0035] The hub simulation fixture 100 is used to fix the blade root 903, is disposed in the test box 600, and passes through the test box 600 and is fixed to the bottom of the test bracket 500;

[0036] The blade clamp 200 is used to clamp the blade 901, and is disposed in the test box 600, and passes through the test box 600 to connect the centrifugal fatigue test assembly 300 and the pneumatic fatigue test assembly 400;

[0037] The fatigue test assembly includes a centrifugal fatigue test assembly 300 and a pneumatic fatigue test assembly 400. The centrifugal fatigue test assembly 300 includes a first actuator 301, the piston end of the first actuator 301 is connected to an upper pulley 303 via a first tension sensor 302, the upper pulley 303 is connected to a lower pulley 305 via a first steel wire rope 304, and the lower pulley 305 is connected to a blade clamp 200; the pneumatic fatigue test assembly 400 includes a second actuator 401, the piston end of the second actuator 401 is connected to a second tension sensor 402, and the second tension sensor 402 is connected to the blade clamp 200 via a second steel wire rope 403.

[0038] Specifically, liquid nitrogen or hot air can be introduced into the test box 600 to achieve the change of its working environment temperature between -196°C and 80°C. The first actuator 301 is installed on the top of the test bracket 500, the upper pulley 303 is installed in the upper pulley seat 303a, the upper pulley seat 303a is installed at the bottom of the first tension sensor 302, the lower pulley 305 is installed in the lower pulley seat 305a, and the lower pulley seat 305a is fixedly connected to the blade clamp 200; the second actuator 401 is installed on the side bracket 501, and the side bracket 501 is fixed to the side of the test bracket 500.

[0039] It should be noted that the present invention realizes simulating the ambient temperature in a sealed test box 600 and realizing the corresponding fatigue test. During the test, the centrifugal force is transmitted to the blade clamp 200 through the first actuator cylinder 301 via the upper pulley 303, the wire rope, and the lower pulley 305. The purpose of using a flexible connection is to avoid the hidden dangers of the component force generated by the deformation of the blade 901 when the force is applied to the equipment, as well as to affect the assessment conditions, so as to assess the centrifugal force bearing capacity of the blade 901 to the greatest extent. The centrifugal force can be directly read through the first tension sensor 302; the lateral tension is transmitted to the blade clamp 200 through the second actuator cylinder 401 via the second wire rope 403; in this way, a two-way synchronous test of fatigue is realized, and the temperature simulation is closer to the real environment, and the test accuracy is higher; the operating temperature of the propeller blade is generally -55°C~60°C, and the fatigue test assessment The blade cross-section is small; the temperature of this wind tunnel compressor blade 901 is -196℃~80℃, the number of working times at different speeds and temperatures is different, and the service life is required to be longer than that of the propeller blade 901; in order to meet the working environment and life requirements of the compressor blade 901, the structural design of the wind tunnel blade 901 is more complicated. In order to better verify the life, it is necessary to conduct an assessment through a low-cycle fatigue test of the blade 901; since the aerodynamic force and centrifugal force applied to the blade 901 under different working conditions are different, in order to better simulate the stress condition of the blade 901 under actual working conditions, a two-way synchronous test is adopted, which can simultaneously assess the bending resistance of the blade 901 at the petiole 902 and the ability of the blade 901 to withstand centrifugal force at the root 903; the design of the fixture can be adjusted according to blades 901 of different sizes, thereby realizing the versatility of the test bench.

[0040] Furthermore, the wheel hub simulation fixture 100 includes a fixing seat 101 fixed in the test box 600, the upper end of the fixing seat 101 is a pair of L-shaped claws 101a, the bottom of the fixing seat 101 is fixedly connected to the upper end of the pull rod 102, and the lower end of the pull rod 102 is fixed to the bottom of the test bracket 500.

[0041] Specifically, the fixing seat 101 is used to fix the end of the blade root 903, the bottom of the fixing seat 101 is connected to the bottom of the test box 600 by screws, the pull rod 102 is used to fix the fixing seat 101 to the test bracket 500, the upper end of the pull rod 102 is set through the fixing seat 101, and the upper end is locked in the fixing seat 101 by a nut, the lower end of the pull rod 102 passes through the test bracket 500, and the lower end is also locked to the bottom of the test bracket 500 by a nut.

[0042] It should be noted that the blade root 903 is directly pushed in when installed so that it is stuck in the claw 101a, which is convenient and quick; in addition, the connection of the screws is mainly for positioning and cannot bear large pulling forces. During the centrifugal fatigue test, the maximum pulling force can reach 1000KN. If the fixing seat 101 is fixed in the test box 600 alone, this pulling force can easily deform and damage the inside of the test box 600. Therefore, the fixing seat 101 is connected to the test bracket 500 by the pull rod 102, thereby greatly improving the reliability of the centrifugal force during the detection process.

[0043] Furthermore, the blade clamp 200 includes a pair of clamps 201 for clamping the blade 901, the space between the clamps 201 and the blade 901 is filled with short glass fibers 202, and through holes are provided on the clamps 201, the short glass fibers 202, and the blade 901, and bolts 203 are provided in the through holes for fixing the clamps 201, the short glass fibers 202, and the blade 901 in series together; a connector 204 is also provided between the clamps 201, and the connector 204 is hinged in the clamps 201 via a connecting pin 205, and the connector 204 passes through the test box 600 to connect the centrifugal fatigue test assembly 300 and the pneumatic fatigue test assembly 400.

[0044] Specifically, a dynamic seal 206 is sleeved between the connector 204 and the test box 600 , and the clamping plate 201 and the blade 901 are fixed by six pin bolts 203 .

[0045] It should be noted that the splint 201 clamps and fixes the blade 901 by bolts 203 to ensure the stable transmission of centrifugal force. Glass short fibers 202 are used between the splints 201 to fix the blade 901 in the splint 201. The short fibers are easy to fill and have low strength, and will not affect the test results. Six pin bolts 203 are used to pass through the carbon beam of the blade 901 to fix the blade 901 to the splint 201. Since the carbon beam is the main load-bearing component of the blade 901, it is possible to further assess whether the strength of the carbon beam after the hole is opened can meet the design requirements, which is more stringent than the load borne by the components in the integral blade profile of other fatigue test benches.

[0046] Furthermore, a first support assembly 601 and a second support assembly 602 are provided in the test box 600. The first support assembly 601 includes a first set of plates 601b installed on a first slide 601a, and the second support assembly 602 includes a second set of plates 602b installed on a second slide 602a.

[0047] Specifically, the first slide 601a has the same structure as the second slide 602a, and both are composed of a slide 607, a slider 608, and a support plate 609 (the specific structure is shown in FIG. Figure 7), each part of the structure is connected by mechanical bolts; the first set of plates 601b is installed on the support plate, and the first set of plates 601b and the second set of plates 602b have the same structure, both of which adopt a clamp structure.

[0048] It should be noted that, during actual installation, the entire blade root 903 is buried in the wheel hub and will not produce radial displacement. The first support assembly 601 is used to support the end of the blade root 903 close to the blade 901, and the second support assembly 602 is used to support the end of the blade root 903 away from the blade 901. The two are for more realistically simulating the installation environment of the blade root 903, avoiding the influence of the corresponding measurement results of the two position displacements here during the lateral tension test, and further improving the accuracy of the test; the two slide seats are designed to support blade roots 903 of different specifications during the test.

[0049] Furthermore, the test box 600 includes a box body 603 with one side open, the other side of the box body 603 is fixed on the test bracket 500, the upper part of the box body 603 is provided with an input pipe 605 connecting the inside and outside of the box body 603, the bottom of the box body 603 is provided with an output pipe 606 connecting the inside and outside, and the open side of the box body 603 is sealed by a box door 604.

[0050] Specifically, a mounting bracket 502 is fixed to the test bracket 500 at the side of the box 603 , and the side of the box 603 is fixed to the mounting bracket 502 .

[0051] It should be noted that the bottom space of the box body 603 is limited, which makes it inconvenient to fix the box body 603. Therefore, fixing the box body 603 by mounting the bracket 502 on the side saves more space.

[0052] Furthermore, the outer periphery of the test box 600 is wrapped with a heat-insulating layer 700 .

[0053] Specifically, the thermal insulation layer 700 also adopts a box body 701 and a top cover 702 . The box body 701 is wrapped around the outer periphery of the box body 603 , and the top cover 702 is wrapped around the outer periphery of the box door 604 . The top cover 702 is pressed tightly on the box body 701 through a pressure rod 703 .

[0054] Furthermore, a temperature sensor 800 is installed on the top of the test box 600 .

[0055] It should be noted that the temperature sensor 800 can actually monitor the temperature in the test box 600 in real time to improve the accuracy of the test.

[0056] A low-cycle fatigue test method for composite blades at low temperature, using the above-mentioned test device, includes the following steps:

[0057] Step 1) Cut off the front end of the blade 901, assemble the middle part of the blade 901 with the blade fixture 200 and put it into the test box 600, pass the connector 204 out of the test box 600, clamp the blade root 903 on the fixing seat 101, sleeve the first set of plates 601b and the second set of plates 602b on the petiole 902, connect the centrifugal fatigue test assembly 300 and the pneumatic fatigue test assembly 400, adjust to the initial stretching state, adjust the positions of the first set of plates 601b and the second set of plates 602b, so that the first set of plates 601b is sleeved on the part close to the blade 901 and the second set of plates 602b is sleeved on the part close to the blade root 903, cover the box door 604, install the top cover 702, and use the pressure rod 703 to press tightly;

[0058] Step 2) cold and hot media are introduced into the test box 600 as required, and when the temperature in the test box 600 reaches a preset value, the centrifugal fatigue test assembly 300 and the pneumatic fatigue test assembly 400 are turned on, and the blade fixture 200 is pulled simultaneously from two directions, and a bidirectional test is performed at the same time, and the tension is monitored in real time.

[0059] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A low-cycle fatigue test device for composite blades at low temperatures, comprising a test box (600) mounted on a test bracket (500), characterized in that: Also includes: A wheel hub simulation fixture (100) is used to fix the blade root (903), is disposed in the test box (600), and passes through the test box (600) and is fixed to the bottom of the test bracket (500); A blade clamp (200) is used to clamp the blade (901), is disposed in the test box (600), and passes through the test box (600) to connect to the centrifugal fatigue test assembly (300) and the pneumatic fatigue test assembly (400); A fatigue test assembly comprises a centrifugal fatigue test assembly (300) and a pneumatic fatigue test assembly (400), wherein the centrifugal fatigue test assembly (300) comprises a first actuator (301), wherein a piston end of the first actuator (301) is connected to an upper pulley (303) via a first tension sensor (302), wherein the upper pulley (303) is connected to a lower pulley (305) via a first steel wire rope (304), and wherein the lower pulley (305) is connected to a blade clamp (200); wherein the pneumatic fatigue test assembly (400) comprises a second actuator (401), wherein a piston end of the second actuator (401) is connected to a second tension sensor (402), wherein the second tension sensor (402) is connected to a lower pulley (305) via a second steel wire rope (403). The hub simulation fixture (100) comprises a fixing seat (101) fixed in the test box (600), the upper end of the fixing seat (101) is a pair of L-shaped claws (101a), the bottom of the fixing seat (101) is fixedly connected to the upper end of the pull rod (102), and the lower end of the pull rod (102) is fixed to the bottom of the test bracket (500); the blade fixture (200) comprises a pair of clamping plates (201) for clamping the blade (901), the space between the clamping plates (201) and the blade (901) is filled with short glass fibers (202), and the clamping plates (201), the short glass fibers (202) and the blade (901) are provided with through pin holes, and the through pin holes are provided with clamping plates (201) and the blade (901) are provided with through pin holes. 1), glass short fibers (202) are filled, and the blades (901) are fixed in series with bolts (203); a connector (204) is also provided between the clamping plates (201), and the connector (204) is hinged in the clamping plates (201) via a connecting pin (205), and the connector (204) passes through the test box (600) to connect the centrifugal fatigue test assembly (300) and the pneumatic fatigue test assembly (400); a first support assembly (601) and a second support assembly (602) are also provided in the test box (600), and the first support assembly (601) includes a first set of plates (601b) installed on a first slide seat (601a), and the second support assembly (602) includes a first set of plates (601b) installed on a first slide seat (601a), and a second support assembly (602) includes a first set of plates (601b) installed on a first slide seat (601a). A second set of plates (602b) on the second slide seat (602a); a pull rod (102) for fixedly connecting the fixed seat (101) and the test bracket (500); the upper end of the pull rod (102) passes through the fixed seat (101) and is locked in the fixed seat (101) by a nut; the lower end of the pull rod (102) passes through the test bracket (500) and is also locked at the bottom of the test bracket (500) by a nut; the first slide seat (601a) and the second slide seat (602a) have the same structure, both consisting of a slide seat, a slider, and a support plate; the first set of plates (601b) is installed on the support plate; the first set of plates (601b) and the second set of plates (602b) have the same structure, both using a clamp structure.

2. A low-cycle fatigue test device for composite blades at low temperatures according to claim 1, characterized in that: The test box (600) comprises a box body (603) with one side open, the other side of the box body (603) being fixed on the test bracket (500), an input pipe (605) communicating with the inside and outside of the box body (603) being provided at the top of the box body (603), an output pipe (606) communicating with the inside and outside being provided at the bottom of the box body (603), and the open side of the box body (603) being sealed via a box door (604).

3. A low-cycle fatigue test device for composite blades at low temperatures according to claim 1 or 2, characterized in that: The outer periphery of the test box (600) is wrapped with a thermal insulation layer (700).

4. A low-cycle fatigue test device for composite blades at low temperatures according to claim 1 or 2, characterized in that: A temperature sensor (800) is installed on the top of the test box (600).

5. A low-cycle fatigue test method for composite blades at low temperatures, using the test device as described in any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1) cutting off the front end of the blade (901), assembling the middle part of the blade (901) with the blade fixture (200) and placing it in the test box (600), fixing the end of the blade root (903) on the hub simulation fixture (100), sleeve-mounting the petiole (902) section in the first support assembly (601) and the second support assembly (602), adjusting the positions of the first set of plates (601b) and the second set of plates (602b) so that the first set of plates (601b) is sleeved at a portion close to the blade (901) and the second set of plates (602b) is sleeved at a portion close to the blade root (903), and closing the box door (604); Step 2) Connect the centrifugal fatigue test assembly (300) and the pneumatic fatigue test assembly (400) to the blade fixture (200), adjust the test state, and then introduce cold and hot media into the test box (600) as required. When the temperature in the test box (600) reaches a preset value, start the centrifugal fatigue test assembly (300) and the pneumatic fatigue test assembly (400), and pull the blade fixture (200) from two directions at the same time to perform a two-way test.

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