Test device and test method for simulating aircraft wheel landing rotation friction

Abstract

The invention provides a test device and a test method for simulating aircraft wheel landing rotation friction, the test device for simulating aircraft wheel landing rotation friction comprises a rigid plane, an accelerated rolling direction is arranged on the rigid plane, two sides of the accelerated rolling direction are respectively an initial side and a target side, and the test device further comprises a swing part, a rotating part and a driving part, and the first end of the swinging piece is hinged above the rigid plane. According to the test device for simulating aircraft wheel landing rotation friction, the ejection assembly is additionally arranged, an elastic piece in the ejection assembly can be used for being matched with a positioning piece to drive a swing piece to swing at high acceleration, and therefore the high-acceleration rolling behavior of a rolling wheel is stimulated; the image acquisition assembly is used for acquiring the deformation image of the roller surface in the test state and performing digital image correlation (DIC) analysis to obtain the deformation condition and the frictional wear characteristic of the roller surface, so that the dynamic instability phenomenon and the surface crease wear phenomenon possibly occurring in high-acceleration and strong-adhesion rolling contact can be conveniently explored.

Description

Technical Field

[0001] The present invention relates to the technical field of tire testing, and in particular to a test device and a test method for simulating the landing rotation friction of aircraft wheels. Background Art

[0002] At the moment of wheel contact, aircraft wheels contact the runway at extremely high slip speeds, generating intense friction. The torque caused by friction causes the wheels to roll at high accelerations. In approximately 0.1 seconds, the wheels accelerate from zero speed to a speed matching the aircraft's taxiing speed. This extreme high-acceleration rolling process is known as the wheel speed build-up (pin-up). At the moment of wheel contact, the rubber tires and the ground generate significant frictional heat, which can even cause smoke and combustion. The intense friction of high-acceleration rolling can not only cause premature wear and failure of the rubber tires, but also cause runway unevenness, increasing operational and maintenance costs. More importantly, the friction and wear characteristics of high-acceleration rolling during wheel contact inevitably affect aircraft landing safety. Therefore, experimental research on the high-acceleration rolling friction behavior during aircraft landing is extremely important. Due to the extremely large rolling acceleration during landing, high-acceleration rolling friction experiments between wheels and the ground are extremely difficult. According to a National Aeronautics and Space Administration report (NASA RP-1189), the Aircraft Landing Dynamics Facility at the Langley Research Center uses a unique water jet acceleration system to achieve high-acceleration rolling of aircraft wheels; in China, the "drop shock" test method is usually used to test the impact resistance of aircraft landing gear.

[0003] However, the above-mentioned prior art has the following deficiencies in the application process:

[0004] The testing equipment required for full-scale prototype experiments is bulky and costly, making it difficult for research institutions to complete. The experimental method for testing the acceleration, braking performance and rolling resistance of rubber tires widely uses a scheme in which the rubber wheel rolls against the runway wheel, which cannot well reflect the working conditions of a circular roller rolling at high acceleration on a straight runway.

[0005] Therefore, in order to solve the above problems, the present invention proposes a test device for simulating the landing rotation friction of aircraft wheels. Summary of the Invention

[0006] In order to solve the above-mentioned technical problems existing in the existing high-speed friction test of aircraft wheels touching the ground, the present invention provides a test device and a test method for simulating the landing rotation friction of aircraft wheels.

[0007] According to one object of the present invention, the present invention provides a test device for simulating the landing rotation friction of aircraft wheels, comprising a rigid plane, wherein an accelerated rolling direction is provided on the rigid plane, wherein two sides of the accelerated rolling direction are an initial side and a target side, respectively, and further comprising:

[0008] a swinging member, wherein a first end of the swinging member is hingedly connected to the upper side of the rigid plane, a second end of the swinging member is rotatably connected to a rubber roller, and the second end of the swinging member moves along the accelerated rolling direction so that the roller has at least two working states, namely an initial state and a test state, when the roller is in the initial state, the roller is located above the initial side of the rigid plane, and when the roller is in the test state, the roller is located on the target side of the rigid plane and rollingly contacts the rigid plane;

[0009] an ejection assembly, the ejection assembly comprising a positioning member and an elastic member, the positioning member being configured to constrain the roller to maintain an initial state, and the elastic member being configured to provide a force toward the target side for the roller in the initial state;

[0010] An image acquisition component can respectively acquire images of the deformation of the roller surface under the test state and perform DIC analysis to obtain the deformation condition and friction and wear characteristics of the roller surface.

[0011] Preferably, in the vertical direction, the height between the center of the roller in the initial state and the center of the roller in the test state is the swing height, and the swing height is adjustable.

[0012] Preferably, the positioning member is detachably connected to the roller in the initial state, one end of the elastic member is connected to the second end of the swing member, and the other end of the elastic member is connected to the target side of the roller in the initial state;

[0013] When the roller is in an initial state, the elastic member provides the roller with an elastic force toward a target side.

[0014] Preferably, the positioning member is an electric unhooking member;

[0015] There are two elastic members, one end of each of the two elastic members is connected to the second end of the swing member, and the other ends of each of the two elastic members are located on both sides of the roller axis.

[0016] Preferably, the rigid plane is a transparent rigid plane, and the image acquisition component includes:

[0017] A contact surface collection member is provided below the rigid plane and can pass through the rigid plane to record changes in the contact area;

[0018] The wheel side collection piece is arranged on the outside of the roller in the direction of the roller axis, and the wheel side collection piece can synchronously record the wrinkle deformation, surface buckling and surface fluctuation that may occur on the roller surface.

[0019] Preferably, the contact surface acquisition component and the wheel side acquisition component are both high-speed cameras, the contact surface acquisition component acquires the contact area image of the roller through a transparent rigid plane, and the wheel side acquisition component acquires the side wall image of the roller, and the acquisition rates of the contact surface acquisition component and the wheel side acquisition component are the same.

[0020] Preferably, the tread pattern of the roller is variable, and grooves and media are provided on the rigid plane.

[0021] A test method, comprising the above-mentioned test device for simulating aircraft wheel landing rotation friction, comprises the following steps:

[0022] S1. A random speckled pattern is sprayed on the outer side of the roller in the axial direction and in the radial direction;

[0023] S2. Release the swinging member by the ejection assembly, switch the roller from the initial state to the test state, and during the process, synchronously capture images of the outer side of the roller in the axial direction and the outer side in the radial direction at the same rate by the image acquisition assembly;

[0024] S3. Process the image collected in S2 to obtain the deformation and friction and wear characteristics of the roller surface.

[0025] Preferably, step S3 includes:

[0026] S31. Track the change of the speckle pattern to extract the displacement field in the plane, calculate the two-dimensional strain field, and obtain the displacement field data by preliminary DIC calculation;

[0027] S32. Adjust the displacement field data size so that the strain calculation points correspond to the original image pixels one by one.

[0028] Preferably, the experiment under each loading state is repeated multiple times, and the average value is taken as the final data, and the standard deviation is calculated to evaluate the fluctuation between experiments.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] This test device, which simulates the rotational friction of aircraft wheels during landing, places a roller above a rigid surface via an oscillating member, creating a situation similar to a physical pendulum. The movement of the oscillating member gives the roller a certain initial velocity. Before the roller contacts the rigid surface, the oscillating member drives the roller to oscillate, achieving a translational velocity in the direction of accelerated rolling. Once the roller contacts the rigid surface, the friction torque generated by the adhesion between the two interfaces causes the roller to achieve rotational acceleration. Once the oscillating member is connected to the roller, it forces the roller to roll. By varying the oscillation height, different rolling accelerations can be achieved.

[0031] Due to the limited length of the swinging member, in order to enable the roller to achieve a high-acceleration rolling state, an ejection component is added on the basis of the above swinging scheme. The elastic member in the ejection component can be used in conjunction with the positioning member to drive the swinging member to swing at a high acceleration, thereby stimulating the high-acceleration rolling behavior of the roller;

[0032] In addition, the image acquisition component is used to collect images of the roller surface deformation under the test state and perform digital image correlation (DIC) analysis to obtain the deformation and friction and wear characteristics of the roller surface, which facilitates the exploration of dynamic instability and surface crease wear that may occur in high-acceleration and strong adhesion rolling contact.

[0033] The present invention is further described below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram from one perspective of a swing drive mode of a test device for simulating aircraft wheel landing rotation friction according to the present invention;

[0035] Figure 2 This is a schematic diagram from another perspective of the swing drive mode of the test device for simulating aircraft wheel landing rotation friction according to the present invention;

[0036] Figure 3 A schematic diagram showing one perspective of a catapult drive method of a test device for simulating aircraft wheel landing rotation friction according to the present invention;

[0037] Figure 4 This is a schematic diagram of an elastic member in a catapult drive mode of a test device for simulating aircraft wheel landing rotation friction according to the present invention;

[0038] Figure 5 This is a schematic diagram from another perspective of the ejection drive method of the test device for simulating aircraft wheel landing rotation friction according to the present invention. DETAILED DESCRIPTION

[0039] The following description is intended to fully illustrate the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are intended to be exemplary only, and those skilled in the art will readily appreciate other obvious variations. The basic principles of the present invention defined in the following description may be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the present invention.

[0040] See also Figures 1 to 5 The present invention provides a technical solution: a test device for simulating the landing rotation friction of aircraft wheels, comprising: a rigid plane 100, wherein the rigid plane 100 is provided with an accelerated rolling direction, wherein the two sides of the accelerated rolling direction are an initial side and a target side respectively, and further comprising:

[0041] A rod-shaped or rope-shaped swinging member 200, wherein a first end of the swinging member 200 is hinged above the rigid plane 100, and a second end of the swinging member 200 is rotatably connected to a roller 300, wherein the roller 300 is a rubber roller 300. The second end of the swinging member 200 moves along the accelerated rolling direction, so that the roller 300 has at least two working states, namely an initial state and a test state. When the roller 300 is in the initial state, the roller 300 is located above the initial side of the rigid plane 100. When the roller 300 is in the test state, the roller 300 is located on the target side of the rigid plane 100 and rolls in contact with the rigid plane 100.

[0042] An ejection assembly 400, comprising a positioning member 401 and an elastic member 402, wherein the positioning member 401 is configured to constrain the roller 300 to maintain an initial state, and the elastic member 402 is configured to provide a force toward the target side for the roller 300 in the initial state;

[0043] The image acquisition component 500 can respectively capture images of the surface deformation of the roller 300 under the test state and perform digital image correlation (DIC) technology analysis to obtain the deformation and friction and wear characteristics of the surface of the roller 300.

[0044] The test device places a roller 300 above a rigid plane 100 via an oscillating member 200, creating a situation similar to a physical pendulum. The movement of the oscillating member 200 gives the roller 300 a certain initial velocity. Before the roller 300 contacts the rigid plane 100, the oscillating member 200 drives the roller 300 to swing to obtain a translational velocity in the accelerated rolling direction. When the roller 300 contacts the rigid plane 100, the friction torque generated by the interfacial adhesion between the two causes the roller 300 to obtain a clockwise rotational acceleration, where the friction torque is approximately equal to the tangential adhesion friction multiplied by the radius of the roller 300. The roller 300 accelerates and rolls until the rolling speed matches the swinging speed of the oscillating member 200. That is, after the oscillating member 200 is connected to the roller 300, it can force the roller 300 to roll. Different rolling accelerations can be obtained by changing the swinging height.

[0045] Although changing the swing height can change the rolling acceleration, due to the limited length of the swing member 200, it is difficult to achieve a high starting acceleration simply by swinging. To enable the roller 300 to achieve a high-acceleration rolling state, an ejection assembly 400 is added to the above swing solution. The elastic member 402 in the ejection assembly 400 cooperates with the positioning member 401 to drive the swing member 200 to swing at a high acceleration, thereby stimulating the high-acceleration rolling behavior of the roller 300.

[0046] In addition, the image acquisition component 500 captures images of the surface deformation of the roller 300 under the test state and performs DIC analysis to obtain the deformation and friction and wear characteristics of the surface of the roller 300, which facilitates the exploration of dynamic instability and surface crease wear that may occur in high-acceleration, strong adhesion rolling contact.

[0047] See also Figure 1 In the vertical direction, the height between the center of the roller 300 in the initial state and the center of the roller 300 in the test state is the swing height, and the swing height is adjustable.

[0048] See also Figure 3 Regarding the specific structure of the ejection assembly 400, the positioning member 401 is detachably connected to the roller 300 in the initial state, one end of the elastic member 402 is connected to the second end of the swing member 200, and the other end of the elastic member 402 is connected to the target side of the roller 300 in the initial state. When the roller 300 is in the initial state, the elastic member 402 is stretched in its length direction, and the elastic member 402 provides the roller 300 with an elastic force toward the target side.

[0049] In this embodiment, see Figure 4 There are two elastic members 402 , one end of each of the two elastic members 402 is connected to the second end of the swing member 200 , and the other ends of each of the two elastic members 402 are located on both sides of the axis of the roller 300 ;

[0050] The positioning member 401 is an electric unhooking device, which is a prior art and will not be described in detail here.

[0051] In order to study the friction and wear behavior of the rubber roller 300 surface during accelerated rolling friction, the rigid plane 100 is a transparent rigid plane 100. Preferably, the rigid plane 100 is a transparent tempered glass.

[0052] See also Figure 1-5 , the image acquisition component 500 includes:

[0053] A contact surface collection member 501 is provided below the rigid plane 100 and can pass through the rigid plane 100 to record changes in the contact area;

[0054] The wheel-side collection piece 502 is arranged on the outside of the roller 300 in the axial direction. The wheel-side collection piece 502 can synchronously record the wrinkle deformation, surface buckling and surface fluctuation that may occur on the surface of the roller 300. Preferably, one wheel-side collection piece 502 is respectively provided on both sides of the axial direction of the roller 300.

[0055] In this embodiment, the contact surface acquisition component 501 and the wheel side acquisition component 502 are both high-speed cameras;

[0056] Preferably, the high-speed camera is a Chronos 2.1-HD high-speed camera, and the contact surface acquisition component 501 and the wheel side acquisition component 502 respectively acquire the strain conditions of the contact surface and the side of the roller 300, wherein the contact surface acquisition component 501 acquires the contact area image of the rubber roller 300 through the transparent rigid plane 100 at a rate of 1000FPS, that is, the top view of the rubber roller 300, and the wheel side acquisition component 502 shoots the side wall of the roller 300 and also acquires images at a rate of 1000FPS to ensure synchronization with the top view.

[0057] In order to compare with the actual situation, the tread pattern of the roller 300 can be further changed, and the situation where the rigid plane 100 has special grooves and media can be considered to explore and discover new unknown phenomena. In one embodiment, the medium is a highly viscous substance, and the adhesion strength of the contact interface is improved by applying the highly viscous substance, thereby studying the complex deformation behavior of the rubber wheel surface under strong adhesion and high-acceleration rolling conditions.

[0058] In summary, the test device uses swinging and ejection methods to drive the rubber roller 300 to roll on the rigid surface 100 at an accelerated speed. There are two ways to apply normal loading: one is to change the axle weight of the roller 300; the other is to change the length of the rocker to change the contact interference between the roller 300 and the rigid surface 100.

[0059] In terms of tangential loading, although changing the swing height can change the rolling acceleration, due to the limited length of the swing member 200, it is not easy to obtain a high starting acceleration by simply swinging. In order to trigger the high-acceleration rolling form, the test device adopts a catapult-start scheme to stimulate high-acceleration rolling behavior. Assuming that the mass of the rubber roller 300 is about 500 grams and the elastic force of the elastic member 402 is about 50 Newtons, it is roughly estimated that the acceleration at the initial moment of ejection can reach about 100m / s2, about 10g, where g is the acceleration of gravity. Therefore, the test device adopts a catapult-start scheme to achieve high-acceleration rolling behavior of the rubber wheel.

[0060] Based on the above-mentioned test device for simulating aircraft wheel landing rotation friction, the present invention also provides a test method that uses DIC technology to quantitatively study the full-field displacement and strain changes of the rubber roller 300 during the loading process, specifically comprising the following steps:

[0061] S1. A random speckle pattern is sprayed on the outer side of the roller 300 in the axial direction and the outer side in the radial direction, and the speckle pattern provides a high-contrast reference for subsequent DIC analysis;

[0062] S2 releases the swing member 200 by the ejection assembly 400, the roller 300 is switched from the initial state to the test state, during which the image acquisition assembly 500 synchronously captures the image of the roller 300 in the axial direction and the radial direction at the same rate;

[0063] S3. Process the image collected in S2 to obtain the deformation and friction and wear characteristics of the surface of the roller 300.

[0064] The step S3 comprises:

[0065] S31. Track the change of the speckle pattern to extract the displacement field in the plane, calculate the two-dimensional strain field, and obtain the displacement field data by preliminary DIC calculation;

[0066] S32. Adjust the displacement field data size so that the strain calculation points correspond one-to-one with the original image pixels;

[0067] S33. The experiment under each loading state was repeated multiple times, and the average value was taken as the final data. The standard deviation was calculated to evaluate the fluctuation between experiments.

[0068] In this embodiment, step S3 uses the open source software Ncorr to perform DIC analysis on the image collected in S2. Ncorr software extracts the displacement field in the plane by tracking the changes in the speckle pattern, and then calculates the two-dimensional strain field. The displacement field data obtained after the preliminary DIC calculation is resized using the imresize function in MATLAB so that the strain calculation points correspond one-to-one with the original image pixels. To improve the reliability of the data, the experiment under each loading state is repeated three times, and the average value is taken as the final data. At the same time, the standard deviation is calculated to evaluate the fluctuation between experiments.

[0069] The above series of experimental techniques have laid a solid experimental foundation for exploring the dynamic instability phenomena (Schallamach wave behavior) and surface crease wear phenomena that may occur in high-acceleration, strong adhesion rolling contact.

[0070] The embodiments described above are only used to illustrate the technical ideas and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. The scope of the patent application of the present invention cannot be limited by these embodiments alone. That is, any equivalent changes or modifications made according to the spirit disclosed by the present invention still fall within the patent scope of the present invention.

Claims

1. A test device for simulating the landing rotation friction of aircraft wheels, comprising a rigid plane (100), wherein an accelerated rolling direction is provided on the rigid plane (100), wherein the two sides of the accelerated rolling direction are an initial side and a target side respectively, and wherein: Also includes: A swinging member (200), wherein a first end of the swinging member (200) is hinged above the rigid plane (100), a second end of the swinging member (200) is rotatably connected to a rubber roller (300), and the second end of the swinging member (200) moves in the accelerated rolling direction so that the roller (300) has at least two working states, namely an initial state and a test state. When the roller (300) is in the initial state, the roller (300) is located above the initial side of the rigid plane (100), and when the roller (300) is in the test state, the roller (300) is located on the target side of the rigid plane (100) and is in rolling contact with the rigid plane (100); An ejection assembly (400), the ejection assembly (400) comprising a positioning member (401) and an elastic member (402), the positioning member (401) being configured to constrain the roller (300) to maintain an initial state, and the elastic member (402) being configured to provide a force toward the target side for the roller (300) in the initial state; An image acquisition component (500) can respectively acquire images of the surface deformation of the roller (300) under a test state and perform DIC analysis to obtain the deformation condition and friction and wear characteristics of the surface of the roller (300).

2. A test device for simulating aircraft wheel landing rotation friction according to claim 1, characterized in that: In the vertical direction, the height between the center of the roller (300) in the initial state and the center of the roller (300) in the test state is the swing height, and the swing height is adjustable.

3. A test device for simulating aircraft wheel landing rotation friction according to claim 1, characterized in that: The positioning member (401) is detachably connected to the roller (300) in the initial state, one end of the elastic member (402) is connected to the second end of the swing member (200), and the other end of the elastic member (402) is connected to the target side of the roller (300) in the initial state; When the roller (300) is in an initial state, the elastic member (402) provides the roller (300) with an elastic force toward a target side.

4. A test device for simulating aircraft wheel landing rotation friction according to claim 3, characterized in that: The positioning member (401) is electrically unhooked; There are two elastic members (402), one end of each of the two elastic members (402) is connected to the second end of the swing member (200), and the other ends of each of the two elastic members (402) are located on both sides of the axis of the roller (300).

5. A test device for simulating aircraft wheel landing rotation friction according to claim 1, characterized in that: The rigid plane (100) is a transparent rigid plane, and the image acquisition component (500) comprises: A contact surface collection member (501), the contact surface collection member (501) being arranged below the rigid plane (100), and the contact surface collection member (501) being capable of passing through the rigid plane (100) to record changes in the contact area; A wheel-side collection member (502) is provided on the outside of the roller (300) in the axial direction, and the wheel-side collection member (502) can synchronously record wrinkle deformation, surface buckling, and surface fluctuation that may occur on the surface of the roller (300).

6. A test device for simulating aircraft wheel landing rotation friction according to claim 5, characterized in that: The contact surface acquisition component (501) and the wheel side acquisition component (502) are both high-speed cameras. The contact surface acquisition component (501) acquires the contact area image of the roller (300) through a transparent rigid plane (100), and the wheel side acquisition component (502) acquires the side wall image of the roller (300). The acquisition rates of the contact surface acquisition component (501) and the wheel side acquisition component (502) are the same.

7. A test device for simulating aircraft wheel landing rotation friction according to claim 1, characterized in that: The tread pattern of the roller (300) is variable, and grooves and media are provided on the rigid plane (100).

8. A test method, characterized in that A test device for simulating aircraft wheel landing rotation friction according to any one of claims 1 to 7, wherein the test method comprises the following steps: S1. A random speckled pattern is sprayed on the outer side of the roller (300) in the axial direction and the outer side in the radial direction; S2. releasing the swinging member (200) through the ejection assembly (400) to switch the roller (300) from the initial state to the test state, and during the process, synchronously capturing images of the outer side of the roller (300) in the axial direction and the outer side in the radial direction at the same rate through the image acquisition assembly (500); S3. Processing the image collected in S2 to obtain the deformation and friction and wear characteristics of the surface of the roller (300).

9. A test method according to claim 8, characterized in that: The step S3 comprises: S31. Track the change of the speckle pattern to extract the displacement field in the plane, calculate the two-dimensional strain field, and obtain the displacement field data by preliminary DIC calculation; S32. Adjust the displacement field data size so that the strain calculation points correspond to the original image pixels one by one.

10. A test method according to claim 9, characterized in that: The experiment under each loading state was repeated multiple times, and the average value was taken as the final data. The standard deviation was calculated to evaluate the fluctuation between experiments.

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