Damping protection supporting device suitable for aircraft test

Abstract

The utility model provides a damping protection supporting device suitable for an aircraft test. Belongs to the technical field of aircraft test. Comprising a transfer frame, a buffer, a damper, a ground platform and the like. A tested aircraft is installed in the center of the transfer frame, a plurality of sets of buffers and dampers are arranged below the transfer frame, the dampers and buffer springs in the buffers jointly act on upper trays of the buffers, a hole is formed in the center of each upper tray, a center rod penetrates through the hole, and a square metal frame is arranged below the transfer frame and makes contact with the upper trays. And a limiting rod is arranged above the buffer center rod. According to the utility model, the safety of the aircraft can be ensured while the degree of freedom of the aircraft pose test is met, and the aircraft can be rapidly stabilized when the test is unstable.

Description

Technical Field

[0001] The utility model belongs to the technical field of aircraft test and measurement, and particularly relates to a shock-absorbing protection support device suitable for aircraft tests. Background Art

[0002] During the test and measurement of an aircraft or an aircraft engine, especially when conducting tests on the pose change of the aircraft, a high degree of freedom is required to ensure the space for pose change. However, a high degree of freedom means a weakening of the rigid protection of the aircraft. And an aircraft or an aircraft engine is a precision product that cannot be bumped. During the pose change test, non-axial thrust is generated due to the pose change, which can easily cause the test system to tip over and damage the aircraft or the engine. Therefore, a test protection device must be supplemented.

[0003] The traditional test protection device fixes the aircraft on a fixed support frame, and the fixed support frame is fixed to the ground or platform by means of anchor bolts, as described in the invention CN112682222B. This form ensures the safety of the aircraft during the test process, but the fixed support frame also limits the degree of freedom of the pose change of the aircraft, and thus limits the test ability of the aircraft to change its pose.

[0004] In addition to ensuring the degree of freedom and safety of the aircraft during the test, the protection device for the pose change test should also be able to quickly stabilize when the pose of the aircraft is unstable, and reduce the impact of the test pose instability on the test itself. Summary of the Utility Model

[0005] In view of this, the utility model provides a shock-absorbing protection support device suitable for aircraft tests, which can ensure the safety of the equipment while providing the degree of freedom for pose tests.

[0006] The technical solution adopted by the utility model is as follows:

[0007] A shock-absorbing and protective support device suitable for aircraft testing, comprising a test adapter frame, buffers, dampers, and a ground platform. The test adapter frame includes a square metal frame, connecting frames, and a test-piece fixing plate. The center of the test-piece fixing plate fixes the aircraft or engine under test, and the outside is connected to multiple square metal frames by connecting frames. The number of square metal frames is generally four and needs to be greater than three. The buffer includes a floor fixing frame, floor bolts, a central rod, a spring, a spring lower limit, a lower limit fixing bolt, an upper tray, and an upper limit rod. The central rod is located above the floor fixing frame. From bottom to top on the central rod, there are successively sleeved: a spring lower limit, a spring, and an upper tray. There is an internal thread hole above the central rod. One side of the upper limit rod has an external thread, which is threadedly matched with the internal thread hole above the central rod. The damper is a rod-shaped telescopic damper, including a damper body and a floor fixing piece. A through hole is drilled in the center of the fixing piece, which can be used for fixing the floor bolt. Multiple round holes are provided in the center of the ground platform, and there is an internal thread in the holes to cooperate with the floor bolts.

[0008] Further, the square metal frame is located in the lower part of the adapter frame. An aircraft is installed in the center of the adapter frame and placed on multiple groups of buffers and multiple groups of dampers. The central rod of the buffer passes through the metal frame. The relationship between the long side length Y of the square metal frame and the maximum test required angle θ is where Z is the distance between two buffers in the long side direction of the square metal frame.

[0009] Further, the square frame and the connecting frame are reinforced by diagonal rods to form a triangular stable structure. The connection position of the diagonal rod and the square frame should be the inner side of the projection of the upper limit rod after assembly onto the square frame directly below, which can make the adapter frame automatically return to the correct position when the pose is unstable.

[0010] Further, the surface of the lower limit fixing bolt is provided with an external thread.

[0011] Further, the spring lower limit is a cylindrical structure. Radial holes are opened on the cylindrical surface, and internal threads are provided in the holes, and the threads are threadedly matched with the external thread on the surface of the lower limit fixing bolt. There is a large round table structure on the upper surface, and the diameter needs to be greater than the outer diameter of the spring.

[0012] Further, there is a thicker section at the lower part of the central rod compared to the rest. There is an external thread on this section, and the spring lower limit has an internal thread hole along the axis. The two are mutually matched, and the position can be adjusted up and down by screwing and rotating on the thread. And the spring lower limit is fixed on the central rod with a lower limit fixing bolt at a suitable position.

[0013] Furthermore, the aperture of the central hole at the lower limit of the spring is larger than the aperture of the thin section of the central rod and smaller than the aperture of the thick section of the central rod. The lower limit of the spring is installed on the thicker part of the central rod with threads and can be rotated to adjust the height position at the external thread of the central rod. The fixing bolt at the lower limit is tightened in the radial hole on the column surface of the lower limit of the spring. There is internal thread in the radial hole for thread fit with the fixing bolt at the lower limit. After tightening, the bolt rod contacts and presses against the central rod, thereby fixing the lower limit of the spring to the central rod.

[0014] Furthermore, a round hole is provided in the upper tray through which the central rod passes and can slide up and down. The upper tray contacts the square metal frame above. The upper tray and the spring cooperate to reduce the impact force conducted by the square metal frame. Rolling bearings can be installed on the inner wall of the upper tray or lubricating grease can be applied to reduce the sliding friction with the central rod.

[0015] Furthermore, the total mass borne by the upper tray is M, the total stiffness of the spring is the sum of the stiffnesses of all springs K = K1 + K2 + …… + Kn, the total damping is the sum of all damping magnitudes C = C1 + C2 + …… + Cn, n is the number of buffers in the system, the maximum dropping distance brought by the test borne by the buffer is L, the maximum compression distance of the spring is X, and the acceleration due to gravity is g = 9.81 m / s^2.

[0016] The natural frequency of the protection device system is:

[0017]

[0018] The damping ratio of the protection device system is:

[0019]

[0020] The motion equation of the vibration of the protection device system is:

[0021]

[0022] where A and φ are determined by the initial conditions of the system (the initial position and initial velocity during vibration), t is the time of motion, and the angular frequency of vibration is:

[0023]

[0024] Since -ζω in the motion equation n represents the vibration attenuation rate, which is independent of K, the stiffness K of the selected spring should be as small as possible, but should exceed:

[0025]

[0026] At this time, it can be ensured that when the linear damping of the system completely fails, the safety of the system can still be guaranteed under the action of the spring.

[0027] When selecting the damping magnitude C of the linear damping, it is necessary to calculate the damping ratio ζ. The optimal damping ratio should be close to but less than 1, which can reduce the oscillation at the fastest speed and tend to be stable.

[0028] Furthermore, through holes are provided on the floor fixing frame in the buffer, the diameter of which is slightly larger than the outer diameter of the floor bolt screw rod, and the direction is parallel to the direction of the central rod.

[0029] Furthermore, the position of the threaded hole corresponds to the position of the floor bolt of the buffer for fixing the buffer.

[0030] Beneficial effects:

[0031] 1. The utility model can meet the degree-of-freedom requirements brought about by the attitude change in the aircraft attitude test. Through the cooperation of the square metal frame and the central rod, the aircraft can achieve translation, rotation on the horizontal plane, and a certain inclination angle in the vertical direction during the test. While ensuring the degree of freedom of the aircraft, it can protect the safety of the aircraft. When the aircraft drops, the spring ensures that the flexible buffer does not damage the aircraft. The position cooperation of the upper limit rod, the inclined rod and the triangular fixing part of the square frame can automatically return to the correct position when the aircraft rises to the highest position, ensuring the stability and safety of the aircraft during the test.

[0032] 2. The utility model uses the cooperation of the stiffness of the spring and the damping value of the damping to quickly stabilize while flexibly protecting the aircraft when the attitude of the aircraft suddenly becomes unstable. Quick stabilization can reduce the fuel consumption during the test and also reduce other risks caused by attitude instability to the aircraft during the test. The utility model first calculates the minimum spring stiffness applicable to the test according to the weight of the aircraft and the value of the maximum rising height. After selecting the spring stiffness, a suitable damping is selected according to the principle that the damping ratio is less than or equal to 1. Thus, the system can quickly tend to be stable during the test.

[0033] 3. The utility model can be applicable to test occasions with different sizes and position requirements. The method of fixing the buffer with floor bolts enables the position of the buffer to be freely adjusted. Thus, it is applicable to aircraft of different sizes. The replaceability of the spring and the linear damping enables the system to be applicable to the attitude tests of aircraft with different thrusts and weights. The fixing method of the lower limit of the spring with threads can adjust the height position of the spring, and thus adjust the position of the aircraft, making it applicable to the attitude tests of aircraft with different position requirements. Description of the drawings

[0034] Figure 1 It is the overall structure diagram of the utility model;

[0035] Figure 2 It is the three-dimensional assembly diagram of the utility model;

[0036] Figure 3 This is the structural decomposition diagram of the present utility model;

[0037] Figure 4 This is the side view of the buffer and the damper;

[0038] Figure 5 This is the position diagram of the diagonal bar of the adapter frame;

[0039] Figure 6 This is the Simulink model used for verifying the design;

[0040] Figure 7 This is the vibration time domain diagram of the 0.3m drop of the aircraft;

[0041] Among them, I - test adapter frame; II - buffer; III - linear damper; IV - ground platform; 1 - fixed disk for the test piece; 2 - upper tray; 3 - anchor bolt; 4 - damper; 5 - buffer spring; 6 - lower limit of the spring; 7 - upper limit rod; 8 - center rod; 9 - lower limit fixing bolt; 10 - ground platform; 11 - anchor bolt hole; 12 - anchor fixing frame; 13 - through hole; 14 - lower limit fixing thread; 15 - square frame; 16 - aircraft fixing hole; 17 - diagonal bar. Specific implementation manner

[0042] The following combines the accompanying drawings and gives examples to describe the present utility model in detail.

[0043] A shock absorption and protection support device suitable for aircraft tests includes an I test adapter frame, a II buffer, a III linear damper, and an IV ground platform. The I test adapter frame includes: 1 fixed disk for the test piece, 15 square frames, 16 aircraft fixing holes, 17 diagonal bars, and the II buffer includes: 2 upper trays, 3 anchor bolts, 5 buffer springs, 6 lower limits of the springs, 7 upper limit rods, 8 center rods, 9 lower limit fixing bolts, and 12 anchor fixing frames.

[0044] The part decomposition diagram of the present utility model is as shown in Figure 3 In the test adapter frame I, the fixed disk 1 for the test piece and the square metal frame 15 are fixedly connected by a connecting frame. In this embodiment, four square metal frames are provided. The inner circular part of the fixed disk for the test piece is provided with an aircraft fixing hole 16 for connecting and fixing with the aircraft. Below the square frame is provided with a buffer II, and the number of buffers is the same as the number of square metal frames on the adapter frame. The structure of the buffer is as shown in Figure 4As shown in the figure, a floor fixing bracket 12 is provided at the bottom of the buffer. A through hole 13 is provided on the floor fixing bracket. The floor bolts 3 pass through the through holes to fix the buffer on the ground platform IV. There are four through holes on each floor fixing bracket. Two of the through holes are used to fix the linear damper. The connection method is to press the damper and the buffer floor fixing bracket onto the ground platform from top to bottom with floor bolts. The other two are directly fixed on the ground platform with floor bolts. A central rod 8 is provided on the floor fixing bracket. One section of the central rod is thicker than other parts, and a thread 14 is provided on the surface. The thread is matched with the internal thread of the spring lower limit. After installing the spring lower limit 6 to the appropriate position on the thread of the central rod, tighten and fix it from the side with the spring lower limit fixing bolt 9. To prevent the spring lower limit from moving, the height of the spring lower limit in all buffers should be as consistent as possible. The buffer spring 5 passes through the central rod and contacts the spring lower limit. The spring lower limit determines the bottom position of the spring. The top of the spring contacts the upper tray. The upper tray 2 is a ring structure, and the center of the ring passes through the central rod. The structure of the upper tray is as Figure 6 shown. There is a protruding hollow cylindrical structure below the upper tray. The inner diameter of the cylinder is slightly larger than the outer diameter of the central rod, and the outer diameter of the cylinder is slightly smaller than the inner diameter of the spring, which is used to standardize the position of the spring and make it coaxial with the central rod. Besides contacting the spring, the upper tray also contacts the linear damper III, as Figure 5 shown. The upper tray makes the elastic force of the spring and the damping force of the linear damper form a resultant force, which has a buffering effect on the impact force conducted on the square metal frame. A limiting rod 7 is fixed on the upper part of the central rod. The direction of the limiting rod is perpendicular to the radial direction of the specimen fixing plate on the transfer rack. The bottom edge of the square metal frame on the transfer rack is also perpendicular to the radial direction of the specimen fixing plate.

[0045] The square metal frame and the connecting frame are reinforced by diagonal rods 17 to form a triangular stable structure. The connection position of the diagonal rod and the square frame is the inner side of the projection of the upper limiting rod after assembly onto the square frame, which can make the transfer rack automatically return to the correct position by gravity when it falls back to the spring shock absorber.

[0046] The position of the floor thread holes on the ground platform is adapted to the position of the transfer rack in the system. The buffer and the linear damper are fixed on the ground platform with floor bolts to prevent movement. When the test vibration is large, gaskets need to be added to prevent the threads from loosening.

[0047] Before the test begins, the aircraft is installed inside the fixed disk of the test piece, and the aircraft is connected to the aircraft fixing hole 16 with bolts. At this time, the weights of both the aircraft and the adapter frame are pressing on the spring through the upper tray. The deformation of the spring generates an elastic force that balances the gravity of the adapter frame and the aircraft. The square frame on the adapter frame contacts the upper tray. During the attitude test, the aircraft generates an upward thrust, and the adapter frame rises with the aircraft. The deformation of the spring gradually recovers. After the spring stretches, the aircraft continues to rise, and the square metal frame on the adapter frame no longer contacts the upper tray. When the attitude of the aircraft becomes unstable and causes the height to be too high, the square frame will contact the upper limit rod of the buffer. The upper limit rod will limit the further rise of the adapter frame, and the cooperation between the upper limit rod and the triangular inclined rod 17 on the adapter frame will make the adapter frame automatically return to the correct position to protect the safety of the aircraft.

[0048] When certain attitude adjustments are required during the test, the cooperation between the square metal frame and the central rod will enable the aircraft to rotate freely within a certain range. Whether it is axial rotation or left - right flipping, the square metal frame and the central rod can ensure a certain margin for attitude transformation.

[0049] When the test ends or the aircraft shuts down emergently due to unexpected conditions, the aircraft and the adapter frame accelerate downward due to the action of gravity. After moving a certain distance, the square frame on the adapter frame contacts the upper tray of the buffer. The upper tray applies the impact force and gravity conducted from the adapter frame to the spring and the linear damper. The spring deforms, enabling the aircraft and the adapter frame to achieve a soft landing. The damper makes the spring quickly tend to be stable and stop fluctuating up and down.

[0050] In this embodiment, the maximum contraction length of the spring is 0.3m, the highest height at which the adapter frame detaches from the spring is 0.3m, and the weight of the aircraft plus the adapter frame is less than 1 ton. It can be calculated that the sum of the spring stiffnesses of the four buffers should be greater than (2gM(L + X)) / X^2 = 138000 N / m to ensure the safety of the adapter frame and prevent the spring from yielding. Therefore, the K value of each spring is taken as 32700 N / m.

[0051] The damping of the used linear damper is 700 N·s / m, and the damping C of the four linear dampers is 2800 N·s / m. It can be calculated that the damping ratio ζ = C / (2√KM)=0.1224. The ζ value is 0.1224 because the test requirements in this embodiment are more sensitive to the maximum force and less sensitive to the oscillation convergence time, so the damping is set relatively small.

[0052] In the design of this embodiment, a simulink model is built to simulate the oscillatory fall. The model is as Figure 6 shown, and the time - domain oscillation relationship between the simulated fall displacement and time is as Figure 7As shown in the figure, the position of the vertical coordinate 0 represents the upper surface of the spring in its free state. Under the combined action of the spring stiffness and the linear damper, the lowest position of the oscillation is not lower than the allowable minimum height of the spring, which is -0.3 m. After three seconds of oscillation, it gradually tends to equilibrium, and the equilibrium position is approximately -0.075 m.

[0053] In summary, the above is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A shock-absorbing protection support device suitable for aircraft testing, comprising an adapter frame, a buffer, a damper and a ground platform; characterized in that: The aircraft is installed at the center of the adapter frame and placed on multiple groups of buffers and multiple groups of dampers, and the buffers and dampers are fixed on the ground platform.

2. A shock absorbing protection support device suitable for aircraft testing as claimed in claim 1, characterized in that: The adapter frame includes a test piece fixing plate and a square metal frame. The relationship between the long side length Y of the square metal frame and the maximum required angle θ of the test is: Where Z is the distance between the two buffers in the long side direction of the square metal frame.

3. A shock absorbing protection support device suitable for aircraft testing as claimed in claim 1, characterized in that: The buffer includes an upper tray, anchor bolts, a buffer spring, a spring lower limit, an upper limit rod, a center rod, a lower limit fixing bolt, and an anchor fixing frame; The center rod has a section at the lower part which is thicker than the rest of the section. The section has an external thread, and the lower limit of the spring has an internal thread hole. The two cooperate with each other, and the position can be adjusted up and down by twisting and rotating on the thread, and the lower limit of the spring is fixed to the center rod at a suitable position with a lower limit fixing bolt; The buffer spring is arranged vertically in the axial direction, and the center rod passes through it. The lower side of the buffer spring contacts the lower limit of the spring, and the upper side contacts the lower surface of the upper tray. The size of the upper tray is designed according to the size of the square metal frame to ensure that the square frame will not slip anywhere on the tray. The upper limit rod is installed on the upper side of the central rod, arranged symmetrically, with a horizontal direction and perpendicular to the radial direction of the test piece fixing plate; The total spring stiffness K should satisfy Where M is the total mass of the upper tray, L is the maximum height of the adapter during the test, and X is the maximum compression distance allowed by the spring.

4. A shock absorbing protection support device suitable for aircraft testing as claimed in claim 1, characterized in that: The damper is a linear damper, arranged vertically and installed near the spring buffer. The upper side of the damper contacts the lower surface of the upper tray. The total damping range of the damper is Where K is the total stiffness of the spring, and M is the total mass borne by the upper tray.

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