Method for determining maximum impact load of guide rod after restraint and release of nose landing gear of airplane

Abstract

The invention belongs to the technical field of determination of impact load of a guide rod after restraining and releasing of a nose landing gear of an airplane, and particularly relates to a method for determining the maximum impact load of the guide rod after restraining and releasing of the nose landing gear of the airplane, which comprises the following steps of: 1, calculating material constants sigma 1 and sigma 2 of two collision bodies of the guide rod; 2, based on the material constants sigma 1 and sigma 2 of two collision bodies of the guide rod, the collision contact rigidity K of the guide rod is calculated; and 3, based on the collision contact rigidity K of the guide rod, the maximum impact load Fmax borne by the guide rod during impact collision is calculated.

Description

Technical Field

[0001] The present application belongs to the technical field of determining the impact load of a guide rod after the front landing gear of an aircraft is restrained and released, and specifically relates to a method for determining the maximum impact load of a guide rod after the front landing gear of an aircraft is restrained and released. Background Art

[0002] The front landing gear of an aircraft capable of catapult takeoff generally includes a strut, a wheel, an anti-torsion arm, a strut, a catapult rod, a check rod, etc., wherein the check rod is connected to the anti-torsion arm through a check chuck, and a guide rod is arranged between the check chuck and the anti-torsion arm, such as Figure 1 shown.

[0003] During the catapult takeoff process, the main force is first applied to the catapult rod, and the engine thrust is superimposed to generate a reaction force on the check rod. When the reaction force reaches the design load of the check rod release, the check rod is disconnected from the check chuck, and the check is released, causing the aircraft to generate a large initial acceleration, thereby achieving an accelerated rolling takeoff. Figure 2 At the moment when the check rod and the check chuck are disconnected, the check chuck and the anti-torsion arm will have relative movement due to the sudden release of energy, which will subject the guide rod to a large impact load. Accurately determining the maximum value of the impact load is of great significance to the strength design of the guide rod and its connection structure.

[0004] At present, the maximum impact load of the guide rod after the front landing gear of the aircraft is released is mostly calculated by multi-body dynamics simulation analysis method. Usually, commercial multi-body dynamics software is used to establish a simulation analysis model of the aircraft body and the front landing gear, and simulate external forces such as engine thrust and ejection force to carry out dynamic load simulation of the ejection process and extract the maximum impact load on the guide rod. This method has high requirements on model quality, a long simulation analysis cycle, and limited result accuracy. In view of this, this application is proposed. Summary of the invention

[0005] The purpose of the present application is to provide a method for determining the maximum impact load of a guide rod after the front landing gear of an aircraft is restrained and released, so as to overcome or alleviate at least one aspect of the known technical defects.

[0006] The technical solution of this application is:

[0007] A method for determining the maximum impact load of a guide rod after the front landing gear of an aircraft is restrained and released, comprising:

[0008] Step 1: Calculate the material constants σ1 and σ2 of the two collision bodies of the guide rod;

[0009] Step 2: Calculate the collision contact stiffness K of the guide rod based on the material constants σ1 and σ2 of the two collision bodies of the guide rod;

[0010] Step 3: Based on the collision contact stiffness K of the guide rod, calculate the maximum impact load F that the guide rod receives during impact collision. max .

[0011] According to at least one embodiment of the present application, in the above-mentioned method for determining the maximum impact load of the guide rod after the front landing gear of the aircraft is restrained and released, step 1 is specifically:

[0012]

[0013] in:

[0014] E 01 、E 02 is the elastic modulus of the materials of the two collision bodies of the guide rod;

[0015] ν1 and ν2 are the Poisson's ratios of the materials of the two collision bodies of the guide rod.

[0016] According to at least one embodiment of the present application, in the above-mentioned method for determining the maximum impact load of the guide rod after the front landing gear of the aircraft is restrained and released, in step 1, the elastic modulus E of the material of the two collision bodies of the guide rod is 01 、E 02 , take the elastic modulus of the bolt and joint material at the threaded connection of the guide rod;

[0017] The Poisson's ratios ν1 and ν2 of the materials of the two collision bodies of the guide rod are taken as the Poisson's ratios of the materials of the bolts and joints at the threaded connection of the guide rod.

[0018] According to at least one embodiment of the present application, in the above-mentioned method for determining the maximum impact load of the guide rod after the release of the front landing gear of the aircraft, in step one, the elastic modulus of the bolts and joint materials at the threaded joint of the guide rod is obtained by referring to the performance manual of the bolts and joint materials at the threaded joint of the guide rod.

[0019] According to at least one embodiment of the present application, in the above-mentioned method for determining the maximum impact load of the guide rod after the release of the restraint of the front landing gear of the aircraft, in step one, the Poisson's ratio of the bolts and joint materials at the threaded joint of the guide rod is obtained by referring to the performance manual of the bolts and joint materials at the threaded joint of the guide rod.

[0020] According to at least one embodiment of the present application, in the above-mentioned method for determining the maximum impact load of the guide rod after the front landing gear of the aircraft is restrained and released, step 2 is specifically:

[0021]

[0022] in:

[0023] r1 and r2 are the curvature radii of the contact surfaces of the two collision bodies of the guide rod.

[0024] According to at least one embodiment of the present application, in the above-mentioned method for determining the maximum impact load of the guide rod after the release of the front landing gear of the aircraft, in step two, the curvature radii r1 and r2 of the contact surfaces of the two collision bodies of the guide rod are taken as the radii of the inner holes of the bolts and joints at the threaded connection of the guide rod.

[0025] According to at least one embodiment of the present application, in the above-mentioned method for determining the maximum impact load of the guide rod after the front landing gear of the aircraft is restrained and released,

[0026] In step 2, the radius of the bolt at the threaded connection of the guide rod is obtained by measuring the three-dimensional model of the bolt or referring to the relevant manual according to the bolt brand.

[0027] According to at least one embodiment of the present application, in the above-mentioned method for determining the maximum impact load of the guide rod after the restraint and release of the aircraft front landing gear, in step 2, the radius of the inner hole of the joint where the guide rod is screwed is obtained by measuring the three-dimensional model of the joint.

[0028] According to at least one embodiment of the present application, in the above-mentioned method for determining the maximum impact load of the guide rod after the front landing gear of the aircraft is restrained and released, step three is specifically:

[0029]

[0030] in,

[0031] J1 is the moment of inertia of the restraining chuck around the rotation axis O;

[0032] J2 is the moment of inertia of the anti-torsion arm around the rotation axis O;

[0033] ω1 is the angular velocity of the restraining chuck around the rotation axis O during impact collision;

[0034] ω2 is the angular velocity of the anti-torsion arm around the rotation axis O during impact collision.

[0035] According to at least one embodiment of the present application, in the above-mentioned method for determining the maximum impact load of the guide rod after the restraint of the front landing gear of the aircraft is released, in step three, during the impact collision, the rotational angular velocity ω1 of the restraint clamp around the rotation axis O is obtained by simulating or measuring the angular velocity time history.

[0036] According to at least one embodiment of the present application, in the above-mentioned method for determining the maximum impact load of the guide rod after the release of the front landing gear of the aircraft, in step three, during the impact collision, the angular velocity ω2 of the anti-torsion arm around the rotation axis O is obtained by simulating or measuring the angular velocity time history.

[0037] This application has at least the following beneficial technical effects:

[0038] A method for determining the maximum impact load of the guide rod after the restraint and release of the front landing gear of an aircraft is provided. Compared with the current multi-body dynamics simulation analysis method, the method is simpler and more efficient, and can directly and quickly calculate the maximum impact load on the guide rod during impact collision, which can well meet the needs of rapid iteration of the strength design of the guide rod and its connecting structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of the structure of the front landing gear of the aircraft;

[0040] Figure 2 It is a schematic diagram of the disconnection of the restraining rod and the restraining clamp when the aircraft is ejected and takes off;

[0041] Figure 3 is a schematic diagram of a simplified model of the impact dynamics of the guide rod during the catapult takeoff process provided by an embodiment of the present application;

[0042] Figure 4 is a schematic diagram of a method for determining a maximum impact load of a guide rod after a front landing gear of an aircraft is restrained and released, provided in an embodiment of the present application;

[0043] Figure 5 It is a schematic diagram of the time history of the relative displacement of the guide rod measured in the ejection test provided in the embodiment of the present application.

[0044] In order to better illustrate the present embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. In addition, the drawings are only used for illustrative purposes and should not be construed as limitations on the present application. DETAILED DESCRIPTION

[0045] In order to make the technical solution and advantages of the present application clearer, the technical solution of the present application will be described in further detail in detail and in detail with reference to the accompanying drawings. It can be understood that the specific embodiments described here are only partial embodiments of the present application, which are only used to explain the present application, not to limit the present application. It should be noted that, for the convenience of description, only the parts related to the present application are shown in the accompanying drawings, and other related parts can refer to the general design.

[0046] In addition, unless otherwise defined, the technical terms or scientific terms used in the description of this application shall have the usual meanings understood by those of ordinary skill in the art to which this application belongs. The words used in the description of this application to indicate orientation are only used to indicate relative directions or positional relationships. When the absolute position of the described object changes, its relative positional relationship may also change accordingly. The word "include" used in the description of this application indicates that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, but does not exclude other elements or objects.

[0047] In addition, it should be noted that, unless otherwise clearly specified and limited, the words "installation", "connection" and similar terms used in the description of this application should be understood in a broad sense. For example, the connection can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Technical personnel in the field can understand its specific meaning in this application according to the specific circumstances.

[0048] In order to solve the impact load of the guide rod during catapult takeoff, the impact process can be simplified as follows: Figure 3 A simplified model of the impact dynamics of a guide rod is shown.

[0049] The check chuck OA rotates around the rotation axis O, the anti-torsion arm BO rotates around the rotation axis O, and the rotation axis O is also moving. At the moment when the check rod and the check chuck are disconnected, assuming that the position of the rotation axis O remains unchanged, the check chuck and the anti-torsion arm are equivalent to rotating around the rotation axis O, which causes the guide rod and the installation points of the check chuck and the anti-torsion arm to move relative to each other, resulting in an impact effect.

[0050] During impact collision, the rotational kinetic energy of the restraining chuck and anti-torsion arm is calculated as follows:

[0051]

[0052] in;

[0053] E1 is the rotational kinetic energy of the restraining chuck around the rotation axis O; E2 is the rotational kinetic energy of the anti-torsion arm around the rotation axis O;

[0054] J1 is the moment of inertia of the restraining chuck around the rotation axis O; J2 is the moment of inertia of the anti-torsion arm around the rotation axis O;

[0055] ω1 is the angular velocity of the restraining chuck around the rotation axis O; ω2 is the angular velocity of the anti-torsion arm around the rotation axis O.

[0056] During impact collision, the total rotational kinetic energy E of the restraining chuck and the anti-torsion arm is:

[0057] E=E1+E2…………(2)

[0058] According to Hertz collision theory, the impact load F on the guide rod during impact collision is:

[0059]

[0060] in:

[0061] K is the collision contact stiffness of the guide rod;

[0062] δ is the deformation displacement of the guide rod.

[0063] The theoretical expression of the collision contact stiffness K of the guide rod is:

[0064]

[0065] Among them: r1, r2 are the curvature radii of the contact surfaces of the two collision bodies, which are always positive values;

[0066] σ1 and σ2 are the material constants of the two colliding bodies.

[0067] The material constants σ1 and σ2 of the two colliding bodies are expressed as follows:

[0068]

[0069] in:

[0070] E 01 、E 02 is the elastic modulus of the materials of the two colliding bodies;

[0071] ν1 and ν2 are the Poisson's ratios of the materials of the two colliding bodies.

[0072] To solve the collision contact stiffness K of the guide rod, it is necessary to identify the two corresponding collision bodies. Since the guide rod itself has no structural gap, the collision mainly occurs at the screw connection between the guide rod and the restraining chuck or the screw connection between the guide rod and the anti-torsion arm, and the bolt sizes at these two places are the same, and the hole diameters of the screw joints are also the same. Therefore, the two collision bodies corresponding to the guide rod can be defined as the bolt surface at the screw connection and the inner hole surface of the joint.

[0073] During impact collision, the impact load F on the guide rod is integrated with the deformation displacement δ of the guide rod, and the deformation potential energy U of the guide rod can be obtained:

[0074]

[0075] in:

[0076] δ max It is the maximum deformation displacement of the guide rod during impact collision.

[0077] According to the total rotational kinetic energy E of the restraining chuck and the anti-torsion arm during impact collision, it is converted into the deformation potential energy U of the guide rod. Let E = U to obtain:

[0078]

[0079] Further:

[0080]

[0081] Substituting equation (8) into equation (3), we can obtain the maximum impact load F on the guide rod during impact collision: max for:

[0082]

[0083] Based on the above, the present application provides a method for determining the maximum impact load of the guide rod after the front landing gear of an aircraft is restrained and released, such as Figure 4 shown.

[0084] Step 1: Calculate the material constants σ1 and σ2 of the two collision bodies of the guide rod.

[0085]

[0086] in:

[0087] E 01 、E 02 is the elastic modulus of the materials of the two collision bodies of the guide rod, and the elastic modulus of the materials of the bolts and joints at the threaded joint of the guide rod is taken. The specific information can be obtained by referring to the performance manual of the materials of the bolts and joints at the threaded joint of the guide rod;

[0088] ν1 and ν2 are the Poisson's ratios of the materials of the two collision bodies of the guide rod. The Poisson's ratios of the bolts and joints at the threaded joints of the guide rod are taken. The specific Poisson's ratios can be obtained by referring to the performance manual of the bolts and joints at the threaded joints of the guide rod.

[0089] Step 2: Calculate the collision contact stiffness K of the guide rod based on the material constants σ1 and σ2 of the two collision bodies of the guide rod.

[0090]

[0091] in:

[0092] r1 and r2 are the curvature radii of the contact surfaces of the two collision bodies of the guide rod, and the radii of the bolts and the inner holes of the joints at the threaded joints of the guide rod are taken. Among them, the radius of the bolts at the threaded joints of the guide rod can be obtained by measuring the three-dimensional model of the bolts or referring to the relevant manuals according to the bolt brands, and the radius of the inner hole of the joints at the threaded joints of the guide rod can be obtained by measuring the three-dimensional model of the joints.

[0093] Step 3: Based on the collision contact stiffness K of the guide rod, calculate the maximum impact load F that the guide rod receives during impact collision. max .

[0094]

[0095] in,

[0096] J1 is the moment of inertia of the containment chuck around the rotation axis O, which can be obtained by measuring the three-dimensional model of the containment chuck;

[0097] J2 is the moment of inertia of the anti-torsion arm around the rotation axis O, which can be obtained by measuring the three-dimensional model of the anti-torsion arm;

[0098] ω1 is the angular velocity of the restraining chuck around the rotation axis O during impact collision, which can be obtained through simulation or actual measurement of the angular velocity time history;

[0099] ω2 is the angular velocity of the anti-torsion arm around the rotation axis O during impact collision, which can be obtained through simulation or actual measurement of the angular velocity time history.

[0100] In a specific example, the input parameters required to determine the impact load of the guide rod after the front landing gear of the aircraft is restrained and released are as follows:

[0101] Step 1: Calculate the material constants σ1 and σ2 of the two collision bodies of the guide rod:

[0102]

[0103] Step 2: Calculate the collision contact stiffness K of the guide rod:

[0104]

[0105] Step 3: Calculate the maximum impact load F on the guide rod during impact collision max for:

[0106]

[0107] Furthermore, the maximum deformation displacement δ of the guide rod during impact collision can be calculated using formula (8): max :

[0108]

[0109] In the ejection test, the relative displacement time history of the guide rod is measured, such as Figure 5 As shown in the figure, only when the relative displacement is negative, the two ends of the guide rod will be squeezed and produce impact collision. The maximum deformation displacement δ of the guide rod during impact collision is measured. max It is 0.2801mm.

[0110] The maximum deformation displacement δ of the guide rod during impact collision is calculated max , and the maximum deformation displacement δ of the guide rod during impact collision is obtained by actual measurement. max The relative error is 2.46%, which can meet the requirements of engineering use. The method for determining the maximum impact load of the guide rod after the front landing gear of the aircraft is restrained and released provided by the above embodiment is accurate and effective.

[0111] The method for determining the maximum impact load of the guide rod after the aircraft front landing gear is restrained and released provided in the above embodiment calculates the maximum impact load of the guide rod based on the conservation of mechanical energy and collision theory. It has sufficient theoretical basis and is simple and efficient compared to the current multi-body dynamics simulation analysis method. It can quickly calculate the maximum impact load on the guide rod during an impact collision, and can well meet the needs of rapid iteration of the strength design of the guide rod and its connecting structure.

[0112] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the scope of protection of the present application.

Claims

1. A method for determining the maximum impact load of a guide rod after the front landing gear of an aircraft is restrained and released, characterized in that: include: Step 1: Calculate the material constants σ1 and σ2 of the two collision bodies of the guide rod; Step 2: Calculate the collision contact stiffness K of the guide rod based on the material constants σ1 and σ2 of the two collision bodies of the guide rod; Step 3: Based on the collision contact stiffness K of the guide rod, calculate the maximum impact load F that the guide rod receives during impact collision. max .

2. The method for determining the maximum impact load of the guide rod after the front landing gear of an aircraft is restrained and released according to claim 1, characterized in that: Step 1 is as follows: in: E 01 、E 02 is the elastic modulus of the materials of the two collision bodies of the guide rod; ν1 and ν2 are the Poisson's ratios of the materials of the two collision bodies of the guide rod.

3. The method for determining the maximum impact load of the guide rod after the front landing gear of an aircraft is restrained and released according to claim 2, characterized in that: In step 1, the elastic modulus E of the two collision body materials of the guide rod 01 、E 02 , take the elastic modulus of the bolt and joint material at the threaded connection of the guide rod; The Poisson's ratios ν1 and ν2 of the materials of the two collision bodies of the guide rod are taken as the Poisson's ratios of the materials of the bolts and joints at the threaded connection of the guide rod.

4. The method for determining the maximum impact load of the guide rod after the front landing gear of an aircraft is restrained and released according to claim 3, characterized in that: In step 1, the elastic modulus of the bolts and joint materials at the threaded joint of the guide rod is obtained by referring to the performance manual of the bolts and joint materials at the threaded joint of the guide rod.

5. The method for determining the maximum impact load of the guide rod after the front landing gear of an aircraft is restrained and released according to claim 4, characterized in that: In step 1, the Poisson's ratio of the bolts and joint materials at the threaded joint of the guide rod is obtained by referring to the performance manual of the bolts and joint materials at the threaded joint of the guide rod.

6. The method for determining the maximum impact load of the guide rod after the front landing gear of an aircraft is restrained and released according to claim 5, characterized in that: Step 2 is as follows: in: r1 and r2 are the curvature radii of the contact surfaces of the two collision bodies of the guide rod.

7. The method for determining the maximum impact load of the guide rod after the front landing gear of an aircraft is restrained and released according to claim 6, characterized in that: In step 2, the curvature radii r1 and r2 of the contact surfaces of the two collision bodies of the guide rod are obtained by taking the radii of the inner holes of the bolts and the joints at the threaded connection of the guide rod.

8. The method for determining the maximum impact load of the guide rod after the front landing gear of an aircraft is restrained and released according to claim 7, characterized in that: In step 2, the radius of the bolt at the threaded connection of the guide rod is obtained by measuring the three-dimensional model of the bolt or referring to the relevant manual according to the bolt brand.

9. The method for determining the maximum impact load of the guide rod after the front landing gear of an aircraft is restrained and released according to claim 8, characterized in that: In step 2, the radius of the inner hole of the joint where the guide rod is screwed is obtained by measuring the three-dimensional model of the joint.

10. The method for determining the maximum impact load of the guide rod after the front landing gear of an aircraft is restrained and released according to claim 9, characterized in that: Step three is as follows: in, J1 is the moment of inertia of the restraining chuck around the rotation axis O; J2 is the moment of inertia of the anti-torsion arm around the rotation axis O; ω1 is the angular velocity of the restraining chuck around the rotation axis O during impact collision; ω2 is the angular velocity of the anti-torsion arm around the rotation axis O during impact collision.

11. The method for determining the maximum impact load of the guide rod after the front landing gear of an aircraft is restrained and released according to claim 10, characterized in that: In step three, during the impact collision, the angular velocity ω1 of the restraining chuck around the rotation axis O is obtained by simulating or measuring the angular velocity time history.

12. The method for determining the maximum impact load of the guide rod after the front landing gear of an aircraft is restrained and released according to claim 11, characterized in that: In step three, during impact collision, the rotational angular velocity ω2 of the anti-torsion arm around the rotation axis O is obtained by simulation or measurement of the angular velocity time history.

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