A method for evaluating the feasibility of a helicopter landing on a field ground

Abstract

The application provides a helicopter field ground landing feasibility evaluation method, which comprises the following steps: determining the diameter of a helicopter landing area based on the overall length of the helicopter; wherein the landing area is a circular area; selecting three measuring points on the boundary of the landing area; measuring the ground bearing capacity at the measuring points based on a ground bearing capacity detection device to obtain test data; inputting the test data into a general ground soil layer model to obtain a landing area ground soil layer model; setting a maximum landing gear allowable settlement amount; performing ground model dynamic loading simulation by using Abaqus finite element simulation software based on tire characteristics and the landing area ground soil layer model, and calculating the ground settlement amount; if the ground settlement amount is equal to the landing gear allowable settlement amount, determining the maximum ground allowable landing load; and determining the landing state by using landing gear landing performance calculation software based on the maximum ground allowable landing load.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of landing gears and helicopter support, and particularly relates to a method for judging the feasibility of field landing of a helicopter. BACKGROUND

[0002] Compared with fixed-wing aircraft, helicopters have the advantages of low altitude, low speed and low landing site requirement, and are mainly used in low-altitude attack, short-distance transportation, disaster relief, battlefield rescue and other scenes. When helicopters perform battlefield rescue, transportation and field disaster relief, they often need to land in the field.

[0003] At present, when a helicopter lands in the field, a ground bearing simple test and helicopter test landing are usually used; this method may cause the helicopter to be unable to actually land in the field. SUMMARY

[0004] In view of the above technical problems, the application provides a method for judging the feasibility of field landing of a helicopter, which comprises the following steps:

[0005] Based on the full length of the helicopter, the diameter of a landing area of the helicopter is determined; wherein the landing area is a circular area;

[0006] Three measurement points are selected on the boundary of the landing area;

[0007] Based on a ground bearing capacity detection device, the bearing capacity of the ground at the measurement points is measured to obtain test data;

[0008] The test data is input into a general ground soil layer model to obtain a landing area ground soil layer model;

[0009] A maximum allowable settlement of a landing gear is set;

[0010] Based on the tire characteristics and the landing area ground soil layer model, Abaqus finite element simulation software is used to perform dynamic loading simulation of the ground model, and the ground settlement is calculated;

[0011] If the ground settlement is equal to the allowable settlement of the landing gear, the maximum allowable landing load of the ground is determined;

[0012] Based on the maximum allowable landing load of the ground, a landing gear landing performance calculation software is used to determine the landing state.

[0013] Preferably, the three measurement points selected on the boundary of the landing area comprise:

[0014] Based on a preset interval angle, three measurement points are selected on the boundary of the landing area; wherein the preset interval angle is 120°.

[0015] Preferably, the length of the heading based on the helicopter, before determining the diameter of the landing area of the helicopter, further comprises:

[0016] The full length of the helicopter is obtained.

[0017] Preferably, the test data is input into the general ground soil layer model to obtain the landing area ground soil layer model, and before that, it further comprises:

[0018] Based on the type of ground soil, the ground soil layer is divided, and the general ground soil layer model is established.

[0019] Preferably, the ground model dynamic loading simulation is carried out based on the tire characteristics and the landing area ground soil layer model using Abaqus finite element simulation software, and the ground settlement is calculated, which comprises:

[0020] Based on the tire size, structure design and filling pressure, a tire finite element model is established.

[0021] Preferably, if the ground settlement is equal to the maximum landing load allowed by the landing gear, the maximum landing load allowed by the ground is determined, which comprises:

[0022] Based on Abaqus finite element simulation software, the ground model and the tire finite element model are used to calculate the landing area settlement corresponding to different landing loads.

[0023] Preferably, based on the maximum landing load allowed by the ground, the landing state is determined by the landing gear landing performance calculation software, which comprises:

[0024] Based on the landing gear performance calculation model and software, the maximum landing load corresponding to different landing states is calculated.

[0025] Preferably, the landing state comprises the weight of the helicopter, the sinking speed of the helicopter and the lifting force of the helicopter.

[0026] The beneficial technical effects of the present application are:

[0027] The evaluation method provided by the present application can judge the ground bearing capacity before the helicopter is dispatched, and can give the allowed landing working condition combined by the weight, sinking speed and lifting force system of the helicopter according to the ground bearing capacity, which can be used for helicopter support design and landing gear design. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The evaluation process of the feasibility of the helicopter landing on the field ground provided by the embodiment of the present application;

[0029] Figure 2 The helicopter landing parking space schematic diagram provided by the embodiment of the present application;

[0030] Figure 3 is a schematic diagram of a ground test point provided by an embodiment of the present application. DETAILED DESCRIPTION

[0031] Please refer to Figures 1-3 In an embodiment of the present application, the size of the landing site required by the helicopter in the field is given according to the size of the helicopter, and then the ground bearing capacity of the given area is detected by using the ground bearing capacity detection device. According to the detection result of the given ground bearing capacity and the tire condition, the landing state of the helicopter allowed is given by setting the ground subsidence amount evaluation condition, and the brief work is shown in Figure 1 .

[0032] It should be noted that the working principle is: when the helicopter lands in the field, the landing site is required to meet Figure 2 the size requirement; wherein D refers to the maximum length or width of the helicopter when the rotor rotates, and the larger value is taken (unit: meter).

[0033] In order to meet the landing requirements of the helicopter, the ground bearing capacity within the range of 0.83D needs to meet the landing requirements. The ground bearing capacity within the range of 0.83D diameter is measured by using the ground bearing capacity test device; the ground test data is given to the ground model, and the landing load allowed by the ground under the premise of given subsidence amount is calculated; according to the landing load calculation of the helicopter landing gear, the landing working condition allowed by the combination of the weight of the helicopter, the subsidence speed and the lift coefficient is given. According to the landing working condition allowed, the conclusion whether the helicopter can land is given.

[0034] In a feasible implementation manner, the operation steps are as follows:

[0035] a) According to the size D of the helicopter, a 0.83D diameter circle (see Figure 2 ) required to bear the landing load is given.

[0036] b) Three measurement points are selected on the 0.83D diameter, and the ground bearing capacity is measured by using the ground bearing capacity detection device (see Figure 3 ).

[0037] c) According to the type of the ground soil, the ground soil layer is divided, and the ground soil layer model is established.

[0038] d) The data of the three test points are input into the landing site ground model.

[0039] e) Set a maximum subsidence amount allowed by the landing gear.

[0040] f) According to the tire characteristics and the established ground model, the ground model dynamic loading simulation is carried out by using the Abaqus finite element simulation software, and the ground subsidence amount is calculated; the maximum landing load allowed by the ground is deduced through the ground subsidence amount;

[0041] g) According to the maximum landing load allowed by the ground, the landing state of different weight, sinking speed and lift combination allowed by the landing gear landing performance calculation software is given;

[0042] h) According to the results of performance calculation, give the conclusion whether it can land or not.

[0043] It should be noted that the following is the key point of the application:

[0044] 1) The size calculation of the landing site is given;

[0045] 2) The ground detection device is configured, and the test point requirement is given;

[0046] 3) The ground soil layer model based on Abaqus is given;

[0047] 4) With the help of landing gear performance calculation software, the allowed landing state is given.

[0048] In a feasible implementation manner, one of the examples of implementing the method of the application needs to be configured as follows:

[0049] 1) Configured with ground bearing capacity detection device, such as foundation bearing capacity detector;

[0050] 2) Configured with data processing device, which has ground bearing detection data input function, landing site size calculation function and helicopter landing working condition calculation function, such as notebook computer.

[0051] Specific operation steps:

[0052] a) According to the full length of the helicopter 35.3 meters, the field landing area is a circle with a diameter of 29.3 meters.

[0053] b) Select 3 measurement points on the 29.3 meter circle, and test the penetration resistance of the three points with the foundation bearing capacity detector.

[0054] c) Determine that the landing surface soil belongs to sandy soil, divide the landing surface soil layer, and establish the landing surface soil layer model.

[0055] d) The penetration resistance data of the three test points is input into the landing site ground model.

[0056] e) Set a maximum landing gear sinking amount of 15 cm.

[0057] f) According to the tire characteristics (diameter 700 mm, width 265 mm, bias tire, inflation pressure 1.8 MPa) and the established ground model, the Abaqus finite element simulation software is used for ground model dynamic loading simulation; the ground settlement is calculated by continuously increasing the load on the tire until the ground settlement reaches the maximum allowable landing gear settlement of 15 cm, and the maximum allowable landing load is calculated to be 380 kN.

[0058] g) In the landing gear landing performance calculation software, different helicopter design landing states (helicopter weight, helicopter sinking speed, helicopter lift coefficient) are input, and the maximum landing load corresponding to each state is calculated, which is not more than 380 kN;

[0059] h) Since the maximum landing load corresponding to different helicopter design landing states is not more than 380 kN, it is considered that the helicopter can land in this landing area.

Claims

1. A method for evaluating the feasibility of helicopter ground landing in the field, characterized in that, The method includes: The diameter of the helicopter landing area is determined based on the total length of the helicopter; wherein the landing area is a circular region. Three measurement points were selected on the boundary of the landing area; Based on the ground bearing capacity testing device, the bearing capacity of the ground is measured at the measurement point to obtain test data; The test data is input into a general ground soil model to obtain a ground soil model of the landing area; Set a maximum allowable settlement of the landing gear; Based on tire characteristics and the ground soil model of the landing area, Abaqus finite element simulation software was used to perform dynamic loading simulation of the ground model and calculate the ground settlement. If the ground settlement is equal to the allowable settlement of the landing gear, determine the maximum allowable landing load on the ground; The landing status is determined using landing gear landing performance calculation software based on the maximum permissible landing load on the ground.

2. The method according to claim 1, characterized in that, The selection of three measurement points on the boundary of the landing area includes: Based on a preset interval angle, three measurement points are selected on the boundary of the landing area; wherein, the preset interval angle is 120°.

3. The method according to claim 2, characterized in that, Before determining the diameter of the helicopter landing area based on the helicopter's heading length, the process also includes: Obtain the total length of the helicopter.

4. The method according to claim 1, characterized in that, Before inputting the test data into a general ground soil model to obtain the landing area ground soil model, the process also includes: Based on the type of ground soil, ground soil layers are divided, and a general ground soil layer model is established.

5. The method according to claim 1, characterized in that, Based on tire characteristics and the ground soil model of the landing area, the Abaqus finite element simulation software was used to perform dynamic loading simulation of the ground model and calculate the ground settlement, including: A finite element model of the tire was established based on its size, structural design, and filling pressure.

6. The method according to claim 5, characterized in that, If the ground settlement is equal to the maximum permissible settlement of the landing gear, determining the maximum permissible landing load includes: The settlement of the landing area corresponding to different landing loads was calculated using Abaqus finite element simulation software, based on ground and tire finite element models.

7. The method according to claim 1, characterized in that, The landing state is determined using landing gear landing performance calculation software based on the maximum permissible landing load on the ground, including: Based on the landing gear performance calculation model and software, the maximum landing load corresponding to different landing states is calculated.

8. The method according to claim 7, characterized in that, The landing conditions include helicopter weight, helicopter descent speed, and helicopter lift.

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