Helicopter hoist and load handling method

Abstract

The application provides a helicopter hoisting load processing method, which comprises the following steps: obtaining relevant parameters for calculating the helicopter hoisting load, i.e. the coordinates of a lifting ring, the coordinates of a support rod, the coordinates of a hub, and the coordinates of a lifting point of a fuselage; since the gravity center of the helicopter and the lifting point are not located on the same vertical line, the fuselage and the lifting device will be deflected when hoisting; in order to consider the influence caused by the deflection, the abaqus software is used for calculation; meanwhile, the application also provides a helicopter hoisting device; and based on the abaqus software, the influence of the attitude change of the helicopter during hoisting is considered, so that the more accurate hoisting point load can be calculated.

Description

Technical Field

[0001] This application belongs to the field of helicopter comprehensive strength technology, and in particular relates to a helicopter lifting device and load handling method. Background Technology

[0002] In the past, when calculating the load at the lifting point of a helicopter, it was assumed that the helicopter was in a horizontal attitude. Based on the input information such as the angle of the sling and the weight and center of gravity of the helicopter, the lifting load was calculated according to the load balance.

[0003] The calculation of the load is inaccurate because it does not account for the helicopter's attitude deviation when the helicopter's center of gravity and the lifting point are not on the same vertical line. Summary of the Invention

[0004] To address the aforementioned technical problems, in a first aspect, this application provides a helicopter lifting device, wherein the helicopter has a center of gravity, a left-side tie-down point, a right-side tie-down point, and a rotor hub lifting point; the device includes:

[0005] Rings;

[0006] A first sling, one end of which is connected to the lifting ring;

[0007] The struts form a triangular structure; wherein, the other end of the first sling is connected to a vertex of the triangular structure; the triangular structure includes a first vertex, a second vertex, and a third vertex;

[0008] A second sling is connected to the lifting point of the propeller hub, with one end of the second sling connected to the first vertex and the other end of the second sling connected to the center of gravity.

[0009] The third sling, one end of which is connected to the second vertex, and the other end of which is connected to the left tie point;

[0010] The fourth sling has one end connected to the third vertex and the other end connected to the right mooring point.

[0011] Preferably, the first sling includes three straps, one end of each of the three straps is connected to the lifting ring, and the other end of each strap is connected to the first vertex, the second vertex, and the third vertex, respectively.

[0012] Preferably, the support rod includes three support rods, which are connected end to end to form the triangular structure.

[0013] Preferably, the second sling includes three slings, one end of which is connected to the first vertex, and the other end of which is connected to the center of gravity; the middle part of the three slings is connected to the lifting point of the propeller hub.

[0014] Preferably, the sling comprises a flexible metal sling or a fabric strap.

[0015] Preferably, the strut comprises a metal rod.

[0016] Secondly, this application also provides a method for handling loads lifted by a helicopter, the method comprising:

[0017] Obtain the helicopter's weight, center of gravity coordinates, ring coordinates, strut connection vertex coordinates, rotor hub lifting point coordinates, and fuselage lifting point coordinates;

[0018] The calculation process is divided into two load steps: In the first load step, a forced displacement is applied to the center of gravity, with a downward displacement of 10-50 mm, to generate initial tension in the lifting device and move the horizontal coordinate of the center of gravity to match the lifting point, so as to avoid large displacements in subsequent load steps; In the second load step, the forced displacement applied in the first load step is released, and the lifting inertial load is applied at the same time. To facilitate convergence of the calculation, the load increment in both load steps is less than 0.1.

[0019] Create a coordinate system fixed to the fuselage;

[0020] In post-processing, the calculation results are read. To obtain the results in the body coordinate system, a coordinate system transformation is performed in "Result Options" Transformation to convert the calculation results to the body coordinate system. Then, the loads at the propeller hub and fuselage lifting points are read.

[0021] Preferably, the helicopter's center of gravity and the lifting ring are not on the same vertical line.

[0022] The beneficial technical effects of this application are as follows:

[0023] This application, based on Abaqus software, calculates a more accurate lifting point load by considering the influence of helicopter attitude changes during lifting. Attached Figure Description

[0024] Figure 1 This is a lifting diagram provided for an embodiment of this application. Detailed Implementation

[0025] This application provides a method for handling helicopter lifting loads, including obtaining relevant parameters for calculating helicopter lifting loads, namely, the coordinates of the lifting ring, the strut coordinates, the rotor hub coordinates, and the fuselage lifting point coordinates. Since the helicopter's center of gravity and the lifting point are not on the same vertical line, the helicopter and the lifting equipment will deflect during lifting. To account for the effects of this deflection, Abaqus software is used for calculation. This application also provides a helicopter lifting device. Based on Abaqus software, this application calculates a more accurate lifting point load by considering the influence of helicopter attitude changes during lifting.

[0026] Please see Figure 1 This application provides relevant parameters for calculating the lifting load of a helicopter, including the coordinates of the lifting ring, the strut, the rotor hub, and the fuselage lifting point.

[0027] Since the helicopter's center of gravity and the lifting point are not on the same vertical line, the helicopter and lifting equipment will deflect during lifting. To account for the effects of this deflection, Abaqus software is used for calculation, and the model is simplified as follows:

[0028] a) The helicopter is simplified as a rigid body (elastic deformation is not considered).

[0029] b) Both the suspension rope and the strut are simulated using connection elements. The suspension rope only bears tensile loads and is simulated using Axial elements; the strut is a rigid rod and is simulated using Axial elements.

[0030] c) Constrain the translational degree of freedom at the lifting ring and constrain the rotational degree of freedom in the Z-axis at the center of gravity. The load is applied at the center of gravity.

[0031] d) To account for changes in strut position, rotor hub position, and lifting point position due to helicopter attitude variations, enable the geometric nonlinearity option.

[0032] e) Since applying a load directly at the center of gravity would cause the results to fail to converge due to excessive displacement at the center of gravity, two load steps were created. In the first load step, a forced displacement was applied to the helicopter's center of gravity to align it with the lifting ring on the same vertical line, and the z-axis coordinate was appropriately shifted downward to generate initial tension. In the second load step, the forced displacement was released, and a load was applied.

[0033] Since the helicopter's coordinate system deflects after it turns, the load components of the joint in the body coordinate system are calculated based on the rotation angle of the coordinate system.

[0034] In other embodiments of this application, the method provided by this application includes the following steps:

[0035] Step 1: Based on the helicopter lifting plan, center of gravity, and lifting interface, obtain the helicopter weight M and the helicopter center of gravity coordinate x. c y c zc The coordinates of the rings are x. r y r z r The coordinates of the strut connection point x a i y a i z a i (i = 1, 2, 3), coordinates of the hub lifting point x p y p z p Coordinates of the fuselage lifting point (x) q y q z q Create the corresponding points in the Abaqus software.

[0036] Step 2: The suspension rope is a flexible metal rigging or fabric strap, simulated using the Axial element in Abaqus. Since the suspension rope can only withstand tensile loads and not compressive loads, a nonlinear stiffness curve is set. The tensile stiffness in the tensile direction is set according to the curve obtained from experiments, while the stiffness in the compressive direction is a minimum value. Stiffness outside the curve range is calculated by extrapolation.

[0037] Step 3: The strut support is a metal rod, simulated using Axial elements in Abaqus. Its stiffness is calculated based on the material and cross-sectional dimensions of the metal rod.

[0038] Step 4: The fuselage stiffness is relatively high compared to the hoisting rope, so it is simplified to a rigid body and simulated using Beam elements in Abaqus. Beam elements are created between the center of gravity and the propeller hub hoisting point, and between the center of gravity and the fuselage hoisting point, with the element stiffness being rigid body.

[0039] Step 5: Constrain the helicopter's translational degrees of freedom in the heading, lateral, and vertical directions at the lifting ring. Although no constraints are applied at the center of gravity during actual lifting, to eliminate calculation non-convergence caused by rotation, the rotational degrees of freedom about the vertical direction are constrained at the helicopter's center of gravity. Apply the inertial load during lifting at the helicopter's center of gravity, with the load vertically downwards.

[0040] Step 6: Since the helicopter's center of gravity and the lifting ring are not on the same vertical line, the helicopter's roll and yaw angles will change during lifting. This will cause changes in the helicopter's center of gravity coordinates, strut connection point coordinates, rotor hub lifting point coordinates, and fuselage lifting point coordinates. To account for the impact of coordinate changes on the lifting load calculation, turn on the large deformation switch "Nlgeom" in "Edit Step".

[0041] Step 7: During the calculation, applying a load directly at the center of gravity can lead to non-convergence due to excessive rigid body displacement. Therefore, the calculation process is divided into two load steps. In the first load step, a forced displacement of 10–50 mm is applied downwards to the center of gravity to generate initial tension in the lifting device. The horizontal coordinate of the center of gravity is also moved to align with the lifting point to avoid large displacements in subsequent load steps. In the second load step, the forced displacement applied in the first load step is released, and a lifting inertial load is applied simultaneously. To facilitate convergence, the load increments in both load steps are less than 0.1.

[0042] Step 8: During helicopter lifting, the helicopter's body coordinate system will deflect relative to the geodetic coordinate system. Since the load read directly is in the geodetic coordinate system, it needs to be converted to the body coordinate system for subsequent strength analysis. Therefore, a coordinate system fixed to the fuselage is created.

[0043] Step 9: Read the calculation results in post-processing. To obtain the results in the body coordinate system, perform a coordinate system transformation in "ResultOptions" under Transformation to convert the calculation results to the body coordinate system. Then, read the loads at the propeller hub and fuselage lifting points.

[0044] This application, based on Abaqus software, calculates a more accurate lifting point load by considering the influence of helicopter attitude changes during lifting.

[0045] In other embodiments of this application, a helicopter lifting device is provided, wherein the helicopter has a center of gravity, a left tether point, a right tether point, and a rotor hub lifting point; the device includes:

[0046] Rings;

[0047] A first sling, one end of which is connected to the lifting ring;

[0048] The struts form a triangular structure; wherein, the other end of the first sling is connected to a vertex of the triangular structure; the triangular structure includes a first vertex, a second vertex, and a third vertex;

[0049] A second sling is connected to the lifting point of the propeller hub, with one end of the second sling connected to the first vertex and the other end of the second sling connected to the center of gravity.

[0050] The third sling, one end of which is connected to the second vertex, and the other end of which is connected to the left tie point;

[0051] The fourth sling has one end connected to the third vertex and the other end connected to the right mooring point.

[0052] The first sling includes three straps, one end of each strap is connected to the lifting ring, and the other end of each strap is connected to the first vertex, the second vertex, and the third vertex, respectively.

[0053] The support rod comprises three support rods, which are connected end to end to form the triangular structure.

[0054] The second sling includes three slings, one end of which is connected to the first vertex, and the other end of which is connected to the center of gravity; the middle part of the three slings is connected to the lifting point of the propeller hub.

[0055] The sling may include a flexible metal sling or a fabric sling.

[0056] The strut includes a metal rod.

[0057] This application, based on Abaqus software, calculates a more accurate lifting point load by considering the influence of helicopter attitude changes during lifting.

Claims

1. A helicopter hoist apparatus, characterized by, The helicopter has a center of gravity, a left-side tie-down point, a right-side tie-down point, and a rotor hub lifting point; the device includes: Rings; A first sling, one end of which is connected to the lifting ring; The struts form a triangular structure; wherein, the other end of the first sling is connected to a vertex of the triangular structure; the triangular structure includes a first vertex, a second vertex, and a third vertex; A second sling is connected to the lifting point of the propeller hub, with one end of the second sling connected to the first vertex and the other end of the second sling connected to the center of gravity. The third sling, one end of which is connected to the second vertex, and the other end of which is connected to the left tie point; The fourth sling, one end of which is connected to the third vertex, and the other end of which is connected to the right tie point; The first sling includes three straps, one end of each of the three straps is connected to the lifting ring, and the other end of each strap is connected to the first vertex, the second vertex, and the third vertex, respectively. The second sling includes three slings, one end of which is connected to the first vertex, and the other end of which is connected to the center of gravity; the middle part of the three slings is connected to the hub lifting point. The device is used to implement a method for handling loads lifted by a helicopter, and the method is calculated using Abaqus software; The method includes: Obtain the helicopter's weight, center of gravity coordinates, ring coordinates, strut connection vertex coordinates, rotor hub lifting point coordinates, and fuselage lifting point coordinates; The calculation process is divided into two load steps: In the first load step, a forced displacement is applied to the center of gravity, with a downward displacement of 10-50 mm, to generate initial tension in the lifting device and move the horizontal coordinate of the center of gravity to match the lifting point, so as to avoid large displacements in subsequent load steps; In the second load step, the forced displacement applied in the first load step is released, and the lifting inertial load is applied at the same time. To facilitate convergence of the calculation, the load increment in both load steps is less than 0.

1. Create a coordinate system fixed to the fuselage; In post-processing, the calculation results are read. To obtain the results in the body coordinate system, a coordinate system transformation is performed in "Result Options" Transformation to convert the calculation results to the body coordinate system. Then, the loads at the propeller hub and fuselage lifting points are read. The helicopter's center of gravity and the hanging ring are not on the same vertical line.

2. The apparatus according to claim 1, characterized in that, The support rod includes three support rods, which are connected end to end to form the triangular structure.

3. The apparatus according to claim 1, characterized in that, The sling may be a flexible metal sling or a fabric strap.

4. The apparatus according to claim 1, characterized in that, The strut includes a metal rod.

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