Insulation isolation device for electrostatic discharge test of aircraft and design method

Abstract

The invention belongs to the technical field of electromagnetic environment effect, and particularly relates to an insulation device for an aircraft electrostatic discharge test and a design method, the insulation device is an insulation plate, and the edge of the upper surface of the insulation plate is provided with a plurality of circles of annular grooves. The design method comprises the following steps: step 1, calculating and determining the size of the edge, constrained by an aircraft wheel, of the insulating plate according to constraint conditions of an aircraft on the insulating plate; 2, calculating the minimum creepage voltage when the insulating plate is not provided with the annular groove; 3, calculating the creepage distance of the insulation board needing to be prolonged through the slotting; step 4, calculating and determining the size of the edge, which is not restrained by the airplane wheel, of the insulating plate; step 5, determining a slotting area range; and 6, calculating the number of the annular grooves. And determining the depth and width of the annular groove.

Description

Technical Field

[0001] The invention belongs to the technical field of electromagnetic environment effects, and in particular relates to an insulation device for aircraft electrostatic discharge testing and a design method thereof. Background Art

[0002] When static electricity discharge occurs during the flight of an aircraft, the aircraft body is isolated from the ground by the atmosphere. Therefore, when conducting an aircraft static electricity discharge performance test, it is necessary to simulate the actual situation of the aircraft flying in the air. This requires the design of an electrostatic isolation device, which is placed between the aircraft and the ground during the test to ensure that the static electricity discharge of the aircraft is released into the atmosphere rather than into the ground.

[0003] The electrostatic isolation device is essentially an insulating material, which can be one of many insulating materials such as plastic, rubber, wood, etc. According to the test characteristics, on the one hand, it needs to meet the load-bearing requirements of the aircraft, and the insulation withstand voltage performance cannot be affected by pressure damage; on the other hand, the size of the insulation device cannot be too large, which affects transportation and daily handling during testing. At the same time, the insulation device should also meet the withstand voltage requirements of the maximum voltage specified in the aircraft electrostatic test. It is necessary to ensure that the isolation device is not broken down by the electrostatic voltage and discharged to the ground, and to ensure that the breakdown voltage of static electricity along the surface of the insulating material to the ground must be greater than the maximum discharge voltage of the aircraft. Therefore, there are certain requirements for the thickness and length and width of the insulation isolation device.

[0004] Since there is no ready-made electrostatic isolation device for reference in China, from the small amount of foreign aircraft electrostatic test data that we have learned, when conducting similar tests abroad, a load-bearing frame structure is designed, and an insulating board, generally square, is placed on the frame structure. During the test, the aircraft is placed on the insulating board by mechanical lifting. Its characteristic is that the size requirements of the insulating board are relatively low, but the cost is that the aircraft needs to be lifted as a whole, and additional auxiliary landing and take-off equipment (such as a crane, etc.) is required. The amount of engineering work for the test has increased significantly, and the attitude of the aircraft needs to be better controlled during lifting, so there are certain safety risks. Summary of the invention

[0005] The purpose of the present invention is to avoid the safety risks and complicated operations caused by lifting the entire aircraft during the electrostatic test, and to provide an electrostatic insulation isolation device that is placed under the wheels by lifting the aircraft with a jack. At the same time, since there is a certain correlation between the jack support point and the position of the landing gear, the size of the electrostatic isolation device is subject to certain restrictions. The present invention provides a design method for an insulation isolation device that meets the requirements of the whole-machine electrostatic discharge test.

[0006] The principle of the present invention is to utilize the difference between the breakdown voltage of air and the creepage voltage along the insulating surface to process a certain number of strip grooves on the surface of the insulating plate, thereby increasing the creepage path length when the static charge is discharged to the ground along the insulating surface, thereby realizing the miniaturization of the insulating isolation device.

[0007] In order to achieve the above tasks, the present invention adopts the following technical solutions:

[0008] An insulating device for aircraft electrostatic discharge testing is provided. The insulating device is an insulating plate. The upper surface edge of the insulating plate is provided with multiple circles of annular grooves.

[0009] Furthermore, the insulating device is an insulating plate, and a side surface of the insulating plate is provided with multiple circles of annular grooves.

[0010] Furthermore, the insulating device is an insulating plate, and parallel grooves are provided on two opposite sides of the upper surface of the insulating plate.

[0011] Furthermore, the insulating plate is in the shape of a rectangular block.

[0012] Furthermore, the cross-sectional shape of the groove is a rectangular groove; the width of the groove is w, the depth is d, and the number of the groove is n.

[0013] A method for designing an insulation device for an aircraft whole-machine-level electrostatic discharge test, the method comprising the following steps:

[0014] Step 1: Calculate and determine the size of the side of the insulation board constrained by the relative positions of the aircraft tire and the jack;

[0015] Step 2: Calculate the minimum creepage voltage of the insulating board when no grooves are cut;

[0016] Step 3: Calculate the creepage path length that needs to be extended by slotting to meet the ESD test voltage requirements;

[0017] Step 4: Calculate and determine the size of the side of the insulation board that is not constrained by the wheel;

[0018] Step 5: Determine the scope of the slotting area;

[0019] Step 6: Calculate and determine the depth, width and number of the annular grooves.

[0020] Furthermore, in step 1, the external dimensions of the insulating board are calculated using the following formula:

[0021]

[0022] L1=2l1

[0023] Where:

[0024] l1: half of the side length of the insulation board;

[0025] d: The distance between the straight line from the center of the wheel to the vertical insulation panel and the vertical line from the jack fulcrum on the machine to the ground;

[0026] r: The radius of the circle formed by the three fulcrums of the jack's stability circle;

[0027] A: The length of the chord formed by the jack's stable circular fulcrum and the moving slide;

[0028] L1: Side length of insulation board.

[0029] Furthermore, in step 2, the minimum creepage voltage calculation formula is as follows:

[0030] V min =(l1+r1-r2+h)×2.5

[0031] Where:

[0032] V min : Minimum creepage voltage (kV);

[0033] r1: tire radius (cm);

[0034] r2: wheel hub radius (cm);

[0035] h: thickness of insulation board (cm);

[0036] l1: Half the width of the insulation board (cm).

[0037] Furthermore, in step 3, the calculation formula for the creepage path distance that needs to be extended by slotting to meet the electrostatic discharge test voltage requirement is as follows:

[0038] D=(VV min ) / 2.5

[0039] Where:

[0040] D: Creepage path distance extended by slotting (cm)

[0041] V: Electrostatic discharge voltage required for electrostatic test (kV)

[0042] Furthermore, the dimension of the unconstrained edge of the insulation top surface is calculated as follows:

[0043] The dimension calculation formula of the side of the insulation board not constrained by the wheel is as follows:

[0044]

[0045] L2=2l2

[0046] Where:

[0047] l2: half of the side length of the insulation board;

[0048] L2: side length of insulation board;

[0049] V: electrostatic discharge voltage required for electrostatic test, kV;

[0050] w: tire width, cm;

[0051] h: thickness of insulation board, cm;

[0052] D: creepage path distance extended by slotting, cm;

[0053] r1: tire radius, cm;

[0054] r2: wheel hub radius, cm.

[0055] Furthermore, the calculation formulas for the parameters of the annular groove and the parallel groove are as follows:

[0056] n=D / 2ds

[0057] Where:

[0058] D: Creepage path distance extended by slotting, cm;

[0059] ds: slot depth cm;

[0060] n: number of slots required;

[0061] The relationship between the width and depth of the groove is calculated as follows:

[0062] ds≤4.5W

[0063] Where:

[0064] ds: rectangular slot depth cm;

[0065] W: Rectangular groove width cm.

[0066] Beneficial technical effects of the present invention:

[0067] 1) Reduce the size of the isolation device, reduce the weight of the device, and facilitate transportation and handling.

[0068] 2) Compared with the insulation isolation facilities composed of insulation panels and building block frames used abroad, the present invention reduces the steps of lifting the fuselage and related supporting work, reduces the test workload, avoids the risk of affecting the safety of the helicopter, and reduces the test costs.

[0069] The insulation isolation device manufactured by the patent of this invention has been applied to the helicopter whole-machine level electrostatic protection verification test, and has achieved certain military and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 This is a schematic diagram of an insulation device for aircraft whole-machine-level electrostatic discharge testing provided by Embodiment 1 of the present invention;

[0071] Figure 2 This is a cross-sectional view of an insulation device for aircraft whole-machine-level electrostatic discharge testing provided by Embodiment 2 of the present invention;

[0072] Figure 3 This is a cross-sectional view of an insulation device for aircraft whole-machine-level electrostatic discharge testing provided by Embodiment 3 of the present invention;

[0073] Figure 4 It is a schematic diagram of the position of the insulation isolation device and the jack provided in the fourth embodiment of the present invention;

[0074] Figure 5 The present invention is a flow chart of a design method of an insulation device for an aircraft whole-machine-level electrostatic discharge test. DETAILED DESCRIPTION

[0075] Embodiment 1: An insulating device for aircraft whole-machine-level electrostatic discharge testing is an insulating plate in the shape of a rectangular block, and a plurality of circumferential annular grooves are formed on the upper edge of the insulating plate.

[0076] Application scenarios of this embodiment: When the wheel is close to the jack support point on the fuselage structure, the size of the isolation plate is restricted, and it is necessary to increase the creepage distance of static charge discharge to the ground by opening a groove on the surface of the isolation plate to meet the discharge voltage isolation requirements specified in the test.

[0077] The implementation plan is as follows:

[0078] Step 1: Calculate and determine the size of the side of the insulation board that is constrained by the relative position of the aircraft tire and the jack. Determine the distance between the straight line from the center of the wheel to the insulation panel and the vertical line from the support point of the jack on the aircraft to the ground. The maximum distance between the upper surface of the insulation board and the side in contact with the jack and its parallel side is twice the aforementioned distance.

[0079] Considering that the edges of the insulation board are not easily damaged during transportation after slotting, the thickness of the insulation board is generally not less than 8 cm, and the groove depth is about half of the board thickness.

[0080] Step 2: Based on the edge determined in step 1 and the maximum dimension between the parallel edges, calculate the minimum creepage voltage of the aircraft tire for electrostatic discharge to the ground along the surface of the insulating plate perpendicular to the edge.

[0081] Step 3: Based on steps 1 and 2, calculate the discharge voltage to the ground along the edge of the wheel perpendicular to the side in contact with the jack. When the discharge voltage meets the electrostatic discharge test voltage requirement, the creepage distance to the ground needs to be extended by slotting;

[0082] Step 4: Considering that an annular groove is opened on the upper surface of the insulating plate, the creepage distance extended by the groove is the same for all sides. Calculate the distance between the two sides that are not in contact with the jack (i.e., the length of the side in contact with the jack) based on the extended creepage distance calculated in steps 1 and 3.

[0083] Step 5: Determine the scope of the slotting area

[0084] It is better to prevent the slotted area on the insulating board from being directly pressed by the tire to avoid damage to the area. Therefore, it is necessary to calculate the slotted area based on the post-compression deformation of the tire after the load is borne during the test. If the size allows, the slotted area is generally located outside the vertical projection area of ​​the tire on the insulating board.

[0085] Step 6: Based on steps 3 and 5, determine the relationship between the groove depth and width, and reasonably allocate the depth, width and number of grooves.

[0086] Embodiment 2: An insulating device for aircraft whole-machine-level electrostatic discharge testing, the device is an insulating plate in the shape of a rectangular block, and the side edge of the insulating plate is provided with multiple circumferential annular grooves.

[0087] Application of this embodiment: In addition to the limitation of the distance between the wheel and the jack support point, the area of ​​the isolation board is further reduced based on the constraints of the first embodiment, and a groove can be opened on the side to transfer the extended creepage distance calculated and determined in the first embodiment to the side of the insulation board. Considering the economy, it is recommended to cut the thinner panel (select the thickness equal to the groove width) according to the two peripheral dimensions after the integral panel is grooved, and bond them layer by layer with structural adhesive, so as to achieve the same result as the integral panel after the groove processing.

[0088] Implementation steps (using layer gluing process):

[0089] Step 1: Refer to Example 1 to preliminarily calculate and determine the size of the side constrained by the relative position of the wheel and the jack. Because the side of the insulation board is grooved, the thickness is higher than that of Example 1. The size of each side of the upper surface can be appropriately reduced. The upper surface size is recommended to be no less than the outer contour of the wheel plus the depth of the expected side groove. The thickness of the insulation board (height of the side groove) and the number of insulation board layers are determined by referring to the thickness specifications of products on the market.

[0090] Step 2: Calculate the minimum creepage voltage along the surface of the insulating plate (upper surface and side surface, without grooves) during wheel-to-ground electrostatic discharge based on the aircraft electrostatic discharge test voltage;

[0091] Step 3: Calculate the creepage path length that needs to be extended by slotting to meet the ESD test voltage requirements;

[0092] Step 4: Calculate and determine the number and depth of the grooves required for the side of the insulating board to meet the electrostatic discharge voltage resistance according to steps 1 and 3;

[0093] Step 5: Determine the size of the unconstrained edge based on step 3, wheel parameters, and electrostatic discharge test voltage;

[0094] Step 6: Design and process two sizes of insulation boards according to the groove depth and outer dimensions determined in step 3, and use structural adhesive to symmetrically bond the insulation boards layer by layer.

[0095] Implementation steps (using a whole thick plate for processing):

[0096] Step 1: First, select the appropriate thickness of the insulation board according to the product specifications available on the market, and refer to Example 1 to calculate and determine the size of the side constrained by the relative positions of the wheel and the jack.

[0097] Step 2: Calculate the minimum creepage voltage along the surface of the insulating plate (upper surface and side surface, without grooves) parallel to the constrained edge during wheel-to-ground electrostatic discharge according to the aircraft electrostatic discharge test voltage;

[0098] Step 3: Calculate the creepage path length that needs to be extended by slotting to meet the ESD test voltage requirements;

[0099] Step 4: Calculate the number, depth and height of the grooves required for the side of the insulating board to meet the electrostatic discharge voltage resistance according to steps 1 and 3;

[0100] Step 5: Calculate the size of the edge not constrained by the relative position of the wheel and the jack based on step 3, the wheel parameters and the electrostatic discharge test voltage requirements.

[0101] Step 6: Process the insulation board according to the number of grooves, groove depth and groove height determined in step 4.

[0102] Embodiment 3

[0103] The invention discloses an insulating device for aircraft whole-machine-level electrostatic discharge test. The device is an insulating plate in a rectangular block shape. Parallel grooves are arranged on two opposite sides of the upper surface of the insulating plate.

[0104] Application scenarios: The distance between the wheel and the supporting point of the jack on the machine limits the distance between the isolation plate and the opposite sides of the contact edge of the jack, but the length of the side in contact with the jack is theoretically not limited. Therefore, in this case, it is only necessary to process a certain number of parallel grooves on the outer edges of the opposite sides of the contact edge with the jack to increase the creepage distance of the narrow side so that it can meet the maximum discharge voltage of the whole machine level electrostatic discharge test.

[0105] Implementation plan:

[0106] The size of the edge in contact with the jack and its parallel edge (i.e., the slotted edge), the electrostatic discharge creepage distance to be extended by the slotting, and the determination of the slot depth and slot width are the same as those in the first embodiment.

[0107] Determination of the length of the side in contact with the jack: Determined based on the tire dimensions, wheel hub dimensions, insulation board thickness and the minimum creepage distance required to withstand the maximum electrostatic discharge voltage of the aircraft.

[0108] Embodiment 4: A design method for an insulation device for aircraft whole-machine-level electrostatic discharge test (grooving on the upper surface)

[0109] The main steps include:

[0110] Step 1: Calculate and determine the size of the constrained edge of the insulation isolation board based on the constraints of the aircraft tires and the jack parameters on the fuselage structure.

[0111] according to Figure 4 , Schematic diagram of the relative position of the insulation isolation device and the jack during the test

[0112]

[0113] L1=2l1

[0114] Where:

[0115] l1: half of the side length of the insulation board;

[0116] d: The distance between the straight line from the center of the wheel to the vertical insulation panel and the vertical line from the jack fulcrum on the machine to the ground;

[0117] r: The radius of the circle formed by the three fulcrums of the jack's stability circle;

[0118] A: The length of the chord formed by the jack's stable circular fulcrum and the moving slide;

[0119] L1: Side length of insulation board.

[0120] Step 2: After determining the dimensions in step 1, calculate the minimum creepage voltage of the insulation board without slotting.

[0121] The minimum creepage voltage calculation formula is as follows:

[0122] V min = <l1+r1-r2+h)×2.5

[0123] Where:

[0124] V min : Minimum creepage voltage (kV);

[0125] r1: tire radius (cm);

[0126] r2: wheel hub radius (cm);

[0127] h: thickness of insulation board (cm);

[0128] l1: Half the width of the insulation board (cm).

[0129] Step 3: Calculate the creepage path length that needs to be extended through slotting to meet the electrostatic discharge test voltage requirements. The calculation formula for the creepage path distance that needs to be extended through slotting is as follows:

[0130] D=(VV min ) / 2.5

[0131] Where:

[0132] D: Creepage path distance extended by slotting (cm)

[0133] V: Electrostatic discharge voltage required for electrostatic test (kV)

[0134] Step 4: Calculate and determine the size of the insulation board edge not constrained by the wheel

[0135] The dimension calculation formula of the side of the insulation board not constrained by the wheel is as follows:

[0136]

[0137] L2=2l2

[0138] Where:

[0139] l2: half of the side length of the insulation board;

[0140] L2: side length of insulation board;

[0141] V: electrostatic discharge voltage required for electrostatic test, kV;

[0142] w: tire width, cm;

[0143] h: thickness of insulation board, cm;

[0144] D: creepage path distance extended by slotting, cm;

[0145] r1: tire radius, cm;

[0146] r2: wheel hub radius, cm.

[0147] Step 5: Determine the scope of the slotting area

[0148] It is better that the slotted area on the insulating board is not directly pressed by the tire to avoid damage to the area and affect reuse. Therefore, it is necessary to calculate the slotted area based on the post-compression deformation of the tire after the load is borne during the test. If the size allows, the slotted area is generally located outside the vertical projection area of ​​the tire on the insulating board.

[0149] Step 6: Calculate the depth, width and number of annular grooves

[0150] The formula for calculating the number of annular grooves or the number of parallel grooves on one side is as follows:

[0151] n=D / 2ds

[0152] Where:

[0153] D: Creepage path distance extended by slotting, cm;

[0154] ds: slot depth cm;

[0155] n: number of slots required;

[0156] The relationship between the width and depth of the groove is calculated as follows:

[0157] ds≤4.5W

[0158] Where:

[0159] ds: rectangular slot depth cm;

[0160] W: Rectangular groove width cm.

[0161] Note: During the project implementation, the number after the decimal point of the number of slots n is rounded up to 1 to ensure that the insulation board has a certain margin for the electrostatic discharge voltage resistance.

Claims

1. An insulation device for aircraft electrostatic discharge testing, characterized in that: The insulating device is an insulating plate, and the upper surface edge of the insulating plate is provided with a plurality of annular grooves.

2. An insulation device for aircraft electrostatic discharge testing, characterized in that: The insulating device is an insulating plate, and a plurality of annular grooves are arranged on the side surface of the insulating plate.

3. An insulation device for aircraft electrostatic discharge testing, characterized in that: The insulating device is an insulating plate, and parallel grooves are arranged on two opposite sides of the upper surface of the insulating plate.

4. The insulation device according to any one of claims 1 to 3, characterized in that: The insulating plate is in a rectangular block shape.

5. The insulation device according to claim 4, characterized in that The cross-sectional shape of the groove is a rectangular groove; the width of the groove is w, the depth is d, and the number of the groove is n.

6. A method for designing an insulation device for an aircraft electrostatic discharge test, characterized in that: The method comprises the following steps: Step 1: Calculate and determine the size of the side of the insulation board constrained by the relative positions of the aircraft tire and the jack; Step 2: Calculate the minimum creepage voltage of the insulating board when no grooves are cut; Step 3: Calculate the creepage path length that needs to be extended by slotting to meet the ESD test voltage requirements; Step 4: Calculate and determine the size of the side of the insulation board that is not constrained by the wheel; Step 5: Determine the scope of the slotting area; Step 6: Calculate and determine the depth, width and number of the annular grooves.

7. The method according to claim 6, characterized in that: In the step 1, the calculation formula for the size of the side of the insulating plate constrained by the aircraft tire and the jack is as follows: L1-2l1 Where: l1: half of the side length of the insulation board; d: The distance between the straight line from the center of the wheel to the vertical insulation panel and the vertical line from the jack fulcrum on the machine to the ground; r: The radius of the circle formed by the three fulcrums of the jack's stability circle; A: The length of the chord formed by the jack's stable circular fulcrum and the moving slide; L1: Side length of insulation board.

8. The method according to claim 6, characterized in that: In step 2, the minimum creepage voltage calculation formula is as follows: In min =(l1+r1-r2+h)×2.5 Where: V min : Minimum creepage voltage, kV; r1: tire radius, cm; r2: wheel hub radius, cm; h: thickness of insulation board, cm; I1: Half the width of the insulation board, cm.

9. The method according to claim 6, characterized in that: In step 3, the calculation formula for the creepage path distance that needs to be extended by slotting to meet the electrostatic discharge test voltage requirement is as follows: D=(VV min ) / 2.5 Where: D: creepage path distance to be extended by slotting, cm; V: The electrostatic discharge voltage required for the electrostatic test, kV.

10. The method according to claim 6, characterized in that: In step 4, the dimension calculation formula of the side of the insulating plate not constrained by the wheel is as follows: L2＝2l2 Where: l2: half of the side length of the insulation board; L2: side length of insulation board; V: electrostatic discharge voltage required for electrostatic test, kV; w: tire width, cm; h: thickness of insulation board, cm; D: creepage path distance extended by slotting, cm; r1: tire radius, cm; r2: wheel hub radius, cm; The formula for calculating the number of annular grooves or the number of parallel grooves on one side is as follows: n=D / 2ds Where: D: Creepage path distance extended by slotting, cm; ds: slot depth cm; n: number of slots required; The relationship between the width and depth of the groove is calculated as follows: ds≤4.5W Where: ds: rectangular slot depth cm; W: Rectangular groove width cm.

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