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

Abstract

The application belongs to the technical field of electromagnetic environment effect, and particularly relates to an insulating device for aircraft electrostatic discharge test and a design method. The insulating device is an insulating plate, and a plurality of annular grooves are arranged on the edge of the upper surface of the insulating plate. The design method comprises the following steps: step one: according to the constraint condition of the aircraft on the insulating plate, the size of the edge of the insulating plate constrained by the wheel is calculated and determined; step two: the minimum creepage voltage of the insulating plate without annular grooves is calculated; step three: the creepage distance of the insulating plate which needs to be extended by grooving is calculated; step four: the size of the edge of the insulating plate not constrained by the wheel is calculated and determined; step five: the range of the grooving area is determined; and step six: the number of annular grooves is calculated. The depth and width of the annular grooves are determined.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electromagnetic environmental effects, and particularly relates to an insulation device for aircraft electrostatic discharge test and a design method thereof. BACKGROUND

[0002] When electrostatic discharge occurs in flight of an aircraft, the aircraft body is isolated from the ground through the atmosphere, and therefore, when the electrostatic discharge performance of the aircraft is tested, the actual situation of the aircraft in flight in the air needs to be simulated, which requires designing an electrostatic isolation device to be placed between the aircraft and the ground during the test to ensure that the electrostatic discharge of the aircraft is released into the atmosphere rather than 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, the aircraft weight requirement needs to be met, and damage due to pressure should not affect the insulation withstand voltage performance; on the other hand, the size of the insulation device should not be too large, which affects transportation and daily handling during the test. At the same time, the insulation device should also meet the withstand voltage requirement of the maximum voltage specified in the aircraft electrostatic test, that is, it is necessary to ensure that the isolation device is not punctured by the electrostatic voltage to cause discharge to the ground, and the breakdown voltage of the electrostatic discharge along the surface of the insulation material to the ground must be greater than the maximum discharge voltage of the aircraft, so the thickness and length-width size of the insulation isolation device have certain requirements.

[0004] Since there is no ready-made electrostatic isolation device in China that can be used for reference, from the limited amount of foreign aircraft electrostatic test data, it can be seen that when similar tests are carried out abroad, a load-bearing frame structure is designed, and an insulating plate is placed on the frame structure, which is generally square. During the test, the aircraft is placed on the insulating plate by mechanical lifting, which has the characteristics of low size requirement for the insulating plate, and the cost is the need for overall lifting of the aircraft, the need for additional auxiliary lifting equipment (such as a crane), the increase of the test engineering quantity, and the need for good control of the attitude of the aircraft when lifting, thus there is a certain safety risk. SUMMARY

[0005] The purpose of the present application is to avoid the safety risk and complicated operation caused by overall lifting of the aircraft during electrostatic test, and the present application provides an electrostatic insulation isolation device for lifting the aircraft by using a jack to place it under the aircraft wheel. At the same time, since there is a certain correlation between the position of the jack support point and the position of the landing gear, the size of the electrostatic isolation device is thus restricted, and the present application provides a design method of the insulation isolation device that meets the requirements of the overall electrostatic discharge test.

[0006] The principle of the present application is to use the difference between the air breakdown voltage and the creeping voltage along the insulating surface to process a certain number of strip grooves on the surface of the insulating plate, increase the creeping path length when the static charge along the insulating surface is discharged to the ground, and realize the miniaturization of the insulating isolation device.

[0007] In order to achieve the above-mentioned task, the present application adopts the following technical solutions:

[0008] An insulating device for aircraft electrostatic discharge test, the insulating device is an insulating plate, and a plurality of annular grooves are arranged on the edge of the upper surface of the insulating plate.

[0009] Further, the insulating device is an insulating plate, and a plurality of annular grooves are arranged on the side surface of the insulating plate.

[0010] Further, the insulating device is an insulating plate, and parallel grooves are arranged on the opposite edges of the upper surface of the insulating plate.

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

[0012] Further, 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 is n.

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

[0014] Step one: calculating and determining the size of the edge of the insulating plate constrained by the relative position of the aircraft tire and the jack;

[0015] Step two: calculating the minimum creeping voltage of the insulating plate without grooves;

[0016] Step three: calculating the creeping path length that needs to be lengthened by grooving to meet the electrostatic discharge test voltage requirement;

[0017] Step four: calculating and determining the size of the edge of the insulating plate unconstrained by the machine wheel;

[0018] Step five: determining the grooving area range;

[0019] Step six: calculating and determining the depth, width and number of annular grooves.

[0020] Further, in step one, the formula for calculating the size of the insulating plate is as follows:

[0021]

[0022] L1=2l1

[0023] In the formula:

[0024] l1: half of the length of the insulating plate;

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

[0026] r: the radius of the circle formed by the three fulcrums of the jack stabilizing circle;

[0027] A: the chord length formed by the jack stabilizing circle fulcrum and the moving slide;

[0028] L1: the length of the insulation panel.

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

[0030] V min = (l1 + r1 - r2 + h) x 2.5

[0031] In the formula:

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

[0033] r1: tire radius (cm);

[0034] r2: hub radius (cm);

[0035] h: insulation panel thickness (cm);

[0036] l1: half the width of the insulation panel (cm).

[0037] Further, in step three, the formula for calculating the creepage path distance through the slot extension to meet the electrostatic discharge test voltage requirement is as follows:

[0038] D = (V - V min ) / 2.5

[0039] In the formula:

[0040] D: creepage path distance through the slot extension (cm)

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

[0042] Further, the size calculation formula of the unconstrained edge of the upper surface of the insulation is as follows:

[0043] The size calculation formula of the unconstrained edge of the insulation panel by the machine wheel is as follows:

[0044]

[0045] L2 = 2l2

[0046] In the formula:

[0047] l2: half the length of the insulation panel;

[0048] L2: length of the insulating plate;

[0049] V: static discharge voltage required by the static test, kV;

[0050] w: tire width, cm;

[0051] h: insulating plate thickness, cm;

[0052] D: the distance of the creeping path extended by the slot, cm;

[0053] r1: tire radius, cm;

[0054] r2: hub radius, cm.

[0055] Further, the annular groove and parallel groove parameter calculation formula is as follows:

[0056] n = D / 2ds

[0057] In the formula:

[0058] D: the distance of the creeping path extended by the slot, cm;

[0059] ds: slot depth, cm;

[0060] n: the number of slots required;

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

[0062] ds≤4.5W

[0063] In the formula:

[0064] ds: rectangular slot depth, cm;

[0065] W: rectangular slot width, cm.

[0066] The beneficial technical effects of the present application are:

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

[0068] 2) Compared with the insulation isolation facility composed of the insulating panel and the block type frame adopted by foreign countries, the present application reduces the steps of lifting the machine body and the related supporting work, reduces the test workload, avoids the risk of affecting the safety of the helicopter, and also reduces the test cost.

[0069] The insulating isolation device made by the present application has been applied to helicopter whole machine level static protection verification test, and has achieved certain military and social benefits. BRIEF DESCRIPTION OF DRAWINGS

[0070] Figure 1 is a schematic diagram of an insulation device for aircraft whole machine level electrostatic discharge test provided by embodiment one of the present application;

[0071] Figure 2 is a sectional view of an insulation device for aircraft whole machine level electrostatic discharge test provided by embodiment two of the present application;

[0072] Figure 3 is a sectional view of an insulation device for aircraft whole machine level electrostatic discharge test provided by embodiment three of the present application;

[0073] Figure 4 is a schematic diagram of an insulation isolation device and jack position provided by embodiment four of the present application;

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

[0075] Embodiment one: an insulation device for aircraft whole machine level electrostatic discharge test, which is an insulation plate in the shape of a rectangular block, and a plurality of circumferential grooves are formed on the edge of the upper surface of the insulation plate.

[0076] The application occasion of this embodiment: when the distance between the machine wheel and the jack support point on the machine body structure is relatively close, the size of the isolation plate is restricted, and it is necessary to increase the creepage distance of the static charge to ground discharge by opening grooves on the surface of the isolation plate, so as to meet the discharge voltage isolation requirement of the test regulation.

[0077] The implementation scheme is as follows:

[0078] Step one: calculate the size of the edge of the insulation plate constrained by the relative position of the aircraft tire and the jack, determine the distance between the straight line of the center of the machine wheel perpendicular to the insulation panel and the vertical line of the jack support point on the machine perpendicular to the ground, and the maximum distance size between the edge of the upper surface of the insulation plate in contact with the jack and its parallel edge is twice the aforementioned distance.

[0079] Considering that the edge of the grooved insulation plate is not easy to be damaged during the handling operation, the thickness of the insulation plate is generally not less than 8 cm, and the groove depth is about half of the plate thickness.

[0080] Step two: calculate the minimum creepage voltage of the static discharge of the aircraft tire to the ground along the surface of the insulation plate perpendicular to the edge on the basis of the maximum size between the edge determined in step one and the parallel edge.

[0081] Step three: calculate the creepage distance to the ground that needs to be extended by grooving when the discharge voltage of the machine wheel to the ground along the edge in contact with the jack meets the electrostatic discharge test voltage requirement on the basis of steps one and two;

[0082] Step four: considering the ring groove on the upper surface of the insulation board, the length of the creepage distance of the groove is the same for all sides, the distance between the two sides not in contact with the jack (i.e. the length of the side in contact with the jack) is calculated according to the extended creepage distance calculated in steps one and three.

[0083] Step five: determine the range of the grooving area

[0084] The grooving area on the insulation board is preferably not directly pressed by the tire to avoid damage to this area, therefore, the grooving area needs to be calculated according to the deformation of the tire after being pressed under load during the test. If the size allows, the grooving area is generally located outside the vertical projection area of the tire on the insulation board.

[0085] Step six: based on steps three and five, determine the relationship between the groove depth and width, and reasonably allocate the depth, width and number of grooves.

[0086] Example two: an insulation device for aircraft whole machine level electrostatic discharge test, the device is an insulation board, which is in the shape of a rectangular block, and multiple rings of circumferential grooves are opened on the side edges of the insulation board.

[0087] Application scenario of this example: in addition to the distance limitation between the machine wheel and the jack support point, the isolation board area is further reduced based on the constraints of example one, and grooves can be opened on the side surface to transfer the extended creepage distance calculated according to example one to the side surface of the insulation board. Considering the economy, it is recommended to cut the panel with a relatively thin thickness (selecting a thickness equal to the groove width) into two sizes after grooving the whole panel, and then adhere layer by layer with structural adhesive, so as to achieve the same result as after grooving and processing the whole panel.

[0088] Implementation steps (using layer board gluing processing):

[0089] Step one: refer to the size of the edge constrained by the relative position of the machine wheel and the jack determined in example one. Since grooves are opened on the side surface of the insulation board, the thickness is higher than that of example one, the size of each edge on the upper surface can be appropriately reduced, and the outer size of the upper surface is recommended to be no less than the outer contour of the machine wheel plus the expected depth of the side groove. The thickness of the insulation board (the height of the side groove) and the number of layers of the insulation board are determined according to the thickness specifications of the products on the market.

[0090] Step two: calculate the minimum creepage voltage along the surface of the insulation board (the upper surface and the side surface, without grooving) when the aircraft electrostatic discharge test voltage is calculated.

[0091] Step three: calculate the length of the creepage path that needs to be extended through the groove to meet the electrostatic discharge test voltage requirement;

[0092] Step four: determine the number of grooves and the groove depth on the side surface of the insulation board required to meet the electrostatic discharge voltage according to the calculations in steps one and three.

[0093] Step five: determine the size of the unconstrained edge according to step three, wheel parameters and electrostatic discharge test voltage calculation;

[0094] Step six: design and process two sizes of insulation plates according to the groove depth and outer contour size determined in step three, and then symmetrically bond the insulation plates layer by layer with structural adhesive.

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

[0096] Step one: first select the appropriate thickness of the insulation plate according to the product specifications available on the market, and determine the size of the edge constrained by the relative position of the wheel and the jack according to the calculation in Example One.

[0097] Step two: calculate the minimum creepage voltage along the surface of the insulation plate (upper surface and side surface, without grooves) parallel to the constrained edge when the aircraft electrostatic discharge test voltage is calculated.

[0098] Step three: calculate the length of the creepage path that needs to be extended by grooving to meet the electrostatic discharge test voltage requirement.

[0099] Step four: calculate the number of grooves, groove depth and groove height required to meet the electrostatic discharge voltage resistance on the side surface of the insulation plate according to the calculations in steps one and three.

[0100] Step five: determine the size of the edge not constrained by the relative position of the wheel and the jack according to step three, wheel parameters and electrostatic discharge test voltage calculation.

[0101] Step six: process the insulation plate according to the number of grooves, groove depth and groove height determined in step four.

[0102] Example Three

[0103] An insulation device for aircraft whole-machine-level electrostatic discharge testing, the device is an insulation plate in the form of a rectangular block, and parallel grooves are provided on the upper surface of the insulation plate.

[0104] Application: The distance between the wheel and the jack support point on the aircraft limits the distance size of the two edges relative to the contact edge of the insulation plate and the jack, but the length of the edge in contact with the jack is theoretically unlimited. Therefore, in this case, only the outer edges of the two edges relative to the contact edge of the jack need to be processed with a certain number of parallel grooves to increase the creepage distance of the narrow edge, so that it can meet the maximum discharge voltage of the whole-machine-level electrostatic discharge test.

[0105] Implementation scheme:

[0106] The size of the edge in contact with the jack and its parallel edge (i.e. the grooved edge), the electrostatic discharge creepage distance that needs to be extended by grooving, and the determination of groove depth and groove width are the same as in Example One.

[0107] Determination of the length of the edge in contact with the jack: determined according to the tire profile size, the hub profile size, the insulating plate thickness and the minimum creepage distance required to meet the maximum static discharge voltage of the aircraft.

[0108] Example Four: A design method for an insulating device for aircraft whole machine level static discharge tests (with a slotted upper surface)

[0109] Mainly includes the following steps:

[0110] Step One: According to the constraints such as the parameters of the jack on the aircraft tire and the body structure, calculate and determine the size of the constrained edge of the insulating isolation plate

[0111] According to Figure 4 , schematic diagram of the relative position of the insulating isolation device and the jack during the test

[0112]

[0113] L1 = 2l1

[0114] In the formula:

[0115] l1: half of the length of the edge of the insulating plate;

[0116] d: the distance between the straight line from the center of the wheel perpendicular to the insulating panel and the vertical line from the jack support point on the aircraft perpendicular to the ground;

[0117] r: the radius of the circle formed by the three support points of the jack stabilizing circle;

[0118] A: the chord length formed by the jack stabilizing circle support point and the moving slide;

[0119] L1: the length of the edge of the insulating plate.

[0120] Step Two: After determining the profile size in Step One, calculate the minimum creepage voltage of the insulating plate without slotting

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

[0122] V min = (l1 + r1 - r2 + h) x 2.5

[0123] In the formula:

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

[0125] r1: tire radius (cm);

[0126] r2: hub radius (cm);

[0127] h: insulating plate thickness (cm);

[0128] l1: half of the width of the insulating plate (cm).

[0129] Step three: Calculate the length of the creeping path that needs to be extended by slotting to meet the static discharge test voltage requirement.

[0130] D = (V - V min ) / 2.5

[0131] In the formula:

[0132] D: the distance of the creeping path extended by slotting (cm)

[0133] V: the static discharge voltage required by the static test (kV)

[0134] Step four: Calculate the size of the edge of the insulating plate that is not constrained by the wheel

[0135] The formula for calculating the size of the edge of the insulating plate that is not constrained by the wheel is as follows:

[0136]

[0137] L2 = 2l2

[0138] In the formula:

[0139] l2: half of the length of the insulating plate;

[0140] L2: the length of the insulating plate;

[0141] V: the static discharge voltage required by the static test, kV;

[0142] w: the width of the tire, cm;

[0143] h: the thickness of the insulating plate, cm;

[0144] D: the distance of the creeping path extended by slotting, cm;

[0145] r1: the radius of the tire, cm;

[0146] r2: the radius of the hub, cm.

[0147] Step five: Determine the range of the slotting area

[0148] The slotting area on the insulating plate should not be directly pressed by the tire to avoid damage to the area and affect repeated use. Therefore, the slotting area needs to be calculated based on the deformation of the tire under load during the test. If the size allows, the slotting area is generally located outside the vertical projection area of the tire on the insulating plate.

[0149] Step six: Calculate the depth, width, and number of the ring slot

[0150] The number of annular grooves or the number of parallel groove single-side slots is calculated according to the following formula:

[0151] n = D / 2ds

[0152] In the formula:

[0153] D: the distance of the creeping path extended by the slot, cm;

[0154] ds: the depth of the slot, cm;

[0155] n: the number of slots required;

[0156] The relationship between the width and the depth of the slot is calculated according to the following formula:

[0157] ds≤4.5W

[0158] In the formula:

[0159] ds: the depth of the rectangular slot, cm;

[0160] W: the width of the rectangular slot, cm.

[0161] Note: In the implementation of the project, the number after the decimal point of the slot number n is rounded up to 1 to ensure that the static discharge voltage of the insulating plate has a certain margin.

Claims

1. A design method for an insulating device for electrostatic discharge testing of aircraft, characterized in that, The method includes the following steps: Step 1: Calculate and determine the dimensions of the side of the insulation plate constrained by the relative positions of the aircraft tires and jacks; Step 2: Calculate the minimum creepage voltage of the insulation board without slotting; Step 3: Calculate the creepage path length that needs to be extended through the slot to meet the electrostatic discharge test voltage requirements; Step 4: Calculate and determine the dimensions of the side of the insulating board that is not constrained by the machine wheel; Step 5: Determine the scope of the slotting area; Step 6: Calculate and determine the depth, width, and number of annular grooves.

2. The method according to claim 1, characterized in that: In step one, the formula for calculating the dimensions of the insulating plate constrained by the aircraft tires and jacks is as follows: In the formula: It is half the side length of the insulation board; d: The distance between the straight line from the center of the wheel to the insulating panel and the vertical line from the jack fulcrum to the ground. r: The radius of the circle formed by the three fulcrums of the jack's stabilizing circle; A: The chord length formed by the stable circular fulcrum of the jack and its sliding motion; : Side length of the insulation board.

3. The method according to claim 2, characterized in that: In step two, the formula for calculating the minimum creepage voltage is as follows: In the formula: Minimum creepage voltage, kV; Tire radius, cm; Wheel hub radius, cm; Insulation board thickness, cm; Half the width of the insulation board, in cm.

4. The method according to claim 3, characterized in that: In step three, the formula for calculating the creepage path distance extended by the slot to meet the electrostatic discharge test voltage requirements is as follows: In the formula: D: The creepage path distance that needs to be extended by slotting, in cm; V: Electrostatic discharge voltage required for electrostatic testing, kV; 5. The method according to claim 4, characterized in that: In step four, the formula for calculating the dimension of the side of the insulating plate not constrained by the machine wheel is as follows: In the formula: It is half the side length of the insulation board; : Side length of the insulation board; V: Electrostatic discharge voltage required for electrostatic testing, kV; w: Tire width, in cm; Insulation board thickness, cm; D: Creepage path distance extended by slotting, in cm; Tire radius, cm; Wheel hub radius, cm; The formula for calculating the number of annular grooves or the number of parallel grooves cut on one side is as follows: In the formula: D: Creepage path distance extended by slotting (cm); : Groove depth (cm); n: Number of slots required; The formula for calculating the relationship between the width and depth of the groove is as follows: In the formula: : Rectangular groove depth (cm); W: Width of the rectangular groove (cm).

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