Method for determining pavement damage of unpaved soil runway

Abstract

The invention belongs to the technical field of flight tests, and particularly relates to a method for determining pavement damage of an unpaved soil runway. The method comprises the following steps: S1, determining the running tire pressure of an unpaved soil runway of an airplane; s2, the minimum ground clearance of an aircraft landing gear and the ground clearance of the widest position of a tire are determined; s3, determining a key airplane wheel load amplification coefficient; s4, the tire compression amount caused by key airplane wheel load amplification is determined; step S5, determining the depth value of the unpaved soil runway pavement damage wheel track adapted by the aircraft; and step S6, according to each determined parameter, evaluating whether the pavement of the runway which is not paved with the soil is damaged or not. According to the method for determining the pavement damage of the unpaved soil runway, whether the runway meets the continuous use condition or not can be judged after it is determined that the airplane slides on the unpaved soil runway or takes off and lands, and the take-off and landing performance and operation safety of the airplane are guaranteed.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of flight test, and particularly relates to a method for determining damage of an unpaved soil runway. BACKGROUND

[0002] With more and more attention to the special task capability of an airplane in the world, the takeoff and landing capability of the airplane on an unpaved soil runway becomes a basic performance for improving the maneuverability and survivability of the airplane, so that the airplane can quickly complete special tasks such as material allocation and task delivery in the shortest time. When the airplane slides, takes off and lands on the unpaved soil runway, the rolling of the wheels causes the deformation of the runway to form a wheel rut, and the deeper wheel rut will seriously affect the takeoff and landing performance and the operation safety of the airplane. After the soil runway is rolled by the airplane for many times, the runway may be seriously damaged, and the runway no longer has the condition for the airplane to continue taking off and landing, so the runway needs to be repaired in time.

[0003] At present, the characteristic research on the unpaved soil runway is relatively less, and the takeoff and landing of the airplane directly on the soil runway is also rare. There is no specific design method for determining the damage of the soil runway, and the damage standard of the unpaved soil runway is relatively arbitrary. This arbitrariness leads to the lack of scientific basis for the maintenance of the unpaved soil runway, which not only shortens the safe service life of the runway, but also may cause takeoff safety risks due to inconsistent damage evaluation.

[0004] Therefore, there is an urgent need for a technical solution to overcome or alleviate at least one of the above-mentioned defects of the prior art. SUMMARY

[0005] The purpose of the present application is to provide a method for determining the damage of an unpaved soil runway, so as to solve at least one problem existing in the prior art.

[0006] The technical solution of the present application is:

[0007] A method for determining the damage of an unpaved soil runway, comprising:

[0008] Step S1, determining the tire pressure of the airplane running on the unpaved soil runway;

[0009] Step S2, determining the minimum ground clearance of the airplane landing gear and the ground clearance of the widest part of the tire;

[0010] Step S3, determining the key wheel load amplification coefficient;

[0011] Step S4, determining the tire compression amount caused by the key wheel load amplification;

[0012] Step S5, determining the damage wheel rut depth value of the unpaved soil runway adapted by the airplane;

[0013] Step S6, according to the determined parameters, evaluate whether the unpaved soil runway pavement is damaged.

[0014] In at least one embodiment of the present application, in step S1, the tire pressure of the aircraft running on the unpaved soil runway includes the actual inflation pressure of the tire and the rated inflation pressure of the tire.

[0015] In at least one embodiment of the present application, in step S1, the tire pressure of the aircraft running on the unpaved soil runway is less than the tire pressure of the aircraft running on the cement dry runway.

[0016] In at least one embodiment of the present application, in step S2, the minimum ground clearance of the aircraft landing gear is greater than the rut depth of the aircraft.

[0017] In at least one embodiment of the present application, in step S2, the ground clearance of the widest part of the tire is greater than the rut depth of the aircraft.

[0018] In at least one embodiment of the present application, in step S2, the minimum ground clearance of the aircraft landing gear and the ground clearance of the widest part of the tire satisfy:

[0019] H2≤0.5H1;

[0020] Wherein H1 is the minimum ground clearance of the aircraft landing gear, and H2 is the ground clearance of the widest part of the tire.

[0021] In at least one embodiment of the present application, in step S3, the key wheel load amplification factor is determined, including:

[0022] Calculate the tire compression amount in the static state of the aircraft:

[0023] ;

[0024] Wherein d is the tire compression amount in the static state of the aircraft, b is the tire compression percentage, D is the inflated outer diameter of the tire, and D F is the rim diameter;

[0025] Calculate the tire footprint area:

[0026] ;

[0027] Wherein A is the tire footprint area, and W is the inflated cross-sectional width of the tire.

[0028] Calculate the tire footprint radius:

[0029] ;

[0030] Wherein R is the tire footprint radius.

[0031] Calculate the ratio of the wheel spacing to the tire footprint radius:

[0032] ;

[0033] wherein C t is the ratio of wheel spacing to tire footprint radius, and T is the wheel spacing;

[0034] The key machine wheel load amplification factor is obtained by interpolation from the key machine wheel load amplification factor curve according to the ratio of wheel spacing to tire footprint radius.

[0035] In at least one embodiment of the present application, in step S4, the tire compression amount caused by key machine wheel load amplification is:

[0036] ;

[0037] wherein is the tire compression amount caused by key machine wheel load amplification, K is the key machine wheel load amplification factor, SWL is the single wheel load, P0 is the actual tire inflation internal pressure, and P r is the tire rated internal pressure.

[0038] In at least one embodiment of the present application, in step S5, determining the damaged rut depth value of the unpaved soil runway pavement adapted by the aircraft, comprises:

[0039] When 5cm≤H2-δ<7.5cm, take r=5cm;

[0040] When 7.5cm≤H2-δ<10cm, take r=7.5cm;

[0041] When H2-δ≥10cm, take r=10cm;

[0042] wherein r is the damaged rut depth value of the unpaved soil runway pavement.

[0043] In at least one embodiment of the present application, in step S6, according to the determined parameters, evaluating whether the unpaved soil runway pavement is damaged, comprises:

[0044] measuring the rut depth r i ;

[0045] When r i <r, then the unpaved soil runway pavement is not damaged;

[0046] When r i ≥r, then the unpaved soil runway pavement is damaged.

[0047] In at least one embodiment of the present application, if the soil is raised on both sides of the rut, the rut depth r i is the distance from the highest part of the raised soil to the lowest part of the bottom of the rut at the same place.

[0048] The application has at least the following beneficial technical effects:

[0049] The method for determining damage of an unpaved soil runway pavement of the application can determine whether the runway has the condition for continuous use after the airplane slides or takes off on the unpaved soil runway, thereby ensuring the take-off performance and operation safety of the airplane. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 is a schematic diagram of the tire widest height parameter definition of an embodiment of the application;

[0051] Figure 2 is a schematic diagram of the airplane landing gear layout of an embodiment of the application;

[0052] Figure 3 is a schematic diagram of the key wheel load amplification factor curve of the multi-wheel landing gear of an embodiment of the application. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical scheme and advantages of the application clearer, the technical scheme of the embodiments of the application will be described in more detail below with reference to the drawings of the embodiments of the application. In the drawings, the same or similar notations represent the same or similar elements or elements with the same or similar functions throughout. The described embodiments are some of the embodiments of the application, not all. The embodiments described below with reference to the drawings are exemplary and are intended to explain the application, and cannot be understood as a limitation of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application. The embodiments of the application will be described in detail below with reference to the drawings.

[0054] In the description of the application, it should be understood that the terms "center", "longitudinal", "transverse", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the scope of protection of the application.

[0055] The drawings will be described below Figures 1 to 3 The application will be further described in detail.

[0056] The application provides a method for determining damage of an unpaved soil runway pavement, comprising the following steps:

[0057] Step S1, determining the tire pressure of the airplane running on the unpaved soil runway;

[0058] Step S2: Determine the minimum ground clearance of the aircraft landing gear and the ground clearance at the widest point of the tires;

[0059] Step S3: Determine the load amplification factor for key machinery wheels;

[0060] Step S4: Determine the tire compression caused by the amplification of the load on the critical wheel;

[0061] Step S5: Determine the wheel rut depth value of the unpaved runway surface damage for aircraft adaptation;

[0062] Step S6: Based on the determined parameters, assess whether the unpaved earth track surface is damaged.

[0063] When aircraft operate on unpaved runways, wheel rut depth characterizes the degree of damage to the runway surface. Deep ruts can cause tires to become stuck on the rut sidewalls, leading to difficulty in steering and increased friction, preventing normal and safe aircraft operation. Different aircraft have different unpaved runway surface damage standards due to variations in wheel size and tire type. This application provides a method for determining the appropriate unpaved runway surface damage standards for different aircraft.

[0064] When aircraft take off and land on unpaved runways, the runway must first meet the strength requirements for aircraft operation. Before takeoff and landing, on-site testing should be conducted, using a dynamic cone penetration tester (DCP) to quickly determine the subgrade strength (CBR) value, ensuring the runway strength exceeds the minimum requirements for aircraft takeoff and landing. Different runway strengths correspond to different numbers of aircraft takeoffs and landings; therefore, runway pavement damage standards should be established based on the specific characteristics of the aircraft.

[0065] Specifically, in step S1, the tire pressure for the aircraft operating on the unpaved runway is determined, including the actual tire inflation pressure and the tire's rated internal pressure.

[0066] First, determine the main tire pressure of the aircraft when operating on an unpaved runway. Generally, the main tire pressure of an aircraft operating on an unpaved runway is lower than the tire pressure of an aircraft operating on a concrete runway.

[0067] Secondly, in step S2, the minimum ground clearance H1 of the aircraft landing gear is determined. The wheel rut depth must never exceed the minimum ground clearance of the aircraft landing gear, as excessively deep ruts may cause the fuselage to drag on the ground. The ground clearance of the widest part of the tire is obtained by measuring the height between the widest part of the tire and the ground. Figure 1 As shown, the height H2 of the main tire cross-section at its maximum allowable weight for takeoff and landing on an unpaved runway is measured. If the wheel rut depth is greater than H2, the aircraft wheels will be subjected to greater friction and affect the turning performance of the wheels. It is also necessary to ensure that H2 ≤ 0.5H1. If this condition is not met, the value of H2 can be appropriately reduced.

[0068] In step S3, the key machine wheel load amplification coefficient K is determined. For a multi-wheel landing gear, as shown in FIG. 1, when the aircraft is running, the key machine wheel load has an amplification effect, and the ratio C of the wheel spacing T to the tire footprint radius R is first calculated Figure 2 t Figure 3 Then, the key machine wheel load amplification coefficient K is determined by interpolation.

[0069] In the preferred embodiment of the present application, the key machine wheel load amplification coefficient is determined, comprising:

[0070] The tire compression amount in the static state of the aircraft is calculated as follows:

[0071] ;

[0072] Where d is the tire compression amount in the static state of the aircraft, b is the tire compression percentage, D is the inflated outer diameter of the tire, and D F is the rim diameter.

[0073] The tire footprint area is calculated as follows:

[0074] ;

[0075] Where A is the tire footprint area, and W is the tire inflated section width.

[0076] The tire footprint radius is calculated as follows:

[0077] ;

[0078] Where R is the tire footprint radius.

[0079] The ratio C of the wheel spacing T to the tire footprint radius R is calculated as follows:

[0080] ;

[0081] Where C t is the ratio of the wheel spacing T to the tire footprint radius R.

[0082] The key machine wheel load amplification coefficient is obtained from the key machine wheel load amplification coefficient curve according to the ratio of the wheel spacing T to the tire footprint radius R.

[0083] In step S4, the tire compression amount caused by the key machine wheel load amplification is:

[0084] ;

[0085] Where is the tire compression amount caused by the key machine wheel load amplification, K is the key machine wheel load amplification coefficient, SWL is the single wheel load, P0 is the actual inflated internal pressure of the tire, and P r ​​The tire is rated for an internal pressure.

[0086] In step S5, the value of the rut depth of the damaged unpaved soil runway pavement adapted to the airplane is determined, including:

[0087] When 5cm≤H2-δ<7.5cm, r=5cm is taken;

[0088] When 7.5cm≤H2-δ<10cm, r=7.5cm is taken;

[0089] When H2-δ≥10cm, r=10cm is taken;

[0090] Wherein, r is the value of the rut depth of the damaged unpaved soil runway pavement.

[0091] In step S6, whether the unpaved soil runway pavement is damaged is evaluated according to the determined parameters, including:

[0092] The rut depth r is measured i ;

[0093] When r i <r, the unpaved soil runway pavement is not damaged;

[0094] When r i ≥r, the unpaved soil runway pavement is damaged.

[0095] After the airplane takes off or lands on the unpaved soil runway, the rut depth of the soil runway is visually inspected. If it is preliminarily judged that the airplane rut depth is close to or exceeds the corresponding r value of the airplane, the rut depth r i is accurately measured by using a ruler. If the soil on both sides of the rut is raised, the rut depth should be the distance from the highest part of the raised soil to the lowest part of the bottom of the rut at the same place. When r i <r, the airplane can continue to operate normally; when r i ≥r, the pavement in this area has been damaged, and the airplane cannot operate normally, and the area should be repaired.

[0096] In one specific embodiment of the present application, the runway is tested on site before the airplane takes off and lands, the dynamic cone penetration instrument (DCP) is used to quickly detect the soil base strength CBR value, and it is confirmed that the runway strength is greater than the minimum requirement for airplane takeoff and landing. Whether the unpaved soil runway pavement is damaged is evaluated in the following way:

[0097] Step 1, determine the tire pressure of the airplane running on the unpaved soil runway. In this embodiment, the rated tire pressure P r of the main tire is 794kPa, and the actual inflation internal pressure P0 of the tire running on the soil runway is 485 kPa.

[0098] Step 2: Determine the minimum ground clearance of the aircraft landing gear and the ground clearance at the widest point of the tires. For a certain type of aircraft, under the maximum allowable weight for takeoff and landing on an unpaved runway, the minimum ground clearance H1 of the landing gear is 46 cm. For the same aircraft, under the maximum allowable weight for takeoff and landing on an unpaved runway, the height H2 at the maximum width of the main tire cross-section from the ground is 11.6 cm, satisfying H2 < 0.5H1. A schematic diagram for measuring H2 is shown below. Figure 1 .

[0099] Step 3: Determine the load amplification factor K for the critical landing gear. See landing gear layout. Figure 2 The outer diameter of the aircraft's main wheel tires when inflated is 112 cm, and the rim diameter is D. F The tire width is 54.3 cm, the tire compression percentage (b) is 32%, and the tire inflation section width (W) is 43.4 cm.

[0100] Using the formula, we can calculate d = 9.24 cm, and then calculate the tire imprint area A as 1291.7 cm². 2 The tire mark radius R is calculated to be 20.3cm using the formula, and the wheel spacing is 76.1cm. Therefore:

[0101] ;

[0102] pass Figure 3 It can be found in C t When the value is 3.75, the load amplification factor K of the critical wheel is 0.25.

[0103] Step 4: Calculate the tire compression caused by the amplification of the load on the critical wheel.

[0104] When the single wheel load SWL is 10580kg, δ is calculated to be 3cm using the formula.

[0105] Step 5: Determine the rut depth r of the unpaved runway surface damage for the aircraft.

[0106] H2-δ=11.6-3=8.6cm. Since 7.5cm≤8.6cm<10cm, we take r= 7.5cm.

[0107] Finally, step 6: Determine if the unpaved runway surface is damaged. After takeoff or landing on the unpaved runway, visually inspect the wheel rut depth. If it is preliminarily determined that the wheel ruts are close to or exceed the corresponding pavement damage value of 7.5 cm, accurately measure the wheel rut depth r using a measuring tape. i The measured values ​​for r1 are 5.5 cm, r2 is 8.2 cm, and r3 is 7.2 cm. Since r2 (8.2 cm ≥ 7.5 cm) indicates that the pavement in area r2 is damaged, preventing the aircraft from operating normally. Repairs should be carried out in this area.

[0108] The method for determining damage of an unpaved soil runway pavement can determine whether the runway has the condition of continuous use after an airplane slides or takes off on the unpaved soil runway, and guarantees the take-off performance and operation safety of the airplane.

[0109] The above merely illustrates the specific implementation of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for determining damage to an unpaved earth runway surface, characterized in that, include: Step S1: Determine the tire pressure for aircraft operating on unpaved runways; Step S2: Determine the minimum ground clearance of the aircraft landing gear and the ground clearance at the widest point of the tires; Step S3: Determine the load amplification factor for key machinery wheels; Step S4: Determine the tire compression caused by the amplification of the load on the critical wheel; Step S5: Determine the wheel rut depth value of the unpaved runway surface damage for aircraft adaptation; Step S6: Based on the determined parameters, assess whether the unpaved earth track surface is damaged.

2. The method for determining damage to an unpaved earth runway surface according to claim 1, characterized in that, In step S1, the tire pressure for aircraft operating on unpaved runways includes the actual internal pressure of the tires and the rated internal pressure of the tires.

3. The method for determining damage to an unpaved earth runway surface according to claim 2, characterized in that, In step S1, the tire pressure of the aircraft operating on the unpaved runway is lower than that of the aircraft operating on the cement dry runway.

4. The method for determining damage to an unpaved earth runway surface according to claim 3, characterized in that, In step S2, the minimum ground clearance of the aircraft landing gear is greater than the wheel track depth of the aircraft.

5. The method for determining damage to an unpaved earth runway surface according to claim 4, characterized in that, In step S2, the maximum height of the tire above the ground is greater than the depth of the aircraft wheel tracks.

6. The method for determining damage to an unpaved earth runway surface according to claim 5, characterized in that, In step S2, the minimum ground clearance of the aircraft landing gear and the ground clearance at the widest point of the tires satisfy the following: H2≤0.5H1; Where H1 is the minimum ground clearance of the aircraft landing gear, and H2 is the ground clearance at the widest point of the tires.

7. The method for determining damage to an unpaved earth runway surface according to claim 6, characterized in that, In step S3, the load amplification factor of the key wheel is determined, including: Calculate the tire compression of an aircraft when it is stationary: ； Where d is the tire compression at a stationary state, b is the tire compression percentage, and D is the tire's inflated outer diameter. F The diameter of the rim; Calculate the area of ​​the tire imprint: ； Where A is the area of ​​the tire imprint and W is the width of the tire inflation section; Calculate the radius of the tire track: ； Where R is the radius of the tire track; Calculate the ratio of wheel track width to tire track radius: ； Among them, C t The ratio of wheel track to tire track radius is given by T, where T is the wheel track. The critical wheel load amplification factor is obtained by interpolating from the critical wheel load amplification factor curve based on the ratio of wheel spacing to tire mark radius.

8. The method for determining damage to an unpaved earth runway surface according to claim 7, characterized in that, In step S4, the tire compression caused by the amplification of the critical wheel load is: ； in, The tire compression caused by the amplification of the critical wheel load, K is the critical wheel load amplification factor, SWL is the single wheel load, P0 is the actual tire inflation pressure, and P r This refers to the tire's rated internal pressure.

9. The method for determining damage to an unpaved earth runway surface according to claim 8, characterized in that, In step S5, the rut depth value of the unpaved runway surface damage for aircraft is determined, including: When 5cm ≤ H2 - δ < 7.5cm, take r = 5cm; When 7.5cm ≤ H2 - δ < 10cm, take r = 7.5cm; When H2-δ≥10cm, take r=10cm; Where r is the depth of wheel ruts caused by damage to the unpaved earth runway surface.

10. The method for determining damage to an unpaved earth runway surface according to claim 9, characterized in that, In step S6, based on the determined parameters, the extent of damage to the unpaved earth track surface is assessed, including: Measuring wheel rut depth r i ; When r i When <r, the unpaved earthen track surface is not damaged; When r i When the value is greater than or equal to r, the unpaved earthen track surface is already damaged.

11. The method for determining damage to an unpaved earth runway surface according to claim 10, characterized in that, If the soil on both sides of the wheel rut bulges, the wheel rut depth r i The distance from the highest point of the raised soil to the lowest point of the wheel rut is the same location.

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