Evaluation method for service performance of cement concrete take-off and landing field of electric vertical take-off and landing aircraft

Abstract

The invention relates to the technical field of airport engineering, in particular to a method for evaluating the service performance of an electric vertical take-off and landing aircraft cement concrete take-off and landing field. The evaluation method comprises the steps of carrying out clearance test and calculating a surface flatness index, carrying out deflection test and calculating a structure bearing index, carrying out surface and internal disease detection and calculating a damage condition index, and calculating a total score of the service performance of the take-off and landing field. According to the method for evaluating the service performance of the cement concrete take-off and landing field of the electric vertical take-off and landing aircraft (eVTOL), the vacancy of indexes and methods for evaluating the service performance of the take-off and landing field of the electric vertical take-off and landing aircraft (eVTOL) at present is effectively filled.

Description

Technical Field

[0001] The invention relates to the technical field of airport engineering, in particular to a method for evaluating the service performance of a cement concrete take-off and landing field for electric vertical take-off and landing aircraft. Background Art

[0002] Electric vertical takeoff and landing (eVTOL) aircraft are a new type of electrically powered aircraft that have emerged and rapidly developed in recent years. They have enormous potential for development and application in logistics, manned operations, and emergency response, and are a key vehicle for the low-altitude economy. eVTOLs take off and land at landing sites, and research on these sites is still in its infancy, focusing on design. However, over long-term service, eVTOL landing sites will experience structural degradation and the development of defects due to takeoff and landing loads and environmental factors, impacting their performance. Currently, there are no performance evaluation metrics or methods for eVTOL landing sites. Summary of the Invention

[0003] This paper proposes a method for evaluating the service performance of cement concrete landing pads for electric vertical takeoff and landing vehicles. This method calculates the surface stability index, structural load-bearing index, and damage index, and then calculates an overall service performance score based on these scores. This method effectively fills the gap in current eVTOL landing pad service performance evaluation indicators and methods.

[0004] The present invention adopts the following technical solutions:

[0005] The evaluation method of the service performance of the cement concrete landing field for electric vertical take-off and landing aircraft of the present invention comprises the following steps:

[0006] S1. Perform clearance test and calculate surface smoothness index I Z , the expression is as follows;

[0007]

[0008] Where Z is the average value of the gap;

[0009] S2. Conduct deflection test and calculate the structural bearing index I J , the expression is as follows;

[0010]

[0011] Where d is the average deflection, d0 is the initial deflection;

[0012] S3. Conduct surface and internal damage inspection and calculate damage index I P , the expression is as follows;

[0013] I P =100-40(P1+P2+P3+P4) 0.5

[0014] Where P1 is the crack damage factor, P2 is the loose damage factor, P3 is the void damage factor, and P4 is the spalling damage factor;

[0015] S4, according to the surface flatness index I Z , Structural bearing index I J , damage index I P , calculate the total service performance score CI of the take-off and landing field by the following formula and assess the grade;

[0016] CI = 0.3I Z +0.2I J +0.5I P

[0017] Assess the service performance level of the take-off and landing field,

[0018] If CI ≥ 90, the assessment grade is excellent;

[0019] If 80≤CI<90, the assessment grade is good;

[0020] If 70≤CI<80, the rating is medium;

[0021] If 60≤CI<70, the assessment level is inferior;

[0022] If CI < 60, the rating is poor.

[0023] In the method for evaluating the service performance of a cement concrete landing pad for an electric vertical take-off and landing vehicle described in the present invention, at least five measuring points are randomly selected in the gap test in step S1, and a three-meter ruler is used to measure the average value Z of the gap at each measuring point on the landing pad surface, in units of mm.

[0024] In the method for evaluating the service performance of a cement concrete landing pad for an electric vertical take-off and landing vehicle according to the present invention, in step S2, a portable drop-weight deflectometer is used to measure the deflection values ​​at each measuring point on the landing pad surface under a certain load based on the established five measuring points, and the average value is recorded as d;

[0025] Each structural layer of the electric vertical take-off and landing aircraft landing field is regarded as an elastic layer. The initial modulus of the cement concrete panel, base layer, and soil base layer is determined from top to bottom. The elastic layered system is adopted.

[0026] In the method for evaluating the service performance of a cement concrete take-off and landing field for an electric vertical take-off and landing vehicle according to the present invention, in step S3,

[0027] The crack damage factor P1 is calculated using the following expression:

[0028]

[0029] in:

[0030]

[0031] Where h is the height difference between the cement concrete slabs on both sides of the misalignment;

[0032] The loose damage factor P2 is calculated using the following expression:

[0033]

[0034] in:

[0035]

[0036] Where V is the total volume of cement concrete panel and base, V s is the volume of the internal loose area;

[0037] The following expression is used to calculate the void damage factor P3:

[0038]

[0039] Where S T is the area of ​​the hollow area at the bottom of the cement concrete panel, and S is the total area of ​​the top or bottom of the cement concrete slab at the landing field;

[0040] The spalling damage factor P4 is calculated using the following expression:

[0041]

[0042] in

[0043]

[0044] Where S B is the surface peeling area.

[0045] Beneficial effects

[0046] Existing research on landing pads is still in its infancy and primarily focused on design. Over long-term service, eVTOL landing pads will experience structural degradation and develop defects due to the loads of takeoff and landing and environmental factors, impacting their performance. However, there are currently no indicators or methods for evaluating the performance of eVTOL landing pads.

[0047] The present invention provides a method for evaluating the service performance of a cement concrete landing pad for an electric vertical take-off and landing vehicle (eVTOL). Based on the detection and identification results of clearance, surface deflection, and surface and internal defects, the surface stability index, structural bearing index, and damage condition index are calculated. On this basis, an overall service performance score is calculated, forming a method for evaluating the service performance of a cement concrete landing pad for an electric vertical take-off and landing vehicle (eVTOL), which effectively fills the gap in current eVTOL landing pad service performance evaluation indicators and methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a schematic diagram of the overall process of the present invention. DETAILED DESCRIPTION

[0049] To make the purpose and technical solutions of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] like Figure 1 As shown:

[0051] The present invention provides a method for evaluating the service performance of an electric vertical take-off and landing vehicle (eVTOL) cement concrete landing field, comprising the following steps:

[0052] S1. Carry out clearance test and calculate surface flatness index;

[0053] S1.1. Randomly select no fewer than five measuring points and use a three-meter ruler to measure the average clearance Z (in mm) at each measuring point on the landing area surface.

[0054] S1.2. Calculate the surface smoothness index I using formula (1) Z .

[0055]

[0056] S2. Conduct deflection test and calculate the structural bearing index;

[0057] S2.1. Randomly select no fewer than five measuring points and use a portable falling weight deflectometer (PFWD) to measure the deflection values ​​at each measuring point on the landing area surface under a certain load. The average value is recorded as d.

[0058] S2.2. Treat each structural layer of the eVTOL landing pad as an elastic layer. Determine the initial modulus of the cement concrete slab, base layer, and soil subgrade layers from top to bottom. Calculate the initial deflection d0 of the landing pad surface under the load of a portable drop-weight deflectometer at the initial modulus using an elastic layered system.

[0059] S2.3. Calculate the structural bearing index I using formula (2) J .

[0060]

[0061] S3. Conduct surface and internal damage inspections and calculate damage indexes;

[0062] S3.1. Combine manual recording and inspection of surface defects with ground-penetrating radar inspection of internal defects to identify various defects on the surface and inside the landing area, covering both the cement concrete slab and the base. The total volume of the cement concrete slab and base is denoted as V. The total area of ​​the top or bottom of the landing area cement concrete slab is equal and denoted as S. Record the length L and total height H of each crack, and the volume V of the internal loose area. s , the area of ​​the void at the bottom of the cement concrete panel S T , surface peeling area S B If there is misalignment at the joints between adjacent cement concrete panels, it is considered as a misalignment crack with a length L equal to the total length of the joint and a total height H equal to the thickness of the cement concrete panel.

[0063] S3.2. Calculate the crack damage factor P1 using formula (3), where K1 is the first correction factor. If the crack is visible on the surface, it is 1.0; if the crack is an internal crack that is not visible on the surface, it is 0.5. If it is a misalignment crack, calculate K1 using formula (4), where h is the height difference between the cement concrete slabs on both sides of the misalignment (unit: mm);

[0064]

[0065] S3.3, calculate the loose damage factor P2 by formula (5), where K2 is the second correction factor, which is calculated by formula (6);

[0066]

[0067] S3.4, calculate the void damage factor P3 by formula (7), where K3 is the third correction factor, which is calculated by formula (8);

[0068]

[0069] S3.5, calculate the spalling damage factor P4 by formula (9), where K4 is the fourth correction factor, which is calculated by formula (10);

[0070]

[0071] S3.6. Calculate the damage index I by formula (11) P .

[0072] I P =100-40(P1+P2+P3+P4) 0.5 (11)

[0073] S4. Calculate the overall service performance score of the take-off and landing field and assess the grade.

[0074] S4.1. Calculate the total service performance score CI of the take-off and landing field using formula (12).

[0075] CI = 0.3I Z +0.2I J +0.5I P (12)

[0076] S4.2. Evaluate the service performance of the take-off and landing field. If CI ≥ 90, the evaluation grade is excellent; if 80 ≤ CI < 90, the evaluation grade is good; if 70 ≤ CI < 80, the evaluation grade is medium; if 60 ≤ CI < 70, the evaluation grade is inferior; if CI < 60, the evaluation grade is poor.

[0077] The present invention is combined with the above technical solutions and lists the following embodiments:

[0078] Example 1: A cement concrete landing pad for an electric vertical takeoff and landing vehicle (eVTOL) consists of, from top to bottom, a 15cm-thick cement concrete slab (made from 5m-square slabs spliced ​​together to form a 15m-square slab), a 25cm-thick cement-stabilized gravel, and a soil base. A three-meter ruler was used to measure the average clearance Z = 5mm at each measuring point on the landing pad surface. The surface smoothness index I was calculated using formula (1). Z =75.

[0079] The average deflection of the landing pad surface was measured using a portable falling weight deflectometer (PFWD), d = 3.8 (0.01 mm). The load in the test was 15 kN and the radius of the circular bearing plate was 5 cm. The structural layers of the eVTOL landing pad were regarded as elastic layers. The initial moduli of the cement concrete panel, base layer, and soil base were 30,000 MPa, 10,000 MPa, and 90 MPa, respectively. Using an elastic layered system, the initial deflection of the landing pad surface under the above PFWD load was calculated to be d0 = 3.3 (0.01 mm) under the initial modulus. The structural bearing index I was calculated using formula (2): J =91.17.

[0080] Through manual recording and detection of surface defects and ground penetrating radar detection of internal defects, the total volume of cement concrete slab and base layer was measured to be V = 90m 3 The total area of ​​the top or bottom of the cement concrete slab of the take-off and landing field is equal, both are S = 225m 2 A crack (crack I) can be seen in the cement concrete panel on the surface of the landing pad, with a length of L = 3m and a total height of H = 0.1m. A crack (crack II) was found in the base layer inside the landing pad by ground penetrating radar, with a length of L = 6m and a total height of H = 0.2m. There is a misalignment at the joint between adjacent cement concrete panels on the surface of the landing pad, which is regarded as a misalignment crack (crack III) with a length of the total joint length L = 5m and a total height of the cement concrete panel thickness H = 0.15m. The height difference of the cement concrete slabs on both sides of the misalignment is h = 7mm. The volume of the internal loose area V was measured. s =5m 3 , the area of ​​the void at the bottom of the cement concrete panel S T =17m 2 , surface peeling area S B =12m 2 .

[0081] According to formulas (3) and (4), for crack I, the first correction factor K1 = 1.0 and the crack damage factor P1 = 0.001 are calculated; for crack II, the first correction factor K1 = 0.5 and the crack damage factor P1 = 0.002 are calculated; for crack III, the first correction factor K1 = 29 and the crack damage factor P1 = 0.0725 are calculated; in summary, the sum of the crack damage factors is P1 = 0.0755.

[0082] According to formulas (5) and (6), the second correction factor K2 = 1.0 and the loose damage factor P2 = 0.0556 are calculated.

[0083] According to formulas (7) and (8), the third correction factor K3 = 1.0 and the air gap damage factor P3 = 0.0666 are calculated.

[0084] According to formulas (9) and (10), the fourth correction factor K4 = 0.3 and the spalling damage factor P4 = 0.0160 are calculated.

[0085] The damage index I is calculated by formula (11): P =86.13, and the total service performance score of the take-off and landing field calculated by formula (12) is CI = 81.51. The assessment level is good.

[0086] Example 2: A cement concrete landing pad for an electric vertical takeoff and landing vehicle (eVTOL) consists of, from top to bottom, a 10cm-thick cement concrete slab (4m square slabs spliced ​​together to form a 12m square slab), a 20cm-thick cement-stabilized gravel, and a soil base. A three-meter ruler was used to measure the average clearance Z = 3mm at each measuring point on the landing pad surface. The surface smoothness index I was calculated using formula (1). Z =90.

[0087] The average deflection of the landing pad surface was measured by a portable falling weight deflectometer (PFWD), d = 4.2 (0.01 mm). The load in the test was 15 kN and the radius of the circular bearing plate was 5 cm. The structural layers of the eVTOL landing pad were regarded as elastic layers. The initial moduli of the cement concrete panel, base layer, and soil base were 32000 MPa, 12000 MPa, and 100 MPa, respectively. Using an elastic layered system, the initial deflection of the landing pad surface under the above PFWD load was calculated to be d0 = 3.5 (0.01 mm) under the initial modulus. The structural bearing index I was calculated using formula (2) J =87.84.

[0088] Through manual recording and detection of surface defects and ground penetrating radar detection of internal defects, the total volume of the cement concrete slab and base layer was measured to be V = 43.2m 3 The total area of ​​the top or bottom of the cement concrete slab of the take-off and landing field is equal, both are S = 144m 2 A crack (crack I) can be seen in the cement concrete panel on the surface of the landing pad, with a length of L = 4m and a total height of H = 0.08m. A crack (crack II) was found in the base layer inside the landing pad by ground penetrating radar, with a length of L = 5m and a total height of H = 0.16m. There is a misalignment at the joint between adjacent cement concrete panels on the surface of the landing pad, which is regarded as a misalignment crack (crack III) with a length of the total joint length L = 4m and a total height of the cement concrete panel thickness H = 0.1m. The height difference of the cement concrete slabs on both sides of the misalignment is h = 12mm. The volume of the internal loose area V was measured. s =14m 3 , the area of ​​the void at the bottom of the cement concrete panel S T =15m 2 , surface peeling area S B =40m 2 .

[0089] According to formulas (3) and (4), for crack I, the first correction factor K1 = 1.0 and the crack damage factor P1 = 0.0022 are calculated; for crack II, the first correction factor K1 = 0.5 and the crack damage factor P1 = 0.0028 are calculated; for crack III, the first correction factor K1 = 60.5 and the crack damage factor P1 = 0.0725 are calculated; in summary, the sum of the crack damage factors is P1 = 0.1681.

[0090] According to formulas (5) and (6), the second correction factor K2 = 1.048 and the loose damage factor P2 = 0.3397 are calculated.

[0091] According to formulas (7) and (8), the third correction factor K3 = 1.054 and the air-loss damage factor P3 = 0.1245 are calculated.

[0092] According to formulas (9) and (10), the fourth correction factor K4 = 0.339 and the spalling damage factor P4 = 0.0941 are calculated.

[0093] The damage index I is calculated by formula (11): P =74.34, and the total service performance score of the take-off and landing field is calculated by formula (12) as CI = 65.79. The evaluation level is second.

[0094] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for evaluating the service performance of a cement concrete landing pad for electric vertical take-off and landing vehicles, characterized by: The following steps are included S1. Perform clearance test and calculate surface smoothness index I Z , the expression is as follows; Where Z is the average value of the gap; S2. Conduct deflection test and calculate the structural bearing index I J , the expression is as follows; Where d is the average deflection, d0 is the initial deflection; S3. Conduct surface and internal damage inspection and calculate damage index I P , the expression is as follows; I P =100-40(P1+P2+P3+P4) 0.5 Where P1 is the crack damage factor, P2 is the loose damage factor, P3 is the void damage factor, and P4 is the spalling damage factor; S4, according to the surface flatness index I Z , Structural bearing index I J , damage index I P , calculate the total service performance score CI of the take-off and landing field by the following formula and assess the grade; <h2 style=";text-align:left;direction:ltr">CI=0.3I<h2 style=";text-align:left;direction:ltr"> Z <h2 style=";text-align:left;direction:ltr"> +0.2I<h2 style=";text-align:left;direction:ltr"> J <h2 style=";text-align:left;direction:ltr"> +0.5I<h2 style=";text-align:left;direction:ltr"> P Assess the service performance level of the take-off and landing field, If CI ≥ 90, the assessment grade is excellent; If 80≤CI<90, the assessment grade is good; If 70≤CI<80, the rating is medium; If 60≤CI<70, the assessment level is inferior; If CI < 60, the rating is poor.

2. The method for evaluating the service performance of a cement concrete take-off and landing site for an electric vertical take-off and landing vehicle according to claim 1, characterized in that: In the gap test in step S1, at least 5 measuring points are randomly selected, and a three-meter ruler is used to measure the average gap Z at each measuring point on the surface of the take-off and landing field, in units of mm.

3. The method for evaluating the service performance of a cement concrete take-off and landing field for electric vertical take-off and landing vehicles according to claim 1, characterized in that In step S2, a portable drop-weight deflectometer is used to measure the deflection value at each measuring point on the landing field surface under a certain load based on the established five measuring points, and the average value is recorded as d; Each structural layer of the electric vertical take-off and landing aircraft landing field is regarded as an elastic layer. The initial modulus of the cement concrete face plate, base layer and soil base layer are determined from top to bottom, and an elastic layered system is adopted.

4. The method for evaluating the service performance of a cement concrete landing pad for electric vertical take-off and landing vehicles according to claim 1 is characterized in that : In step S3, The crack damage factor P1 is calculated using the following expression: in: Where h is the height difference between the cement concrete slabs on both sides of the misalignment; The loose damage factor P2 is calculated using the following expression: in: Where V is the total volume of cement concrete panel and base, V s is the volume of the internal loose area; The following expression is used to calculate the void damage factor P3: Where S T is the area of ​​the hollow area at the bottom of the cement concrete panel, and S is the total area of ​​the top or bottom of the cement concrete slab at the landing field; The spalling damage factor P4 is calculated using the following expression: in Where S B is the surface peeling area.

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