Multi-configuration unmanned aerial vehicle low-cost strength design and test criterion cutting method

Abstract

The invention belongs to the field of strength design and test, and particularly relates to a multi-configuration unmanned aerial vehicle low-cost strength design and test criterion cutting method. Sequentially carrying out multi-configuration unmanned aerial vehicle strength design criterion cutting, multi-configuration unmanned aerial vehicle static strength digital design and static test optimization, multi-configuration unmanned aerial vehicle fatigue strength design and fatigue test cutting research and multi-configuration unmanned aerial vehicle test flight monitoring; according to the method, the design targets of low cost, high efficiency and high performance of the multi-configuration unmanned aerial vehicle are achieved, economic benefits are brought to rapid strength design and rapid strength test of the multi-configuration unmanned aerial vehicle, and the integrity of a structural platform is kept with the strength design cost and the strength test cost as low as possible; and the design requirements of use safety, applicability and other performances of the multi-configuration unmanned aerial vehicle are met.

Description

Technical Field

[0001] The invention belongs to the field of strength design and testing, and specifically relates to a low-cost strength design and test criterion tailoring method for a multi-configuration unmanned aerial vehicle. Background Art

[0002] High-performance UAVs refer to reusable UAVs used to perform special tasks, such as refueling, transportation, patrolling and other high-value tasks. With the development of UAV technology, it has brought a lot of practical value to mankind. However, the high R&D cost of high-performance UAVs has restricted their application scope and popularity. How to reduce the R&D, manufacturing and maintenance costs of high-performance UAVs throughout their life cycle through low-cost design has become one of the concerns of UAV R&D personnel and manufacturing companies.

[0003] In the field of drone design, the term consumable is used to describe new high-performance drones that are low-cost, highly reliable, and durable. Unlike manned aircraft that must be maintained and serviced for decades, new consumable drones have cheaper components and their life cycles are usually measured in years or months. New consumable high-performance drones use a modular structure design, where drones are divided into multiple components and produced separately, and then combined together to form a complete drone. This not only reduces the production cost of each component, but also facilitates later maintenance and replacement.

[0004] A multi-configuration UAV includes a type A UAV composed of short wings and a type B UAV composed of long wings. The short wings achieve the special mission objectives of type A, see Figure 1 As shown, the short-wing UAV is composed of a fuselage 101 and a short wing 102. In contrast, another long-wing UAV achieves a Class B special mission objective, see Figure 2 As shown, the long-wing UAV is composed of a fuselage 101 and long wings 103. This multi-configuration UAV is different from traditional UAV equipment in that its structural components exist in independent forms and are assembled in different structural combinations to achieve different mission performances.

[0005] The design of the UAV structural platform must comply with the requirements of the structural integrity outline to ensure that the structural safety, durability and security of the UAV are above the expected level throughout the design service life. At present, the design standards and specifications followed by high-performance UAVs in the structural strength design are mainly: "Aircraft Structural Integrity Outline", "Aircraft Structural Strength Specifications" and "UAV Strength and Stiffness Specifications", etc. These design standards and specifications are basically consistent with the requirements of manned aircraft or evolved from the standard specifications of manned aircraft. When designing and testing the strength of multi-configuration UAVs, if they are fully implemented in accordance with the standards of special mission models, it is necessary to consider the strength design and testing of short-wing UAVs and long-wing UAVs separately. The working conditions of strength analysis and strength testing will be doubled compared to single-configuration aircraft. The development cycle of the entire multi-configuration UAV is long, the R&D cost is high, and it is difficult to adapt to the survival and development of the UAV market. Summary of the invention

[0006] Purpose of the invention: The present invention proposes a method for tailoring low-cost strength design and test criteria for multi-configuration UAVs, tailors existing UAV strength design and strength test specifications, innovates low-cost strength design and test criteria for multi-configuration UAVs, and ensures the structural strength safety of multi-configuration UAVs while achieving the low-cost strength design and test purposes of multi-configuration UAVs.

[0007] The technical solution of the present invention is a method for tailoring low-cost strength design and test criteria of a multi-configuration UAV, the method comprising the following steps:

[0008] The first step is to tailor the strength design criteria for multi-configuration UAVs, which mainly includes: selection of UAV structural materials, UAV strength design coefficients, UAV strength design loads and UAV fatigue load spectrum design;

[0009] Among them: the selection of UAV structural materials needs to balance the mechanical properties, economy, maturity and support capabilities of UAV structural materials, with the goal of reducing structural weight and cost and obtaining the best comprehensive benefits. The strength design coefficient of UAV includes a detailed study of the overall performance requirements of UAVs, the body development specifications and other general requirement documents on the basis of the strength design specifications of UAVs, and fully considers the factors of low-cost design in the strength design criteria of multi-configuration UAVs, and cuts and selects various strength coefficients and strength design conditions. The strength design load of UAVs is aimed at the performance requirements of multi-configuration UAVs, reduces the overall load of the aircraft through the optimization of the overall and flight control, cuts the environmental adaptability clauses, reduces the environmental adaptability requirements for the finished product, and modifies the design load of the UAV by analogy with similar test results. The fatigue load spectrum design of UAVs determines the typical flight mission profile of multi-configuration UAVs, combines the fatigue test results of typical test pieces, and draws on the experience of compiling load spectra of military aircraft to compile a load spectrum of multi-configuration UAVs.

[0010] The second step is to conduct digital design and static test optimization of the static strength of multi-configuration UAVs, which mainly includes: virtual test technology of composite material allowable values, static strength design by digital means, static test optimization, and rapid R&D mode change from design to test.

[0011] Among them: The virtual test technology of composite material allowable value is aimed at composite materials that are applied for the first time. According to the requirements, the composite material pyramid matrix test verification is carried out. The composite material design allowable value is determined by studying a small amount of physical tests on composite materials combined with comprehensive virtual tests, appropriately reducing the test batches of composite materials, shortening the test cycle and reducing the test cost. The static strength design of digital means is based on the strength digital simulation means. Through digital virtual tests, physical tests are reduced or partially replaced, and verification that is difficult to implement in physical tests is completed, reducing the development risk, shortening the development cycle and reducing the development cost; static test optimization is carried out through digital strength analysis, reducing the scale of component, typical parts and component-level tests, optimizing and streamlining strength verification conditions, and reasonably verifying the structural bearing capacity and other design indicators more efficiently and economically through the test verification of sections and simulated parts in the overall test planning. The design-test rapid R&D mode has changed, and the strength test design and preparation work have been put in place in advance to achieve rapid R&D with high parallel strength analysis and test design, and accelerate the progress of strength tests.

[0012] The third step is to conduct research on UAV fatigue strength design and fatigue test cutting, which mainly includes: fatigue analogy method and fatigue test cutting;

[0013] Among them: The fatigue analogy method is based on the use mode, use environment characteristics, use load characteristics and other factors of multi-configuration UAVs. On the basis of drawing on the experience of manned aircraft load spectrum compilation, the typical use mission profile of multi-configuration UAVs is determined. Combined with the fatigue test results of typical test pieces, the high-load interception and low-load interception methods are used to analogically evaluate the fatigue life of multi-configuration UAV structures. Fatigue test tailoring carries out research on fatigue load spectrum simplification and aggravation technology. Based on the principle of damage consistency and equal damage theory, component-level test pieces are used to verify the fatigue performance of the entire aircraft structure, shorten fatigue test time, and save test costs.

[0014] The fourth step is to conduct test flight monitoring of multi-configuration UAVs, which mainly includes digital twin test flight monitoring of the UAV body structure.

[0015] Among them: The digital twin test flight monitoring of the UAV body structure uses the time history of flight parameters recorded by the flight parameter recording system of the multi-configuration UAV to carry out the "flight parameter-load" correlation study, and obtains the stress of key parts of the structure through the load transfer function, and then conducts health monitoring of key parts of the multi-configuration UAV structure.

[0016] Furthermore, in the first step, the strength design factor of the UAV is determined to be 1.3, and the strength design uncertainty factor for a specific known load condition is taken as 1.05.

[0017] Furthermore, in the first step, when optimizing the strength design load of the UAV, the landing gear turning load of the multi-configuration UAV is reduced by 30%;

[0018] The rotational rebound coefficient of the landing gear ground load was corrected, reducing the rotational load by 13.3% and the rebound load by 12.5%.

[0019] Furthermore, in the second step, when performing static test optimization, a multi-configuration UAV test machine is designed to complete the static strength test, wherein the multi-configuration UAV test machine includes a fuselage and a short wing installed on one side of the fuselage and a long wing installed on the other side.

[0020] Furthermore, during the static strength test, the test loads of the multi-configuration UAV test aircraft are designed in the same test condition, and the four main components: wing, fuselage, vertical tail, and horizontal tail are all tested in one test condition, saving three test conditions. Specifically, there are four severe load conditions in actual flight: 100% severe load condition for wing, 100% severe load condition for fuselage, 100% severe load condition for vertical tail, and 100% severe load condition for horizontal tail. One test condition is designed, so that: 90% severe load is tested for wing, 80% severe load is tested for fuselage, 75% severe load is tested for vertical tail, and 82% severe load is tested for horizontal tail. Then, the simulation model is corrected using the data measured in the strength test, and the corrected simulation model is used to predict the 100% severe load condition, thereby saving three test conditions.

[0021] Furthermore, when conducting static strength tests, a pallet loading system that does not damage the aircraft surface is used; the pallet loading system is to set pallets that are in full contact with the surface of the component on both sides of the component to be loaded on the testing machine; and the pallets on both sides are loaded synchronously.

[0022] Furthermore, when conducting static strength tests, the loading percentage of the strength static test is reduced to only 90% to 100% of the limit load, and through reliable strain and deformation measurements, the extrapolation method is used to perform verification under the limit load.

[0023] Furthermore, in the third step, based on the experience of compiling load spectra of manned aircraft, the typical usage mission profile of multi-configuration UAVs is determined, and the fatigue load spectrum of multi-configuration UAVs is compiled. Combined with the fatigue test results of typical test pieces, the high-load interception and low-load interception methods are used to analogically evaluate the fatigue life of the multi-configuration UAV structure.

[0024] Furthermore, when compiling the fatigue load spectrum of multi-configuration UAVs, reference is made to the measured long-wing configuration aircraft loads and short-wing configuration aircraft loads.

[0025] Furthermore, in the fourth step, when conducting multi-configuration UAV test flight monitoring, the maneuver type is identified from the flight parameters, the maneuver action is automatically identified based on the flight parameter data, and a maneuver action library is established. After the maneuver action library is available, the flight parameter data is compared with the actions in the maneuver action library and the action type is determined to obtain the UAV flight load. Through the simulation analysis results based on the reliability probability assessment of the UAV body digital twin, the aircraft body structure fault decision-making technology supported by probability data is studied, thereby realizing the safety monitoring of UAV test flight.

[0026] Beneficial effects of the invention: The invention proposes a low-cost strength design and test criterion tailoring method for multi-configuration UAVs, which achieves the goal of reducing the load in extreme conditions by 50% and reducing the test conditions by 50% while meeting the flight safety of multi-configuration UAVs, saving half a static machine and one fatigue machine.

[0027] The present invention also specifically conducts a unified design for the strength test of the long and short wings of multi-configuration UAVs, and designs a corresponding multi-configuration UAV test machine; the multi-configuration UAV test machine includes a fuselage and a short wing installed on one side of the fuselage and a long wing installed on the other side; the use of the multi-configuration UAV test machine for testing can simultaneously meet the strength test assessment of the two configuration wings, and the test method saves one long and short wing test piece. When conducting static strength tests, a cardboard loading system that does not damage the surface of the aircraft is designed, which can effectively ensure that the appearance of the test machine is not damaged, and it can continue to be used to perform flight missions after the test is completed.

[0028] At the same time, in the same test condition, the test load is designed to test the four main parts: wing, fuselage, vertical tail, horizontal tail, etc. in one test condition, saving 3 test conditions. Specifically, there are 4 severe load conditions in actual flight: 100% severe load condition for wing, 100% severe load condition for fuselage, 100% severe load condition for vertical tail, and 100% severe load condition for horizontal tail. One test condition is designed, so that: 90% severe load is tested for wing, 80% severe load is tested for fuselage, 75% severe load is tested for vertical tail, and 82% severe load is tested for horizontal tail. Then, the simulation model is corrected using the data measured in the strength test, and the corrected simulation model is used to predict the 100% severe load condition, thus saving 3 test conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the overall structure of a short-wing UAV;

[0030] Figure 2 This is a schematic diagram of the overall structure of a long-wing UAV;

[0031] Figure 3 Tailoring method flow for low-cost strength design and test criteria for a multi-configuration UAV;

[0032] Figure 4 This is a schematic diagram of the principles for selecting structural materials for UAVs;

[0033] Figure 5 This is a schematic diagram of the heterogeneous composition of the multi-configuration UAV strength testing machine of the present invention;

[0034] Figure 6 It is a schematic diagram of the physical test and virtual test loading test of the strength of the multi-configuration UAV of the present invention;

[0035] Figure 7 This is a loading diagram for the tape test;

[0036] Figure 8 Loading diagram for the pallet test. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the 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.

[0038] The following is a further description of the technical solution of the present invention in conjunction with the accompanying drawings and examples. Figures 1 to 8 , taking the design of a multi-configuration UAV as an example; a specific multi-configuration UAV low-cost strength design and test criteria tailoring method process is proposed in Figure 3 As shown; the strength design and testing personnel of multi-configuration UAV mainly carry out 2. tailoring of multi-configuration UAV strength design criteria, 3. digital design of multi-configuration UAV static strength and static test optimization, 4. research on multi-configuration UAV fatigue strength design and fatigue test tailoring, 5. multi-configuration UAV test flight monitoring to implement the technology of the present invention.

[0039] 1) The strength design criteria tailoring of multi-configuration UAVs 2 is mainly aimed at the conservative design concept adopted in the current UAV structural strength design, introducing new strength design concepts in the structural integrity design of multi-configuration UAVs, improving the strength design criteria, achieving more effective weight reduction, and maintaining the structural safety level. The main functions are divided into: UAV structural material selection 201, UAV strength design coefficient tailoring 202, UAV strength design load optimization design 203 and UAV fatigue load spectrum design 204.

[0040] 1.1) UAV structural material selection 201. Figure 4As shown in the figure, firstly, a mathematical relationship between the number of multi-configuration UAVs put into production and the economic efficiency of materials is established. For multi-configuration UAVs with a large number of production, the use of new materials, new processes, new connection methods and new structural solutions can significantly reduce the cost of the UAV throughout its life cycle. The physical properties of the new material design can be evaluated according to relevant requirements. For multi-configuration UAVs with a small number of production, mature, appropriate and economical materials, processes, connection methods and structural solutions are selected to avoid excessive strength assessment tests, thereby increasing the design cost. Secondly, mature structural materials are selected as the main structural materials of multi-configuration UAVs. Mature structural materials have complete performance data, stable performance in design, production and use, reliable quality and unobstructed supply channels, which ensure that the price of mature structural materials will not be too high. At the same time, the maturity of materials means that a lot of time and cost for basic tests can be saved. Mature materials are equipped with mature manufacturing processes and assembly processes, and these mature processes also greatly reduce the manufacturing risks of products. Finally, try to make use of existing parts in the past and combine them into new parts that meet functional requirements. Mature parts that have been produced in the past have mature tooling, fixtures and processing methods, and workers are highly skilled, which will reduce a lot of costs.

[0041] 1.2) Tailoring of UAV strength design coefficients 202. First, on the basis of the military aircraft strength design specifications, a detailed study is conducted on the overall design conditions of multi-configuration UAVs, airframe development specifications, strength design specifications and other general requirement documents. The low-cost design factor is fully considered in the strength design criteria of multi-configuration UAVs, and various strength coefficients and strength design conditions are tailored. Considering the characteristics of low-cost design of multi-configuration UAVs and drawing on previous model design experience, the strength design coefficient is further tailored. The present invention specifically gives a general determination coefficient of 1.3 for multi-configuration UAVs, and takes an uncertainty coefficient of 1.05 for strength design under specific known load conditions, while the uncertainty coefficient given in the military aircraft strength design specification is 1.5. The uncertainty coefficient given by the present invention after tailoring is reduced, and the reduced uncertainty coefficient directly brings weight and space design benefits to the structural design of multi-configuration UAVs.

[0042] 1.3) UAV strength design load optimization design 203. Aiming at the performance requirements of multi-configuration UAVs, the overall load of the aircraft is reduced by optimizing the overall and flight control, and the environmental adaptability clauses are tailored to reduce the environmental adaptability requirements for the finished product. The design load of high-end UAVs is corrected by analogy with similar test results. The present invention specifically provides a limit on ground taxiing turns through flight control instructions during design: speed <15km / h, control angle <32°. Based on this limit, the lateral load coefficient during turning required by the military aircraft strength design specification is directly reduced from 0.5 to 0.35, and the landing gear turning load of multi-configuration UAVs is reduced by 30%. The present invention also provides a drop shock test result of a landing gear with reference to a similar structural form, and corrects the rotation rebound coefficient in the ground load of the landing gear. The rotation coefficient is corrected from 0.75 to 0.65, and the load is reduced by 13.3%. The rebound coefficient is corrected from 0.80 to 0.70, and the load is reduced by 12.5%. The ground design load of the landing gear of the multi-configuration UAV when landing is directly reduced, thereby reducing the structural weight of the aircraft and achieving the effect of reducing the design cost.

[0043] 1.4) Optimization design of fatigue load spectrum of UAV 204. Based on the experience of fatigue load spectrum compilation of military aircraft, the use characteristics of multi-configuration UAVs are studied, the typical use mission profile of multi-configuration UAVs is determined, and the load spectrum compilation principle of high-load interception and low-load interception of multi-configuration UAVs is designed in combination with the fatigue test results of typical test pieces, which provides input load conditions for fatigue life analysis of multi-configuration UAV structures.

[0044] 2) UAV static strength digital design and static test optimization 3 mainly uses structural strength virtual test technology to evaluate the structural strength of multi-configuration UAVs and predict the value of structural damage. The main functions are divided into: virtual test technology of composite material allowable value 301, static strength design by digital means 302, static test optimization 303, and design-test rapid R&D mode change 304.

[0045] 2.1) Virtual test technology for composite material allowable values ​​301. Reduce the low-cost composite material strength test matrix used in multi-configuration UAVs, study and judge the composite material building block test verification method, appropriately reduce the composite material test batches, focus on key test items, and determine the composite material design allowable values ​​based on small sample physical test data through physical tests of a small number of composite materials.

[0046] 2.2) Static strength design 302 by digital means. The traditional strength analysis and research and development system of military aircraft is a research and development process based on physical tests. First, the structural strength design of aviation equipment is carried out, and then the physical object is produced and manufactured. The structural strength is evaluated through the physical strength test. Once the structural strength design problem is found in the physical test, the structural strength design is modified again. Such a design process will lead to a long strength design cycle, high R&D risk, many strength tests and high costs. Static strength design 302 by digital means guides the design through digital virtual tests during design, guides the production and manufacturing through comprehensive tests combining virtual and real tests during production and manufacturing, verifies the process and controls the risk. During the physical test, the physical test is planned through virtual tests, guides the physical test and controls the risk of the physical test. Static strength design 302 using digital means can not only serve as preliminary preparation for real physical tests, but can also replace traditional physical tests to a certain extent, reduce the number of physical prototype manufacturing and tests, and make the tests not limited by site, time and number of tests. It can also repeat and reproduce the test process, and provide information feedback on the advantages and disadvantages of the structure and layout of multi-configuration UAVs during the design phase, so that designers can discover and solve potential problems in the design process as early as possible, thereby shortening the test cycle of new products, reducing test costs and improving product quality.

[0047] 2.3) Static test optimization 303. In static test optimization 303, digital analysis is strengthened, physical tests are reduced, and strength digital analysis methods are fully utilized to minimize the scale of component, typical part and component-level tests, optimize and streamline strength verification conditions, save test pieces and test costs, and shorten the development cycle.

[0048] The present invention specifically provides a multi-configuration UAV in the same test condition, designs the test load, and tests the four test parts of the main components: wing, fuselage, vertical tail, horizontal tail, etc. in one test condition, saving three test conditions. Specifically, there are four severe load conditions in actual flight: 100% severe load condition of wing, 100% severe load condition of fuselage, 100% severe load condition of vertical tail, and 100% severe load condition of horizontal tail. One test condition is designed, so that: 90% severe load is tested on the wing, 80% severe load is tested on the fuselage, 75% severe load is tested on the vertical tail, and 82% severe load is tested on the horizontal tail. Then, the simulation model is corrected by using the data measured by the strength test, and the corrected simulation model is used to predict the 100% severe load condition, thereby saving three test conditions.

[0049] The present invention also specifically designs a uniform type for the strength test of long and short wings of multi-configuration UAVs. Multi-configuration UAVs involve short wings and long wings. If they are in accordance with military aircraft specifications, two strength test machines are required, one for the short wing and one for the long wing. The present invention designs a heterogeneous strength test machine, such as Figure 5 As shown, a multi-configuration UAV fuselage 101 is installed with a short wing 102 on one side and a long wing 103 on the other side for testing. This heterogeneous strength testing machine simultaneously meets the strength test assessment of two configuration wings. This test method saves one long wing test piece and one short wing test piece.

[0050] The present invention conducts nondestructive testing on the heterogeneous strength tester after completing the strength test task. If the heterogeneous strength tester finds no structural damage, it can continue to perform the flight mission. The present invention appropriately reduces the loading percentage of the strength static test based on the results of the strength analysis, and uses the extrapolation method to verify under the limit load through reliable strain and deformation measurement, such as Figure 6 As shown, the purpose of both testing and verifying the strength design and ensuring the subsequent use of the aircraft body structure is achieved. When the test piece has other high-value uses (such as for flight testing), it can only be tested to 90% to 100% of the limit load, and the verification under the limit load can be carried out by extrapolation method through reliable strain and deformation measurement.

[0051] When conducting a heterogeneous strength test machine test, if the traditional military aircraft strength test tape loading system is used, such as Figure 7 As shown, the tape used in this loading method is not easy to remove and will damage the surface of the aircraft, which is not conducive to the subsequent flight missions of the test aircraft.

[0052] The present invention adopts a pallet loading system that does not damage the aircraft surface, such as Figure 8 As shown, the structure of the heterogeneous strength test aircraft is protected. After the strength test, the heterogeneous strength test aircraft continues to be used for flight missions, saving a static aircraft.

[0053] 2.4) The design-test rapid R&D model has changed by 304. If the multi-configuration UAV completes the entire strength design and strength test work in accordance with the "design-manufacturing-testing" full process sequence required by the military aircraft specifications, it will take a long time. The design-test rapid R&D model has changed by 304 to reorganize the "design-manufacturing-testing" process, pre-stage the strength test design and preparation work of the multi-configuration UAV, realize the rapid R&D with highly parallel strength analysis and test design, and speed up the progress of strength testing.

[0054] 3) Research on fatigue strength design and fatigue test tailoring of UAV4 is mainly based on the use mode, use environment characteristics, use load characteristics and other factors of multi-configuration UAVs. On the basis of drawing on the experience of manned aircraft load spectrum compilation, the typical use mission profile of multi-configuration UAVs is determined, and the fatigue load spectrum of multi-configuration UAVs is compiled. Combined with the fatigue test results of typical test pieces, the high-load interception and low-load interception methods are used to analogically evaluate the fatigue life of multi-configuration UAV structures. The main functions are divided into: fatigue analogy method 401, fatigue test tailoring 402.

[0055] 3.1) Fatigue analogy method 401. The fatigue strength design of multi-configuration UAVs reduces fatigue key parts and retains important structural characteristics. Aiming at the low-cost use characteristics, the fatigue strength design of multi-configuration UAVs is appropriately simplified in the design process of military aircraft. By comparing the same type of aircraft, using similar aircraft load spectrum spectrum, and conducting fatigue strength design of multi-configuration UAV structures based on engineering experience, preliminary fatigue strength analysis of some important structures is carried out to save design labor costs. When durability requirements need to be considered, fatigue life analogy method is mainly used to evaluate the durability of key structures to prove whether the structure meets the durability requirements. When damage tolerance requirements need to be considered, crack extension life analogy method is mainly used to analyze the most dangerous parts of the flight safety structure. The maximum load that the analyzed structure may encounter within an inspection period (one time life for uninspectable structures) is used as the residual strength load to determine the critical crack size. The analysis proves whether the structure meets the damage tolerance requirements.

[0056] 3.2) Fatigue test tailoring 402. Develop virtual fatigue tests to determine the fatigue life of the structure. The load of the virtual fatigue test takes into account the distributed load of the simulated flight during the entire design life, thereby generating a more realistic fatigue spectrum. In the virtual fatigue test, the gust statistics of multi-configuration UAVs are considered to simulate the flight during the entire design life, providing accurate load history for multi-configuration UAVs. Based on the principle of damage consistency and equal damage theory, the fatigue load spectrum is simplified and aggravated, the number of fatigue load spectrum cycles is reduced, and component-level test pieces are used to verify the fatigue performance of the entire aircraft structure, saving a fatigue aircraft and saving test costs.

[0057] 4) Multi-configuration UAV flight test monitoring 5 mainly conducts research on the digital twin flight test monitoring technology of UAV airframe structure 501. By creating a digital twin of the multi-configuration UAV structure, sensors are used to continuously monitor the load and operating status of the aircraft, and the history of the UAV structure in terms of flight parameters, load, environment, structural changes, repairs, and maintenance is tracked. The current physical state of the structure is calculated in combination with the probabilistic failure mechanism, and compared with the data obtained from the virtual test to achieve predictive maintenance and optimized maintenance plans for the structure. The maneuver type is identified from the flight parameters, and the maneuver action is automatically identified based on the flight parameter data. A maneuver action library is established. After the maneuver action library is obtained, the flight parameter data is compared with the actions in the maneuver action library and the action type is determined to obtain the UAV flight load. Through the simulation analysis results based on the probability evaluation of the UAV airframe digital twin reliability, the aircraft airframe structure failure decision-making technology based on probability data is studied, thereby realizing the safety monitoring of UAV flight test.

[0058] Based on the design goal of focusing on "low cost, high efficiency and high performance" of multi-configuration UAVs, the present invention proposes a low-cost strength design and test criterion tailoring method for multi-configuration UAVs in the entire process of strength design, strength test and maintenance of multi-configuration UAVs, which brings economic benefits to the rapid strength design and rapid strength test of multi-configuration UAVs, maintains the integrity of the structural platform with the lowest possible strength design cost and strength test cost, and realizes and meets the design requirements of safety, applicability and other performances of multi-configuration UAVs.

[0059] The above is only a specific embodiment of the present invention, and the present invention is described in detail. The unexplained part is a conventional technology. However, the protection scope of the present invention is not limited to this. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. The protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A low-cost strength design and test criteria tailoring method for multi-configuration UAVs, characterized in that: The cutting method comprises the following steps: The first step is to tailor the strength design criteria for multi-configuration UAVs, including: selection of UAV structural materials, UAV strength design coefficients, UAV strength design loads, and UAV fatigue load spectrum design; Among them: the selection of UAV structural materials needs to balance the mechanical properties, economy, maturity and support capability factors of UAV structural material selection, with the goal of reducing structural weight and cost and obtaining the best comprehensive benefits; the UAV strength design coefficient includes a detailed study of the overall performance requirements of UAVs, the body development specifications and other general requirement documents on the basis of the UAV strength design specifications, and fully considers the factors of low-cost design in the strength design criteria of multi-configuration UAVs, and makes trade-offs between various strength coefficients and strength design conditions; the UAV strength design load targets the performance requirements of multi-configuration UAVs, reduces the overall load of the aircraft through overall and flight control optimization, cuts the environmental adaptability clauses, reduces the environmental adaptability requirements for the finished product, and modifies the design load of the UAV by analogy with similar test results; the UAV fatigue load spectrum design determines the typical flight mission profile of the multi-configuration UAV, combines the fatigue test results of typical test pieces, and draws on the experience of compiling load spectra of military aircraft to compile a multi-configuration UAV load spectrum; The second step is to design a multi-configuration UAV test machine, conduct digital design of the static strength of the multi-configuration UAV and optimize the static test; including: virtual test technology for composite material allowable values, static strength design by digital means, static test optimization, and change of the design-test rapid R&D model; Among them: virtual test technology for composite material allowable values ​​is aimed at composite materials that are applied for the first time. According to the requirements, pyramid matrix test verification of composite materials is carried out. The design allowable values ​​of composite materials are determined by studying a small number of physical tests on composite materials combined with comprehensive virtual tests, appropriately reducing the test batches of composite materials, shortening the test cycle and reducing the test cost; static strength design with digital means is based on strength digital simulation means. Digital virtual tests reduce or partially replace physical tests, complete verification that is difficult to implement with physical tests, reduce development risks, shorten development cycles and reduce development costs; static test optimization reduces the scale of component, typical parts and component-level tests through digital strength analysis, optimizes and streamlines strength verification conditions, and reasonably verifies the structural bearing capacity design indicators more efficiently and economically through section and simulation test verification methods in the overall test planning; the design-test rapid R&D mode is changed, and the strength test design and preparation work are pre-placed to achieve rapid R&D with highly parallel strength analysis and test design, and accelerate the progress of strength tests; The third step is to conduct research on UAV fatigue strength design and fatigue test cutting, including fatigue analogy method and fatigue test cutting. Among them: the fatigue analogy method is based on the factors of the use mode, use environment characteristics, and use load characteristics of multi-configuration UAVs. On the basis of drawing on the experience of compiling manned aircraft load spectra, the typical use mission profile of multi-configuration UAVs is determined. Combined with the fatigue test results of typical test pieces, the high-load interception and low-load interception methods are used to analogically evaluate the fatigue life of the multi-configuration UAV structure; fatigue test tailoring carries out research on fatigue load spectrum simplification and aggravation technology. Based on the principle of damage consistency and equal damage theory, component-level test pieces are used to verify the fatigue performance of the entire aircraft structure, shorten the fatigue test time, and save test costs; The fourth step is to conduct test flight monitoring of multi-configuration UAVs, including test flight monitoring of the digital twin of the UAV body structure; Among them: The digital twin test flight monitoring of the UAV body structure uses the time history of flight parameters recorded by the flight parameter recording system of the multi-configuration UAV to carry out the "flight parameter-load" correlation study, and obtains the stress of key parts of the structure through the load transfer function, and then conducts health monitoring of the key parts of the multi-configuration UAV structure.

2. A method for tailoring low-cost strength design and test criteria for multi-configuration UAVs as claimed in claim 1, characterized in that: In the first step, the strength design factor of the UAV is determined to be 1.3, and the strength design uncertainty factor for a specific known load condition is taken as 1.

05.

3. A method for tailoring low-cost strength design and test criteria for multi-configuration UAVs as claimed in claim 2, characterized in that: In the first step, when optimizing the strength design load of the UAV, the landing gear turning load of the multi-configuration UAV is reduced by 30%; The rotational rebound coefficient of the landing gear ground load was corrected, reducing the rotational load by 13.3% and the rebound load by 12.5%.

4. A low-cost strength design and test criteria tailoring method for a multi-configuration UAV as claimed in claim 1, characterized in that: In the second step, when performing static test optimization, a multi-configuration UAV test machine is designed to complete the static strength test. The multi-configuration UAV test machine includes a fuselage and a short wing installed on one side of the fuselage and a long wing installed on the other side.

5. A method for tailoring low-cost strength design and test criteria for multi-configuration UAVs as claimed in claim 4, characterized in that: During the static strength test, the test load is designed for a multi-configuration UAV test aircraft in the same test condition, and the four main components: wing, fuselage, vertical tail, and horizontal tail are all tested in one test condition to save three test conditions; specifically, there are four severe load conditions in actual flight: 100% severe load condition for the wing, 100% severe load condition for the fuselage, 100% severe load condition for the vertical tail, and 100% severe load condition for the horizontal tail. One test condition is designed so that: 90% severe load is tested on the wing, 80% severe load is tested on the fuselage, 75% severe load is tested on the vertical tail, and 82% severe load is tested on the horizontal tail. Then, the data measured in the strength test is used to correct the simulation model, and the corrected simulation model is used to predict the 100% severe load condition.

6. A method for tailoring low-cost strength design and test criteria for multi-configuration UAVs as claimed in claim 5, characterized in that: When conducting static strength tests, a pallet loading system that does not damage the aircraft surface is used; the pallet loading system is to set pallets that are in full contact with the surface of the component on both sides of the component to be loaded on the test machine; and the pallets on both sides are loaded synchronously.

7. A method for tailoring low-cost strength design and test criteria for multi-configuration UAVs as claimed in claim 6, characterized in that: When conducting static strength tests, reduce the loading percentage of the static strength test to only 90% to 100% of the limit load. Through reliable strain and deformation measurements, the extrapolation method is used to verify under the limit load.

8. A method for low-cost strength design and test criteria tailoring of multi-configuration UAVs as claimed in claim 1, characterized in that: In the third step, based on the experience of compiling load spectra of manned aircraft, the typical usage mission profile of multi-configuration UAVs is determined, and the fatigue load spectrum of multi-configuration UAVs is compiled. Combined with the fatigue test results of typical test pieces, the high-load interception and low-load interception methods are used to analogically evaluate the fatigue life of the multi-configuration UAV structure.

9. A method for tailoring low-cost strength design and test criteria for multi-configuration UAVs as claimed in claim 1, characterized in that: When compiling the fatigue load spectrum of multi-configuration UAVs, reference is made to the measured long-wing configuration aircraft loads and short-wing configuration aircraft loads.

10. A low-cost strength design and test criteria tailoring method for a multi-configuration UAV as claimed in claim 1, characterized in that: In the fourth step, when conducting test flight monitoring of multi-configuration UAVs, the maneuver type is identified from the flight parameters, the maneuver action is automatically identified based on the flight parameter data, and a maneuver action library is established; then the flight parameter data is compared with the actions in the maneuver action library and the action type is determined to obtain the UAV flight load. Through the simulation analysis results based on the reliability probability assessment of the UAV body digital twin, the aircraft body structure fault decision-making technology supported by probability data is studied, thereby realizing the safety monitoring of UAV test flight.

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