Accelerated Simulation Test Method for Coating System of Helicopter Connection Structure in Plateau Atmospheric Environment

Abstract

The present invention provides a method for accelerating the simulation test of the coating system of a helicopter connection structure in a plateau atmospheric environment, including: S1, obtaining the environmental factor data required for the test; S2, presetting the test duration; S3, according to the environmental factor data, repeatedly performing low-temperature fatigue tests, multi-environment factor comprehensive tests of temperature-humidity-air pressure-solar radiation-wind, sand and dust tests, and salt solution spray-drying tests on the coating system of the helicopter connection structure within the preset duration. The present invention can stably, accurately, flexibly and quickly obtain the key environmental factor of the amount of sand and dust experienced by the coating system of the helicopter connection structure in the plateau environment, and is applicable to quickly and accurately obtaining the amount of sand and dust experienced by the coating system of the helicopter connection structure of any model helicopter and any parking site in the plateau environment.

Description

Technical Field

[0001] This document relates to the technical field of helicopter environmental testing, and in particular to an accelerated simulation test method for a helicopter connection structure coating system in a plateau atmospheric environment. Background Art

[0002] Compared with plain areas, the natural environment in plateau areas generally has the typical "three lows and two strongs" characteristics, namely "low temperature, low air pressure, low oxygen content in the air, strong ultraviolet rays, and strong wind and sand". The low air pressure, low temperature, large temperature difference between day and night, strong sunlight radiation and sandstorms in the plateau environment have a huge impact on the use of helicopters, especially the helicopter engine system, hydraulic system, environmental control system, power electronic components, exposed moving parts of the mechanical system, optical components, exposed pneumatic sensors, non-metallic materials, exposed open wires and non-airtight cabin electrical plugs are easily affected by the plateau environment and various problems may occur. The combined effects of factors such as low temperature, low pressure, strong solar radiation, and dust will increase the viscosity of the lubricating oil in the engine lubrication system, leading to an increase in the rotational resistance torque of the engine's rotating parts; aggravate the wear of the running parts of the engine and transmission system, the moving units of mechanical equipment, etc.; change the properties of non-metallic materials such as rubber and plastic, such as rubber parts becoming hard and brittle, and the sealing effect of rubber seals in the oil system becoming worse, causing oil leakage; cause weapon systems to get stuck during shooting, and optical, laser, infrared and other guidance systems and reconnaissance systems to be unable to perform their performance, reducing reliability; cause precision electronic equipment to operate abnormally or malfunction, causing a series of mechanical or electrical faults such as poor electrical contact; cause filters to be clogged with sand and oil lines to be clogged; aggravate the abrasion or corrosion of engine blades, erode the helicopter body, and induce multiple faults; and greatly shorten the service life of the main components of the helicopter and a large number of onboard equipment.

[0003] The aging of non-metallic materials in helicopters under plateau conditions is the most common and typical of all environmental adaptability problems faced by helicopters, such as damage and shedding of coating in the helicopter overlap area, wear and tear of rotor and rotor joint bearings / peeling of coating, aging of exposed cables / cracking of sealing rubber, and leakage of fuel / lubricating oil due to aging of sealing rubber. According to on-site feedback and survey results, the air in plateau areas is thin, the solar radiation is strong, the temperature difference between day and night is large, the non-metallic aging phenomenon is serious, and the failure rate of helicopters is high. At this stage, how to quickly and accurately assess the environmental adaptability of the coating system of the helicopter connection structure under plateau conditions is of great research value for the long-term safe and reliable use of helicopters under plateau conditions.

[0004] At present, there are two main test methods for the environmental adaptability assessment of helicopter connection structure coating systems in plateau environments: natural environment tests and laboratory simulation acceleration tests. Among them, natural environment tests are generally time-consuming and limited in application; traditional laboratory simulation acceleration test methods are usually presented in the form of multi-factor combinations (such as single-factor multi-spectrum block combination test spectra represented by the US military CASS spectrum, etc.), but there is a great deal of arbitrariness and uncertainty in the simulation and acceleration of the test. In recent years, based on traditional test methods, many scholars in this field have proposed a new idea of "using comprehensive simulation methods, with the help of multi-factor comprehensive test equipment, to develop new and efficient multi-factor coupling acceleration test methods." Guided by this idea, the single-factor multi-spectrum block combination test spectrum represented by the US military CASS spectrum has gradually derived different types of multi-factor single-spectrum block / multi-spectrum block comprehensive / combination test spectra, which has broken through the limitations of traditional test methods to a certain extent and achieved good results.

[0005] However, most of the existing technical routes are new methods proposed for the combination of multiple factors, but they ignore the accurate acquisition of the required environmental factor data, especially how to stably, accurately, flexibly and quickly obtain the key environmental factor of the amount of dust that the helicopter connection structure coating system is subjected to in the plateau environment. There is no reliable and effective technical means so far. Summary of the invention

[0006] The present invention provides a plateau atmospheric environment accelerated simulation test method for a helicopter connection structure coating system, aiming to solve the above-mentioned problem.

[0007] The embodiment of the present invention provides a plateau atmospheric environment accelerated simulation test method for a helicopter connection structure coating system, comprising:

[0008] S1. Obtain the environmental factor data required for the test and preset the test duration. The environmental factor data specifically include: conventional meteorological factors, medium environmental factors, dust fall factors and sand and dust factors of the plateau atmospheric environment; among which, the sand and dust factors are obtained through a pre-designed sand and dust collector;

[0009] S2. Based on the environmental factor data, the helicopter connection structure coating system is repeatedly subjected to low-temperature fatigue tests, temperature-humidity-air pressure-solar radiation-wind multi-environmental factor comprehensive tests, sand and dust tests, and salt solution spray-drying tests within a preset test duration.

[0010] By adopting the embodiments of the present invention, a key environmental factor, namely the amount of dust experienced by the helicopter connection structure coating system in a plateau environment, can be stably, accurately, flexibly and quickly acquired through a pre-designed dust collector. The dust collector is suitable for quickly and accurately acquiring the amount of dust experienced by the helicopter connection structure coating system in any model of helicopter and any parking area in a plateau environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] To more clearly illustrate the technical solutions in one or more embodiments of this specification or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in this specification. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0012] Figure 1 It is a flowchart of an accelerated simulation test method for the high-altitude atmospheric environment of a helicopter connection structure coating system according to an embodiment of the present invention;

[0013] Figure 2 It is a three-dimensional schematic diagram of a sand collector according to an embodiment of the present invention

[0014] Figure 3 It is a side schematic diagram of a sand collector according to an embodiment of the present invention;

[0015] Figure 4 It is a front schematic diagram of a sand collector according to an embodiment of the present invention;

[0016] Figure 5 It is a combined schematic diagram of multiple sand collectors according to an embodiment of the present invention;

[0017] Figure 6 It is the main flowchart of the accelerated simulation test of the high-altitude atmospheric environment of the helicopter connection structure coating system according to an embodiment of the present invention. Specific embodiments

[0018] In order to enable those skilled in the art to better understand the technical solutions in one or more embodiments of this specification, the following will clearly and completely describe the technical solutions in one or more embodiments of this specification with reference to the drawings in one or more embodiments of this specification. Obviously, the described embodiments are only some embodiments of this specification, rather than all embodiments. Based on one or more embodiments of this specification, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this document.

[0019] Method embodiments

[0020] According to an embodiment of the present invention, there is provided an accelerated simulation test method for the high-altitude atmospheric environment of a helicopter connection structure coating system, Figure 1 It is a flowchart of an accelerated simulation test method for the high-altitude atmospheric environment of a helicopter connection structure coating system according to an embodiment of the present invention. According to Figure 1 as shown, an accelerated simulation test method for the high-altitude atmospheric environment of a helicopter connection structure coating system according to an embodiment of the present invention includes:

[0021] S1. Obtain the environmental factor data required for the test and preset the test duration. The environmental factor data specifically includes: the conventional meteorological factors, medium environmental factors, dustfall factors, and sand dust factors of the plateau atmospheric environment. Among them, the sand dust factors are obtained through a pre-designed sand dust collector.

[0022] S2. According to the environmental factor data, repeat the low-temperature fatigue test, the comprehensive test of multiple environmental factors such as temperature - humidity - air pressure - solar radiation - wind, the sand dust test, and the salt solution spray - drying test on the helicopter connection structure coating system within the preset test duration.

[0023] Among them, the sand dust in the plateau atmospheric environment is collected by means of a sand dust collector. The sand dust collector includes four legs, and the tops of the four legs are connected to the same arc-shaped plate. One side of the arc-shaped plate is hermetically connected to a baffle. The included angle between the arc-shaped plate and the baffle is 70 - 88°, and the concave area of the arc-shaped plate intersects with the bottom edge of the baffle.

[0024] Preferably, each of the legs is a tapered rod structure.

[0025] Furthermore, each of the legs is composed of several detachably connected rod bodies and a cone threadedly connected to the bottom of the rod body, and the rod body and the cone are detachably connected.

[0026] Furthermore, during the process of obtaining the sand dust factor data, a plurality of the sand dust collectors are arranged at the position where the helicopter connection structure coating system is located. The height and orientation of the root of the included angle between the arc-shaped plate and the baffle of the sand dust collector are the same as the height and orientation of the position where the overlapping gap on the helicopter connection structure is located, and the total length of the combined plurality of sand dust collectors is the same as the total length of the overlapping gap on the helicopter connection structure. In the present invention, the upper overlapping gap refers to the upper gap of the overlapping structure.

[0027] In the present invention, the steps of obtaining the sand dust factor data include:

[0028] S11. Determine the height, orientation, length, and the type of the parking place of the position where the helicopter connection structure coating system is located.

[0029] S12. Select a rod body and a cone with appropriate lengths and connect the cone to the bottom of the rod body of the sand dust collector.

[0030] S13. When the type of the parking place is an unhardened road surface, insert each cone of the sand dust collector into the parking place; when the type of the parking place is a hardened road surface, directly place the bottom of each rod body of the sand dust collector on the hardened road surface; and ensure that the height and orientation of the root of the included angle between the arc-shaped plate and the baffle of the sand dust collector are the same as the height and orientation of the position where the overlapping gap on the helicopter connection structure is located.

[0031] S14. Install multiple dust collectors with reference to step S13 until the total length of the combined multiple dust collectors is the same as the total length of the overlapping gaps on the helicopter connection structure.

[0032] S15. After the dust collection is completed, collect the dust accumulated on the arc plate for subsequent analysis and processing.

[0033] In the embodiment of the present invention:

[0034] The test conditions for the low-temperature fatigue test are as follows: the waveform is a sine wave, the test frequency is 16 Hz, the stress peak value is 74.5 Mpa, the stress valley value is 4.47 Mpa, the stress ratio is 0.06, the number of fatigue load cycles is 8000 times, and the test temperature is -43 ± 2 °C.

[0035] The test conditions for the comprehensive test of multiple environmental factors such as temperature - humidity - air pressure - solar radiation - wind are as follows: the total time of a single cycle test is 18 d, and it circulates according to "light cycle 8 h + dark cycle 4 h + light cycle 8 h + dark cycle 4 h + ···"; among them, the radiation intensity in the light cycle is 1.1 W / (m 2 ·nm) at 340 nm. The light source uses UVA - 340 fluorescent lamps, the temperature is a constant temperature of 60 ± 1 °C, the heating and cooling rate is 3 °C / min, the relative humidity is a constant humidity of 60 ± 5%, and the low air pressure is a constant air pressure of 600 ± 50 hPa; the temperature in the dark cycle is -43 ± 2 °C, the cooling rate is 3 °C / min, the relative humidity is a constant humidity of 60 ± 5%, and the low air pressure is a constant air pressure of 600 ± 50 hPa.

[0036] After trimming the obtained dust deposition factor data and dust factor data, the test conditions for the sand and dust test are determined as follows:

[0037] The wind speed for the dust blowing test is 3 - 4 m / s, the concentration is 10.6 ± 7 g / m 3 , the diameter of the dust is 30 - 149 μm, the relative humidity RH ≤ 30%, the normal temperature is T = 23 ± 1 °C, the high temperature is T = 30 ± 1 °C, and the normal temperature lasts for 6 h + the high temperature lasts for 6 h.

[0038] The wind speed for the sand blowing test: 3 - 4 m / s, the concentration is 2.2 ± 0.5 g / m 3 , the diameter of the dust is 150 - 650 μm, the relative humidity RH ≤ 30%, the high temperature is T = 30 ± 1 °C, and the duration is 1.5 h.

[0039] The test conditions for the salt solution spray - drying test are as follows:

[0040] The single-cycle test time is 7 days; Salt spray conditions: 0.05% sodium sulfate solution, adjusted to pH = 6 - 8 with dilute sulfuric acid or NaOH solution, and the salt solution sedimentation rate is controlled at 1 - 3 mL / (80 cm 2 .h); The cycle period is 8 h of spraying + 16 h of ventilation and drying; Temperature: Spraying T = 35 ± 1 °C, drying T = 35 ± 1 °C; Humidity RH ≤ 50 ± 3%.

[0041] Preferably, the total duration of each cycle test is 18 days. After the test, at least the appearance, gloss, color difference, thickness, adhesion, and infrared detection of the specimen are carried out.

[0042] The following is illustrated by specific test examples: According to the results of previous investigations, when a helicopter serves in a certain plateau area, there are phenomena such as coating damage and peeling in the lap area of the helicopter skin riveting structure. Based on this, taking the external coating system of a certain type of helicopter skin structure as the object of spectrum compilation, a study on the compilation of an accelerated simulation test environmental spectrum for ground parking is carried out to provide methods and technical support for reproducing the corrosion / aging damage of helicopters in the plateau environment under laboratory conditions

[0043] The environment where the external coating system of the helicopter skin is located is mainly the natural environment of external parking. According to the analysis of the environmental characteristics of the aforementioned plateau area, the main characteristics of the external field environment A in a certain plateau area are as follows: The annual average air pressure is very low and fluctuates little, the annual average temperature is moderate, the annual temperature change range is large, the winter temperature is low, the low-temperature time is long, the day-night temperature difference is large, the solar radiation, especially ultraviolet radiation, is strong, the environmental factors such as temperature, solar radiation, and rainfall are highly correlated with seasons, the annual average relative humidity is low, the air is relatively dry and the content of atmospheric pollutants is very low, there is dust fall and sand dust, the precipitation is less and seasonally unevenly distributed, and the pH value of rainwater is neutral, etc.

[0044] In the atmospheric environment of the plateau area, the external coating system of the skin is mainly affected by the combined action of environmental factors such as solar radiation, temperature and humidity, dust fall and sand dust, and various pollutants in the atmosphere, resulting in coating aging and failure. Therefore, according to the interaction situation of the above environmental factors, an accelerated test spectrum composed of a multi-environment factor comprehensive test of temperature - humidity - air pressure - solar radiation, a sand dust test, and a salt solution spray - drying test is designed. At the same time, considering that the fuselage skin structural parts are subjected to the action of dynamic and static alternating load environmental factors during the ground parking stage and the flight stage, which may cause phenomena such as micro-cracks in the coating, accelerating the corrosion / aging of the coating in the ground parking environment. Therefore, a low-temperature fatigue test is designed with reference to the CASS spectrum to supplement the accelerated test spectrum to reflect the influence of alternating loads on the skin structure and the surface protective coating. The order of its action reflects the actual situation of high solar radiation, low air pressure, large outdoor day-night / winter-summer temperature difference, more dust fall and sand dust, night-time condensation, wet-dry alternation, and erosion by corrosive media when the helicopter is parked

[0045] Specifically, the accelerated simulation test method for the coating system of the helicopter connection structure in this embodiment under the plateau atmospheric environment includes the following steps:

[0046] Step 1: Obtain the environmental factor data required for the test, including collecting the conventional meteorological / medium environmental factor data of the plateau atmospheric environment, as well as the dust factor data and sand dust factor data;

[0047] Step 2: Based on the obtained environmental factor data, sequentially conduct a low-temperature fatigue test, a comprehensive multi-environment factor test of temperature-humidity-air pressure-solar radiation-wind on the helicopter connection structure, a sand and dust test, and a salt solution spray-drying test. The overall process is shown in Figure 6 as follows; in this step, the total duration of the cyclic test is 26 days. After the test, at least conduct appearance inspection, gloss inspection, color difference inspection, thickness inspection, adhesion, and infrared inspection on the specimens.

[0048] Among them, the low-temperature fatigue test and its test conditions are as follows:

[0049] The dynamic and static alternating load environment factors experienced by the fuselage skin structural components during ground parking and flight phases can affect the surface protective coating and riveted parts. When a certain type of army aviation helicopter takes off from a stationary state, it takes about 1.5 minutes for the rotor to rotate from slow to stable output (stationary - slow speed (72% - 76% of power, taking about 1 minute) - fast speed (taking about 30 seconds) - leaving the ground (completed within a few seconds)). During flight, the rotor shaft rotates clockwise (viewed from above) at a speed of 192 revolutions per minute. The helicopter has 5 blades, so the alternating shear load frequency is taken as 16 Hz (each blade rotates 16 / 5 circles per second). Taking the force on the fuselage skin of a certain type of helicopter as a reference, the maximum shear stress on the right side is 73.8 Mpa, and the maximum shear stress on the left side is 74.5 Mpa. It takes 1.5 minutes for the helicopter to fly from stationary to stable, and at this time, the load on the fuselage skin changes from 0 MPa in the parked state in a sawtooth sine wave to a stress peak of 74.5 MPa. When landing, the load on the fuselage skin changes from the stress peak of 74.5 MPa in a sawtooth sine wave to 0 MPa in the parked state. Therefore, the load borne by the fuselage skin structure during helicopter flight can be simplified to a constant amplitude sine wave tensile - tensile load with a stress peak of 74.5 Mpa and a frequency of 16 Hz. The stress valley value is calculated according to the conventional stress ratio value of 0.06 (4.47 Mpa). The fatigue load cycle count is based on 500 times according to the US military CASS spectrum, and considering the relevant design requirements and strengthening ratio coefficients of the helicopter design department, it is set at 8000 times. In addition, considering that the air temperature is lower than the ground temperature during helicopter flight, considering the most extreme situation, the fatigue test is designed to be carried out under low - temperature conditions. The lowest ground temperature in some places in Lhasa and Nyingchi from 2018 to 2020 - 2021 is - 12.5 °C. The normal flight altitude of plateau helicopters is about 5000 m, and the temperature during flight is about 30 °C lower than the ground temperature. Therefore, the fatigue test is designed to be carried out under the condition of (-43 ± 2) °C.

[0050] Among them, the comprehensive test of temperature - humidity - air pressure - solar radiation multi - environmental factors and its test conditions are as follows:

[0051] The effect of solar radiation spectrum on organic coatings is mainly the photo - degradation of the coating caused by ultraviolet rays. In the plateau environment, due to the action of environmental factors such as low temperature, the surface coating of the fuselage skin structural components of the helicopter is prone to becoming brittle and hard (resulting in reduced flexibility). At the same time, under the impact of cyclic hot and cold temperature, micro - cracks are likely to occur on the surface coating of the structural components due to thermal expansion and contraction, accelerating the aging damage of the coating; and the low - air - pressure condition often leads to the accelerated escape of small molecules generated after the aging degradation of the coating, which has a certain promoting effect on the coating aging. By coupling the four environmental factors of temperature, humidity, air pressure, and solar radiation in one test device and applying them to the coating system of the helicopter connection structure at the same time, the coating damage can be quickly induced.

[0052] In terms of specific parameter design, first, referring to the test conditions of relevant standards such as ASTM D5894 "Standard Practice for Cycle Exposure of Painted Metals to Salt Spray / Ultraviolet Light", GB / T 16422.3-1997 "Plastics - Methods of Exposure to Laboratory Light Sources - Part 3: Fluorescent Ultraviolet Lamps", GJB150.3A-2009 "Environmental Test Methods for Military Equipment in Laboratory - Part 3: High Temperature Test", GJB 150.4A-2009 "Environmental Test Methods for Military Equipment in Laboratory - Part 4: Low Temperature Test", and GJB 150.5A-2009 "Environmental Test Methods for Military Equipment in Laboratory - Part 5: Temperature Cycle Test", etc., it is determined that the alternating mode of the light and dark cycles corresponding to solar radiation is "light cycle 8h + dark cycle 4h + light cycle 8h + dark cycle 4h +...". During the light cycle, there is light, and ultraviolet light irradiation is applied to the specimen. The irradiation level is 1.1 W / (m 2 ·nm) at 340 nm. When irradiating with ultraviolet light, the environmental temperature is controlled at (60 ± 1) °C; during the dark cycle, there is no light, and the test temperature is taken as the temperature (-43 ± 2) °C in the aforementioned low-temperature fatigue test to simulate phenomena such as low-temperature freezing and condensation of the coating in the plateau low-temperature environment. In terms of low-pressure parameters, referring to the test conditions of GJB 150.2A-2009 "Environmental Test Methods for Military Equipment in Laboratory - Part 2: Low Pressure (Altitude) Test", based on the ground minimum air pressure of 625 hPa in a certain place in Lhasa and a certain place in Nyingchi in 2018, 2020 - 2021, the test is designed to be carried out under a constant low-pressure condition, and the constant low pressure is controlled at (600 ± 50) hPa. In terms of relative humidity, referring to the test conditions of GJB 150.9A-2009 "Environmental Test Methods for Military Equipment in Laboratory - Part 9: Damp Heat Test", based on the larger value of 61% of the annual average relative humidity on the ground in a certain place in Lhasa and a certain place in Nyingchi in 2018, 2020 - 2021, the test is designed to be carried out under a constant humidity condition, and the constant relative humidity is controlled at (60 ± 5)%. In terms of the duration, considering that the helicopter is only exposed to sunlight outdoors (including outdoor parking + outdoor flight) for a few hours throughout the year, it is reasonably assumed that both the outdoor parking time and the outdoor flight time are sunny hours, and the total solar ultraviolet radiation can be evenly distributed within the sunny hours (that is, the change of solar radiation within the sunny hours is not considered), so as to estimate the total ultraviolet radiation that the coating specimen may receive throughout the year. The measured total solar ultraviolet radiation in a certain plateau area A from 2020 to 2021 is 315.1 MJ / m 2 , the annual sunshine hours are 2962 h, both the outdoor parking time and the outdoor flight time are taken as 300 h, and the total ultraviolet radiation equivalent to ultraviolet light irradiation at 1.1 W / (m 2 ·nm) at 340 nm is 60 W / m 2 , so the total test time is designed to be 18 days (315.1 MJ / m2 × 1 / 4.94 (the proportion of outdoor time in the total annual sunshine hours, 600 h / 2962 h) ÷ 60 W / m 2 ÷ 3600 s ÷ 16 h (UV irradiation for 16 h every 24 h) ≈ 18 d), to simulate the total annual UV radiation received by the coating specimens.

[0053] Among them, the sand and dust test and its test conditions are as follows:

[0054] Under the ground parking environment, the surface coating of the helicopter fuselage skin structural components is affected by environmental factors such as dust fall and sand and dust mainly in two aspects: on the one hand, the impact of large particulate matters such as sand and dust is likely to cause the coating at the structural connection parts (especially the lapping parts) to be damaged and fall off; on the other hand, the soluble and insoluble components in the dust fall and sand and dust will change the surface state of the structural components, resulting in phenomena such as moisture absorption and reduction of critical wetting humidity. Especially after the more corrosive chlorine in them dissolves in rainwater (snowmelt), dew, and the surface wetting film, it will accelerate the corrosion / aging reaction at the coating / metal interface.

[0055] In this process, it is first necessary to accurately obtain the data of dust fall factors and sand and dust factors.

[0056] Use a sedimentation collection device to obtain the data of dust fall factors. The sedimentation collection device uses a dust collection cylinder with an inner diameter of 30 cm and a height of 40 cm, which is fixed on a platform with a height of 100 cm. By placing a dust collection cylinder to collect both dust fall and sand and dust at the same time, 60 mL - 80 mL of ethylene glycol is added to the dust collection cylinder to fill the bottom of the cylinder; an appropriate amount of water is added to form an ethylene glycol aqueous solution, and the amount of water added depends on the local climate conditions. Generally, 50 mL is added in winter, and 100 mL - 200 mL is added in other seasons to maintain sampling under wet conditions. In the rainy season in summer, attention should be paid to the water accumulation situation in the cylinder to prevent water from overflowing. If the water is about to be full, a new cylinder should be replaced in time. After the dust fall collection is completed, the collected dust fall is analyzed and processed.

[0057] Use a sand and dust collector to collect the sand and dust in the plateau atmospheric environment; as Figures 2 to 4 shown, Figure 2 is the three-dimensional schematic diagram of the sand and dust collector in the embodiment of the present invention, Figure 3 is the side schematic diagram of the sand and dust collector in the embodiment of the present invention, Figure 4This is the main view schematic diagram of the dust collector according to the embodiment of the present invention. The dust collector includes four legs 1 of the same specification. The tops of the four legs 1 are connected to the same arc-shaped plate 2. One side of the arc-shaped plate 2 is hermetically connected to a baffle 3. The included angle between the arc-shaped plate 2 and the baffle 3 is 85°. The concave area of the arc-shaped plate 2 intersects with the bottom edge of the baffle 3. Among them, each leg 1 is a tapered rod structure. Each leg 1 is composed of a plurality of detachably connected rod bodies 11 (only one rod body 11 on the leg 1 is schematically shown in the figure) and a cone 10 threadedly connected to the bottom of the rod body 11. The rod body 11 and the cone 10 are detachably connected. During the process of obtaining dust factor data, multiple dust collectors are arranged at the location of the helicopter connection structure coating system. The height and orientation of the root of the included angle between the arc-shaped plate 2 and the baffle 3 of the dust collector are the same as the height and orientation of the overlapping gap on the helicopter connection structure, and the total length of the combined multiple dust collectors is the same as the total length of the overlapping gap on the helicopter connection structure. In one of the solutions, the helicopter can be parked in the dust collection area first, and then the location, height, and length of the overlapping gap on the helicopter connection structure are marked, and then the helicopter is removed, and then the dust collector is installed according to the marked points; in another solution, the helicopter is parked in the dust collection area first, and then the dust collector is directly installed. In this case, the arc-shaped plate 2 of the dust collector abuts against the helicopter connection structure. Among them, the consistent orientation means that the orientation of the overlapping gap on the helicopter connection structure is the same as the orientation of the included angle between the arc-shaped plate 2 and the baffle 3. Taking the overlapping area shown in Figure 1 as an example in Document CN113670801A, the overlapping gap on its connection structure faces right, so the included angle between the arc-shaped plate 2 and the baffle 3 of the installed dust collector should also face right.

[0058] The steps of obtaining dust factor data include:

[0059] S11. Determine the height, orientation, length, and type of the parking area of the helicopter connection structure coating system;

[0060] S12. Select a rod body 11 and a cone 10 of appropriate length, and connect the cone 10 to the bottom of the rod body 11 of the dust collector;

[0061] S13. When the type of the parking area is a non-hardened road surface (such as grassland, sandy ground, sandy land), insert each cone 10 of the dust collector into the parking area; when the type of the parking area is a hardened road surface, directly place the bottom of each rod body 11 of the dust collector on the hardened road surface; and ensure that the height and orientation of the root of the included angle between the arc-shaped plate 2 and the baffle 3 of the dust collector are the same as the height and orientation of the overlapping gap on the helicopter connection structure;

[0062] S14. Refer to step S13 to install multiple dust collectors until the total length of the combined multiple dust collectors is the same as the total length of the overlapping gaps on the helicopter connection structure. If the length of the upper overlapping gap at the overlapping part of the helicopter connection structure is the sum of the total lengths of six dust collectors, then six dust collectors need to be arranged along its upper overlapping gap, with adjacent dust collectors arranged closely, as Figure 5 shown;

[0063] S15. After the dust collection is completed, collect the dust accumulated on the arc plate 2 for subsequent analysis and processing.

[0064] After analyzing the obtained dustfall and dust, the measured (collected) average median diameter of the dust is 35.74 - 36.90 μm, and the maximum particle size range of the measured dust is 116.1 - 633.6 μm.

[0065] Refer to the relevant test conditions in GJB 150.12A - 2009 "Environmental Test Methods for Military Equipment - Part 12: Dust and Sand Test" to design a combined test of normal temperature ((23 ± 1) °C) dust blowing + high - temperature dust blowing + high - temperature sand blowing to simulate the effects of dustfall and dust on the helicopter fuselage skin structural components. Among them, the temperature of the high - temperature dust blowing and sand blowing tests is designed as 30 ± 1 °C according to the ground maximum temperature of 30.2 °C in a certain place in Lhasa and a certain place in Nyingchi from 2018 to 2020 - 2021, the relative humidity ≤ 30%, the wind speed of the dust blowing test and the sand blowing test is controlled at 3 - 4 m / s according to the maximum monthly average wind speed of 3.5 m / s. The diameter of the dust in the dust blowing test is controlled at 30 - 149 μm with reference to the measured average median diameter of the dust of 35.74 - 36.90 μm, and the diameter of the sand in the sand blowing test is controlled at 150 - 650 μm with reference to the measured maximum particle size range of the dust of 116.1 - 633.6 μm. The concentration of the dust blowing test is 10.6 ± 7 g / m 3 ³, and the concentration of the sand blowing test is 2.2 ± 0.5 g / m 3 ³. The installation directions of both the dust blowing and sand blowing tests are such that the test surface is perpendicular to the direction of the dust blowing (to make the test piece bear the maximum abrasion effect). The duration of the dust blowing test is 12 h (6 h at normal temperature + 6 h at high temperature), and the duration of the sand blowing test is 1.5 h (it is recommended to carry out a sand blowing pre - test and adjust the sand blowing test time according to the pre - test results).

[0066] Among them, the salt solution spray - drying test and its test conditions are as follows:

[0067] Corrosion media (pollutants) in the atmospheric environment include chlorine-containing gases, sulfur oxide gases, nitrogen oxide gases, etc., which also have a certain impact on the aging of the helicopter structure surface coating and the reduction of adhesion. On the one hand, the polluted gas can dissolve into the water film formed on the surface of the organic coating, thus forming a conductive electrolyte solution, and then enter the coating / metal interface to occur corrosion reaction, and the corrosion product reacts with the groups on the molecular chain; on the other hand, the polluted gas diffuses into the coating interior, and the active groups in the gas react with some groups on the molecular chain, changing the molecular chain structure and thus causing the organic coating to age. In a humid air environment, a water film will be generated on the surface of the coating specimen due to condensation. From the rainwater analysis results of a certain plateau area A, the lowest pH value of rainfall in a certain place in Lhasa and a certain place in Nyingchi from 2020 to 2021 is 6.61, and the highest value is 7.89. At the same time, considering that there is a certain amount of sulfur oxide gas in the atmosphere of a certain plateau area A, therefore, referring to ASTM D5894-05 "Standard Practice for Salt Spray / Ultraviolet (UV) Cyclic Exposure of Painted Metals", the test conditions for the salt solution spray-drying sub-test are determined as follows: use a 0.05% Na2SO4 solution, and adjust the pH value to 6-8 (neutral) with dilute sulfuric acid or NaOH solution to simulate the action of corrosion media in the atmospheric environment, and the sedimentation rate of the salt solution is controlled at 1-3 mL / (80 cm 2 ·h). Secondly, the coating exposed to the atmospheric environment will experience repeated wetting-drying processes, which will continuously increase the concentration of corrosion media on the coating surface and accelerate corrosion. According to the relative humidity statistical results of a certain place in Lhasa and a certain place in Nyingchi from 2018, 2020 to 2021, the ratio of the annual wetting time (recorded as wetting when the temperature is above 0°C and the relative humidity ≥ 80%) to the drying time is about 1:1.9 (calculated by taking the extreme value of humid air of 3048 h), so, a cycle time ratio of 1:2 is adopted for spraying / drying, that is, 8 h of spraying and 16 h of ventilation drying in every 24 h cycle to highlight the influence of wet-dry alternation on the coating. The spraying temperature is taken as 35 ± 1°C considering the ground temperature of a certain place in Lhasa and a certain place in Nyingchi and the dissolved oxygen concentration in the salt solution; referring to ASTM D5894-05 "Standard Practice for Salt Spray / Ultraviolet (UV) Cyclic Exposure of Painted Metals" and GJB 150.11A "Environmental Test Methods for Military Equipment Laboratories Part 11: Salt Spray Test", the drying temperature is determined as 35 ± 1°C, the drying humidity RH ≤ 50 ± 3%, and the test time for one cycle is 7 days.

[0068] The embodiments of the present invention can effectively simulate the actual situations of a helicopter parked on the ground in a plateau environment, such as high solar radiation during the day, low air pressure, large outdoor day-night / winter-summer temperature differences, more dust and sandstorms, night-time condensation, wet-dry alternation, and erosion by corrosive media. This solution significantly improves the effectiveness of the simulation test in a plateau environment, can more quickly and accurately evaluate the adaptability of the coating system of the helicopter connection structure in the plateau atmospheric environment, can quickly and accurately reproduce the main damage phenomena of the coating system of the helicopter connection structure in the plateau environment, is very close to the test results in the natural parking state, and one cycle of the test can simulate the situation of a helicopter connection structure parked outdoors in a plateau area for one year.

[0069] By adopting the embodiments of the present invention, the following beneficial effects are achieved:

[0070] It can stably, accurately, flexibly, and quickly obtain the key environmental factor of the amount of dust and sand endured by the coating system of the helicopter connection structure in a plateau environment, and is applicable to quickly and accurately obtaining the amount of dust and sand endured by the coating system of the helicopter connection structure of any model helicopter and at any parking site in a plateau environment.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for accelerating the simulation test of a coating system for a helicopter connection structure in a plateau atmospheric environment, characterized in that Including: S1. Obtain the environmental factor data required for the test and preset the test duration. The environmental factor data specifically includes: the conventional meteorological factors, medium environmental factors, dustfall factors, and sand dust factors of the plateau atmospheric environment. Among them, the sand dust factors are obtained through a pre-designed sand dust collector; S2. According to the environmental factor data, sequentially conduct low-temperature fatigue tests, temperature-humidity-pressure-solar radiation multi-environment factor comprehensive tests, sand dust tests, and salt solution spray-drying tests on the helicopter connection structure coating system within the preset test duration; The method further includes: after the test cycle is completed, conduct appearance, gloss, color difference, thickness, adhesion, and infrared detection on the specimen; The design steps of the pre-designed sand dust collector specifically include: Set four legs, and connect the same arc plate at the tops of the four legs. One side of the arc plate is hermetically connected to a baffle, and the included angle between the arc plate and the baffle is 70-88°. The concave area of the arc plate intersects with the bottom edge of the baffle; Among them, the four legs are conical rod structures, and each leg is composed of several detachably connected rod bodies and a cone threadedly connected to the bottom of the rod body. The rod body and the cone are detachably connected; The steps for obtaining the sand dust factors specifically include: S11. Determine the height, orientation, length, and parking ground type of the location where the helicopter connection structure coating system is located; S12. Select a rod body and a cone with appropriate lengths, and connect the cone to the bottom of the rod body of the sand dust collector; S13. When the parking ground type is a non-hardened road surface, insert each cone of the sand dust collector into the parking ground; when the parking ground type is a hardened road surface, directly place the bottom of each rod body of the sand dust collector on the hardened road surface; and ensure that the height and orientation of the root of the included angle between the arc plate and the baffle of the sand dust collector are the same as the height and orientation of the location where the lap joint gap on the helicopter connection structure is located; S14. Install multiple sand dust collectors with reference to step S13 until the total length of the combined multiple sand dust collectors is the same as the total length of the lap joint gap on the helicopter connection structure; S15. After collecting the sand dust, collect the sand dust accumulated on the arc plate for subsequent analysis and processing; The test conditions of the sand dust test are obtained by tailoring the dustfall factor data and the sand dust factor data; The sand dust test includes a dust blowing test and a sand blowing test; The conditions of the dust blowing test are as follows: the wind speed is 3 - 4 m / s, the concentration is 10.6 ± 7 g / m 3 , the diameter of the dust is 30 - 149 μm, the relative humidity RH ≤ 30%, the normal temperature is 23 ± 1 °C, the high temperature is 30 ± 1 °C, 6 hours at normal temperature + 6 hours at high temperature; The conditions for the sandblasting test are as follows: the wind speed is 3 - 4 m / s, the concentration is 2.2 ± 0.5 g / m 3 , the diameter of the dust is 150 - 650 μm, the relative humidity RH ≤ 30%, the high temperature is 30 ± 1 °C, and the duration is 1.5 h.

2. The method according to claim 1, wherein The conditions of the low-temperature fatigue test are: the waveform is a sine wave, the test frequency is 16 Hz, the stress peak value is 74.5 Mpa, the stress valley value is 4.47 Mpa, the stress ratio is 0.06, the number of fatigue load cycles is 8000 times, and the test temperature is -43±2°C.

3. The method according to claim 1 or 2, characterized in that The total time of a single cycle test for the comprehensive test of multiple environmental factors of temperature, humidity, air pressure and solar radiation is 18 days, and it is cycled according to the cycle unit of lighting cycle 8h + dark cycle 4h; among them, the radiation intensity in the lighting cycle is 1.1 W / (m 2 ·nm) at 340 nm, the light source uses UVA-340 fluorescent lamp, the temperature is a constant temperature of 60±1°C, the heating and cooling rate is 3°C / min, the relative humidity is a constant humidity of 60±5%, the low air pressure is a constant air pressure of 600±50 hPa, the temperature in the dark cycle is -43±2°C, the cooling rate is 3°C / min, the relative humidity is a constant humidity of 60±5%, and the low air pressure is a constant air pressure of 600±50 hPa.

4. The method according to claim 1, wherein The single-cycle test time of the salt solution spray-drying test is 7 days; Salt spray conditions: 0.05% sodium sulfate solution, adjusted to pH = 6 - 8 with dilute sulfuric acid or NaOH solution, and the salt solution sedimentation rate is controlled at 1 - 3 mL / (80 cm 2 .h); The cycle period is 8 h spraying + 16 h ventilation and drying; The temperature conditions are: spraying at 35 ± 1 °C, drying at 35 ± 1 °C, and the humidity RH ≤ (50 ± 3)%.

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