GB/T 9747-2026Test methods for aircraft tyres (English PDF)

4.3 Test Conditions

4.3.1 Test Load Unless otherwise specified, the test load of the tire shall be greater than or equal to the rated load of the tire in GB/T 9746.

4.3.2 Test inflation internal pressure The test inflation pressure should be such that the load radius of the tire on the test flywheel is the same as that of the tire under rated load and rated inflation pressure. The internal pressure during inflation when the load radii on the plate are equal. Both measurements should be performed at the same ambient temperature. The test inflation should not be adjusted. Internal pressure is used to compensate for changes in inflation internal pressure caused by temperature variations during the test.

4.3.3 Correction for test inflation pressure To compensate for the influence of the flywheel curvature of the testing machine, the tire inflation pressure should be corrected. The correction method is as follows:

a) At the same temperature, apply the rated load to the tire, such that its static load radius on the flywheel of the testing machine is the same as its static load radius on the flat plate. Equal radii;

b) Unless otherwise specified, the tire inflation pressure shall be corrected according to the relationship diagram in Figure 1;

c) The test inflation pressure should not be adjusted to compensate for changes in inflation pressure caused by temperature variations during the test.

4.3.4 Tire cooling after the test After each test, the tires should be cooled to the specified temperature before the next test.

4.4 Test Methods

4.4.1 Number of trials The tires should complete 50 takeoffs, 8 taxiings, 2 taxiings at

1.2 times the rated load, and 1 takeoff at

1.5 times the rated load. test.

4.4.2 Test Temperature The temperature of the gas inside the tire cavity or the temperature of the hottest point of the tire body shall meet the following requirements.

a) The temperature at the start of the overload takeoff test and at least 45 of the 50 takeoff tests should not be lower than 41°C;

b) In at least 9 out of 10 taxiing tests, the temperature should not be lower than 49°C at the start of the test;

c) For the remaining test cycles, the gas temperature inside the tire cavity or the tire body temperature should not be lower than 27°C at the start of the test. This can be used in... The method of rolling a tire on a test flywheel to reach the initial temperature.

4.4.3 Test Speed Table 1 shows the dynamic performance test speeds corresponding to the maximum takeoff speed. If the takeoff speed exceeds 394 km/h, the test speed should be set according to the most stringent tire requirements. Test the load-speed-time requirements of the instrument and determine the appropriate rated speed accordingly.

4.4.4 Test Procedure

4.4.4.1 Takeoff Test Unless otherwise specified, the load, speed and distance curves of the tires during takeoff tests shall conform to the provisions of Figure 2, Figure 3 or Figure 4. in.

a) Figure 2 applies to tires with rated speeds of 193 km/h and 257 km/h;

b) Figure 3 applies to tires with a rated speed greater than 257 km/h;

c) Figure 4 applies to tires with other rated speeds. Unless otherwise specified, the test load should be selected based on the tire's most demanding takeoff conditions. Load, speed, and distance.

4.4.4.2 Overload Takeoff Test Except for increasing the test load to

1.5 times the rated load, the provisions are the same as those for the takeoff test (4.4.4.1).

4.4.4.3 Coasting Test The tires should undergo 10 skidding tests under the test conditions specified in Table 2.

4.4.5 Measurement of Tire Inflation Pressure The measurement of tire inflation pressure should meet the following requirements.

a) Unless otherwise specified, the tire inflation pressure shall be measured after every 5 tests. After the first 5 tests, the temperature of the gas inside the tire cavity shall be measured. Measure the internal inflation pressure by cooling the tire to the temperature at which the hottest point of the tire carcass cools down to the corrected pressure. After measurement, if the tire internal pressure is found to be lower than the corrected pressure... Air pressure, replenish air.

b) After the 10th test, measure the pressure every 10 tests. If the tire pressure is found to be lower than the specified value after measurement, inflate the tire. High tire pressure... The pressure correction is attributed to increased temperature, and this increase in internal pressure is not adjusted.

c) After completing 61 dynamic performance tests and parking the tires for 24 hours, measure the internal inflation pressure. The rate of decrease in internal inflation pressure should not exceed the rate at which the test began. 10% of the internal pressure during inflation.

4.5 Alternative Testing

4.5.1 Test Principles For low-speed tires with a rated speed of 193 km/h or less, the variable mass flywheel program can be used instead of the dynamic test program.

4.5.2 Test Requirements The kinetic energy that the tire should absorb during the test is provided by the speed decay of a certain mass flywheel. Kinetic energy. If the calculated kinetic energy cannot be obtained using the actual number of flywheel blades, the number of flywheel blades can be appropriately increased, and the testing machine speed adjusted accordingly. To obtain the required kinetic energy.

4.5.3 Number of Tests The tires should be able to pass.200 landing tests on a testing machine, namely 100 low-speed landing tests and 100 high-speed landing tests.

4.5.4 Test Temperature In.200 landing tests, at least 180 of them had the following temperature at the start of the test. the gas temperature inside the tire cavity or the temperature of the hottest spot on the tire body was not... The initial temperature should be below 41°C; for the remaining 20 tests, the temperature should not be below 27°C at the start of the test. Rolling tires on the test flywheel is permitted. Reach the minimum starting temperature.

4.5.5 Kinetic Energy The kinetic energy (EK) absorbed by the tire from the flywheel during the test should be calculated according to formula (1).

4.5.6 Test Procedure

4.5.6.1 Low-speed landing test The tires should pass 100 low-speed landing tests, meaning the maximum landing speed of the tires is 145 km/h, and the minimum speed of the flywheel upon landing is... The speed is 0 km/h. Adjust the flywheel speed upon landing so that the tires can absorb 56% of EK calculated according to formula (1), but the adjusted landing speed should be The landing speed should be no less than 129 km/h. If the adjusted landing speed is less than 129 km/h, the following actions should be taken.

a) Determine tire landing by adding 28% of EK to the flywheel kinetic energy (E) at a speed of 103 km/h (i.e., E + 28%EK). speed;

b) Determine the tire's landing completion by subtracting 28% of EK from the flywheel kinetic energy (E) at a speed of 103 km/h (i.e., E - 28%EK). speed.

4.5.6.2 High-speed landing test The tires should pass 100 high-speed landing tests, meaning the minimum landing speed of the tires is 193 km/h, and the minimum speed of the flywheel upon landing is... The speed is 145 km/h. Adjust the speed of the flywheel when landing so that the tire can absorb 44% of EK calculated by formula (1).

4.5.7 Measurement of Tire Inflation Pressure Unless otherwise specified, tire inflation pressure should be measured after every 5 tests. After the 10th test, it should be measured every 10 tests. After 50 tests, measurements should be taken every 50 tests. If the tire pressure is found to be lower than the specified value after measurement, it should be inflated. If the tire pressure is higher than the specified value... The value can be attributed to the increase in temperature, and this increase in internal pressure should not be adjusted.

4.6 Test Report The test report should include the following.

a) Tire specifications, ply rating, production serial number, manufacturer's name or trademark;

b) Test items and test conditions;

c) Original test records (speed, load, time, distance, tire temperature before the test, internal inflation pressure, and tire damage condition, test...) (Indoor ambient temperature and relative humidity, etc.)

d) This document number;

e) Experimental conclusions;

f) Test date, tester, and reviewer.

5.4 Test Procedure

5.4.1 Mount the tire on the test rim and place it inside the safety cover. Connect the tire to the high-pressure water pump using a high-pressure hose.

5.4.2 After the inspection confirms that the requirements are met, start the high-pressure water pump and fill the tire with water at a rate of no more than 300 kPa per minute.

5.4.3 When the test pressure reaches not less than 4 times the rated inflation pressure of the tire, hold for 3 seconds.

5.4.4 If the tire does not burst during this period, release the water and depressurize. If the tire bursts during inflation or pressure maintenance, record the burst. The burst pressure value, burst location, ambient temperature of the test, and other issues that need to be explained.

5.4.5 If it is necessary to measure the actual burst pressure of the tire, continue filling with water until the tire bursts.

5.5 Safety Requirements During the test, the test tire and rim assembly should be placed inside a safety enclosure, and all personnel should maintain a safe distance from the test site.

5.6 Test Report The test report should include the following.

a) Tire specifications, ply rating, production serial number, manufacturer's name or trademark;

b) The tire's rated internal pressure;

c) Ambient temperature and relative humidity during the test;

d) This document number;

e) Measurement results and experimental conclusions;

f) Test date, tester, and reviewer.

6.2 Test Equipment

6.2.1 The testing machine shall meet the range requirements and have an automatic recording device.

6.2.2 The radial loading of the testing machine and the angle between the testing machine's simulation platform and the actual load are 90°, with a deviation of less than or equal to ±1°.

6.2.3 The radial force loading device of the testing machine can make the radial load accurate to ±1.0% of the full scale.

6.2.4 The pressure gauge has a scale division of 10 kPa.

6.3 Sample The test tires should meet the following requirements.

a) The tire surface quality conforms to the requirements of GB/T 13652;

b) The test tires were left to stand at ambient temperature for more than 24 hours after vulcanization;

c) After inflating the tires to the rated internal pressure, leave them at the test site for at least 12 hours under ambient temperature; before measurement, check the tires after they have been left at the test site. If the internal pressure drops during air pressure measurement, air pressure should be added until the specified internal pressure is reached before the test can proceed.

d) For radial tires, the static load radius was measured after 50 takeoff tests, and the radius was determined to be

1.5 times the rated internal pressure. Load-sinking curve under load.

6.4 Test Conditions

6.4.1 Test Temperature Static load performance tests should be conducted at ambient temperature.

6.4.2 Test compression speed The test compression speed shall meet the following specified values.

a) Tires with an outer diameter less than or equal to 762 mm and a compression speed less than or equal to

b) For tires with an outer diameter greater than 762 mm, the compression speed is less than or equal to

6.4.3 Inflation internal pressure Each test tire can undergo eight different internal pressure tests, resulting in eight corresponding load-deformation curves. The eight different internal pressures are... Don't be.

a) Zero pressure; b)

0.55 times the rated internal inflation pressure; c)

0.70 times the rated internal inflation pressure; d)

0.85 times the rated internal inflation pressure;

e) Rated internal inflation pressure; f)

1.15 times the rated internal inflation pressure; g)

1.30 times the rated internal inflation pressure; h)

1.60 times the rated inflation pressure. Unless otherwise specified, one or more internal pressures should be selected for testing as needed. During testing, the internal pressure is generally increased from low to high.

6.5 Test Procedure

6.5.1 After inflating and parking the tires as specified in 6.3, install them onto the support of the testing machine. The tires should be located at the center of the support of the testing machine.

6.5.2 Pre-compress the test tire. Pre-compression is performed at two points 180° apart circumferentially. Compression is applied once at each point. The compression deflection should reach 50% of the tire section height.

6.5.3 Measure the tire's outer diameter, section width, load radius, and sag.

a) For radial tires, the static load radius should be measured only after 50 takeoff tests have been completed;

b) After pre-compression, check the tire inflation pressure and adjust it to the rated value, then let it sit for 20 minutes;

c) After parking for 20 minutes, measure the outer diameter and section width of the tire according to GB/T 521;

d) Adjust the platform position so that the zero point is when the tire just touches the test platform. Measure the distance between the tire axle and the zero point position of the test tire. The vertical distance d between the center point and the tire contact surface;

e) Start the testing machine and apply a load to the test tire at the specified compression speed. Stop when the rated load is reached; measure the tire pressure at this point. The vertical distance R between the center point of the tire axle and the tire contact surface is the normal load radius of the test tire, and (dR) is the distance between the center point of the tire axle and the contact surface of the tire. The value represents the amount of sinking of the test tire under rated conditions.

6.5.4 Measuring the contact patch of the test tire. Lay a pressure blanket or two overlapping sheets of carbon paper and white paper on the test platform to... Measure the contact patch of the test tire. Measuring the contact patch generally involves applying a load to the rated value, but can also be done up to full compression if necessary. The load was applied until it reached its maximum. The final load application time remained constant at 1 minute. This test can be conducted simultaneously with 6.5.3.

6.5.5 Plot the load-deformation curve.

a) After adjusting the test tire to the required internal pressure as specified in 6.4.3, place it for at least 20 minutes;

b) Adjust the test tire to the zero position, start the testing machine, and apply load to the tire at the specified compression rate until full compression is achieved. Then, unload the load, adjust the internal pressure according to the requirements of 6.4.3, and stop for 20 minutes before conducting the next test.

6.6 Calculation of Experimental Results

6.6.1 The tire's sinkage rate (f) under rated conditions is calculated using formula (2).

6.6.2 The area of the tire imprint is calculated by a planimeter or computer.

6.7 Test Report The test report should include the following.

a) Tire specifications, ply rating, production serial number, manufacturer's name or trademark;

b) Tire rated load and rated inflation pressure, as well as the other 7 test inflation pressures used when plotting deformation curves;

c) Ambient temperature and relative humidity during the test;

d) This document number;

e) Test results include. static load radius, settlement rate, imprint diagram, and load-deformation curve;

f) Test date, tester, and reviewer.

8.2 Test Equipment

8.2.1 Tire pressure gauge. Scale division value is 10 kPa.

8.2.2 Metal measuring tape (without curvature). graduation value is 1mm.

8.2.3 Vernier calipers. graduation value is 0.1mm.

8.3 Sample

8.3.1 Tires undergoing outer dimension measurement should be left to stand for at least 24 hours after vulcanization. Before inflation, they should be left to stand at room temperature for at least 3 hours. If... If necessary, clean the tire surface at the measurement location before measurement, and trim any venting rubber residue and mold seam rubber edges.

8.3.2 For radial tires, the outer edge dimension measurement test should be carried out only after 50 takeoff tests have been completed. 8...