T/CSAE 93-2018Basic tire testing method for steady state lateral slip property (English PDF)

3.1 Wheel geometry and tire coordinate system wheel geometry and tire axis system

The following defines terms related to wheel geometry and tire coordinate system.

3.1.1

Wheel center plane wheel plane A plane equidistant from the inner edges of the two sides of the wheel rim, the normal of which is parallel to the centerline of rotation of the wheel.

[GB/T 12549-2013, definition 4.1.1] (see Figure 1) 3.1.2 Wheel center wheel center the intersection of the center plane of the wheel and the centerline of the wheel's revolution.

[GB/T 12549-2013, meaning 4.1.2] (see Figure 1) 3.1.3 Tire grounding center the intersection of the intersection of the center plane of the wheel and the road surface and the projection of the center line of the wheel on the road surface.

[GB/T 12549-2013, definition 5.1.1] (see Figure 1) 3.1.4 Tire coordinate system (X, Y, Z) tire axis system (X, Y, Z) T/CSAEXX-2018 Right-handed rectangular coordinate system with the tire grounding center as the origin. The X axis is the intersection of the center plane of the wheel and the road surface, with the center plane of the wheel the direction of travel is positive; the Z-axis is the normal to the road surface, and the upward direction is positive; the Y-axis is in the road surface, and the direction is determined according to the right-hand rule.

[GB/T 12549-2013, definition 5.1.2] (see Figure 1)

Figure 1 tire coordinate system

3.1.5

Load radius

The distance from the center of the wheel to the grounding center of the tire.

The load radius of a static tire under a vertical load is a static loaded radius.

[GB/T 12549-2013, definition 5.1.5] 3.1.6 Side angle slip angle the angle between the direction of travel of the tire grounding center and the X-axis of the tire coordinate system.

In the tire coordinate system, from the X-axis to the direction of travel of the tire grounding center, the right-hand rule is used to judge the sign of its right and negative, as shown in Figure 1.

The side angle is negative.

[GB/T 12549-2013, definition 5.1.3] (see Figure 1) 3.1.7 Inclination angle T/CSAEXX-2018 the angle between the XZ plane of the tire coordinate system and the center plane of the wheel.

In the tire coordinate system, from the XZ plane to the center plane of the wheel, determine the positive and negative signs according to the right-hand rule, the roll angle shown in Figure 1.

It is positive.

3.2 Tire rolling and slip characteristics tire rolling characteristics and tire slip

3.2.1

Free rolling tire

Rolling tires with a vertical load (see 3.3.2) but no driving torque (see 3.3.9) or braking torque (see 3.3.10). free the rolling tire can have a side angle and a roll angle, and the track of the tire ground center on the road surface can be a straight line or a curve.

3.2.2

Tire free rolling speed the product of the angular velocity of the rolling tire and the effective rolling radius of the tire (see 3.2.3).

3.2.3

Tire effective rolling radius the value obtained by dividing the distance moved by the free rolling tire from the grounding center of the tire by 2pi is called the effective rolling radius of the tire.

3.2.4

Tire travel speed tire trajectory velocity the speed at which the grounding center of the tire moves on the road surface.

Its component in the X direction of the tire coordinate system is called the tire longitudinal velocity, which is in the tire coordinate system Y direction.

The component is called the tire lateral velocity.

3.2.5

Tire longitudinal slip velocity the difference between the free rolling speed of the tire under driving or braking conditions and the longitudinal speed of the tire at this time.

3.2.6

Tire longitudinal slip ratio or the longitudinal slip ratio of the tire is the ratio of the longitudinal slip speed of the tire to the free rolling speed of the tire, expressed as.

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The longitudinal slip ratio of the tire is the ratio of the longitudinal slip speed of the tire to the longitudinal speed of the tire, expressed as.

In the formula.

- Tire longitudinal speed.

3.3 Tire force and moment tire force and moment

3.3.1

Tire normal force

The component of the force acting on the tire along the Z-axis.

3.3.2

Tire vertical load

The absolute value of the normal force of the tire.

3.3.3

Tire lateral force

The component of the force acting on the tire along the Y-axis.

3.3.4

Tire longitudinal force the component of the force acting on the tire along the X-axis.

3.3.5

Tire overturning moment the component of the moment vector acting on the tire along the X-axis.

3.3.6

Tire rolling resistance moment the component of the moment vector acting on the tire along the Y-axis.

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3.3.7

Tire aligning torque the component of the moment vector acting on the tire along the Z-axis.

3.3.8

Wheel torque wheel torque the external moment acting on the wheel rim about the axis of rotation of the wheel (see Figure 1).

Note. Rewrite GB/T 12549-2013, definition 5.3.4.

3.3.9

Driving torque

Equal to positive wheel torque.

[GB/T 12549-2013, definition 5.3.5] 3.3.10 Braking torque Equal to negative wheel torque.

[GB/T 12549-2013, definition 5.3.6]

3.4 Force and moment coefficient coefficients of force and moment

3.4.1

Tire lateral force coefficient the ratio of the lateral force of the tire to the vertical load of the tire.

3.4.2

Tire cornering stiffness the absolute value of the tire's lateral force relative to the first derivative of the side angle.

Tire cornering stiffness is typically determined at zero side yaw angle, zero roll angle, and zero tire longitudinal slip ratio.

3.4.3

Tire cornering stiffness coefficient the ratio of the tire's cornering stiffness to the vertical load of the tire.

3.4.4

Tire alignment stiffness (tire aligning torque stiffness) the absolute value of the tire's positive moment relative to the first derivative of the side angle.

The tire return stiffness is typically determined at zero side yaw angle, zero roll angle, and zero tire longitudinal slip.

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3.4.5

Tire back stiffness coefficient (tire back stiffness moment coefficient) tirealigningstiffness coefficient(tire aligning torque Stiffness coefficient ) the ratio of the tire's return stiffness to the vertical load of the tire.

3.4.6

Tire roll stiffness

The absolute value of the first derivative of the tire lateral force relative to the roll angle.

Tire roll stiffness is typically determined at zero side yaw angle, zero roll angle, and zero tire longitudinal slip ratio.

3.4.7

Tire roll stiffness coefficient tire camberstiffness coefficient the ratio of tire roll stiffness to tire vertical load.

3.4.8

Tire roll back stiffness, tire camber aligning stiffness the absolute value of the tire's positive moment relative to the first derivative of the roll angle.

The tire rollback stiffness is typically determined at zero side yaw angle, zero roll angle, and zero tire longitudinal slip ratio.

3.4.9

Tire rollback positive stiffness coefficient tire camber aligningstiffness coefficient the ratio of the tire's rollback stiffness to the tire's vertical load.

3.4.10

Tire lateral force load sensitivity the first derivative of the tire lateral force relative to the vertical load of the tire at a determined side angle.

3.5 Steady state steady state

The tire motion state and the state and the state of the tire cause the tire's force and moment to not change with time in the tire coordinate system.

3.6 Inflation pressure inflation pressure

3.6.1

Cold inflation pressure the internal pressure of the tire at ambient temperature does not include the increased air pressure due to the increase in temperature during driving.

[GB/T 6326-2014, definition 11.2.7] 3.6.2 Warm pressure T/CSAEXX-2018 the equilibrium air pressure achieved by the heat generated by the movement of the tire under certain conditions of use.

4.1 General

In order to ensure the integrity and reliability of the test, the test equipment used to carry out the test of the steady-state lateral deflection characteristics of the tire shall meet the requirements described below.

4.2 Loading and positioning system requirements

The test equipment shall be provided with a loading and positioning system and shall meet the following requirements.

a) achieving vertical loading of the tire on the test road surface, setting the tire side yaw angle and setting the tire roll angle;

b) Meet the requirements of the load and positioning system range for the test of the steady-state deflection characteristics of the tire.

4.3 Test pavement requirements

The indoor test equipment shall have a uniform, stable and reliable test pavement, and the following conditions shall be met.

a) Ensure that there is no bending, lateral offset, severe wear, cracks, or dirt on the road surface in contact with the test tire during the test.

Dyeing and surface overheating, etc. affecting the reliability of test results;

b) The test pavement shall have a certain roughness to ensure the test of the steady-state lateral deflection characteristics of the tire;

c) Ensure that the tire running speed of the test tire relative to the test road surface can meet the requirements of the tire steady-state side-off characteristic test.

The test pavement of the outdoor test equipment is a real road surface and is selected according to actual test requirements.

4.4 Sensing Measurement System Requirements

The test equipment shall have an accurate and reliable sensing measurement system and shall meet the following conditions.

a) meet the requirements of the measurement range of the sensing system for the test of the steady-state deflection characteristics of the tire;

b) Accurately measure the rotational angular velocity of the test tire, tire travel speed, load radius, tire vertical load, side yaw angle, roll angle, Tire lateral force, tire return torque and inflation pressure data.

4.5 Data Acquisition System Requirements

The test equipment shall have an accurate data acquisition system, and the sampling frequency shall satisfy a minimum of 32 points collected during the rolling of the tire.

4.6 Other requirements

The test equipment should also meet the following requirements.

a) The equipment should be regularly monitored, maintained and calibrated to ensure that the test data is stable and reliable;

b) If it is a pressure control test, the test equipment shall have a pressure control mechanism.

5.1 Ambient temperature requirements

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Set the ambient temperature according to the test requirements, and ensure that the temperature change does not affect the normal implementation of the test process.

5.2 Test preparation

It is advisable to prepare the test tires before the test, including the selection of the test tires, the cleaning of the tread oil, the storage of the test tires, Assembly and parking of tire rims, recording of necessary test information, tire dynamic balance test, tire pre-run and proper installation on test equipment Test tires, etc.

It is advisable to record the necessary test information before the test, including the following.

a) tire number;

b) Basic information about the tire, including specifications, pattern, brand, load index, speed grade, maximum pressure, origin, production time (DOT);

c) test rim type and size;

d) Inflation pressure.

5.3 Test

5.3.1 General

The steady-state lateral deflection characteristics of the tire are affected by inflation pressure, tire running speed, roll angle, tire vertical load, side yaw angle, tread wear amount, and ring.

The influence of multidimensional input variables such as ambient temperature. The test method for the steady-state lateral deflection characteristics of the tires stipulates that the requirements for the amount of tread wear are met and the test is correctly installed.

Test the test tire on the equipment and complete the test of the steady-state lateral deflection characteristic test of the tire under the conditions of other input variables determined.

5.3.2 Test procedure

5.3.2.1 The test tires that have been prepared for the test, meet the tread wear requirements and are correctly installed on the test equipment are not connected to the test road surface.

Touch state

5.3.2.2 Check and adjust the test tire inflation pressure, roll angle, and ambient temperature to achieve the required values;

5.3.2.3 Perform zero mark. record test data;

5.3.2.4 to cause the test tire to produce a predetermined direction of motion relative to the test surface and to achieve the required speed of the tire;

5.3.2.5 apply vertical load and side yaw angle to the test tire and bring it to the required value;

5.3.2.6 After the free-rolling tires to meet the above test conditions reach the steady state, record the test data and complete a test of the steady-state lateral deflection characteristics of the tire.

Test.

5.3.3 Test procedure example

The test procedure consists of multiple tests of the steady-state lateral deflection characteristics of the tire. Generally, each test is constructed using a pattern of nested loops of input variables.

The combination of input variables. A variety of test procedures can be designed by changing the position of the input variables in the nested loop. Table 1 shows the steady state side of the tire an example of a test procedure for the characteristics.

Table 1 Example of tire steady-state side-off characteristic test procedure

Cycle sequence. outside Program number input variable 1 input variable 2 input variable 3 input variable 4 input variable 5

e) select a side angle;

f) according to the input variable conditions determined in steps a) to e), complete the test of the steady-state lateral deflection characteristic of the tire according to the test procedure described in 5.3.2;

g) Select another side angle and repeat step f) until all the side angle sequences are completed;

h) Select another tire vertical load and repeat steps e) to g) until all tire vertical load sequences are completed;

i) Select another roll angle and repeat steps d) to h) until all roll angle sequences are completed;

j) Select another tire travel speed and repeat steps c) to i) until all tire travel speed sequences are completed;

k) Select another inflation pressure and repeat steps b) to j) until all inflation pressure sequences are completed;

l) Complete 1

a) tire longitudinal force ( );

b) tire tipping moment ( );

c) tire rolling resistance torque ( );

d) tire running speed (V);

e) load radius ( );

f) Tire rotation angular velocity ( ).

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Note. The data unit of each variable is metric.

6.2 Test data processing requirements

The recorded test data should be filtered, wilded out and averaged to obtain accurate tire force and moment characteristics.

The effect of tire uniformity on test data should be removed.

6.3 Indicator calculation

6.3.1 Drawing a curve

After the test data is processed, the following curve should be drawn.

a) a curve of the tire lateral force versus the side angle;

b) a curve of the relationship between the positive torque of the tire and the side angle;

c) Curve of tire lateral force load sensitivity versus tire side declination.

6.3.2 Calculation indicators

After the test data is processed, the following indicators should be calculated.

a) tire lateral stiffness;

b) tire lateral stiffness coefficient;

c) tire return stiffness;

d) the positive stiffness coefficient of the tire;

e) tire roll stiffness;

f) tire roll stiffness coefficient;

g) tire rollback stiffness;

h) tire rollback positive stiffness coefficient;

i) Tire lateral load sensitivity.