JP2020085843A - Method for evaluating friction - Google Patents

Abstract

To clarify a magnitude of an adhesion component and a hysteresis component of friction force.SOLUTION: A method for evaluating friction includes the steps of: creating a first simulated road surface made of resin that reproduces irregularities of an actual road surface; preparing a second simulated road surface by removing micro irregularities from the first simulated road surface; examining temperature dependency of adhesive force between a rubber member and a resin surface; determining a temperature dependency coefficient of an adhesion component of frictional force between the rubber member and the resin surface based on results of an adhesive friction test; measuring friction force of the rubber member relative to each of a real road surface, the first simulated road surface, and the second simulated road surface at reference temperature, and measuring friction force of the rubber member relative to the second simulated road surface at temperature other than the reference temperature; and obtaining an adhesion component and a hysteresis component of the friction force using measured friction force and the temperature dependency coefficient.SELECTED DRAWING: Figure 1

Description

The present invention relates to a friction evaluation method.

It is known that the frictional force generated between a rubber member (for example, a tread portion of a pneumatic tire) and a friction surface (for example, a road surface) is composed of an adhesion component and a hysteresis component. In recent years, it has been required to clarify the magnitude of the adhesion component and the magnitude of the hysteresis component in the frictional force. If the size of the cohesive component and the size of the hysteresis component can be clarified, it is possible to know how much the cohesive component or the hysteresis component has changed when the type of rubber of the rubber member has changed. Can be used for designing.

In order to meet this demand, as described in Patent Document 1, a friction coefficient when a rubber material is rubbed on a friction surface on which water containing a surfactant (water containing a surfactant) is sprayed is measured. A first step, a second step of measuring a friction coefficient when a rubber material is rubbed on a friction surface on which water containing no surfactant (water containing no surfactant) is sprayed, and a first step A friction evaluation method has been proposed, which includes a third step of calculating a difference between the friction coefficient measured in (1) and the friction coefficient measured in the second step.

According to this method, the friction coefficient caused by the hysteresis friction is measured in the first step, and the friction coefficients caused by the adhesive friction and the hysteresis friction are measured in the second step. Therefore, the adhesive friction component is calculated in the third step. It is supposed to be done.

Further, Non-Patent Document 1 also describes a method based on the same idea as Patent Document 1. Specifically, we try to remove the cohesive component of the frictional force by wetting the metal mesh, which is the friction surface, with silicone oil.

JP, 2016-200563, A

Naoya Amino et al., "Study on friction mechanism of silica-blended and carbon-blended SBR", Journal of Japan Rubber Association, Vol. 77, No. 5 (2004), pp. 173-179.

However, actually, even if the friction surface is wetted with water containing a surfactant or the like, the cohesive component of the frictional force cannot be completely removed. Therefore, it was not possible to clarify the size of the adhesion component and the size of the hysteresis component by the above-mentioned conventional technique.

Therefore, in the embodiment, it is an object to clarify the size of the adhesion component and the size of the hysteresis component of the frictional force.

The friction evaluation method of the embodiment, in the friction evaluation method for obtaining the adhesion component and the hysteresis component in the frictional force between the rubber member and the friction surface, the resin-made first surface unevenness as the friction surface is reproduced. 1 step of creating a simulated road surface, step of creating a second simulated road surface in which micro irregularities are removed from the first simulated road surface, and temperature dependence of the adhesive force between the rubber member and the resin surface Based on the step of conducting a test for examining the property and the result of the test, as a temperature dependent coefficient of the adhesion component of the frictional force between the rubber member and the resin surface, with respect to the coefficient 1 at the reference temperature T _base . Another step of obtaining each coefficient a _i at a temperature T _i of 1 or 2 or more, a frictional force F1 between the rubber member and the actual road surface at the reference temperature T _base , the rubber member and the first Friction force F2 at the reference temperature T _base between the first simulated road surface, friction force F3 _base at the reference temperature T _base between the rubber member and the second simulated road surface, the rubber member and the Measuring the respective frictional forces F3 _i at one or more temperatures T _i with the second simulated road surface;
F1=F1 _adh +F1 _his ... (Equation 1)
F2=F2 _adh +F2 _his ... (Equation 2)
F3 _base =F3 _adh +F3 _his ... (Equation 3)
F3 _i =a _i ×F3 _adh +F3 _his ... (Equation 4)
(F1 _adh in Formula 1, F2 _adh in Formula 2, F3 _adh in Formula 3, and a _i ×F3 _adh in Formula 4 are adhesion components at each frictional force, F1 _his in Formula 1, F2 _his in Formula 2, and Formula 3 hysteresis component in _{F3 his-each} frictional force in _{F3 his-and} formula 4 in)
And regarded, a step of determining the _{F3 adh} and _{F3 his-from} equations 3 and 4 _which, regarded as F3 adh _{= F2 adh,} a step of determining the _{F2 his-calculates} the _{F2-F3 adh} based on equation _{2, F2 his-} =F1 _his, and calculating F1-F2 _his based on Equation 1 to obtain F1 _adh .

According to the above means, it is possible to clarify the size of the adhesion component and the size of the hysteresis component of the frictional force.

The flowchart of the friction evaluation method of embodiment. The flowchart which confirms that the suitable 2nd simulated road surface was created. The figure which shows the outline of an adhesive force test. The figure which shows the example of the measurement result of an adhesive force test. The figure which shows the adhesion component and the hysteresis component by the difference of the road surface.

Embodiments will be described with reference to the drawings. The embodiments described below are merely examples, and those appropriately modified without departing from the gist of the present invention are included in the scope of the present invention.

<Overall process>
As shown in FIG. 1, in the friction evaluation method of the embodiment, a first simulated road surface creating step (S1) of creating a resin first simulated road surface that reproduces the unevenness of an actual road surface, and macro unevenness and micro unevenness. The second simulated road surface creating step (S2) of removing the micro unevenness from the first simulated road surface having the step S2 and the temperature dependence of the adhesive force between the rubber member and the resin surface. Adhesion test step (S3) of conducting a test to be examined, and temperature dependence coefficient determination step of determining the temperature dependence coefficient of the cohesive component of the frictional force between the rubber member and the resin surface based on the result of the adhesion test ( S4) and the frictional force of the rubber member on each of the actual road surface, the first simulated road surface and the second simulated road surface is measured at the reference temperature, and the frictional force of the rubber member on the second simulated road surface is measured at a temperature other than the reference temperature. The frictional force measurement step (S5) and the calculation step (S6) of obtaining the adhesion component and the hysteresis component of the frictional force by using the measured frictional force and the temperature-dependent coefficient.

<First simulated road surface creation process>
In the first simulated road surface creating step, a resin-made first simulated road surface that reproduces the unevenness of the actual road surface made of asphalt or the like is created. As a specific example of the forming method, the unevenness of the actual road surface is molded with silicon rubber, a resin is poured into the mold of the silicon rubber, and the resin is cured to form a first simulated road surface. The resin used is, for example, a two-component mixed type resin, and a more specific example is a two-component mixed type urethane resin.

Here, the reason why the first simulated road surface, and thus the second simulated road surface, which will be described later, is made of resin is that the adhesive force between the rubber and the resin greatly changes depending on the temperature. This is because the adhesion component of the frictional force between the member and the second simulated road surface made of resin changes greatly depending on the temperature. As will be described later, this temperature dependence is used in this embodiment. That is, when the frictional force is measured while changing the temperature on the same resinous surface, the frictional force changes depending on the temperature, and it can be considered that the change in the frictional force is due to the temperature change of the adhesion component. From this, the adhesion component and the hysteresis component of the frictional force can be obtained. The temperature dependence of the adhesive force between the actual road surface made of asphalt or the like and the rubber is small.

It is preferable that the first simulated road surface reproduce the surface roughness of the actual road surface in the order of 1 μm when the surface roughness is measured by a needle contact type surface roughness meter. In addition, the first simulated road surface needs to have a hardness that does not cause visible deformation when the rubber member is pressed. Specifically, the durometer type D hardness of the first simulated road surface is preferably 80 or more and 84 or less. The elastic modulus of the resin forming the first simulated road surface is preferably 10 times or more the elastic modulus of the rubber forming the rubber member. The tensile strength of the resin forming the first simulated road surface measured by the method of JIS K 7113 is, for example, 55 MPa or more and 65 MPa or less.

<Second simulated road surface creation process>
In the second simulated road surface creating step, the surface of the first simulated road surface is polished to remove the micro unevenness from the first simulated road surface having the macro unevenness and the micro unevenness, and the second simulated road surface is obtained. .. A fine polishing cloth is used for polishing.

Here, the actual road surface is formed by embedding aggregates such as pebbles in a base material such as asphalt. The macroscopic unevenness is a large unevenness based on the rough shape of the aggregate. Further, the microscopic unevenness is a small unevenness based on the fine unevenness on the surface of the base material or the fine unevenness on the surface of the aggregate. It is known that the microscopic unevenness works on the hysteresis component of the frictional force, and by removing the microscopic unevenness from the first simulated road surface, the hysteresis component of the frictional force decreases on the second simulated road surface.

<How to confirm that the second simulated road surface is proper>
It is confirmed by the method shown in FIG. 2 that the proper second simulated road surface is created. First, as described above, the micro unevenness is removed from the first simulated road surface to create the second simulated road surface (S2-1).

Next, the surface roughness of each of the first simulated road surface and the second simulated road surface is measured by a surface roughness meter (S2-2). The measured surface roughness data is loaded into the frequency analysis device and subjected to frequency analysis (S2-3).

Here, of the waves obtained by frequency-analyzing the surface roughness data of the road surface, a wave having a predetermined wavelength within a range of 0.1 mm or more and 1.0 mm or less is used as a reference, and a wavelength of a wavelength larger than the wavelength of the reference wave is used. It is considered that the waves are due to macro unevenness, and the waves having a wavelength smaller than the wavelength of the reference wave are due to micro unevenness. Based on this idea, the frequency of the wave of a predetermined wavelength within the range of 0.1 mm or more and 1.0 mm or less among the waves obtained by frequency-analyzing the surface roughness data of the road surface is set as the cutoff frequency. A filter that attenuates components having a frequency lower than the cutoff frequency and attenuates components having a frequency higher than the cutoff frequency is set as a low-pass filter (S2-4). In addition, a filter that attenuates components having a frequency lower than the cutoff frequency while hardly attenuating components having a frequency higher than the cutoff frequency is set as the high-pass filter (S2-4).

Next, a low-pass filter is applied to the frequency analysis result of the surface roughness of the first simulated road surface, and a wave having a large wavelength is acquired. The waveform obtained by synthesizing the waves thus obtained can be regarded as reproducing the macro unevenness of the first simulated road surface. Therefore, the surface roughness (for example, the arithmetic mean roughness) is calculated from the above-mentioned synthesized waveform (S2-5). The calculation result can be regarded as the surface roughness (macro surface roughness) based on the macro unevenness of the first simulated road surface. Similarly, a waveform is synthesized from a wave obtained by applying a low pass filter to the frequency analysis result of the surface roughness of the second simulated road surface, and the surface roughness (for example, arithmetic mean roughness) is obtained from the synthesized waveform. Is calculated (S2-5).

Next, the surface roughness (that is, macro surface roughness) of a waveform formed by applying a low-pass filter to the frequency analysis result of the surface roughness of the first simulated road surface and the surface of the second simulated road surface. The frequency analysis result of the roughness is compared with the surface roughness (that is, macroscopic surface roughness) of the waveform formed of the waves obtained by low-pass filtering. When the difference between the two is 5% or less, that is, when the difference between the two is 5% or less of either value (YES in S2-6), the macro unevenness on the first simulated road surface and the second simulated road surface. Is determined to be almost unchanged, and the macro unevenness of the second simulated road surface is determined to be appropriate.

Next, a high-pass filter is applied to the frequency analysis result of the surface roughness of the second simulated road surface, and a wave with a small wavelength is acquired. The waveform obtained by synthesizing the waves acquired in this way can be regarded as reproducing the microscopic unevenness of the second simulated road surface. Therefore, the surface roughness (for example, the arithmetic mean roughness) is calculated from the above-mentioned synthesized waveform (S2-7). The calculation result can be regarded as the surface roughness (micro surface roughness) based on the micro unevenness of the second simulated road surface. When this surface roughness (for example, arithmetic mean roughness) is 10 μm or less (YES in S2-8), it is determined that the second simulated road surface has microscopic unevenness, and the second simulated road surface is microscopic. The unevenness is judged to be appropriate.

When it is determined that the macro unevenness or the micro unevenness of the second simulated road surface is not appropriate (NO in S2-6, NO in S2-8), the second simulated road surface is created so that each unevenness is appropriate. It is fixed (S2-1).

The steps from S2-3 to S2-8 are executed by the frequency analyzer or a computer connected thereto. The order of the steps S2-5 to S2-6 and the steps S2-7 to S2-8 may be interchanged.

<Adhesion test process>
On the other hand, a test is conducted to examine the temperature dependence of the adhesive force between the rubber member and the resin-made adhesive force test surface. As shown in FIG. 3, in this test, the rubber member 1 is pressed against the resin adhesive strength test surface 2 with a predetermined load and then separated, and the force (N) required for the separation is measured. Known devices can be used for this measurement.

As the rubber member 1 in this test, a rubber member to be finally evaluated for friction is used. The adhesive strength test surface 2 is formed of the same resin as the resin forming the first simulated road surface and the second simulated road surface. The reason is that if the resin is the same, the temperature dependence of the adhesive force (and the adhesive component of the frictional force) between the rubber member and the resin surface is the same, so the adhesive strength test results (that is, the adhesive strength test surface) This is because the temperature dependence of the adhesive force in 2) can be used for the temperature dependence of the adhesion component of the frictional force on the second simulated road surface. The adhesive strength test surface 2 is preferably the second simulated road surface itself, but may be the first simulated road surface, or may be a resin-made road surface prepared separately from the first simulated road surface and the second simulated road surface. good.

As the test temperature for investigating the temperature dependence of the adhesive strength, it is necessary to select a temperature of 2 points or more, and it is more preferable to select a temperature of 3 points or more. The temperature selected in that case is, for example, normal temperature (for example, 20 to 25° C.), and a low temperature (for example, 0 to 10° C.) at which the cohesive component of the frictional force is expected to be approximately twice that at normal temperature A high temperature (for example, 35 to 40° C.) at which the cohesive component of the frictional force is expected to be about ½ of the normal temperature is included. Then, the above measurement is performed at each temperature. The measurement is performed in a state where the rubber member 1 and the adhesive strength test surface 2 have reached the test temperature. In the present embodiment, the test is performed at three points, that is, room temperature, low temperature, and high temperature.

Since the adhesive force between the rubber member and the resin surface greatly changes depending on the temperature, as an adhesive force test result, a measurement result that greatly differs depending on the temperature can be obtained. An example of the measurement result is shown as a bar graph in FIG.

<Temperature dependence coefficient determination process>
Next, the temperature-dependent coefficient of the cohesive component of the frictional force between the rubber member and the resin surface is determined based on the result of the adhesive strength test.

Specifically, first, as a temperature-dependent coefficient of the adhesive force between the rubber member and the adhesive force test surface, each coefficient a _{i at} another temperature T _{i with} respect to the coefficient 1 at a certain reference temperature T _base is obtained.

As an example of how to obtain it, linear regression by the method of least squares or the like is performed on the data of the adhesive force for each temperature to approximate the change of the adhesive force with respect to the temperature change (in the case of FIG. 4, the bar graph A function (approximating the vertices of a plurality of bars) is obtained (an example of the function is shown by a straight line in FIG. 4). Then, based on the obtained function, the ratio of the adhesive force at another temperature T _i when the adhesive force at a certain reference temperature T _base is set to 1 is determined as the coefficient a _{i at the} temperature T _i . For example, the adhesive force at the reference temperature T _base that is room temperature is 26.0 N, the adhesive force at the low temperature T ₁ (that is, i=1) is 48.4 N, and the adhesive force at the high temperature T ₂ (that is, i=2). If the adhesive strength is 8.8 N, the coefficient _{a 1} is 48.4 / 26.0 = 1.86 at a temperature _{T 1,} the coefficient _{a 2} in temperature _{T 2} is a 8.8 / 26.0 = 0.34 .

Here, as the reference temperature T _base and the other temperature T _i , the temperature at the time of measuring the frictional force described later is selected. In the present embodiment, it is assumed that the frictional force measurement described below is performed at the above-mentioned three points of normal temperature, low temperature and high temperature, normal temperature is selected as the reference temperature T _base , and low temperature T ₁ and high temperature T _{2 are set} as different temperatures T _i. Shall be selected.

Here, the force referred to as the adhesive force in the present embodiment is the force required to separate the rubber member pressed against the resin road surface as described above, and is the coagulation of the frictional force when the rubber member slides on the road surface. The size is different from the wearing component. However, regarding the temperature dependence, it can be considered that the adhesive force and the adhesive component are the same. Therefore, the temperature dependence coefficient of the adhesive force between the rubber member and the adhesion test surface obtained as described above is the same as the temperature dependence of the cohesive component of the frictional force between the rubber member and the adhesion test surface. It is a coefficient.

Further, the temperature dependence coefficient of the adhesive force (or the adhesive component of the frictional force) on the adhesive force test surface can be used as it is for the entire surface formed of the same resin as the adhesive force test surface. The resin forming the adhesion test surface and the resin forming the second simulated road surface are the same. Therefore, the temperature dependence coefficient of the adhesion component of the frictional force between the rubber member and the adhesion test surface is the same as the temperature dependence coefficient of the adhesion component of the frictional force between the rubber member and the second simulated road surface. Can be considered to be.

As described above, the temperature dependence coefficient of the adhesion component of the frictional force between the rubber member and the resin surface (specifically, the adhesive strength test surface or the second simulated road surface) is determined.

The cohesive component of the frictional force at each temperature is determined by using the temperature dependence coefficient. That is, if the adhesion component of the frictional force at the reference temperature T _base is F3 _adh , the adhesion component of the frictional force at another temperature T _i is obtained as a _i ×F3 _adh .

<Friction force measurement process>
Next, the frictional force F1 between the rubber member and the actual road surface at the reference temperature T _base , the frictional force F2 between the rubber member and the first simulated road surface at the reference temperature T _base , and the rubber member and the second reference temperature T and the frictional force F3 _base at _base, a rubber member and the temperature T _{i (i} is one or more) each of the frictional force F3 _i in between the second simulated road surface between the simulated road surface And are measured.

Here, in the present embodiment, the low temperature T ₁ and the high temperature T ₂ are selected as the temperature T _i as described above. Accordingly, in the present embodiment, as a friction force between the rubber member and the second simulated road surface, a frictional force F3 _base at a reference temperature T _base, and the frictional force F3 ₁ at low temperature T _1, at a high temperature T ₂ a frictional force F3 ₂ is measured.

A known friction force measuring device can be used for the measurement. The measurement is performed in a state where the rubber member and each road surface reach their respective temperatures.

The measured frictional force shall consist of an adhesion component and a hysteresis component. That is,
F1=F1 _adh +F1 _his ... (Equation 1)
F2=F2 _adh +F2 _his ... (Equation 2)
F3 _base =F3 _adh +F3 _his ... (Equation 3)
F3 _i =a _i ×F3 _adh +F3 _his ... (Equation 4)
(F1 _adh in Formula 1, F2 _adh in Formula 2, F3 _adh in Formula 3, and a _i ×F3 _adh in Formula 4 are adhesion components at each frictional force, F1 _his in Formula 1, F2 _his in Formula 2, and Formula 3 hysteresis component in _{F3 his-each} frictional force in _{F3 his-and} formula 4 in)
Shall hold.

As shown here, since the measurement temperature of the frictional force is different between the formula 3 and the formula 4, the adhesion component of the frictional force is different. Specifically, the adhesion component of the frictional force at the reference temperature T _base is F3 _adh (see Formula 3), and the adhesion component of the frictional force at another temperature T _i is a _i ×F3 _adh (Formula 3) 4)). a _i is a coefficient determined in the above temperature-dependent coefficient determination step.

On the other hand, assuming that the unevenness of the road surface is the same even if the temperature at which the frictional force is measured is different, the hysteresis components are almost the same, assuming that the hysteresis components are the same.

Strictly speaking, it is considered that the hysteresis component is slightly different when the frictional force measurement temperature is different. However, since the micro unevenness is removed from the second simulated road surface, the hysteresis component of the frictional force on the second simulated road surface is small (see FIG. 5). Therefore, the magnitude of the hysteresis component of the frictional force on the second simulated road surface and its change amount are much smaller than the magnitude of the adhesion component and its change amount. Therefore, regarding the frictional force on the second simulated road surface, the difference in hysteresis component due to the difference in measured temperature can be ignored. In that respect, since the first simulated road surface has micro unevenness and a large hysteresis component (see FIG. 5), the difference in the hysteresis component due to the difference in the measured temperature cannot be ignored on the first simulated road surface.

As described above, in the present embodiment, the frictional force between the rubber member and the second simulated road surface is measured at the low temperature T ₁ and the high temperature T ₂ in addition to the reference temperature T _base. Therefore, the equation 4 is F3 ₁ =a ₁ ×F3 _adh +F3 _his ... (Equation 4-1)
F3 ₂ =a ₂ ×F3 _adh +F3 _his ... (Equation 4-2)
It consists of two expressions.

<Calculation process>
Based on the above equations 1 to 4, the adhesion component F1 _adh and the hysteresis component F1 _his of the frictional force between the rubber member and the actual road surface are calculated. This calculation is performed by a computer, for example. The following is assumed as the premise of the calculation.

As shown in Table 1, the actual road surface and the first simulated road surface are made of different materials and have the same surface roughness. Since the first simulated road surface is made of resin while the actual road surface is made of asphalt, assuming that the adhesion component of the friction force on the actual road surface is the reference value, the adhesion component of the friction force on the first simulated road surface is the reference value. Greater than On the other hand, since it can be said that the actual road surface and the first simulated road surface have the same unevenness, it can be assumed that the hysteresis components of the frictional force are the same.

Further, as shown in Table 1, the first simulated road surface and the second simulated road surface are made of the same material but different in surface roughness. Since the first simulated road surface and the second simulated road surface are made of the same resin, it can be assumed that the adhesion components of the frictional force on these road surfaces are the same. On the other hand, since the surface roughness of the first simulated road surface includes micro roughness, the surface roughness of the second simulated road surface does not include micro roughness, so that the friction force on the second simulated road surface is included. It can be assumed that the hysteresis component of is smaller than the hysteresis component of the frictional force on the actual road surface or the first simulated road surface.

The above assumption is illustrated in FIG. In the bar graph of FIG. 5, the grid-shaped portion represents the adhesion component, and the dot-shaped portion represents the hysteresis component. From the above, in Expressions 1 to 4, it can be considered that F3 _adh =F2 _adh and F2 _his =F1 _his . Utilizing this fact, the adhesion component F1 _adh and the hysteresis component F1 _his of the frictional force between the rubber member and the actual road surface can be obtained.

First, F3 _adh and F3 _his are obtained from the equations 3 and 4. As an example of a specific method for obtaining F3 _adh and F3 _his , all combinations of two formulas are extracted from formula 3 and a plurality of formulas 4 that are satisfied for each temperature, and provisional combinations are obtained from the respective combinations. F3 _adh and provisional F3 _his are obtained, and the median value of the plurality of provisional F3 _adh obtained and the value of F3 _his when the F3 _adh is the median value are the final F3 _adh And F3 _his .

As a specific example, in the present embodiment, there are Formula 3, Formula 4-1 and Formula 4-2 as the formula of the frictional force on the second simulated road surface. From these three expressions, three combinations of two expressions can be made. That is,
F3 _base =F3 _adh +F3 _his ... (Equation 3) and F3 ₁ =a ₁ ×F3 _adh +F3 _his ... (Equation 4-1)
The first combination of
F3 ₁ =a ₁ ×F3 _adh +F3 _his ... (Equation 4-1) and F3 ₂ =a ₂ ×F3 _adh +F3 _his ... (Equation 4-2)
, And F3 _base =F3 _adh +F3 _his ... (Equation 3) and F3 ₂ =a ₂ ×F3 _adh +F3 _his ... (Equation 4-2)
Is a third combination.

Since F3 _base , F3 ₁ and F3 ₂ are clarified by the measurement, and a ₁ and a ₂ are obtained, the simultaneous equations of the first combination are solved, and the provisional F3 _adh and the provisional F3 are solved. You can ask for _his . Similarly, Motomari is provisional _{F3 adh} and provisional _{F3 his-from} simultaneous equations of the second combination, provisional _{F3 adh} and provisional _{F3 his-is} determined from simultaneous equations of the third combination.

Ideally, the provisional F3 _adh and the provisional F3 _his have the same value regardless of which simultaneous equations of the first to third combinations are solved. However, in practice, the provisional F3 _adh and the provisional F3 _{his that} are obtained differ for each simultaneous equation due to an error in measuring the frictional force or the like.

Therefore, the median value of the three provisional F3 _adh obtained is set as the final (in other words, official) F3 _adh . Then, when F3 _adh is that value (that is, the above-mentioned median value), F3 _his is calculated from Equation 3 (Equation 4-1 or Equation 4-2 may be used), and the final F3 _his is obtained.

Next, since it can be considered that F3 _adh =F2 _adh as described above, the value of F3 _adh can be input as F2 _adh in Expression 2, and F2-F3 _adh can be calculated to obtain F2 _his .

Then, it is possible to, as described above regarded as _{F2 his = F1} his, putting the value of _{F2 his-as F1 his-formula} 1, can be obtained _{F1 adh} calculates the _{F1-F2 his.}

As described above, the adhesion component F1 _adh and the hysteresis component F1 _his of the frictional force between the rubber member and the actual road surface are obtained.

As described above, according to the method of this embodiment, the adhesion component F1 _adh and the hysteresis component F1 _his of the frictional force between the rubber member and the actual road surface can be clarified.

<Modification 1>
A modification example will be described. In this modification, as the temperature dependence coefficient of adhesion component of friction force between the rubber member and the resin surface, the coefficient a ₁ in one temperature T ₁ of the alternative for the coefficients 1 at a certain reference temperature T _base is determined Be done. Further, as a friction force between the rubber member and the second simulated road surface, a frictional force F3 _base at a reference temperature T _base, and the frictional force F3 ₁ at another temperature low T ₁ is measured.

Therefore,
F3 _base =F3 _adh +F3 _his ... (Equation 3)
F3 ₁ =a ₁ ×F3 _adh +F3 _his ... (Equation 4)
There are two expressions. Since F3 _base and F3 ₁ are measured and the coefficient a ₁ is obtained, F3 _adh and F3 _his can be obtained by solving these two simultaneous equations. If F3 _adh and F3 _his are obtained, the adhesion component F1 _adh and the hysteresis component of the frictional force between the rubber member and the actual road surface are calculated based on the equations 1 and 2 in the same manner as the calculation process of the above embodiment. F1 _his is required.

When the measurement error of the frictional force is small, F3 _adh and F3 _his with sufficient accuracy can be obtained by solving the simultaneous equations of the above two equations, and F1 _adh and F1 _his can be clarified.

<Modification 2>
Another modification will be described. In this modified example, as the frictional force between the rubber member and the second simulated road surface, the frictional force F3 _base at the reference temperature T _base and the temperatures T _i at three or more different points (i=1, 2, 3,... ..) and the respective frictional forces F3 _i (i=1, 2, 3...) are measured. Further, the temperature dependence coefficient a _i (i=1, 2, 3,...) Of the adhesive component of the frictional force between the rubber member and the resin surface at each temperature is obtained.

Therefore,
F3 _base =F3 _adh +F3 _his ... (Equation 3)
F3 _i =a _i ×F3 _adh +F3 _his (i=1, 2, 3,...) (Equation 4)
You can do more than four expressions. All combinations of two expressions are extracted from these expressions, and provisional F3 _adh and provisional F3 _his are obtained from each combination. Then, a median of a plurality of provisional _{F3 adh} which _{Motoma', F3 adh} there is a _{F3 his-the} value at the center value is the final _{F3 adh} and _{F3 his-.}

1...rubber member, 2...adhesive strength test surface

Claims (5)

In the friction evaluation method for obtaining the adhesion component and the hysteresis component in the friction force between the rubber member and the friction surface,
A step of creating a resin-made first simulated road surface that reproduces the unevenness of the actual road surface as the friction surface;
Creating a second simulated road surface from which microscopic irregularities have been removed from the first simulated road surface;
A step of conducting a test for examining the temperature dependence of the adhesive force between the rubber member and the resin surface;
Based on the result of the test, as a temperature-dependent coefficient of the adhesion component of the frictional force between the rubber member and the resin surface, another temperature T of 1 or 2 or more with respect to the coefficient 1 at the reference temperature T _base . a step of obtaining the respective coefficients _{a i} in _i,
A frictional force F1 at the reference temperature T _base between the rubber member and the actual road surface;
A frictional force F2 between the rubber member and the first simulated road surface at the reference temperature T _base ;
A frictional force F3 _base at the reference temperature T _base between the rubber member and the second simulated road surface;
Measuring each frictional force F3 _i between the rubber member and the second simulated road surface at the temperature T _i of 1 or 2 or more;
F1=F1 _adh +F1 _his ... (Equation 1)
F2=F2 _adh +F2 _his ... (Equation 2)
F3 _base =F3 _adh +F3 _his ... (Equation 3)
F3 _i =a _i ×F3 _adh +F3 _his ... (Equation 4)
(F1 _adh in Formula 1, F2 _adh in Formula 2, F3 _adh in Formula 3, and a _i ×F3 _adh in Formula 4 are adhesion components at each frictional force, F1 _his in Formula 1, F2 _his in Formula 2, and Formula 3 hysteresis component in _{F3 his-each} frictional force in _{F3 his-and} formula 4 in)
And a step of _obtaining F3 _adh and F3 _his from Equation 3 and Equation 4,
F3 _adh =F2 _adh, and F2-F3 _adh is calculated based on Equation 2 to obtain F2 _his .
F2 _his =F1 _his, and calculating F1-F2 _his based on Equation 1 to obtain F1 _adh ;
A friction evaluation method comprising: Examples coefficients _{a i,} obtains the coefficients _{a 1} in one temperature _{T 1} of the alternative for the coefficients 1 of the reference temperature T _base,
As a frictional force between the rubber member and the second simulated road surface,
A frictional force F3 _base at the temperature reference temperature T _base between the rubber member and the second simulated road surface;
The frictional force F3 ₁ at the temperature T ₁ between the rubber member and the second simulated road surface is measured,
F3 ₁ =a ₁ ×F3 _adh +F3 _his ... (Equation 4)
And F3 _adh and F3 _his are obtained by solving the simultaneous equations of Equation 3 and Equation 4,
The friction evaluation method according to claim 1. As the coefficient a _i , each coefficient a _i at another two or more temperatures T _{i with} respect to the coefficient 1 at the reference temperature T _base is obtained,
As a frictional force between the rubber member and the second simulated road surface,
A frictional force F3 _base at the reference temperature T _base between the rubber member and the second simulated road surface;
The respective frictional forces F3 _i between the rubber member and the second simulated road surface at the above-mentioned two or more temperatures T _i are measured,
All the combinations of the two expressions are extracted from the expression 3 and the plurality of expressions 4 that are satisfied for each temperature, and the provisional F3 _adh and the provisional F3 _his are obtained from the respective combinations,
The median value of the obtained provisional F3 _adh and the value of F3 _his when the median value of F3 _adh is the final F3 _adh and F3 _his .
The friction evaluation method according to claim 1. The friction evaluation method according to any one of claims 1 to 3, wherein the durometer type D hardness of the first simulated road surface and the second simulated road surface is 80 to 84. Of the waves obtained by frequency-analyzing the surface roughness data of the simulated road surface, the low-pass filter and the high-pass filter are set with the frequency of the wave having a predetermined wavelength within the range of 0.1 mm or more and 1.0 mm or less as the cutoff frequency,
A surface roughness of a waveform formed of a wave obtained by applying a low-pass filter to the frequency analysis result of the surface roughness of the first simulated road surface obtained by the measurement, and the surface of the second simulated road surface obtained by the measurement. The difference between the frequency analysis result of the roughness and the surface roughness of the waveform formed by the low-pass filter is 5% or less, and the surface roughness of the second simulated road surface obtained by the measurement. The surface roughness of the waveform composed of the waves obtained by applying the high-pass filter to the frequency analysis result of 10 μm or less,
Removing the micro unevenness from the first simulated road surface to create the second simulated road surface,
The friction evaluation method according to claim 1.

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