CN111812025A - Dynamic friction coefficient measuring device and method - Google Patents
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Abstract
The invention relates to a dynamic friction coefficient measuring device and a measuring method, wherein the measuring device comprises: the test block, the slide, work platform, U type spout, jacking device, transmission, fixing device, buffer, universal air level, data acquisition and analytic system. Work platform depends on the rigidity terrace and passes through universal air level leveling and be used for fixed jacking device, the jacking device passes through the transmission drive, connects U type spout one side and promotes it and remove along vertical direction, it is fixed through fixing device to arrange the slide of contact B material in the U type spout, acceleration sensor depends on the test block of contact A material. And measuring physical parameters of the test block in the initial sliding and gliding processes, calculating the static friction coefficient and establishing a functional relation between the dynamic friction coefficient of the two contact bodies and the relative sliding speed time course. The method can accurately and conveniently measure the static and dynamic friction coefficients based on test measurement, data acquisition and processing and formula regression.
Description
Technical Field
The invention belongs to the technical field of friction coefficient measurement, and particularly relates to a dynamic friction coefficient measurement device and a dynamic friction coefficient measurement method.
Background
The coefficient of friction is the ratio between the frictional resistance and the positive pressure between the two object contact surfaces, and is related to the roughness of the surfaces, and is not related to the size of the contact area. In engineering practice, static and dynamic friction coefficients are usually used to characterize the relative mechanical relationship between two contact surfaces. Studies have shown that the coefficient of dynamic friction is much more complex than the coefficient of static friction, and is generally not a definite value, but rather varies non-monotonically with the relative sliding speed between the two contact bodies. This property significantly affects the mechanical behavior between contacts and may therefore lead to serious errors in the test results if this property is ignored. Most of the existing testing equipment and methods do not consider the influence of the sliding speed on the dynamic friction coefficient, are mostly carried out in an approximately constant speed state, or are finished quickly after relative sliding occurs, and cannot comprehensively consider the influence mechanism and degree of the sliding speed and the amplitude thereof on the dynamic friction coefficient. In scientific research experiments and precision engineering which need to accurately consider the change of the friction coefficient, the existing testing equipment and method are not comprehensive and complete, and the requirement on the precise parameters of the parameters cannot be met. The invention provides a dynamic friction coefficient measuring device and a dynamic friction coefficient measuring method under the condition of considering the influence of speed on a friction coefficient.
Disclosure of Invention
In order to solve the above-mentioned problems, the present invention provides a dynamic friction coefficient measuring apparatus and a dynamic friction coefficient measuring method, considering the influence of speed on the dynamic friction coefficient.
A dynamic friction coefficient measuring device comprises a test block, a slide way, a working platform, a U-shaped chute, a jacking device, a transmission device, a fixing device, a buffering device, a universal air level and a data acquisition and analysis system, wherein the working platform is attached to a rigid terrace and is leveled by the universal air level and used for fixing the jacking device, the slide way is fixed in the U-shaped chute through the fixing device, the jacking device is connected with one side of the U-shaped chute and drives the U-shaped chute to move along the vertical direction through the transmission device, the data acquisition and analysis system comprises an acceleration sensor, an inclination angle sensor, a dynamic acquisition instrument and a computer terminal, the acceleration sensor is fixed on the upper part of the test block, the inclination angle sensor is fixed on the outer side of the middle part of the U-shaped chute, and the acceleration sensor and the inclination angle sensor are respectively connected with the dynamic acquisition system through signal, the dynamic acquisition system is connected with the computer terminal, the computer terminal is connected with the jacking device to control the jacking device to lift, the computer terminal receives the acceleration sensor data and controls the jacking device to stop when the data start to be larger than zero, and the buffer device is installed at the bottom of the inner side of the U-shaped sliding groove.
Furthermore, the test block has no designated shape, the surface of the test block, which is in contact with the slide way, is a receiving side surface, and the test block is made of any required material or has different surface characteristics of the same material; the slide can be dismantled, and the material of slide is any required material or has the different surface characteristics of same material, the slide is the plane with the contact surface of slider.
Furthermore, a rack of the jacking device is fixed on the working platform through a bolt, and the jacking device transmits power through a transmission device and a wheel belt.
Further, the transmission device is driven by a motor, and the gear is driven to rotate through the belt wheel, so that the jacking device is driven to lift along the vertical direction.
Further, fixing device includes two, settles both ends about U type spout respectively, fixing device can adjust through the hand wheel, adapts to the slide of different thickness and material.
Further, the width of the U-shaped sliding groove can ensure that the test block is not in contact with the two sides of the U-shaped sliding groove at the initial position and in the gliding process.
A method for determining a dynamic friction coefficient, the method comprising the steps of:
and 6, controlling the transmission device and drawing the jacking device to slowly rise through the computer terminal, acquiring the acceleration time course a (t) acquired by the acceleration sensor and the inclination angle data acquired by the inclination angle sensor in real time, controlling the transmission device to stop acting at the moment when the test block starts to slide, wherein the inclination angle data acquired by the inclination angle sensor is theta, performing fitting calculation through the computer terminal according to the acquired real-time data, establishing a functional relation between the dynamic friction coefficient of the test block and the relative sliding speed time course, and acquiring the dynamic friction coefficient through the sliding speed time course.
Further, the calculation method of the function of the dynamic friction coefficient and the relative sliding speed time course in the step 6 is as follows:
step 6.1, the computer terminal automatically judges the relative sliding starting time t according to the acceleration time course a (t)iAnd a corresponding inclination angle theta, wherein the slip start time tiThe following conditions are satisfied,
a(ti-1)＝0and a(ti)≠0 (1)
tithe time-corresponding inclination angle θ is recorded as:
θ＝θ(ti) (2)
at tiAt the moment, the inclination angle rotated by the lifting of the slideway is theta, and when the acceleration begins to appear, the inclination angle is thetaRepresenting that the test block starts to slide, the lifting of the slide way is stopped, and the angle of the slide way also reaches theta from 0 degrees in the period;
6.2, the computer terminal calculates the sliding time of the test block and the static friction coefficient mu between the test block and the slideway according to the mechanical balance principlesNamely:
μs＝tanθ (3)
6.3, the computer terminal obtains the correlation between the dynamic friction coefficient and the static friction coefficient:
according to Newton's second law, starting from the moment when the test block starts to slide down, calculating the dynamic friction coefficient mu between the test block and the slideway based on the acceleration time course data a (t) in the process of sliding down the test block and the corresponding inclination angle theta of the slide triggering moment of the test blockd(t), namely:
coefficient of dynamic friction mudCoefficient of static friction musThere is a correlation between:
wherein g is the acceleration of gravity in m/s2(ii) a Theta is an included angle between the U-shaped chute and the horizontal workbench at the moment when the test block starts to slide; mu.sd(t) is the coefficient of dynamic friction; mu.ss(t) is the static friction coefficient of the test block at the moment of starting to slide down; a (t) is acceleration time course in m/s2；
6.4, obtaining the correlation among the dynamic friction coefficient, the static friction coefficient and the relative sliding speed time interval:
and (3) calculating the acceleration time course through numerical integration to obtain a relative sliding speed time course V (t) of the two contact bodies of the test block and the slideway, namely:
in a time coordinate system, motion is establishedRatio mu of coefficient of friction to coefficient of static frictiond/μsAnd the correlation between the relative sliding speed time interval V (t) of the two contact bodies of the test block and the slideway:
μd(t)＝μs·f(V(t)) (7)
step 6.5, repeating the steps 6.1-6.4, taking the average value of the multiple measurement results to carry out parameter regression, obtaining the relation between the dynamic friction coefficient, the static friction coefficient and the relative sliding speed time course between the test block and the two contact bodies of the slide way, namely,
wherein the content of the first and second substances,
according to the characteristics of the function graph, parameter regression is carried out on the measurement result through a numerical method, and a sliding friction coefficient calculation formula is obtained:
where a, b, c and d are parameters obtained by fitting, the experimental data obtained for different materials or different surface characteristics of the same material are different.
Has the advantages that: the relation between the relative sliding speed time course and the dynamic friction coefficient is established, and parameters are given through test, data acquisition and formula fitting, so that the method can be better applied to the measurement of the sliding speedAccurately calculating the values of the static friction coefficient and the dynamic friction coefficient of different materials, namely, setting an exact speed V and a known static friction coefficient mu according to an obtained formulasThen, parameters a, b, c and d obtained by fitting are substituted into solution, and a determined dynamic friction coefficient mu can be conveniently and accurately obtaineddAnd fitting parameters are data actually measured through tests and are obtained by fitting an exponential function in software.
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FIG. 1 is a flowchart of a dynamic friction coefficient measuring method according to the present invention;
FIG. 2 is a schematic view showing the construction of the dynamic friction coefficient measuring apparatus according to the present invention;
FIG. 3 is an exploded view of the dynamic friction coefficient measuring apparatus according to the present invention;
FIG. 4 is a force analysis chart of the dynamic friction coefficient measurement of the present invention;
FIG. 5 is a data fitting graph of a concrete test block and a smooth steel plate slideway for dynamic friction coefficient measurement according to the present invention;
FIG. 6 is a data fitting graph of a concrete test block and a rough steel plate slideway for dynamic friction coefficient measurement according to the present invention;
FIG. 7 is a data fitting graph of a mortar test block and a smooth steel plate slideway for measuring dynamic friction coefficient according to the present invention;
FIG. 8 is a data fitting graph of a mortar test block and a rough steel plate slideway for measuring the dynamic friction coefficient of the invention.
In the figure, 1, test block; 2. a slideway; 3. a working platform; 4. a U-shaped chute; 5. a jacking device; 6. a transmission device; 7. a fixing device; 8. a buffer device; 9. an acceleration sensor; 10. a tilt sensor; 11. a universal leveling bubble; 12. a dynamic acquisition instrument; 13. a computer terminal; 14. and a signal line.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
The utility model provides a dynamic friction coefficient survey device, the survey device includes test block 1, slide 2, work platform 3, U type spout 4, jacking device 5, transmission 6, fixing device 7, buffer 8 and data acquisition and analytic system, for guaranteeing 3 levels of work platform and stable, work platform 3 depends on the rigidity terrace and passes through 11 levelings of universal air level and be used for fixed jacking device 5, and jacking device 5's rack passes through the bolt fastening on work platform 3. The jacking device 5 is driven by the transmission device 6, the transmission device 6 is driven by a motor, and the gear is driven to rotate through a belt, so that the jacking device 5 is lifted along the vertical direction. Jacking device 5 connects U type spout 4 one side and promotes it and removes along vertical direction, and it is fixed to arrange slide 2 and pass through fixing device 7 in the U type spout 4, data acquisition and analytic system includes acceleration sensor 9, inclination sensor 10, dynamic collection appearance 12 and computer terminal 13, and jacking device 5 is gone up and down by computer terminal 13 automatic control, and fixing device 7 is installed on U type spout 4, and upper and lower tip respectively settles one for fixed slide 2, the slide is arranged in U type spout 4, and buffer 8 is installed in U type spout 4 bottom, avoids 1 striking bottom of test block to produce the damage and makes its speed reduction stop, acceleration sensor 9 fixes on 1 test block, inclination sensor 10 is fixed on the limit platform of U type spout 4 recess, and all is related with computer terminal 13 through soft signal line 14. An inclination angle sensor 10 is arranged on the outer side of the middle part of the U-shaped sliding chute 4, and an acceleration sensor 9 and the inclination angle sensor 10 are connected with a dynamic acquisition system 12 through a signal line 14 and are connected with a computer terminal 13 through the dynamic acquisition system 12. And establishing connection between the control system of the jacking device 5 and the computer terminal 13. And the computer terminal controls the jacking device to stop acting when receiving the data of the acceleration sensor, wherein the data of the acceleration sensor is greater than zero.
The test block has no designated shape, the surface of the test block, which is in contact with the slideway, is a receiving side surface, and the test block is made of any required material or has the same material with different surface characteristics; the slide can be dismantled, and the material of slide is any required material or has the different surface characteristics of same material, the slide is the plane with the contact surface of slider.
The rack of the jacking device is fixed on the working platform through a bolt, and the jacking device is driven by a transmission device through a wheel belt.
The transmission device is driven by a motor, and the gear is driven to rotate through a belt wheel, so that the jacking device is driven to lift along the vertical direction.
The fixing devices comprise two fixing devices which are respectively arranged at the upper end and the lower end of the U-shaped sliding groove, and the fixing devices can be adjusted through hand wheels to adapt to sliding ways with different thicknesses and materials.
The width of the U-shaped sliding groove 4 is wide, so that the test block 1 is ensured to be not contacted with both sides of the U-shaped sliding groove 4 at the initial position and in the gliding process.
The following dynamic friction coefficient test is performed by taking a concrete test block 1 and a smooth steel plate slideway 2 as an example:
And 2, building a basic test system consisting of a working platform 3, a U-shaped sliding chute 4, a jacking device 5, a transmission device 6 and the like as shown in fig. 2.
And 5, connecting the acceleration sensor 9 and the inclination angle sensor 10 with a computer terminal 13 through a dynamic acquisition system 12. And establishing connection between the control system of the jacking device 5 and the computer terminal 13.
And 6, controlling the transmission device and drawing the jacking device to slowly rise through the computer terminal, acquiring the acceleration time course a (t) acquired by the acceleration sensor and the inclination angle data acquired by the inclination angle sensor in real time, controlling the transmission device to stop acting at the moment when the test block starts to slide, wherein the inclination angle data acquired by the inclination angle sensor is theta, performing fitting calculation through the computer terminal according to the acquired real-time data, establishing a functional relation between the dynamic friction coefficient of the test block and the relative sliding speed time course, and acquiring the dynamic friction coefficient through the sliding speed time course.
The calculation method of the function of the dynamic friction coefficient and the relative sliding speed time course in the step 6 comprises the following steps:
step 6.1, controlling the transmission device 6 and drawing the jacking device 5 through the computer terminal 13, acquiring acceleration data a (t) and inclination angle data in real time, and automatically judging the relative sliding starting moment t by the computer terminal 13 according to the acceleration time course a (t)iAnd a corresponding tilt angle theta. Wherein, the time tiThe following conditions are satisfied,
a(ti-1)＝0and a(ti)≠0 (1)
in the formula, is represented byiThe acceleration appears at a time instant, which is ti-1The acceleration is 0 value. t is tiThe time-corresponding inclination angle θ is recorded as:
θ＝θ(ti) (2)
in the formula, at tiAt that moment, the inclination angle at which the slide way is lifted to rotate is theta. At the beginning of the acceleration, which represents the beginning of the sliding of the test block, the lifting of the slide is stopped, during which the angle also reaches θ from 0 °.
Step 6.2, the computer terminal determines the angle θ corresponding to the slide when the relative sliding occurs according to the principle of mechanical balance mg · sin θ ═ μ shown in fig. 4sMg cos θ, calculate the coefficient of static friction μ between the slider and the slidewaysNamely:
μs＝tanθ (3)
as can be seen from the formula, a unique angle determines a unique coefficient of static friction μs. Here below an average is taken for a number of measurements that are accurate.
6.3, calculating and obtaining a correlation between the dynamic friction coefficient and the static friction coefficient by the computer terminal:
according to Newton's second law, starting from the moment when the test block starts to slide down, calculating the dynamic friction coefficient mu between the test block and the slideway based on the acceleration time course data a (t) in the process of sliding down the test block and the corresponding inclination angle theta of the slide triggering moment of the test blockd(t), namely:
the determined angle theta determines the parameters of the formula, a (t) from tiThe data, also a time-dependent course curve, and thus mu, starts to appear after the momentd(t) is also a time history curve, and in order to ensure the data accuracy, the curve is averaged.
Coefficient of dynamic friction mudCoefficient of static friction musThere is a correlation between:
wherein g is the acceleration of gravity in m/s2(ii) a Theta is an included angle between the U-shaped chute and the horizontal workbench at the moment when the test block starts to slide; mu.sd(t) is the coefficient of dynamic friction; mu.ss(t) is the static friction coefficient of the test block at the moment of starting to slide down; a (t) is acceleration time course in m/s2；
6.4, obtaining the correlation among the dynamic friction coefficient, the static friction coefficient and the relative sliding speed time interval:
considering that the relative speed of the contact body is easier to calculate or measure in practical application, the method is also more convenient in practical application. Therefore, the acceleration time course is calculated through numerical integration to obtain the speed time courses of the two contact bodies, and the acceleration time course is calculated through numerical integration to obtain the relative sliding speed time course V (t) of the two contact bodies of the test block and the slide way, namely:
sit at the timeWithin the criteria, the ratio mu of the coefficient of dynamic friction to the coefficient of static friction is establishedd/μsAnd the correlation between the relative sliding speed time interval V (t) of the two contact bodies of the test block and the slideway:
μd(t)＝μs·f(V(t)) (7)
i.e. to express that there is a certain relation between dynamic and static friction coefficients and speed.
Step 6.5, in order to make the obtained data more accurate, a method of measuring and removing the mean value for a plurality of times is adopted to carry out, the step 6.1 to 6.4 is repeated, the mean value of the measurement results for a plurality of times is taken to obtain the relation between the dynamic friction coefficient, the static friction coefficient and the relative sliding speed between the test block and the two contact bodies of the slide way, namely,
wherein the content of the first and second substances,
according to the measured data, one mu can be directly calculated each timedAnd each mu is then addeddIs added and averaged to obtain a
The value of (a) is,
a plurality of ai(t) averaging the integral sums of the curves to obtain an averaged velocity profile,
according to the test results, μ is plottedd/μsThe graphs relating to the velocity V are shown in fig. 5, 6, 7 and 8.
According to the characteristics of the function graph, parameter regression is carried out on the measurement result through a numerical method, and a sliding friction coefficient calculation formula is obtained:
where a, b, c and d are parameters obtained by regression fitting, the experimental data obtained for different materials or different surface characteristics of the same material are different. The formula (13) is used to express the final
And V (t). In the embodiment, the data actually measured in the test is fitted by an exponential function in software to obtain a fitting type.
The following table parameters are the formula parameters obtained by fitting the measured data of the present embodiment according to fig. 5, fig. 6, fig. 7, and fig. 8.
For a given contact body, according to a regression formula, for the measured static friction coefficient musAnd a relative sliding speed time course V (t), which is obtained by solving the parameters a, b, c and d in the table, and can conveniently and accurately obtain the determined dynamic friction coefficient time course mud(t)。
It is to be understood that the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make modifications, alterations, additions or substitutions within the spirit and scope of the present invention.
Claims (8)
1. A dynamic friction coefficient measuring device comprises a test block, a slide way, a working platform, a U-shaped chute, a jacking device, a transmission device, a fixing device, a buffering device, a universal air level and a data acquisition and analysis system, and is characterized in that the working platform is attached to a rigid terrace and is leveled by the universal air level and used for fixing the jacking device, the slide way is fixed in the U-shaped chute by the fixing device, the jacking device is connected with one side of the U-shaped chute and is driven by the transmission device to lift the U-shaped chute to move along the vertical direction, the data acquisition and analysis system comprises an acceleration sensor, an inclination angle sensor, a dynamic acquisition instrument and a computer terminal, the acceleration sensor is fixed on the upper part of the test block, the inclination angle sensor is fixed on the outer side of the middle part of the U-shaped chute, and the acceleration sensor and the inclination angle sensor are respectively connected with the dynamic acquisition, the dynamic acquisition system is connected with the computer terminal, the computer terminal is connected with the jacking device to control the jacking device to lift, the computer terminal receives the acceleration sensor data and controls the jacking device to stop when the data start to be larger than zero, and the buffer device is installed at the bottom of the inner side of the U-shaped sliding groove.
2. The dynamic friction coefficient measuring apparatus according to claim 1, wherein: the test block has no designated shape, the surface of the test block, which is in contact with the slideway, is a receiving side surface, and the test block is made of any required material or has the same material with different surface characteristics; the slide can be dismantled, and the material of slide is any required material or has the different surface characteristics of same material, the slide is the plane with the contact surface of slider.
3. The dynamic friction coefficient measuring apparatus according to claim 1, wherein: the rack of the jacking device is fixed on the working platform through a bolt, and the jacking device is driven by a transmission device through a wheel belt.
4. The dynamic friction coefficient measuring apparatus according to claim 1, wherein: the transmission device is driven by a motor, and the gear is driven to rotate through a belt wheel, so that the jacking device is driven to lift along the vertical direction.
5. The dynamic friction coefficient measuring apparatus according to claim 1, wherein: the fixing devices comprise two fixing devices which are respectively arranged at the upper end and the lower end of the U-shaped sliding groove, and the fixing devices can be adjusted through hand wheels to adapt to sliding ways with different thicknesses and materials.
6. The dynamic friction coefficient measuring apparatus according to claim 1, wherein: the width of the U-shaped sliding groove can ensure that the test block is not contacted with both sides of the U-shaped sliding groove at the initial position and in the gliding process.
7. The measuring method using a dynamic friction coefficient measuring apparatus according to any one of claims 1 to 6, characterized by comprising the steps of:
step 1, preparing a test block and a slideway which are made of materials required by testing;
step 2, building a basic test system consisting of a working platform, a jacking device, a transmission device and a U-shaped sliding chute;
step 3, arranging a slide way in the U-shaped chute, fixing the slide way through a fixing device, and arranging a buffer device at the bottom end of the U-shaped chute;
step 4, fixing the acceleration sensor on the upper part of the test block, measuring the total weight of the acceleration sensor and the test block by using a balance, placing the test block on the top of the U-shaped chute, ensuring that the lower surface of the test block is closely contacted with the upper surface of the contact slideway during the test block is placed on the top of the U-shaped chute, and arranging the inclination angle sensor on the outer side of the middle part of the U-shaped chute;
step 5, connecting the acceleration sensor and the tilt sensor with a computer terminal through a dynamic acquisition system, and connecting the jacking device with the computer terminal;
and 6, controlling the transmission device and drawing the jacking device to slowly rise through the computer terminal, acquiring the acceleration time course a (t) acquired by the acceleration sensor and the inclination angle data acquired by the inclination angle sensor in real time, controlling the transmission device to stop acting at the moment when the test block starts to slide, wherein the inclination angle data acquired by the inclination angle sensor is theta, performing fitting calculation through the computer terminal according to the acquired real-time data, establishing a functional relation between the dynamic friction coefficient of the test block and the relative sliding speed time course, and acquiring the dynamic friction coefficient through the sliding speed time course.
8. The method of claim 7, wherein the function of the kinetic friction coefficient and the relative sliding speed time course in step 6 is calculated by:
step 6.1, the computer terminal automatically judges the relative sliding starting time t according to the acceleration time course a (t)iAnd a corresponding inclination angle theta, wherein the slip start time tiThe following conditions are satisfied,
a(ti-1)＝0 and a(ti)≠0 (1)
tithe time-corresponding inclination angle θ is recorded as:
θ＝θ(ti) (2)
at tiAt the moment, the inclination angle of the lifting rotation of the slide way is theta, when the acceleration begins to appear, the test block begins to slide, the lifting of the slide way is stopped, and the angle of the slide way also reaches theta from 0 degrees in the period;
6.2, the computer terminal calculates the sliding time of the test block and the static friction coefficient mu between the test block and the slideway according to the mechanical balance principlesNamely:
μs＝tanθ (3)
6.3, the computer terminal obtains the correlation between the dynamic friction coefficient and the static friction coefficient:
according to Newton's second law, starting from the moment when the test block starts to slide down, calculating the dynamic friction coefficient mu between the test block and the slideway based on the acceleration time course data a (t) in the process of sliding down the test block and the corresponding inclination angle theta of the slide triggering moment of the test blockd(t), namely:
coefficient of dynamic friction mudCoefficient of static friction musThere is a relationship betweenLinking type:
wherein g is the acceleration of gravity in m/s2(ii) a Theta is an included angle between the U-shaped chute and the horizontal workbench at the moment when the test block starts to slide; mu.sd(t) is the coefficient of dynamic friction; mu.ss(t) is the static friction coefficient of the test block at the moment of starting to slide down; a (t) is acceleration time course in m/s2；
6.4, obtaining the correlation among the dynamic friction coefficient, the static friction coefficient and the relative sliding speed time interval:
and (3) calculating the acceleration time course through numerical integration to obtain a relative sliding speed time course V (t) of the two contact bodies of the test block and the slideway, namely:
establishing the ratio mu between the dynamic friction coefficient and the static friction coefficient in a time coordinate systemd/μsAnd the correlation between the relative sliding speed time interval V (t) of the two contact bodies of the test block and the slideway:
μd(t)＝μs·f(V(t)) (7)
step 6.5, repeating the steps 6.1-6.4, taking the average value of the multiple measurement results to carry out parameter regression, obtaining the relation between the dynamic friction coefficient, the static friction coefficient and the relative sliding speed time course between the test block and the two contact bodies of the slide way, namely,
wherein the content of the first and second substances,
according to the characteristics of the function graph, parameter regression is carried out on the measurement result through a numerical method, and a sliding friction coefficient calculation formula is obtained:
where a, b, c and d are parameters obtained by fitting, different materials or different surface characteristics of the same material give different experimental data.
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Application publication date: 20201023 |