DESC:FIELD OF THE INVENTION
The present invention relates to the field of estimating Rolling Resistance characteristics. The present invention relates to a system and method for evaluating Rolling Resistance (RR) characteristics of elastomeric/ rubber compounds using Universal Testing Machine (UTM).

BACKGROUND OF THE INVENTION
Characterization of the rolling resistance of an elastomeric compound is a vital/essential aspect of its utilization in a tire product. Bearing a strong implication on the fuel consumption of the overall vehicle, this has become a point of attention in recent times and expected to be so in future.

Conventionally, the rolling resistance characterization for an elastomeric compound is performed on a DMA (Dynamic Mechanical Analyzer) machine. The machine is expensive equipment, and the rolling resistance characterization test requires 90 – 100 minutes for each compound. High skilled labor is needed to operate the machine further adding to the cost of performing the test.

The proposed method eliminates the usage of expensive DMA procedures and utilizes the more generically used testing on a UTM. The UTM utilizes a simple dumbbell specimen loading it in the tensile direction and recording the load vs. deformation of the specimen. The load/deflection data is then processed suitably to characterize the rolling resistance properties of elastomeric compounds. The testing procedure itself can be completed in 5-7 minutes for each compound.

Reference may be made to the following:
Patent No. US6467330 relates to apparatus for testing rolling physical characteristics of materials, especially rolling contact fatigue resistance of materials, represents the most simple and universal solution, by which it is possible to test not only laboratory tested objects prepared in advance, but also various final products or parts thereof. Thanks to linearly oscillating movement of the testing ball foreseen by the apparatus according to the invention, it is much easier to test the surface of the tested object. While appropriate point contact between the testing ball and appropriate surface of the tested object is ensured, the testing ball is linearly oscillatory rolled here and there along the surface of the tested object, which is thereby clamped in appropriate clamping unit. The loading unit of the present invention comprises a bearing surface arranged opposite to the tested object and is equipped with a groove arranged in the direction of rolling of the testing ball. In this invention rolling fatigue testing is been performed using a fabricated equipment. Present invention utilizes Universal Testing Machine (UTM) for evaluating Rolling Resistance (RR) characteristics.
Patent No. US6494076 relates to a method and apparatus for directly measuring the rolling resistance of a material, especially an elastomeric material, using a relatively small sample of the material. A pendulum device is used to test the rolling resistance of a material. The device includes a rolling unit for contact with the material being tested, an assembly for initiating pendulum motion of the device, and measuring the amplitude of the pendulum motion over time. The rate of decrease of the amplitude of the pendulum motion is a measure of the rolling resistance of the material. This patent uses a pendulum device for evaluation, Present invention utilizes Universal Testing Machine (UTM) for evaluating Rolling Resistance (RR) characteristics.

Patent No. US6199424 relates to a friction testing machine and method for measuring friction characteristics between a test sample and a friction surface. The machine and method are particularly suited for measuring the coefficient of friction between a rubber specimen or a tread element and different friction surfaces at different sliding velocities, contact pressures and orientations. A preferred embodiment of machine is self-contained and portable, configured for easy and quick changing of the friction surface, and provides for rotating the test sample about an axis normal to the sliding surface and the direction of movement of the sample relative to the friction surface. This does not use a dumbbell sample [IS 3400 (Part 1): 2012 considered as reference] or UTM as used in present invention.

Publication No. WO0037921 relates to a method and apparatus for directly measuring the rolling resistance of a material, especially an elastomeric material, using a relatively small sample of the material. A pendulum device is used to test the rolling resistance of a material. The device comprises a rolling means for contact with the material being tested, a means for initiating pendulum motion of the device, and a means for measuring the amplitude of the pendulum motion over time. The rate of decrease of the amplitude of the pendulum motion is a measure of the rolling resistance of the material. In the present invention pendulum device is used for evaluation, Present invention utilizes Universal Testing Machine (UTM) for evaluating Rolling Resistance (RR) characteristics.

Patent No. US10775272 relates to a systems and methods for measurement of rubber footprint and rolling resistance of rubber substrates. A system for measuring rolling resistance of a substrate may include a transparent support member including a contact surface, a rolling member including a cylindrical convex surface with the substrate attached on the cylindrical convex surface, the cylindrical convex surface placed on the contact surface, an oscillation mechanism coupled with the rolling member configured to drive an oscillatory rotational movement of the rolling member about a longitudinal axis of the rolling member. An oscillatory movement of sample with a cylindrical convex shape is used for evaluating RR, which is similar to the pendulum-based testing. Present invention utilizes dumbbell sample based UTM testing.
Publication No. GB271328 relates to improvements in or relating to machines for testing resistance to wear, lubrication properties and the like. 271,328. Spindel, M. Oct. 29, 1926. Addition to 197,730. Testing physical qualities of materials; testing lubricating efficiency of liquids. - In the machine of the parent invention, the bodies to be tested and their supports are arranged and constructed to admit of testing material under rolling or rolling and sliding friction and to test flexible material and the lubricating properties of lubricants at different temperatures. The test body N which is supported by the lever L<1>, L<2> and loaded by a weight S is cylindrical and mounted to rotate about its axis in the bearing member M. The disc F grinds a groove in the body N the depth of the groove and the friction being determined as in the parent invention. This concerns liquid lubrication characteristics evaluation during a rolling/sliding of flexible rubber like material contact. This does not concern rubber compounds evaluation as provided in present invention.

Publication No. JP2012247301 relates to a rubber friction/abrasion characteristic testing method and a rubber friction/abrasion characteristic testing apparatus in which, when rolling a rubber test member on a turn table, evaluation accuracy can be improved by excluding influences of a lateral force with a circumferential speed difference within a contact area. A turn table is rotated and a disk-shaped rubber test member pressed onto the turn table is rolled. A lateral force generated in the rubber test member rolling on the turn table is then detected and on the basis of the detected lateral force, a slip angle SA of the rubber test member is adjusted. Present invention utilizes Universal Testing Machine (UTM) for evaluating Rolling Resistance (RR) characteristics.

Publication No. JP2007292587 relates to a friction testing machine capable of measuring easily rolling friction and sliding friction by the compact testing machine of a suppressed cost, and capable of obtaining a treading behavior of a tire close to actual one. This friction testing machine of the present invention has a support means for supporting rotatably a disk-like rubber sample S, a loading means for loading a prescribed load onto the rubber sample S supported by the support means, and a moving means to reciprocation-move rectilinearly a friction test face contacting with the rubber sample S loaded with the load by the loading means. Testing has been performed using fabricated equipment. Present invention utilizes Universal Testing Machine (UTM) for evaluating Rolling Resistance (RR) characteristics.

Publication No. CN107501660 relates to a tire tread rubber composition used for a standard test. The tire tread rubber composition is characterized by being prepared from the following components in parts by weight: 100 parts of butadiene styrene rubber, 30-70 parts of carbon black, 20-60 parts of white carbon black, 5-12 parts of an organic silicon mixture, 10-40 parts of filling oil, 1.5-3.5 parts of sulfur, and other common rubber auxiliaries in the tire industry. This pertains to rubber composition evaluation. Present invention utilizes Universal Testing Machine (UTM) for evaluating Rolling Resistance (RR) characteristics.
Publication No. GB359211 relates to a method of measuring the plasticity of materials in which a test piece is drawn between surfaces moving at constant speed and the power necessary for the stretching is measured. In one form, the specimen is passed between two parallel rollers, one at least of which is driven and the surfaces of which are a less distance apart than the thickness of the specimen. In another form, the specimen is laid across two loosely mounted rollers and pushed between them by a prism-shaped ram the distance between which and a roller is less than the thickness of material. This pertains to plasticity evaluation. Present invention utilizes Universal Testing Machine (UTM) for evaluating Rolling Resistance (RR) characteristics.

Publication No. CN111307709 relates to a method for detecting the friction coefficient of an ultrathin rubber asphalt wearing layer, and the method comprises the following steps: S1, determining a friction coefficient detection road segment after an ultrathin rubber asphalt wearing layer is laid, and cleaning a to-be-detected pavement; S2, detecting a transverse force coefficient through a transverse force coefficient detection vehicle, descending a test tire before driving into the road section to be detected, and reserving running for 500m; S3, detecting a longitudinal force coefficient through a dynamic friction coefficient tester; S4, analyzing influence factors of the transverse force coefficient and the longitudinal force coefficient according to the transverse force coefficient and the longitudinal force coefficient measured in the S2 and the S3, further determining the relation between the transverse force coefficient and the longitudinal force coefficient, and determining the comprehensive friction coefficient of the ultrathin rubber asphalt wearing layer. This pertains to measurement of friction of road surface. Present invention utilizes Universal Testing Machine (UTM) for evaluating Rolling Resistance (RR) characteristics.

Publication No. CN104792636 relates to an environment-changeable rubber roll friction wearing test apparatus. The environment-changeable rubber roll friction wearing test apparatus comprises a frame, and also comprises a driving module, a transmission module, a loading module, a water tank module and a data acquisition box. The environment-changeable rubber roll friction wearing test apparatus allows the rotating speed of a motor and the temperature of a liquid in a water box to be changed through a control button on the data acquisition box in order to realize rubber roll wearing test under different loads, rotating speeds, temperatures and media. In this invention testing is been performed using a fabricated equipment. Present invention utilizes Universal Testing Machine (UTM) for evaluating Rolling Resistance (RR) characteristics.

Publication No. CN207199159 relates to physics friction test device, including base and fixed hang plate, fixed hang plate passes through the hinge and installs at the fixed intracavity of the swash plate of base, the base that rotates push pedal one side runs through in has inner thread sleeve, the slip swash plate of upper surface on the coplanar is inserted to the other end of fixed hang plate, fixed hang plate and slip swash plate in side set up the top respectively and leave open -ended rolling groove, the rolling and fix in the rolling at both ends epaxially respectively of transparent PVC soft rubber plate's both ends, it has a carousel fixing bolt to run through respectively on every fixed turn plate, a plurality of friction test sliders have been placed to the storing intracavity, the tight spiral shell rasp bar in top places the piece, the tight spiral shell rasp bar in top places the in slot of piece and places the tight spiral shell rasp bar in the top that can twist in inner thread sleeve. In this invention testing has been performed using fabricated equipment. Present invention utilizes Universal Testing Machine (UTM) for evaluating Rolling Resistance (RR) characteristics.

Publication No. CN107141537 relates to a rubber composition for a standard test tyre tread. The rubber composition is characterized by comprising: 5-15 parts by weight of butadiene rubber, 5-25 parts by weight of natural rubber, 60-90 parts by weight of styrene butadiene rubber, 50-75 parts by weight of carbon black, 10-30 parts by weight of filling oil, 1.5-2.5 parts by weight of sulfur, and a tire industry commonly used weight part of rubber assistants. The rubber composition by the invention ensures the reliability of tensile strength, stress at definite elongation and other mechanical properties of the rubber material, at the same time, the prepared tyre has scientific and effective snowfield holding performance evaluation effect, also can be used for other evaluations, like wear resistance, rolling resistance, pavement friction properties, noise and the like, and the rubber composition can be used for 195/75R14 TE305 specification standard test tyre tread parts. This pertains to rubber composition evaluation. Present invention utilizes Universal Testing Machine (UTM) for evaluating Rolling Resistance (RR) characteristics.

Publication No. CN104864997 relates to a device for measuring a rolling friction force. The interior of a support internal cavity of a frame structure with two horizontal supporting plates which are respectively provided with a spring tension meter and a motor. The motors are electrically connected with a reduction gear unit which drives a transmission pulley block to rotate through a belt. A central part of a support with a rolling shaft, and the left and right ends of the rolling shaft are respectively connected with a rolling wheel. The central part of the rolling shaft is connected with a pulley, and the pulley is in transmission-belt connection with the transmission pulley block. A friction plate is horizontally placed on the rolling wheels, and the central part of the support with an L-shaped supporting rod. This pertains to rubber composition evaluation. Present invention utilizes Universal Testing Machine (UTM) for evaluating Rolling Resistance (RR) characteristics.

Patent No. US5635623relates to a device in which two identical mounted assemblies E are assembled by a connecting arm which is provided with ballasting means (7) such that the center of gravity G of the loaded device is located below a straight-line ZZ' connecting the centers of rotation of the two assemblies E. The device is rotated to impart a cycloidal movement to the center of gravity G to a given angular position. The measurement is performed on tires rather than dumbbell samples.

Patent No. US8442777 relates to the system and method for measuring rolling resistance the measurement of various properties associated with pre-rolling resistance. A cruciform pendulum is formed from a rigid rod having opposed upper and lower ends and a horizontal support extending orthogonal thereto. Pair of substantially hemispherical samples formed from a first material is mounted on opposing ends of the horizontal support. Flat, planar samples of a second test material are placed upon spaced apart supporting surfaces. Thus utilizes a pendulum device for evaluation. Present invention utilizes Universal Testing Machine (UTM) for evaluating Rolling Resistance (RR) characteristics.

Publication No. KR100683950 relates to an apparatus and a method for measuring the rolling resistance of a tire using a rubber sample are provided to shorten the test time by manufacturing the rubber sample simply and using the rubber sample. An apparatus for measuring the rolling resistance of a tire using a rubber sample includes a test disc, a shaft rod, and a rubber sampling wheel. A rotating central shaft is formed at a central portion of the upper surface of the test disc. The central shaft is inclined by a predetermined angle. One end of the shaft rod is assembled in one end of the central shaft of the test disc. The rubber sample wheel is assembled at the free end of the shaft rod so as to roll along the periphery of the upper surface of the disc. A rubber sample ring is inserted into the outer periphery of the rubber sample wheel. The testing has been performed using fabricated equipment. Present invention utilizes Universal Testing Machine (UTM) for evaluating Rolling Resistance (RR) characteristics.

Publication No. CN106769839 relates to material contact fatigue test equipment, which comprises a cabinet, test devices and a lubricating system, wherein a tooling of the test devices comprises a sample holder and a connector; the sample holder comprises a sample holder main body, a fixed sleeve and a movable seat; the movable seat is linearly positioned and in sliding fit in the fixed sleeve; the movable seat is connected with a push rod; the push rod penetrates out of a bottom cap and is connected with a load end of an axial load mechanism; the push rod is in tight fit with the bottom cap fixed at the bottom of the fixed sleeve; a barrel test cavity is arranged at the top of the movable seat; the sample holder body is fixed at the bottom of the test cavity; an oil baffle cover covers an opening of the test cavity; an axle hole through which a main shaft passes and which is in tight fit is formed in the oil baffle cover; an oil inlet hole and an oil outlet hole higher than the sample holder are arranged in the upper part of the test cavity; the oil outlet hole communicates with the test cavity and a barrel cavity of the fixed sleeve; an oil return hole communicating with the barrel cavity is arranged in the bottom of the fixed sleeve; the oil inlet hole and the oil return hole are connected with the lubricating system; and at least two sets of test devices are arranged in the cabinets. Fatigue testing has been performed using fabricated equipment, Present invention utilizes Universal Testing Machine (UTM) for evaluating Rolling Resistance (RR) characteristics.

Publication No. XP002112004 relates to adherence, contact geometry and rolling friction of rigid cylinder in adhesive contact with the flat and smooth surface of a rubber-like material. A cylindrical specimen has been used for the testing and evaluation. The method is different from the present invention method of using a dumbbell sample.

The article entitled “A test method for studying the rolling resistance of rubber compounds” by A.N. Gent; D.D. Gallagher; R.B. Steven; Polymer Engineering and Science 47(10):1576 - 1579; October 2007 talks about the measuring energy losses in rolling, using the damped oscillations of a pendulum that makes a rigid cylinder roll backwards and forwards across a rubber block. The mechanics of small swings, in which the displacement of the contact patch is smaller than its length, are shown to be different from those governing swings of larger amplitude. Thus, starting with relatively large swings of the pendulum, the amplitude of oscillation decays initially at a constant rate and then changes to a decreasing rate as the swings become small. In principle, the two processes provide separate measures of the energy losses in rolling. The proposed test method may be useful for studying the effects of the surface features of tire treads and road surfaces on tire rolling resistance, in addition to characterizing the dissipative properties of rubber compounds. Present invention utilizes Universal Testing Machine (UTM) for evaluating Rolling Resistance (RR) characteristics.

The conventionally available apparatus is relatively complicated. Nevertheless, to enable testing of certain material, a special test object of appropriate material must be available. The testing has been performed using a fabricated equipment. Thus, there is a need for developing a system and method that allows accurate measurement of Rolling Resistance characteristics using Universal Testing Machine (UTM).

In order to overcome deficiencies in the above listed prior art, the present invention aims to provide a system and method for evaluating Rolling Resistance (RR) characteristics of the elastomeric/ rubber compound using Universal Testing Machine (UTM) which is accurate, simple, and easy to use.

OBJECTS OF INVENTION
It is the primary object of the present invention to provide a system and method for determining Rolling Resistance (RR) characteristics of the elastomeric/ rubber compound.

It is another object of the present invention to provide a system and method using Universal Testing Machine (UTM) for determining Rolling Resistance (RR) characteristics of elastomeric/ rubber compound.
It is another object of the present invention to provide simple and easy to use testing equipment and a method for determining Rolling Resistance (RR) characteristics of the elastomeric/ rubber compound which provides better accuracy.

It is another object of the present invention to provide an economical and efficient method for determining Rolling Resistance characteristics of elastomeric/ rubber compounds.

SUMMARY OF THE INVENTION
One or more of the problems of the conventional prior art may be overcome by various embodiments of the present invention.

It is the primary aspect of the present invention to provide a method of characterizing Rolling Resistance property of a test compound, comprising:
testing of a compound on a Universal Testing Machine (UTM) using a standard dumbbell specimen;
removing Mullin’s effect by repeated loading up to 100% strain for 25 cycles, wherein the rate of repeated loading is 500 mm/minute;
removing the dumbbell specimen and relaxing the dumbbell specimen for 2 minutes;
reloading the dumbbell specimen on the UTM and testing for Stress vs Strain;
extracting the Stress-Strain data from the dumbbell specimen;
calculating the value of the UTM data by obtaining the derivative of the Stress-Strain data and averaging it over 20% to 30% strain values;
testing the Coefficient of Rolling Resistance (CRR) on a standard drum; and
measuring correlations of Rolling Resistance values of actual tires on a lab drum,
wherein an inverse correlation exists between the UTM data and the CRR values.

It is another aspect of the present invention to provide a method of characterizing rolling resistance property of a test compound, wherein the test compound comprises elastomeric compound, rubber compound and the like.

DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to the field of estimating Rolling resistance (RR) characteristics. The present invention relates to a system and method for evaluating Rolling resistance (RR) characteristics of elastomeric/ rubber compounds using Universal Testing Machine (UTM).

The present invention provides a system and method for quantifying Rolling Resistance (RR) characteristics of the elastomeric/ rubber compound using Universal Testing Machine (UTM). The system quantifies Rolling Resistance characteristics of elastomeric compound as it is moulded into a tire. The simple test data of the compound, extracted from the monotonic loading test in a UTM machine is utilized. A good correlation of the data with actual Rolling Resistance values is observed. The method of characterizing Rolling Resistance property of elastomeric compounds includes following steps:
The compound testing is performed on a Universal Testing Machine (UTM) using standard dumbbell specimen. Mullin’s effect is removed by repeated loading up to 100% strain for 25 cycles. The rate of repeated loading is 500 mm/minute. The dumbbell specimen is removed, and relaxed for 2 minutes. The specimen is then reloaded on the UTM and tested for Stress vs Strain. Stress-Strain data are then extracted from the dumbbell specimen and the rate of loading for both cases is 500 mm/min. The single value of UTM data is calculated by obtaining the derivative of the Stress-Strain data and averaging it over 20% to 30% strain values i.e., the UTM data as plotted with strain values along x-axis and the corresponding stress values along y-axis is considered. The first derivative of each row of the data is obtained by calculating dy/dx for each row of data from the UTM. An average of the values from 20% strain value to 30% strain value is then used as the single point UTM data as shown in the Table-1, the mathematical expression is given below. The results are shown in Table-1, and further discussed below.

UTM data = {(dy20/dx20) + (dy21/dx21) + (dy22/dx22) +……. + (dy30/dx30)}/ n
where,
dy20 - is the change in stress at 20% strain level.
dx20 – is the change in strain at 20% strain level.
n – is the number of data points considered for averaging.

The Coefficient of Rolling Resistance (CRR) is tested on a standard drum. The correlations of Rolling resistance values of actual tires on a lab drum are measured. The inverse correlation exists between the UTM data and the CRR values. The test compound comprises elastomeric compound, rubber compound and the like.

The invention is more fully understood from the following example. The example is to be constructed as illustrative of the invention and not limitative thereof:
Example:
Experiments are performed to generate full set of data for the RR values of a 4.00-8 size auto-rickshaw (a three-wheeler with a single front wheel and two rear wheels) tyre. Dumbbell tests are also performed on compound specimen for the tread compounds used in the tyres on a UTM. The UTM data is extracted from the Stress-Strain plots of the corresponding compounds.

The Coefficient of Rolling Resistance (CRR) is tested on a standard 1.7m diameter drum. Standard operating methodologies of warming up the tire followed by constant velocity run at 50 kmph is used. The 4.00-8 tire is loaded on a 3.0-inch rim, inflated to 425 kPa (62psi) inflation pressure, and a load of 400 kgs applied- the rim, inflation pressure and load being selected as per the Bureau of Indian Standards IS15627:2005 for a 6 PR (ply rating) tyre.

The compound testing is performed on an Instron 5966 UTM machine. Standard dumbbell specimen Type 1 as per IS 3400 (Part 1): 2012 is used. Mullin’s effect is removed by repeated loading up to 100% strain for 25 cycles. The specimen is then removed and relaxed. Stress-Strain data is then extracted from the specimen. The rate of loading for both cases was 500 mm/min.

The single value of UTM data is calculated by obtaining the derivative of the Stress-Strain data and averaging it over 20% to 30% strain values. The results are shown in Table-1, and further discussed below.

Table-1
Compound Coefficient of Rolling Resistance (CRR) as tested UTM Data
(N/mm2)
A 13.50 1.96
B 13.93 1.88
C 16.50 1.58

The data in Table-1 provides CRR values for the tires made with the respective compounds, the UTM data for the compounds is also provided. It is observed that an inverse correlation exists between the UTM data and the CRR values. For the Compound-A, and Compound-B, there is a reduction of 0.08 in UTM value, the corresponding increase in CRR value is 0.43. Similarly, between the Compound-B and Compound-C, the UTM value reduction is 0.30 and the corresponding increase in CRR value is 2.57. There is a consistent correlation in terms of magnitudes and directions between the CRR and UTM values. “Coefficient of Rolling Resistance” is a standard and one single parameter used to characterize a tire’s Rolling resistance.

Correlations of Rolling Resistance values of actual tires are measured on a lab drum. The present invention provides simple testing equipment utilized to derive Rolling Resistance characteristics of compound. This utilizes fundamental concepts of physics of material behavior. The present invention overcomes limitations of a conventional DMA based testing and provides more accurate and simple testing method.

This method uses simple and easy to use Universal Testing Machine (UTM) which provides better accuracy. The present invention provides more accurate evaluation of RR characteristics using less time and resources.

Advantages:
• Rolling Resistance characteristics estimation of a compound based on generic UTM testing.
• Much shorter times to Rolling Resistance characterization of a compound compared to conventional methods is achieved.
• Expensive/special purpose machineries and resources for operating the same are eliminated.

Although, the invention has been described and illustrated with respect to the exemplary embodiments thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omissions and additions may be made therein and thereto, without parting from the spirit and scope of the present invention. ,CLAIMS:WE CLAIM:
1. A method of characterizing Rolling Resistance property of a test compound, comprising:
testing of a compound on a Universal Testing Machine (UTM) using a standard dumbbell specimen;
removing Mullin’s effect by repeated loading up to 100% strain for 25 cycles, wherein the rate of repeated loading is 500 mm/minute;
removing the dumbbell specimen and relaxing the dumbbell specimen for 2 minutes;
reloading the dumbbell specimen on the UTM and testing for Stress vs Strain;
extracting the Stress-Strain data from the dumbbell specimen;
calculating the value of the UTM data by obtaining the derivative of the Stress-Strain data and averaging it over 20% to 30% strain values;
testing the Coefficient of Rolling Resistance (CRR) on a standard drum; and
measuring correlations of Rolling Resistance values of actual tires on a lab drum,
wherein an inverse correlation exists between the UTM data and the CRR values.

2. The method of characterizing Rolling Resistance property of a test compounds as claimed in claim 1, wherein the test compound comprises elastomeric compound, rubber compound and the like.