Conference Paper

Physical Modeling of a Dynamic Dial Indicator for the Non-Destructive Evaluation of Tire Tread Viscoelastic Characteristics

Conference Paper

Physical Modeling of a Dynamic Dial Indicator for the Non-Destructive Evaluation of Tire Tread Viscoelastic Characteristics

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Abstract

The evaluation of the tire tread viscoelastic characteristics, especially by means of non-destructive procedures, is a particularly interesting topic for motorsport teams and companies, used to work with unknown and confidential compounds. The availability of such information would define new scenarios in vehicle analysis field, as the possibility to provide physical inputs to tire grip models or the study of the suspensions setup able to make tires work inside their optimal thermal working range. The employment of commercial devices allows to select by means of specific indices the optimal combination of tires to be installed on a vehicle, but it does not provide any information physically correlated with the tread polymers characteristics. The aim of the presented activity is the modelling of one of the cited devices, a dynamic dial indicator, interacting with a viscoelastic half-space. The obtained results allow, analyzing the signals acquired by the device, to identify the tread equivalent stiffness and damping as a function of tire working temperature, providing the basic guidelines for the development of an innovative procedure for a full non-destructive viscoelastic characterization of the tire compounds. Index Terms-Material non-destructive characterization, temperature effect, tire tread compound behavior, TSD, viscoelastic characteristics.

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... Hence, a real-time compounds characterization, which could be performed by means of a portable device [2], allows engineers to analyse directly the effects due to tire heating and cooling [3,14,15], tread wear [16,17], aging or winter and summer season compound choice on road so that the safety and handling performances can be improved by taking into account tire viscoelastic behaviour in friction coefficient evaluation for vehicle dynamics onboard algorithms. ...
... From this point of view, the current work is an experimental analysis of the tire tread response in the above-mentioned working conditions evaluated by a commercial dial indicator, which is developed with the commercial aim to provide a distinction criterion among the tires by means of particular indices based on the analysis of the measured signal [2]. ...
... Firstly, the device has been fully characterised before performing the experimental session shown in this work. Particularly, the mass of the indenter m TSD has been evaluated by means of the analysis of rod displacement curve in no-contact range and the determination of the stiffness of the spring k TSD measuring the normal load through a load cell [2]. These magnitudes are very important for the evaluation of compound indexes linked to viscoelastic behaviour. ...
Chapter
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The knowledge of tires tread viscoelastic behaviour plays a fundamental role in automotive to optimize vehicle performance and safety. These properties are usually characterized by means of Dynamic Mechanical Analysis [1] which implies the testing of compound sample that can be obtained by destroying the tire of interest or manufactured in different condition respect to the final product provided by tiremakers. Nowadays, the non-destructive analysis procedures are an attractive solution. These techniques are essentially advantageous for being employed in testing the whole tire, allowing the analysis of a great number of them without affects costs. The purpose of this work is the experimental analysis of the tire tread response, in different working condition, evaluated by a commercial dial indicator [2] considering the measured displacement values of the device. Experimental tests have been carried out on different tread compounds and, being the tire performance strictly affected by the working temperature, additional tests have been performed by heating and cooling each sample in a range of interest [3, 4]. Moreover, the effects of aging on a tire has been studied. The comparison of the testing activity results shows the reliability of the dynamic dial indicator to capture the tires tread different behaviour within the operating condition of interest. These encouraging results lead to next step of the research activity which will focus on the evaluation of properties characterizing the hysteretic behaviour of tires.
... For these reasons, the development of innovative methodologies, as well as the nondestructives, are an attractive solution replacing the standard test methods involving complex and expensive benches for the investigation of a compound specimen manufactured in different conditions respect to the final product provided by tiremakers [7]. Further, Motorsport racing teams use to face with the restrictions due to the employment of confidential tires and not available to invasive testing. ...
Chapter
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The evaluation of the viscoelastic properties is a key topic for the analysis of the dynamic mechanical behaviour of polymers. In vehicle dynamics field, the knowledge of the viscoelasticity of tread compound is fundamental for tire-road contact mechanics modelling and friction coefficient prediction for the improvement of vehicle performance and safety, i.e. motorsport field. These properties are usually characterised by means of Dynamic Mechanical Analysis, which implies testing a compound sample obtained by destroying the tire of interest or a slab manufactured in different conditions respect to the final product provided by tiremakers. In this scenario, the non-destructive procedures are an advantageous solution for the analysis of the tread viscoelasticity, without affecting the tire integrity, allowing a great number of tests in the shortest possible time. For this reason, the authors propose an innovative instrument, called VESevo, for viscoelasticity evaluation by means of non-destructive and user-friendly technique. The purpose of the following work is the preliminary analysis of the dynamic response of the tires tested employing the VESevo in order to determine viscoelastic behaviour indexes for mechanical properties evaluation.
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Comparative test of the effect on wet ice friction of adding a special aggregate in the tread rubber of a retreaded M+S tyre type
  • O Nordström
Nordström O., "Comparative test of the effect on wet ice friction of adding a special aggregate in the tread rubber of a retreaded M+S tyre type", Linköping: Statens väg-och transportforskningsinstitut, VTI notat 15A-2001, 2001.