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Tire having a model-based description enabling determination of road handling characteristics

  • US 20010020386A1
  • Filed: 04/26/2001
  • Published: 09/13/2001
  • Est. Priority Date: 04/07/1998
  • Status: Active Grant
First Claim
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1. Method for determining the road handling of a tire of a wheel for a vehicle, said tire being comprised by selected mixes of rubber and reinforcing materials, said method comprising:

  • a) a first description of said tire by means of a first, concentrated-parameter, physical model, said first physical model comprising a rigid ring which represents the tread band provided with inserts, a belting structure and corresponding carcass portion of said tire, a disk which represents a hub of said wheel and beading of said tire, principal springs and dampers connecting said rigid ring to said hub and representing sidewalls of said tire and air under pressure inside said tire, supplementary springs and dampers representing deformation phenomena of said belting structure through the effect of a specified vertical load and a brush model simulating physical phenomena in an area of contact between said tire and a road, said area of contact having a dynamic length 2a, b) a definition of selected degrees of freedom of said first physical model, and c) an identification of equations of motion suitable for describing the motion of said first physical model under selected dynamic conditions, characterized in that it comprises d) the definition of said concentrated parameters, said concentrated parameters consisting of the mass Mc and a diametral moment of inertia Jc of said rigid ring, the mass Mm and a diametral moment of inertia Jm of said disk, structural stiffnesses Kc and structural dampings Rc respectively of said principal springs and dampers, and residual stiffnesses Kr and residual dampings Rr respectively of said supplementary springs and dampers, wherein said structural stiffnesses Kc consist of lateral stiffness Kcy between said hub and said belt, camber torsional stiffness K

    x
    between said hub and said belt and yawing torsional stiffness K

    z
    between said hub and said belt, said structural dampings Rc consist of lateral damping Rcy between said hub and said belt, camber torsional damping R

    x
    between said hub and said belt and yawing torsional damping R

    z
    between said hub and said belt, said residual stiffnesses Kr consist of residual lateral stiffness Kry, residual camber torsional stiffness K

    x
    and residual yawing torsional stiffness K

    z
    , and said residual dampings Rr consist of residual lateral damping Rry, residual camber torsional damping R

    x
    and residual yawing torsional damping R

    z
    , e) a description of said tire by means of a second, finite-element model comprising first elements with a selected number of nodes, suitable for describing said mixes, and second elements suitable for describing said reinforcing materials, each first finite element being associated with a first stiffness matrix which is determined by means of a selected characterization of said mixes and each second element being associated with a second supplementary stiffness matrix which is determined by means of a selected characterization of said reinforcing materials, f) a simulation on said second, finite-element model of a selected series of virtual dynamic tests for exciting said second model according to selected procedures and obtaining transfer functions and first frequency responses of selected quantities, measured at selected points of said second model, g) a description of the behaviour of said first physical model by means of equations of motion suitable for representing the above dynamic tests for obtaining second frequency responses of said selected quantities, measured at selected points of said first physical model, h) a comparison between said first and said second frequency responses of said selected quantities to determine errors that are a function of said concentrated parameters of said first physical model, and i) the identification of values for said concentrated parameters that minimize said errors so that said concentrated parameters describe the dynamic behaviour of said tire, j) the determination of selected physical quantities suitable for indicating the drift behaviour of said tire, and k) the evaluation of the drift behaviour of said tire by means of said physical quantities.

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