Patent ID: 6338270
Filing Date: 2002-01-15
Classification: B60C,G01M,G06F

Abstract:
Method for determining the road handling of a tire of a wheel for a vehicle, said tire comprising selected mixes of rubber and reinforcing materials, said method comprising:describing said tire by means of a first, concentrated-parameter, physical model, said first physical model comprising a rigid ring representing a tread band provided with inserts, a belting structure and corresponding carcass portion of said tire, a disk representing 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 an 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; defining selected degrees of freedom of said first physical model; identifying equations of motion suitable for describing motion of said first physical model under selected dynamic conditions; defining the concentrated parameters, said concentrated parameters comprising mass Mc and a diametral moment of intertia Jc of said rigid ring, 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 comprise lateral stiffness Kcy between said hub and said belt, camber torsional stiffness Kc0x between said hub and said belt, and yawing torsional stiffness Kc0z between said hub and said belt, said structural dampings Rc comprise lateral damping Rcy between said hub and said belt, camber torsional damping Rc0x between said hub and said belt, and yawing torsional damping Rc0z between said hub and said belt, said residual stiffnesses Kr comprise residual lateral stiffness Kry, residual camber torsional stiffness Kr0x, and residual yawing torsional stiffness Kr0z, and said residual dampings Rr comprise residual lateral damping Rryâ€² residual camber torsionl damping Rr0x, and residual yawing torsional damping Rr0z, describing 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 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 stiffness matrix, which is determined by means of a selected characterization of said reinforcing materials, performing a simulation on said second, finite-element model using 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, describing the behavior of said first physical model by means of equations of motion suitable for representing the dynamic tests and obtaining second frequency responses of said selected quantities, measured at selected points of said first physical model, comparing 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 identifying values for said concentrated parameters that minimize said errors so that said concentrated parameters describe the dynamic behavior of said tire, determining selected physical quantities suitable for indicating the drift behavior of said tire, and evaluating the drift behavior of said tire by means of said physical quantities.