MODEL-BASED METHOD FOR DETERMINING THE ROAD HANDLING PERFORMANCE OF A TYRE OF A WHEEL FOR A VEHICLE
First Claim
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 Kcθ
x between said hub and said belt and yawing torsional stiffness Kcθ
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 Rcθ
x between said hub and said belt and yawing torsional damping Rcθ
z between said hub and said belt, said residual stiffnesses Kr consist of residual lateral stiffness Kry, residual camber torsional stiffness Krθ
x and residual yawing torsional stiffness Krθ
z, and said residual dampings Rr consist of residual lateral damping Rry, residual camber torsional damping Rrθ
x and residual yawing torsional damping Rrθ
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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Abstract
A method for determining the road handling of a tire, comprising descriptions of the tire by means of a first, concentrated-parameter, physical model and by means of a second, finite-element model, a simulation on the second, finite-element model of a selected series of dynamic tests and an application to the first physical model of equations of motion suitable for representing the dynamic tests in order to obtain first and second frequency responses of selected quantities; a comparison between the first and second frequency responses of the selected quantities for determining the concentrated parameters of the first physical model and physical quantities indicative of the drift behavior of the tire.
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Citations
13 Claims
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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:
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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 Kcθ
x between said hub and said belt and yawing torsional stiffness Kcθ
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 Rcθ
x between said hub and said belt and yawing torsional damping Rcθ
z between said hub and said belt,said residual stiffnesses Kr consist of residual lateral stiffness Kry, residual camber torsional stiffness Krθ
x and residual yawing torsional stiffness Krθ
z, andsaid residual dampings Rr consist of residual lateral damping Rry, residual camber torsional damping Rrθ
x and residual yawing torsional damping Rrθ
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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. Tire for a wheel of a vehicle, said tire being made from selected mixes of rubber and reinforcing materials and comprising a carcass, a belting structure, a tread band provided with inserts, shoulders, sidewalls, beads provided with bead wires and bead fillings, said tire being representable by means of a first, concentrated-parameter, physical model and a brush model with a road, characterized in that said concentrated parameters comprise structural stiffnesses Kc consisting of lateral stiffness Kcy, camber torsional stiffness Kcθ
- x and yawing torsional stiffness Kcθ
z, structural dampings Rc consisting of lateral damping Rcy, camber torsional damping Rcθ
x and yawing torsional damping Rcθ
z, residual stiffnesses Kr consisting of residual lateral stiffness Kry, residual camber torsional stiffness Krθ
x and residual yawing torsional stiffness Krθ
z, and residual dampings Rr consisting of residual lateral damping Rry, residual camber torsional damping Rrθ
x and residual yawing torsional damping Rrθ
z,said tire also being representable 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, said concentrated parameters being identified by means of a selected series of dynamic tests on said second, finite-element model and represented by equations of motion applied to said first physical model, said tire having construction characteristics substantially equivalent to said concentrated parameters which describe the dynamic behaviour of said tire and enabling the determination of selected physical quantities suitable for indicating the drift behaviour of said tire for evaluation of said tire in relation to its road handling. - View Dependent Claims (11, 12, 13)
- x and yawing torsional stiffness Kcθ
Specification