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Method for determining preselected performance characteristics of a tread of a tire and tire provided with a tread having optimal characteristics with reference to said performance characteristics

  • US 6,539,788 B1
  • Filed: 12/22/1999
  • Issued: 04/01/2003
  • Est. Priority Date: 12/22/1998
  • Status: Expired due to Fees
First Claim
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1. A method for determining preselected performance characteristics of a tread of a tyre, comprising ride comfort, noise, and handling;

  • wherein a longitudinal direction, a transversal direction, and a vertical direction are associated with the tread;

    wherein the tread has a preselected thickness and a preselected circumferential development;

    wherein the tread comprises a preselected rubber compound and blocks and grooves having at least a preselected pitch; and

    wherein each portion of the tread in contact with a road surface comprises a contact area;

    comprising the steps of;

    a) dividing the tread into a 3-D grid of full cells and empty cells of preselected dimensions;

    b) identifying piles of the cells in the grid, each pile of cells having a base area equal to that of a cell and a height equal to the thickness of the tread, the piles of cells being full, partially full, or empty;

    c) identifying a group of the piles of cells present under a contact area;

    d) determining a stiffness value in the longitudinal direction and a stiffness value in the transversal direction for each pile of cells in the contact area;

    e) identifying families of discrete areas in the contact area, each discrete area of each family having preselected dimensions in the longitudinal direction and in the transversal direction;

    f) dividing the contact area in transversal strips with a preselected length in the longitudinal direction, each transversal strip comprising a set of the piles of cells;

    g) determining a stiffness value per unit of length in the longitudinal direction and a stiffness value per unit of length in the transversal direction for each of the transversal strips, by summing the stiffness values in the longitudinal direction and the stiffness values in the transversal direction of the piles of cells of the set, respectively;

    h) assigning a preselected deformation state to each of the transversal strips;

    i) determining at least one force per unit of length associated with each transversal strip by means of a preselected function linking one of the stiffness values and the deformation state;

    j) summing preselected forces per unit of length of all the transversal strips associated with a discrete area to attain at least one preselected single force acting in one of the longitudinal and transversal directions;

    k) determining at least one total force associated with the contact area by means of a suitable summation of preselected single forces associated with all the discrete areas of the contact area, the total force being representative of at least one of the performance characteristics;

    l) repeating the steps from c) to k) for all the portions of the tread which are arranged in succession on the circumferential development and come in contact with the road surface in an entire revolution of the tyre by means of respective contact areas to attain a plurality of total forces associated with all the contact areas of the tread; and

    m) evaluating the pattern of the plurality of total forces to establish whether the arrangement of the full cells and empty cells in the 3-D grid is substantially uniform along the circumferential development and generates total forces with substantially equal and constant values, so as to optimize at least one preselected performance characteristic of the tread.

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