JP2014074688A - Tire performance simulation method and tire performance simulation program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately predict tire performance on ice.SOLUTION: A tire performance simulation method includes steps of: setting a tire model by dividing at least a part of a tire into finite number of elements; setting an on-ice road surface model representing an on-ice road surface; setting a plurality of calculation points on a contact surface of the on-ice road surface with at least a part of the tire; calculating, about each of the plurality of calculation points, frictional energy of friction which generates when at least a part of the tire moves on the on-ice road surface; calculating, about each of the plurality of calculation points, a road surface temperature at each of the calculation points after at least a part of the tire moves on the on-ice road surface on the basis of an initial temperature and the frictional energy at the calculation points before at least a part of the tire is brought into contact with the on-ice road surface; and extracting a region whose temperature is equal to or more than the melting point of ice on the contact surface on the basis of the road surface temperatures of the plurality of calculation points.

Description

  The present invention relates to a tire performance simulation method, a tire performance simulation apparatus, and a tire performance simulation program, and more particularly to a tire performance simulation method and a tire performance simulation program for analyzing tire performance by a finite element method.

  Conventionally, as a method for simulating tire performance, the tire to be evaluated is approximated by a tire finite element model obtained by dividing a tire into a finite number of elements, and characteristics such as density and elastic modulus are given to each finite element. The Finite Element Method (Finite Element Method) is often used to give boundary conditions such as internal pressure and load to a model and calculate the deformation state of each of the above elements to numerically analyze the tire dynamics such as tire deformation and rolling resistance. ing.

  Further, a technique for simulating tire performance in consideration of friction between the tire and the road surface when simulating tire performance has been proposed (for example, see Patent Document 1).

JP 2003-294586 A

  However, in the above prior art, for example, the melting of water due to friction with the tire on the ice as in the case where the road surface is frozen is not taken into consideration, and therefore the tire performance on the ice cannot be accurately simulated.

  The present invention has been made in view of the above facts, and an object of the present invention is to provide a tire performance simulation method and a tire performance simulation program capable of accurately predicting tire performance on ice.

  In order to achieve the above object, a tire performance simulation method according to a first aspect of the present invention includes a step of setting a tire model in which at least a part of a tire is divided by a finite number of elements, and an on-ice road surface model representing an on-ice road surface. A step of setting, a step of setting a plurality of calculation points on a contact surface of the icy road surface with at least a part of the tire, and for each of the plurality of calculation points, at least a part of the tire is on the icy road surface Calculating the friction energy of the friction generated when the vehicle moves, and for each of the plurality of calculation points, the initial temperature and the friction at the calculation points before at least a part of the tire is in contact with the road surface on ice. And the road surface temperature at the calculation point after at least a part of the tire moves on the road surface on ice based on energy. A step of calculation, based on the road surface temperature of the plurality of calculation points, characterized in that it comprises the steps of: extracting a temperature comprised range above the melting point of ice of the contact surface.

  According to a second aspect of the present invention, the method may further include a step of calculating a contact surface characteristic related to the contact surface based on a region above the melting point of the ice and a region below the melting point of the ice.

  According to a third aspect of the present invention, the contact surface characteristic may be a coefficient of friction on the contact surface.

  The tire performance simulation program of the invention according to claim 4 sets a tire model in which at least a part of a tire is divided by a finite number of elements in a computer, a step of setting an on-ice road surface model representing an on-ice road surface, A step of setting a plurality of calculation points on a contact surface of the icy road surface with at least a part of the tire; and for each of the plurality of calculation points, when at least a part of the tire moves on the icy road surface Calculating the friction energy of the generated friction, and for each of the plurality of calculation points, based on the initial temperature and the friction energy at the calculation point before at least a part of the tire contacts the road surface on ice. Calculating the road surface temperature at the calculation point after at least a part of the tire has moved on the road surface on ice. A step that, based on the road surface temperature of the plurality of calculation points, characterized in that to execute a process including the steps of extracting a region to be a temperature higher than the melting point of the ice out of the contact surface.

  According to the present invention, there is an effect that the tire performance on ice can be accurately predicted.

It is a schematic block diagram of a computer. It is a flowchart of a tire performance simulation program. It is a figure for demonstrating generation | occurrence | production of a water film. It is a figure for demonstrating the temperature of an ice surface when a tread block moves on an ice surface. It is a figure which shows an example of a simulation result. It is a figure which shows an example of a simulation result.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a configuration of a computer 12 as a tire performance simulation apparatus for creating, designing, and analyzing performance of a tire model of a pneumatic tire as an example. The computer 12 executes creation of a three-dimensional tire model, analysis of tire performance, design, and the like according to a processing program stored in advance.

  As shown in FIG. 1, the computer 12 includes a CPU (Central Processing Unit) 12A, a ROM (Read Only Memory) 12B, a RAM (Random Access Memory) 12C, a non-volatile memory 12D, and an input / output interface (I / O) 12E. Are connected to each other via a bus 12F.

  The I / O 12E includes a keyboard 10 for inputting data, a display 14 for displaying calculation results and various screens by the computer 12, a cursor displayed on the display 14 is moved to a desired position, a cursor position A mouse 16, a hard disk 18, and a CD-ROM drive 22 into which a CD-ROM as a recording medium can be inserted and removed are connected for selecting, deselecting and dragging menu items and objects. .

  The hard disk 18 stores a tire performance simulation program, which will be described later, and various parameters and data necessary for the execution thereof. The CPU 12A reads and executes a tire performance simulation program stored in the hard disk 18.

  Note that a tire performance simulation program, which will be described later, can be read from and written to the CD-ROM using, for example, the CD-ROM drive 22, so that the tire performance simulation program, which will be described later, is recorded in advance on the CD-ROM. In addition, the tire performance simulation program recorded on the CD-ROM via the CD-ROM drive 22 may be read and executed. Further, the recording medium is not limited to the CD-ROM, but includes an optical disk such as a DVD-ROM and a magneto-optical disk such as an MD or MO. A DVD-ROM drive, MD drive, MO drive or the like may be used.

  Next, as a function of the present embodiment, a processing routine of a tire performance simulation program executed by the computer 12 will be described with reference to a flowchart shown in FIG.

  First, in step 100, a tire model is set. The tire model may be created in this step, or may be set by storing already created tire model data in the hard disk 18 and reading it out.

  The creation of the tire model differs slightly depending on the numerical analysis method used. As a numerical analysis method, for example, a finite element method (FEM) can be used. In this case, the tire model is divided into a plurality of elements by element division corresponding to the finite element method (FEM), that is, mesh division, and the tire is input data to a computer program created based on a numerical / analytical method. This is a numerical value. This element division refers to dividing an object such as a tire and a road surface into several small (finite) small parts, that is, elements. After calculating each element and calculating all the elements, the whole response can be obtained by adding all the elements.

  In creating a tire model, first, a tire radial section model (tire section model) is created. The outer shape of the tire cross-section model can be created, for example, using values obtained by measuring the tire outer shape with a laser shape measuring instrument or the like. In addition, an accurate value such as a design drawing and actual tire cross-section data can be used for the structure inside the tire.

  After the tire cross-section model is created, the tire cross-section model is developed in one round (360 degrees) in the circumferential direction to create a three-dimensional (3D) model of the tire. In this way, a tire model is created.

  In addition, although a tire model may be created about the whole tire, you may create about a part of tire. In the present embodiment, a case where one tread block of the tread portion of the tire is modeled will be described.

  In step 102, an on-ice road surface model representing the on-ice road surface is set. Similarly to the tire model, the on-ice road surface model may be created in this step, or the already created on-ice road surface model data may be stored in the hard disk 18 and read out for setting.

  The road surface is modeled by dividing the road surface shape into elements and modeling the road surface, and selecting and setting the road surface friction coefficient μ. That is, since there is a road friction coefficient μ corresponding to dry (DRY), wet (WET), on ice, snow, non-paved, etc., depending on the road surface condition, by selecting an appropriate value for the friction coefficient μ, The road surface condition can be reproduced. In the present embodiment, an on-ice road surface model is set by setting the friction coefficient μ of ice.

  In step 104, a plurality of calculation points are set on the contact surface with the tire (the tread block) on the road surface on ice. The plurality of calculation points are two-dimensionally arranged, for example, so as to be equally spaced in the circumferential direction of the tire and each direction orthogonal to the circumferential direction. The setting of calculation points is not limited to the case where the calculation points are arranged at equal intervals, and the calculation points may be arranged two-dimensionally at non-uniform intervals.

  In step 106, for each of the plurality of calculation points set in step 104, the frictional energy of the friction generated when the tread block moves in a predetermined direction on the road surface on ice is calculated. The friction energy is calculated from the friction coefficient between the ice and the tread block (dynamic friction coefficient), the slip amount of the tread block with respect to the road surface on ice, the sliding speed of the tread block with respect to the road surface on ice, and the like.

  As shown in FIG. 3, when the rubber 30 as the main component of the tire moves on the ice 32 in the direction of the arrow A, first, heat 36 is generated on the contact surface 34 by friction, and the generated heat 36 is iced. Conduct to. As a result, the temperature of the region 38 below the contact surface 34 rises, and the water film 40 is generated in the region where the surface temperature of the ice 32 is 0 ° C. or higher.

  Therefore, in step 108, for each of the plurality of calculation points, the temperature rise from the initial temperature at the calculation point before the tread block contacts the road surface on ice is calculated based on the friction energy calculated in step 106. This rising temperature is calculated based on the thermal conductivity of ice, the heat ratio of ice, the melting energy, and the like.

  In step 110, for each of the plurality of calculation points, the road surface temperature at the calculation point after the tread block moves on the road surface on ice is calculated. This road surface temperature is calculated by adding the rising temperature calculated in step 108 to the initial temperature at the calculation point before the tread block contacts the icy road surface.

  As shown in FIG. 4, when the tread block 50 is moved in the arrow B direction with the tread block 50 in contact with the icy road surface 52, the surface temperature of the icy road surface 52 increases from the right side to the left side in FIG. Rise gradually. And when it becomes 0 degreeC or more which is melting | fusing point of ice, ice melts and it becomes water (melting water) 54.

  Therefore, in step 112, based on the road surface temperature at a plurality of calculation points, a region having a temperature equal to or higher than the melting point of ice, that is, 0 ° C. or higher, is extracted from the contact surface with the tread block on the ice surface.

  In step 114, the contact surface related to the contact surface with the tread block on the road surface on ice based on the region above the melting point of ice, that is, the region that has become water, and the region below the melting point of ice, that is, the region that remains ice. Calculate the properties, for example the coefficient of friction of the entire contact surface. Specifically, for example, when the predetermined friction coefficient of the water region is μ1, the predetermined friction coefficient of the ice region is μ2, the area of the water region is S1, and the area of the ice region is S2, the following expression To obtain the friction coefficient μ3 of the entire contact surface.

μ3 = {S1 / (S1 + S2)} × μ1 + {S2 / (S1 + S2)} × μ2

  In step 116, the temperature distribution of the contact surface with the tread block on the road surface on ice is displayed on the display 14. For example, the contact surface may be displayed in two colors, such as a water region and an ice region, or may be displayed in different colors at predetermined temperature increments.

  FIG. 5 shows the result of simulation by the inventor executing the process shown in FIG. In the figure, when the initial road surface temperature is −2 ° C. and the sliding speed of the tread block with respect to the ice surface is 2 km / h, the temperature distribution of the contact surface with the tread block on the ice surface is −2.0 ° C. to 0 °. The range is C or more.

  FIG. 6 shows the temperature distribution of the contact surface with the tread block on the icy road surface when the initial road surface temperature is −2 ° C. and the sliding speed of the tread block with respect to the icy road surface is 10 km / h. It showed in the range of 0 degreeC or more.

  If the area of 0 ° C. or higher shown in FIG. 5, that is, the area of the water area (hatched area hatched) is 100, the area of the water area (hatched area hatched) shown in FIG. 150. In other words, it was found that when the sliding speed is 10 km, the area that becomes water becomes 1.5 times as compared with the case where the sliding speed is 2 km. The measured value of the friction coefficient in the case of FIG. 5 was 0.21, and the measured value of the friction coefficient μ in the case of FIG. 6 was 0.11.

  In this way, the region where water is generated and the region where water is not generated can be ascertained from the temperature distribution, so that the ratio and distribution of these regions can be used for designing the shape of the sipe, the arrangement of the sipe, the shape of the tread block, etc. It becomes possible.

  As described above, in the present embodiment, the frictional energy of friction generated when the tread block moves on the ice surface is calculated for each of a plurality of calculation points set on the contact surface with the tread block on the ice surface. Based on the initial temperature and frictional energy at the calculation point before the tread block contacts the ice surface, the road surface temperature at the calculation point after the tread block moves on the ice surface is calculated. And since the area | region which becomes the temperature more than melting | fusing point of ice is extracted among contact surfaces based on the road surface temperature of a some calculation point, the tire performance on ice can be estimated accurately.

  In this embodiment, the case where the tread block, which is a part of the tire, is moved on the ice surface to calculate the friction energy has been described. However, the entire tire is rolled on the ice surface (free rolling). ), Braking (braking), driving (acceleration), and the friction energy may be calculated.

10 keyboard, 12 computer, 14 display, 16 mouse, 18 hard disk, 22 CD-ROM drive

Claims (4)

Setting a tire model in which at least a part of the tire is divided by a finite number of elements;
Setting an icy road surface model representing the icy road surface;
Setting a plurality of calculation points on a contact surface with at least a part of the tire on the icy road surface;
For each of the plurality of calculation points, calculating a friction energy of friction generated when at least a part of the tire moves on the ice surface;
For each of the plurality of calculation points, based on the initial temperature and the frictional energy at the calculation points before at least a part of the tire contacts the ice road surface, at least a part of the tire is on the ice road surface. Calculating the road surface temperature at the calculation point after moving
Based on the road surface temperature of the plurality of calculation points, extracting a region of the contact surface that has a temperature equal to or higher than the melting point of ice;
A tire performance simulation method including: The tire performance simulation method according to claim 1, further comprising: calculating a contact surface characteristic related to the contact surface based on a region above the melting point of the ice and a region below the melting point of the ice. The tire performance simulation method according to claim 2, wherein the contact surface characteristic is a coefficient of friction at the contact surface. On the computer,
Setting a tire model in which at least a part of the tire is divided by a finite number of elements;
Setting an icy road surface model representing the icy road surface;
Setting a plurality of calculation points on a contact surface with at least a part of the tire on the icy road surface;
For each of the plurality of calculation points, calculating a friction energy of friction generated when at least a part of the tire moves on the ice surface;
For each of the plurality of calculation points, based on the initial temperature and the frictional energy at the calculation points before at least a part of the tire contacts the ice road surface, at least a part of the tire is on the ice road surface. Calculating the road surface temperature at the calculation point after moving
Based on the road surface temperature of the plurality of calculation points, extracting a region of the contact surface that has a temperature equal to or higher than the melting point of ice;
Tire performance simulation program for executing processing including