JP6415951B2 - Tire performance evaluation method, tire performance evaluation apparatus, and tire performance evaluation program - Google Patents

Description

  The present invention relates to a tire performance evaluation method, a tire performance evaluation device, and a tire performance evaluation program.

  Conventionally, a method using a finite element method is known as a tire performance evaluation method (see Patent Documents 1 to 4). In this method, a tire model is approximated by a plurality of small elements, characteristics such as elastic modulus are set for each element, and boundary conditions such as internal pressure and friction coefficient are set for the tire model. Then, a calculation for rolling the tire model on the road surface model is performed to obtain a contact pressure distribution, a shear stress distribution, and the like. The results obtained are fed back to the tire design and used to improve the tire design.

JP 2003-294586 A JP 2006-76404 A JP 2012-37280 A JP 2004-189205 A

  However, in the conventional evaluation method, the contact pressure distribution and shear stress distribution of the entire contact surface of the tire are obtained, and the behavior of each fine part of the tire (for example, the center rib and shoulder rib) and the burden ratio of physical quantity, etc. Did not see. Therefore, the evaluation results could not be sufficiently fed back to the tire design.

  Then, this invention makes it a subject to provide the tire performance evaluation method, tire performance evaluation apparatus, and tire performance evaluation program which can know the burden ratio etc. of the physical quantity for every fine part of a tire.

The tire performance evaluation method according to the embodiment includes a step of classifying each part on a contact surface of a tire model, which is a finite element model, into one of a plurality of groups, and contacting the tire model with a road surface model by a finite element method. Analyzing the behavior, obtaining a physical quantity of each node of the tire model, classifying each node of the contact surface of the tire model as either an adhesive region or a sliding region, the same group and the same region And adding the physical quantities of the nodes classified into (1) to determine the behavior or the share of physical quantity for each part of the same group and the same area .

Further, the tire performance evaluation apparatus according to the embodiment includes a grouping unit that classifies each part on the contact surface of the tire model, which is a finite element model, into one of a plurality of groups, and the tire model is grounded to the road surface model to be finite. Same as the behavior analysis unit for analyzing the behavior by the element method and obtaining the physical quantity of each node of the tire model, and the classification unit for classifying each node of the contact surface of the tire model as either an adhesive region or a slip region An integration unit that integrates the physical quantities of the nodes classified into the group and the same region, respectively , and obtains a behavior or a share of the physical quantity for each part of the same group and the same region .

Further, the tire performance evaluation program of the embodiment is based on the result of the behavior analysis by the finite element method performed by bringing the tire model, which is a finite element model, into contact with the road surface model. Or a physical quantity as a result of the behavior analysis, and a physical quantity of a node in each group in which each part on the ground contact surface of the tire model is classified. And calculating a burden ratio of the behavior or physical quantity for each part of the same group and the same region .

  According to the tire performance evaluation method, the tire performance evaluation device, and the tire performance evaluation program of the embodiment, it is possible to know the burden ratio of the physical quantity for each fine portion of the tire.

The block diagram of the tire performance evaluation apparatus 1 of this embodiment. The flowchart of the tire performance evaluation method of embodiment. The perspective view of a three-dimensional tire model. The figure which shows the adhesion area | region and sliding area | region of the ground-contact surface of a tire. An example in which physical quantities are accumulated and displayed for each group and area. Another example in which physical quantities are accumulated and displayed for each group and area.

  FIG. 1 shows a tire performance evaluation apparatus 1 that implements the tire performance evaluation method described below. The tire performance evaluation apparatus 1 includes a tire model creation unit 10 that creates a tire model, a road surface model creation unit 11 that creates a road surface model, and a grouping unit 12 that groups the created tire models into parts as described later. The behavior analysis unit 13 that performs behavior analysis as described later, the classification unit 14 that classifies the nodes of the tire model into the adhesion region or the slip region as described later, and the behavior analysis by the behavior analysis unit 13 are obtained. And an accumulating unit 15 for accumulating the physical quantities of the nodes for each group and each region.

  Each of these units is realized by causing the processor of a computer including a processor, a hard disk, a memory, a keyboard, a mouse, a display, and the like to execute a program.

  When the program executes a tire performance evaluation method described below, the program is stored in, for example, a hard disk included in the computer or a removable recording medium such as a CD-ROM. For example, the processor reads and executes the programs stored in these.

  The tire performance evaluation method of this embodiment will be described based on the flowchart of FIG.

  First, in ST1, as illustrated in FIG. 3, based on various conditions (tire shape, material physical properties such as Young's modulus and Poisson's ratio of tire constituent members) for tire model creation input to the tire model creation unit 10. A three-dimensional tire model. This tire model is a finite element model to be analyzed by the finite element method, and is divided into a plurality of elements and has nodes at the vertices of these elements. As a detailed method of creating the finite element model, a known method may be used.

  Generally, a tread pattern is formed on a tire model. Although the tread pattern is not limited, for example, a main groove extending in the tire circumferential direction is provided, and a plurality of ribs extending in the same direction are formed so as to be separated by the main groove and aligned in the tire width direction. Further, for example, a main groove extending in the tire circumferential direction and a lateral groove extending in the tire width direction are provided, and a plurality of blocks are formed so as to be aligned in the tire circumferential direction and the tire width direction, separated by these grooves. However, a tread pattern may not be formed.

  Next, in ST2, the grouping unit 12 classifies each part on the contact surface of the tire model created in ST1 into one of a plurality of groups. Here, the definition of “part” as a unit of grouping is arbitrary. For example, a grounding surface of one rib may be defined as one part, and a grounding surface of one block may be defined as one part. Further, one rib or block may be divided into finer parts, and the ground contact surface of each part may be defined as a part. Moreover, you may define a site | part by the distance from a tire grounding end.

  The grouping method is also arbitrary. For example, when the ground contact surface of one rib is one part, the ground contact surface of one rib may be classified into one group, or the ground contact surfaces of two or more ribs (for example, two shoulder ribs) may be classified. You may classify into one group.

  This grouping may be performed after the behavior analysis described below, but it is desirable from the viewpoint of ease of processing that the boundary conditions are set and the behavior analysis is performed.

  Next, in ST3, various boundary conditions are set. Boundary conditions include tire internal pressure, load applied to the tire, coefficient of friction between the tire and the road surface, rim assembly conditions, slip angle, travel speed, and the like.

  The actual coefficient of friction varies depending on the pressure between the tire and the road surface and the slipping speed of the tire. Therefore, in ST3, it is desirable to set the friction coefficient as a function of pressure and sliding speed. For example, the relationship between the friction coefficient, the pressure, and the sliding speed is obtained in advance by experiments or the like, and a table of friction coefficients is created and set with the pressure being used and the sliding speed being the column. For the friction coefficient of pressure and sliding speed that do not exist in the table, substitute the nearest friction coefficient of pressure and sliding speed, or obtain the approximate expression from the friction coefficient, pressure, and sliding speed values in the table. You may set so that it may calculate from a type | formula. However, the coefficient of friction may be a constant value that does not depend on pressure or sliding speed.

  In ST3, the friction coefficient is initially set to a constant (for example, 0), an inflation analysis is performed (analysis of the deformation of the tire when an internal pressure is applied), and then a friction coefficient depending on the pressure and the sliding speed is set. May be.

  Next, in ST4, the behavior analysis unit 13 performs behavior analysis by the finite element method. For example, by applying a brake or turning the rudder, it is reproduced that a force in the front-rear direction or the lateral direction is applied to the tire pressed against the road surface, and the behavior of the tire at that time is analyzed. In the analysis, as time passes, physical quantities such as contact pressure and sliding speed at each node are determined. Specific methods of behavior analysis include dynamic rolling analysis using an explicit solution method, quasi-static analysis using an implicit method, and steady-state transport analysis (Lagrange / Euler mixed method). In a detailed analysis focusing on the contact surface behavior as in this embodiment, it is desirable to use an implicit method that is excellent in solution stability.

  The road surface model to which the tire model is pressed in the behavior analysis is a finite element model similar to the tire model, and is created by the road surface model creation unit 11 before the behavior analysis. The road surface model may be a rigid plane, or a road surface with a special road surface condition (for example, an uneven state or a wet state) may be set.

  As a result of this behavior analysis, the node number and the physical quantity of each node are output. There are various physical quantities, and examples include shear stress, contact pressure, sliding speed, area allocated to nodes, and the like.

  Next, in ST5, the classification unit 14 classifies each node on the ground contact surface into one of an adhesive region and a slip region. Here, the adhesion region is a region of the tire contact surface that is determined not to slip on the road surface. The slip region is a region where it is determined that the tire is slipping with respect to the road surface.

  The classification of each node of the ground contact surface into the adhesion region or the slip region is performed based on, for example, the sliding speed (speed of the node with respect to the road surface) obtained in ST4. Specifically, an allowable slip speed γ defined by the following equation is used as a classification criterion. When the sliding speed of the node is lower than the allowable sliding speed γ, the node is classified as an adhesive region. On the other hand, when the sliding speed of the node is higher than the allowable sliding speed γ, the node is classified into the sliding region. When the sliding speed of the node coincides with the allowable sliding speed γ, it is arbitrary whether the node is classified into the sliding area or the adhesive area.

Here, f is an arbitrarily determined slip tolerance value, ω is an angular velocity of rotation of the tire, and R is an effective radius of the tire (a distance from the rotation center of the tire to the road surface). Note that ω × R coincides with the rolling speed of the tire (a distance that the tire travels per unit time by its rotation when it is assumed that the tire does not slip on the road surface). When the brake is applied to the tire, the rolling speed of the tire changes with the passage of time, so that the allowable slip speed γ also changes with the passage of time.

  As a specific example, let us consider a case where the slip tolerance value f is 0.02 and the tire rolling speed is 40 km / hour. At this time, the allowable slip speed γ is 444 mm / sec. Therefore, when the sliding speed of the node is lower than 444 mm / sec, the node is classified into the adhesive region. Further, when the sliding speed of the node is higher than 444 mm / second, the node is classified into the sliding region.

  Thus, when each node is classified into the adhesion area or the sliding area, the ground contact surface of the tire is divided into an adhesion area and a sliding area as shown in FIG.

  Finally, in ST6, the accumulating unit 15 classifies the nodes for each group and for each region, and accumulates the physical quantities of the respective nodes within the classified range. That is, the integration of the physical quantities of a plurality of nodes classified into the same group and the same region is performed for each region of each group. The physical quantity is the physical quantity output in ST4. The group is a group classified in ST2, and the region is an adhesive region or a sliding region classified in ST5. Then, the integration result of the physical quantity for each group and for each area is displayed on a display device such as a display.

  As a display example, a case where a relationship between a slip ratio and a braking force of a tire model having four ribs is observed, and a contact surface of each of the four ribs is classified into a group of RIB1 to RIB4.

  In this case, in ST2, each node on the contact surface of the tire model is classified as one of four groups (ribs). In ST5, each node is classified as being included in any region (adhesion region or slip region) at each slip rate. Therefore, in ST6, the magnitudes of braking forces of a plurality of nodes classified into each group and each region at each slip rate are integrated. The result is displayed as shown in FIG. 5 where the horizontal axis represents the slip ratio and the vertical axis represents the braking force.

  A curve p in FIG. 5 shows a change in braking force in the entire tire. A curve q represents a change in braking force generated in the adhesion region of the tire. Accordingly, the height of the curve q indicates the magnitude of the braking force generated in the tire adhesion region at the slip rate, and the height of the portion sandwiched between the curve q and the curve p indicates the tire slip region at the slip rate. The magnitude of the braking force generated at is shown. Further, the height of each region indicated by RIB1 to RIB4 in FIG. 5 indicates the magnitude of the braking force generated at each rib at the slip rate. In this way, it is possible to know the magnitude of the braking force generated in each region of each group and their changes accompanying changes in the slip ratio. Incidentally, FIG. 4 shows the classification of the adhesion region and the slip region at the slip rate of 5% in FIG.

  The slip ratio is the ratio of the difference between the tire forward speed and the rolling speed to the tire forward speed, and the smaller this is, the closer the tire forward speed and the tire rolling speed are. When the tire is slipping without rotating, the slip ratio is 100%, and when the tire forward speed is the same as the tire rolling speed, the slip ratio is 0%. The braking force is a shear stress in the front-rear direction when the rolling tire is braked.

  As another display example, the relationship between the slip angle of a tire model having four ribs and the cornering force (lateral shear stress when turning a rolling tire) is examined. A case where the ground contact surface of each rib is classified into a group of RIB1 to RIB4 will be given.

  Also in this case, in ST2, each node of the contact surface of the tire model is classified as one of four groups (ribs). In ST5, each node is classified as being included in any region (adhesion region or slip region) at each slip rate. In ST6, the cornering forces of the plurality of nodes classified into each group and each region at each slip angle are integrated. The result is displayed as shown in FIG. 6 where the horizontal axis represents the slip angle and the vertical axis represents the cornering force.

  A curve p in FIG. 6 shows a change in cornering force in the entire tire. A curve q indicates a change in cornering force that occurs in the adhesion region of the tire. Therefore, the height of the curve q indicates the size of the cornering force generated in the adhesion region of the tire at the slip angle, and the height of the portion sandwiched between the curve q and the curve p indicates the slip of the tire at the slip angle. The size of the cornering force generated in the area is shown. Moreover, the height of each area | region shown by RIB1-RIB4 of FIG. 6 has shown the magnitude | size of the cornering force which generate | occur | produces with each rib in the slip angle. Thus, it is possible to know the size of the cornering force generated in each region of each group, and the change associated with the change in the slip angle.

  Of the above steps, steps ST1 to ST4 can be performed with finite element analysis software, and steps ST5 to ST6 can be performed with another analysis software.

  The result obtained by the above method is fed back to the tire design, and based on this, the tire design is improved.

  In such a tire performance evaluation method, it is possible to know the burden ratio of the behavior and the physical quantity for each fine portion of the tire, specifically, for each group and each region. Therefore, the evaluation results can be fully utilized by feeding them back to the tire design.

  For example, if the plurality of ribs arranged in the tire width direction are classified into groups in the step ST2 above, for example, the burden ratio of the physical quantity between the center rib and the shoulder rib can be known, and the analysis result can be obtained as the shape of the rib or groove. Can be used for design.

DESCRIPTION OF SYMBOLS 1 ... Tire performance evaluation apparatus, 10 ... Tire model preparation part, 11 ... Road surface model preparation part, 12 ... Grouping part, 13 ... Behavior analysis part, 14 ... Classification part, 15 ... Accumulation part

Claims (4)

Classifying each part on the contact surface of the tire model, which is a finite element model, into one of a plurality of groups;
The tire model is grounded to the road surface model and analyzed by a finite element method, and the physical quantity of each node of the tire model is obtained;
Classifying each node of the contact surface of the tire model as either an adhesive region or a sliding region;
Adding the physical quantities of the nodes classified into the same group and the same area, respectively , and determining the behavior or physical quantity burden ratio for each part of the same group and the same area ;
Tire performance evaluation method including   The tire performance evaluation method according to claim 1, wherein the tire model is classified into groups for each of a plurality of parts arranged in the tire width direction of the tire model. A grouping unit that classifies each part on the contact surface of the tire model, which is a finite element model, into one of a plurality of groups;
A behavior analysis unit for grounding the tire model on a road surface model and analyzing a behavior by a finite element method to obtain a physical quantity of each node of the tire model;
A classification unit for classifying each node of the contact surface of the tire model as either an adhesive region or a sliding region;
Accumulating units that respectively calculate the physical quantity of each node classified into the same group and the same area, and determine the behavior or physical quantity burden ratio for each part of the same group and the same area ;
A tire performance evaluation apparatus comprising: Classifying each node of the contact surface of the tire model as either an adhesion region or a slip region based on the result of a behavior analysis by a finite element method performed by contacting a tire model that is a finite element model to a road surface model; and ,
The physical quantity as a result of the behavior analysis, the physical quantity of the nodes in each group in which each part on the contact surface of the tire model is classified and the nodes in each region are respectively integrated , and the same group and the same A step of determining a behavioral ratio or a physical quantity burden ratio for each part of the region ;
Tire performance evaluation program for causing a computer to execute processing including