Generation device, generation method and program for space model around tire

Abstract

To improve accuracy in modeling a space around a tire which has influence on audio analysis, in tire testing on a drum, while suppressing increase of memories and of calculation costs.SOLUTION: A generation device 1 for a space model around a tire comprises a grounding analyzing part 44 that performs grounding analysis of a state where a predetermined load is applied on a drum in a predetermined shape, using a tire model, so as to obtain a deformed tire model, and a space model creating part that creates a space model by dividing a predetermined space including a first space formed on a grounding part and a second space in a predetermined shape outside of the tire model into a plurality of elements, on the basis of a grounding shape of the tire model. The space model creating part models a space below an opening between an upper surface of the drum and a flat surface including an edge of an opening of a floor surface for exposing the drum, but does not model an underfloor space between the floor surface and the drum, and sets an audio impedance boundary at an outer edge of the space below the opening.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an apparatus, a method, and a program for generating a spatial model around a tire.

Background Art

[0002] Patent Document 1 describes creating an outer space acoustic model of a tire model in a grounding state based on the analysis result of the grounding deformation of a tire model with a tread pattern, and in this case, modeling a continuous space of the inside of the groove of the tire and the space around it.

[0003] Patent Document 2 describes connecting data on the outer surface of a tire in which a tread model and a body model are connected, data on a road surface, and data on the outermost surface of a space around the tire having a predetermined shape, and generating a tire surrounding space model of a closed space surrounded by these respective data.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In both Patent Document 1 and Patent Document 2, the generation of the spatial model around the tire assumes a smooth road surface as the ground contact surface where the tire touches the ground. On the other hand, during the tire development process, the tire test is often conducted on a drum in an anechoic chamber. Therefore, accurately simulating the situation of this test is also important for improving the actual noise performance of the tire in the generation of the spatial acoustic model around the tire. In particular, in the spatial acoustic model around the tire, the space between the upper surface of the drum and the plane including the floor surface affects the acoustic transmission characteristics in the front-rear direction of the tire. For this reason, it is important to improve the accuracy of the modeling of the space around the tire that affects the acoustic analysis for the tire test on the above drum.

[0006] However, the modeling of the space between the upper surface of the drum and the plane including the floor surface is quite complex and the amount of calculation becomes extremely large. For this reason, the scale of model creation becomes large, and the memory and calculation costs increase.

[0007] An object of the present invention is to improve the accuracy of the modeling of the space around the tire that affects the acoustic analysis for the tire test on the drum while suppressing an increase in memory and calculation costs in a device, method, and program for generating a spatial model around the tire.

Means for Solving the Problem

[0008] The apparatus for generating a spatial model around a tire according to the present invention uses a tire model obtained by dividing a tire into a plurality of elements to perform a grounding analysis on a state in which a predetermined load is applied on a drum having a predetermined shape, and obtains the deformed tire model. The grounding analysis unit and the grounding shape of the tire model are based on the grounding shape of the tire model. A spatial model creation unit that creates a spatial model by dividing a predetermined space including a first space formed in the grounding portion and a second space having a predetermined shape outside the tire model into a plurality of elements, and the spatial model creation unit includes the upper surface of the drum and the floor surface for exposing the drum. The apparatus for generating a spatial model around a tire models the space below the opening between the plane including the edge of the opening of the floor surface, but does not model the space below the floor surface existing between the floor surface and the drum, and sets an acoustic impedance boundary at the outer edge of the space below the opening.

[0009] The method for generating a spatial model around a tire according to the present invention uses a tire model obtained by dividing a tire into a plurality of elements to perform a grounding analysis on a state in which a predetermined load is applied on a drum having a predetermined shape, and obtains the deformed tire model. A step of creating a spatial model by dividing a predetermined space including a first space formed in the grounding portion and a second space having a predetermined shape outside the tire model into a plurality of elements, and the step of creating the spatial model includes the upper surface of the drum and the floor surface for exposing the drum. The method for generating a spatial model around a tire models the space below the opening between the plane including the edge of the opening of the floor surface, but does not model the space below the floor surface existing between the floor surface and the drum, and sets an acoustic impedance boundary at the outer edge of the space below the opening.

[0010] The program according to the present invention is a program for causing a computer to execute the method for generating a spatial model around a tire according to the present invention.

Advantages of the Invention

[0011] According to the apparatus, method, and program for generating a spatial model around a tire according to the present invention, in generating the spatial model, since the space below the opening between the upper surface of the drum and the plane including the edge of the opening of the floor surface for exposing the drum is modeled, for the tire test on the drum, the accuracy of modeling the space around the tire that affects the acoustic analysis can be increased. On the other hand, the space under the floor existing between the floor surface and the drum is not modeled, and an acoustic impedance boundary is set at the outer edge of the space below the opening. At this time, the influence of omitting the modeling of the space under the floor on the analysis result of the sound around the tire is small. Therefore, since the spatial model at the time of model creation can be simplified, an increase in the memory and calculation cost for calculating the spatial model can be suppressed.

Brief Description of the Drawings

[0012]

Fig. 1A

Fig. 1B

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Fig. 9

Embodiments for Carrying Out the Invention

[0013] Hereinafter, with reference to the drawings, an example of an embodiment of a simulation device, a simulation method, and a program according to the present invention will be described in detail. The embodiments described below are merely examples, and the present invention is not limited to the following embodiments.

[0014] Hereinafter, with reference to FIGS. 1A to 3, a generation device 1 for a space model around a tire, which is an embodiment of the present invention, will be described.

[0015] FIG. 1A is a side view showing an upper floor model 30, which is a space model above the floor, in a tire surrounding space model 10 according to an example of the embodiment. FIG. 1B is a cross-sectional view showing the tire surrounding space model 10 including a lower floor model 32, which is a space model below the floor. FIG. 2 is an enlarged view of the periphery of the contact portion between the drum model 23 and the tire model 20 in FIG. 1B. The tire surrounding space model 10 is a space acoustic model around the tire, and as shown in FIG. 2, it includes a first space model 12a (see FIG. 5 described later) formed at the contact portion and a second space model 14 outside the tire model 20. The second space model 14 has an upper floor model 30 and a lower floor model 32 (FIGS. 1B and 2).

[0016] The upper floor model 30 defines an upper floor space 31 surrounded by the tire model 20, the floor model 22, and the outermost surface 24 on the floor in the tire surrounding space. The first space model 12a models the space existing between the ground contact boundary model 12 and the outer peripheral surface of the drum model 23. The ground contact boundary model 12 is composed of the deformed tire model 20 and the drum model 23 (FIG. 2).

[0017] Tire model 20 is in contact with drum model 23 in contact area 20a. Tire model 20 is installed on drum model 23 exposed from opening 40 (FIG. 1B, FIG. 2) provided at the center of floor surface model 22 having a planar disk shape. Opening 40 is, for example, substantially rectangular in top view. The drum represented by drum model 23 constitutes a drum tester for measuring noise, and rotates the tire on the drum by rotating about an axis along the horizontal direction.

[0018] The outermost surface 24 on the floor of the tire surrounding space is hemispherical with tire model 20 as the center and is connected to the outer edge of floor surface model 22.

[0019] On the other hand, as shown in FIGS. 1B and 2, floor surface lower model 32 defines opening lower space 25 formed between plane α including the edge of opening 40 of floor surface model 22 and the upper surface of drum model 23. On the other hand, a floor acoustic impedance boundary 26 is set at the boundary between opening lower space 25 and underfloor space 50 below floor surface model 22. Floor acoustic impedance boundary 26 is set above drum model 23 and is annularly configured by a plurality of planes along the vertical direction. Floor acoustic impedance boundary 26 defines the outer edge of opening lower space 25. In FIG. 2, the upper floor space 31 defined by the upper floor model 30 is shown by a diagonal grid, and the opening lower space 25 defined by the lower floor model 32 is shown by a sandy area.

[0020] FIG. 3 is a block diagram showing a generator 1 of a tire surrounding space model 10 according to an example of an embodiment. The generator 1 is configured by an information processing device including, for example, a control device having a processor 41 and a memory 42. The information processing device is configured by a computer including, for example, a processor 41, a memory 42, an input unit such as a keyboard for inputting data and execution instructions, and a display for outputting calculation results such as the generation result of the tire surrounding space model 10. The processor 41 executes arithmetic processing for controlling the generator 1. The memory 42 stores a control program for controlling the processor 41 and is configured by, for example, a RAM, a ROM, a hard disk, etc. The control program includes a program for causing the information processing device to execute a method for generating the tire surrounding space model 10. The generator 1 may be configured by one information processing device or may be configured by a plurality of information processing devices.

[0021] The generator 1 includes a ground contact analysis unit 44 and a space model generation unit 46. The ground contact analysis unit 44 performs a ground contact analysis on a state in which a predetermined load is applied on a drum having a predetermined shape using a tire model 20 obtained by dividing the tire into a plurality of elements. The tire model 20 is a model obtained by dividing the tire into a plurality of elements, and the ground contact analysis can be performed using, for example, the finite element method (FEM). The tire model 20 includes data related to the internal and external structures of the tire. Note that the tire model is not limited to an analysis model by the finite element method as described below, and may be an analysis model by, for example, the finite difference method (FDM), the boundary element method (BEM), etc.

[0022] The ground contact analysis unit 44 obtains a deformed tire model 20 by the ground contact analysis. This tire model 20 includes data on the magnitude of the contact pressure received by the elements from the drum. Further, the tire model 20 includes data on the position coordinates of the nodes of the elements and data on the sectional line segments of the elements. Here, a node means a vertex of an element, and a sectional line segment means a side that divides an element.

[0023] The spatial model generation unit 46 includes a ground plane model creation unit 47 that creates a drum model 23 having a ground plane 23a using the results of the grounding analysis. Further, the spatial model generation unit 46 includes a ground plane boundary model creation unit 48 that creates a ground plane boundary model 12 from the drum model 23 created by the ground plane model creation unit 47. First, the ground plane model creation unit 47 identifies the contour of the contact area 20a that contacts the upper part of the outer peripheral surface of the drum in the tire model 20. Also, the ground plane model creation unit 47 simulates a drum having the same shape as that used in the grounding analysis, and creates a drum model 23 that has a ground plane 23a which is the upper part of the drum contacting the contact area 20a and is divided into a plurality of elements.

[0024] Next, the ground plane model creation unit 47 creates a projection view by projecting the identified contour of the contact area 20a onto the upper part of the outer peripheral surface of the drum model 23, and creates a drum model 23 by deleting the portion corresponding to the projection view from the upper part of the outer peripheral surface of the drum model 23. The ground plane model creation unit 47 creates the drum model 23, for example, by dividing the drum from which the portion corresponding to the projection view has been deleted into a plurality of elements.

[0025] Note that, as will be described later, the drum model may be created by dividing only a substantially rectangular portion, which is the portion of the upper part of the outer peripheral surface of the drum where the outer edge contacts the lower end of the underfloor acoustic impedance boundary 26 and has the same size as the opening of the road surface in plan view, into a plurality of elements.

[0026] The ground plane boundary model creation unit 48 generates a ground plane boundary model 12 by connecting the tire model 20 and the drum model 23. The ground plane boundary model creation unit 48 creates a continuous ground plane boundary model 12 by connecting the nodes of the elements of the approaching tire model 20 and the nodes of the drum model 23 in the vicinity of the contact area 20a. Since the contour of the contact area 20a is composed of broken lines based on the elements of the tire model 20, it is easy to connect the nodes of the elements of the tire model 20 and the nodes of the drum model 23.

[0027] The ground plane model creation unit 47 preferably ensures that the drum model 23 does not have an element having a section line segment shorter than the section line segment of the element on the outer surface of the tire model 20. As a result, the nodes of the tire model 20 and the nodes of the drum model 23 can be made to correspond, so that when generating the continuous ground plane boundary model 12, it becomes possible to easily couple the tire model 20 and the drum model 23.

[0028] Also, as will be described later, when generating the tire surrounding space model 10, the space model generation unit 46 models the lower opening space 25 between the upper surface of the drum and the plane including the edge of the floor opening 40 for exposing the drum.

[0029] The space model generation unit 46 includes a space modeling unit 49. The space modeling unit 49 simulates the floor surface and creates a floor surface model 22 divided into a plurality of elements. The floor surface model 22 has a rectangular opening 40 in top view for exposing the drum. The space modeling unit 49 sets an outermost upper floor surface 24 that is hemispherical with the tire model 20 as the center and is connected to the outer edge of the floor surface model 22 above the floor surface model 22. The outermost upper floor surface 24 is an acoustic impedance boundary on the upper floor surface in the space above the floor surface.

[0030] Furthermore, the space modeling unit 49 sets an underfloor acoustic impedance boundary 26 that extends along the vertical direction over the entire circumference of a substantially rectangular frame obtained by projecting the inner peripheral edge of the opening 40 from above onto the upper part of the outer peripheral surface of the drum model 23 below the floor surface model 22, with the lower end edge being the inner peripheral edge of the opening 40. The underfloor acoustic impedance boundary 26 is an annular outermost lower floor surface whose upper end is connected to the inner peripheral edge of the opening 40.

[0031] Then, the space modeling unit 49 generates a tire surrounding space model 10 by dividing a predetermined space in which a first space model 12a formed in the contact portion and a second space model 14 having a predetermined shape outside the tire model 20 are connected, based on the contact shape of the tire model 20, into a plurality of elements. The tire surrounding space model 10 is a model that models a space filled with gas around the tire, and is an analysis model by the finite element method.

[0032] The first space is a space formed in the contact portion between the tire model 20 and the drum, and is a space formed between the tire circumferential grooves and lug grooves and the outer peripheral surface of the drum. The second space is a space connected to the first space, and is a space around the tire excluding the tire portion. The second space is configured to include a space above the floor surface whose outer surface is defined by the floor upper outermost surface 24 and an opening lower side space 25 below the floor surface whose outer edge is defined by the underfloor acoustic impedance boundary 26.

[0033] Also, the space model generation unit 46 models the opening lower side space 25 on the lower side of the floor surface, but does not model the underfloor space 50 existing between the floor surface and the drum. For this purpose, the space model generation unit 46 sets an underfloor acoustic impedance boundary 26 at the outer edge of the opening lower side space 25.

[0034] Also, the space modeling unit 49 can set the sound pressure reflectance γ used for creating the impedance value of the underfloor acoustic impedance boundary 26 to be 0 or more and 0.25 or less. The reflectance γ may be preset in the generation device 1, or the user may be able to set an arbitrary value in the range of 0 or more and 0.25 or less using the input unit of the information processing device.

[0035] The impedance value of the underfloor acoustic impedance boundary 26 is represented by the following Z using the above reflectance γ, the density ρ of air, and the bulk modulus K of air.

[0036] Z=(1 + γ)(ρ×K) 1 / 2 / (1 - γ)

[0037] By setting the reflectance γ to 0 or more and 0.25 or less as described above, the analysis result of the tire radiation noise can be made closer to the measured value, particularly in the high-frequency region.

[0038] Note that the tire surrounding space model is not limited to the analysis model by the finite element method, and may be an analysis model by the finite difference method, the boundary element method, or the like. Further, depending on the boundary conditions and the like, the most appropriate analysis method may be selected, or an analysis model combining a plurality of analysis methods may be used.

[0039] An example of a method for the ground contact model creation unit 47 to specify the contour of the contact area 20a will be described with reference to FIGS. 4 and 5. FIG. 4 is a side view of the vicinity of the contact area 20a of the tire model 20 according to an example of the embodiment, showing the state of the tire model 20 deformed by the load. FIG. 5 is a diagram showing the contour of the contact area 20a of the tire model 20 according to an example of the embodiment. In FIG. 5, the contour of the contact area 20a is composed of five figures Z1 to Z5. The direction Y in FIGS. 4 and 5 indicates the tire axial direction.

[0040] First, the ground contact model creation unit 47 extracts contact elements having contact pressure at all nodes from the elements constituting the outer surface of the tire model 20. In FIG. 5, the elements included inside each of Z1 to Z5 are contact elements. For example, the contact elements E1 and E2 included inside Z1 are both rectangular and have contact pressure at four nodes (vertices). The portion formed between adjacent figures of Z1 to Z5 and where a plurality of non-contact elements are connected in the X direction corresponds to the tire circumferential groove.

[0041] Next, the ground plane model creation unit 47 acquires each sectional line segment of the extracted contact elements, and identifies the contour of the contact area 20a from the sectional line segments. For example, the sectional line segments partitioning the contact element E1 are four, namely L1 to L4. Since the elements adjacent to the contact element E1 via L1 and L2 are not contact elements, L1 and L2 constitute the contour. On the other hand, since the elements adjacent to the contact element E1 via L3 and L4 are contact elements, L3 and L4 do not constitute the contour. Also, since the contact element E2 is adjacent to a contact element at any of the four sectional line segments by which it is partitioned, it does not constitute the contour.

[0042] The ground plane model creation unit 47 may extract contour components that constitute the contour from the sectional line segments surrounding the contact elements. In the example of FIG. 5, L1 and L2 are contour components, and L3 and L4 are not contour components. Since the sectional line segments acquired by the ground plane model creation unit 47 include both contour components and those that are not contour components (non-contour components), the ground plane model creation unit 47 classifies the contour components and non-contour components and extracts only the contour components.

[0043] By acquiring the coordinates of the nodes at both ends of the sectional line segment and investigating the number of sectional line segments where the coordinates of both nodes match, the contour components and non-contour components may be classified. Since the contour components are adjacent to elements that are not contact elements via the sectional line segments, there are no sectional line segments where the coordinates of both nodes match. On the other hand, since the non-contour components are adjacent to contact elements via the sectional line segments, there are other sectional line segments where the coordinates of both nodes match.

[0044] The ground plane model creation unit 47 may directly extract, as contour components, those among the sectional line segments surrounding the contact elements where there are no sectional line segments where the coordinates of both nodes match. Also, the ground plane model creation unit 47 may extract, as non-contour components, those among the sectional line segments surrounding the contact elements where there are other sectional line segments where the coordinates of both nodes match, and further indirectly extract the contour components by removing the non-contour components from the sectional line segments surrounding the contact elements.

[0045] When creating the ground contact model section 47, when specifying the contour from the sectional line segments surrounding the contact elements, an algorithm for continuous drawing may be used. The continuous drawing algorithm is a procedure for specifying the contour by connecting the contour components so as to be continuously drawn, and a contour closed by continuous drawing is created. In the example shown in FIG. 5, continuous drawing is performed for each of Z1 to Z5, and the contour of the contact area 20a is formed. The continuous drawing algorithm ends when all the contour components are used for continuous drawing. In FIG. 5, the space in the tire circumferential direction groove that exists between the contours of the contact area 20a and is formed between the outer peripheral surface of the drum model corresponds to the first space model 12a.

[0046] Hereinafter, with reference to FIG. 6, a method for generating the tire surrounding space model 10 using the above-described generating apparatus 1 will be described.

[0047] FIG. 6 is a flowchart of a method for generating the tire surrounding space model 10 according to an example of the embodiment. First, the ground contact analysis section 44 performs a ground contact analysis on the tire model 20 grounded on the drum and acquires the deformed tire model (S1). The road surface shape and the magnitude of the load during the ground contact analysis can be arbitrarily set.

[0048] The ground contact model creation section 47 projects the contour of the contact area 20a obtained from the result of the ground contact analysis onto the drum and creates a projection drawing (S2). At this time, the same-shaped drum as that used for the ground contact analysis is used. Thereafter, the ground contact model creation section 47 deletes the portion corresponding to the projection drawing from the road surface to create the drum model 23 (S3). The ground contact model creation section 47 creates the drum model 23, for example, by dividing the drum from which the portion corresponding to the projection drawing has been deleted into a plurality of elements.

[0049] The ground contact boundary model creation section 48 connects the tire model 20 and the drum model 23 to create the ground contact boundary model 12 (S4).

[0050] Subsequently, while the spatial modeling unit sets the floor upper outermost surface 24 and the floor lower acoustic impedance boundary 26 as acoustic impedance boundaries on the floor upper side and the floor lower side, a tire surrounding space model 10 in which the first spatial model 12a and the second spatial model 14 are connected is generated (S5), and this generation method ends.

[0051] At this time, in step S5, based on the grounding shape of the tire model 20, a predetermined space including the first space formed at the grounding portion and the second space having a predetermined shape outside the tire model 20 is divided into a plurality of elements, thereby generating the tire surrounding space model 10. Also, in step S5, the upper surface of the drum and the opening lower side space 25 are modeled, but the floor lower space 50 is not modeled, and the above-described floor lower acoustic impedance boundary 26 is set at the outer edge of the opening lower side space 25. At this time, the sound pressure reflectance γ used for creating the impedance value of the floor lower acoustic impedance boundary 26 can be set to 0 or more and 0.25 or less. More preferably, the reflectance γ is 0.

[0052] FIG. 7 is a diagram showing an example when viewed from below the opening of the floor surface in the generation result of the tire surrounding space model 10. In FIG. 7, the floor surface model is omitted. Also, in FIG. 7, the drum model is indicated by two-dot chain lines α1, α2, α3, α4, but in the actual output image, the drum model may be omitted.

[0053] As shown in FIG. 7, a floor upper side space 31 is formed above the tire surrounding space model 10, and the opening lower side space 25 is connected below the floor upper side space 31. The lower surface of the opening lower side space 25 has a curved surface shape that is concave upward in a circular arc cross section so as to match the upper surface of the drum.

[0054] And at the outer edge of the opening lower side space 25, a floor lower acoustic impedance boundary 26 shown as a wall painted black in FIG. 7 is set. Also, the four two-dot chain lines along the vertical direction shown by β1, β2, β3, β4 in FIG. 7 are along the four sides in the vertical direction of the annular portion along the vertical direction indicating the floor lower acoustic impedance boundary 26.

[0055] According to the above-described generating apparatus 1, generating method, and program, in the generation of the tire surrounding space model 10, the opening lower space 25 between the upper surface of the drum and the plane α including the edge of the floor surface opening 40 for exposing the drum is modeled. Thereby, for the tire test on the drum, the accuracy of modeling the tire surrounding space that affects the acoustic analysis can be increased. In particular, when the reflectance γ of the sound pressure used for creating the impedance value of the underfloor acoustic impedance boundary 26 is set to 0 or more and 0.25 or less, the analysis result of the acoustic transmission characteristics in the front-rear direction of the tire obtained using the tire surrounding space model 10 can be made closer to the measured value. In particular, when the reflectance γ is set to 0, the analysis result of the acoustic transmission characteristics in the front-rear direction of the tire obtained using the tire surrounding space model 10 can be made even closer to the measured value.

[0056] On the other hand, the underfloor space 50 existing between the floor surface and the drum is not modeled, and the underfloor acoustic impedance boundary 26 is set at the outer edge of the opening lower space 25. At this time, the omission of modeling the underfloor space 50 has little influence on the analysis result of the sound around the tire. Therefore, the space model at the time of model creation can be simplified, so that an increase in memory and calculation cost for calculating the space model can be suppressed.

[0057] Using FIGS. 8 and 9, the result of performing acoustic analysis using the tire surrounding space model 10 will be described. FIG. 8 is a diagram showing an example of the relationship between the input point A1 and the observation point A2 when performing acoustic analysis around the tire when the tire surrounding space model 10 is viewed from below.

[0058] The acoustic analysis around the tire was performed using the above-described tire surrounding space model 10. The acoustic analysis was performed using analysis software that uses the finite element method. In this acoustic analysis, the boundary condition of the uppermost outer surface 24 on the floor was set to complete radiation, and the boundary conditions of the outer peripheral portion of the tire and the floor surface were set to complete reflection.

[0059] In addition, as an arbitrary point near the circumferential groove or lug groove of the grounding portion, an input point A1 (Fig. 8) for inputting the radiated sound generated from the space formed between the groove and the drum was set. Then, acoustic analysis was performed by steady response analysis. In steady response analysis, the amplitude value of the sound pressure or the particle velocity of the gas can be set for each frequency of the radiated sound to be analyzed at the input point.

[0060] Here, the frequency of the radiated sound input to the input point A1 was changed from 800 Hz to 1500 Hz, and steady response analysis was performed. Then, as an arbitrary position within the tire surrounding space model 10, an observation point A2 (Fig. 8) for observing the radiated sound was set at a position away from the grounding portion of the tire in the front-rear direction. Then, data on the transfer function of the sound pressure for each frequency of the radiated sound at the observation point A2 was acquired. The transfer function is the ratio (P / Q) of the sound pressure P at the observation point to the volume velocity Q at the input point A1.

[0061] In addition, in the acoustic analysis, the reflectivity γ of the sound pressure used for creating the impedance value of the underfloor acoustic impedance boundary 26 was changed in three types: 0, 0.25, and 1. The fact that the reflectivity γ is 0 means perfect radiation. The fact that the reflectivity γ is 1 means perfect reflection.

[0062] Fig. 9 is a diagram showing the results of the acoustic analysis around the tire, and is a diagram showing the relationship between the frequency of the radiated sound and the transfer function (P / Q) of the sound pressure at the observation point A2. Fig. 9 also shows the relationship between the frequency of the radiated sound and the transfer function (P / Q) in the measured values.

[0063] In Fig. 9, the thick solid line B1 indicates that the reflectivity γ = 0, the one-dot chain line B2 indicates that the reflectivity γ = 0.25, the two-dot chain line B3 indicates that the reflectivity γ = 1, and the thin solid line B4 indicates the measured value, respectively.

[0064] From the results of Fig. 9, in this embodiment, it was confirmed that by setting the underfloor acoustic impedance boundary 26, the reflectance γ can be made to approach the measured transfer function in any case, particularly in the high-frequency range of 1100 to 1500 Hz. Also, when the reflectance γ is in the range of 0 or more and 0.25 or less (the range from B1 to B2 in Fig. 9), it was confirmed that in the high-frequency range of 1100 to 1500 Hz, the reflectance γ can be made to approach the measured transfer function much more closely compared to the case where the reflectance γ is 1 (B3 in Fig. 9). Further, when the reflectance γ = 0, it was confirmed that in the high-frequency range of 1100 to 1500 Hz, the reflectance γ can be made to approach the measured transfer function even more closely compared to other cases of reflectance.

[0065] As described above, according to the tire surrounding space model generation device 1, generation method, and program according to the present invention, while suppressing an increase in memory and calculation costs, for tire tests on a drum, the accuracy of modeling the space around the tire that affects acoustic analysis can be increased.

Explanation of Signs

[0066] 1 Generation device, 10 Tire surrounding space model, 12 Ground contact boundary model, 12a First space model, 14 Second space model, 20 Tire model, 20a Contact area, 22 Floor model, 23 Drum model, 23a Ground contact surface, 24 Outermost surface on the floor, 25 Space below the opening, 26 Underfloor acoustic impedance boundary, 30 Model above the floor, 31 Space above the floor, 32 Model below the floor, 40 Opening, 41 Processor, 42 Memory, 44 Ground contact analysis unit, 46 Space model generation unit, 47 Ground contact boundary model creation unit, 48 Ground contact surface boundary model creation unit, 49 Space modeling unit, 50 Space under the floor.

Claims

1. Using a tire model in which a tire is divided into a plurality of elements, a grounding analysis is performed on a state in which a predetermined load is applied on a drum having a predetermined shape, and a grounding analysis unit that obtains the deformed tire model; Based on the grounding shape of the tire model, a space model creating unit that creates a space model by dividing a predetermined space including a first space formed in the grounding portion and a second space having a predetermined shape outside the tire model into a plurality of elements; The space model creating unit models an opening lower space between an upper surface of the drum and a plane including an edge of an opening of a floor surface for exposing the drum, but does not model a space under the floor existing between the floor surface and the drum, and sets an acoustic impedance boundary at an outer edge of the opening lower space. A device for generating a space model around a tire.

2. The reflectance of the sound pressure used for creating the impedance value of the acoustic impedance boundary is 0 or more and 0.25 or less. The device for generating a space model around a tire according to Claim 1.

3. Using a tire model in which a tire is divided into a plurality of elements, a step of performing a grounding analysis on a state in which a predetermined load is applied on a drum having a predetermined shape and obtaining the deformed tire model; Based on the grounding shape of the tire model, a step of creating a space model by dividing a predetermined space including a first space formed in the grounding portion and a second space having a predetermined shape outside the tire model into a plurality of elements; The step of creating the space model models an opening lower space between an upper surface of the drum and a plane including an edge of an opening of a floor surface for exposing the drum, but does not model a space under the floor existing between the floor surface and the drum, and sets an acoustic impedance boundary at an outer edge of the opening lower space. A method for generating a space model around a tire.

4. The reflectance of the sound pressure used for creating the impedance value of the acoustic impedance boundary is 0 or more and 0.25 or less. The method for generating a space model around a tire according to Claim 3.

5. A program for causing a computer to execute the method according to Claim 3 or Claim 4.

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