JP2017068320A - Vehicle body rigidity analysis method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle body rigidity analysis method for performing rigidity analysis in consideration of inertia force acting on fittings and lids during traveling of a vehicle.SOLUTION: In a vehicle body rigidity analysis method, a computer performs rigidity analysis by using a vehicle body skeleton model of a vehicle, which has fixing/connection parts for fixing or connecting fittings or lids and which is configurated by using plane elements and/or stereoscopic elements. The vehicle body rigidity analysis method includes: a mass-set vehicle body skelton model creation step S1 of setting mass equivalent to mass of the fittings or the lids at predetermined positions in areas of fixing or connecting the fittings or the lids to the fixing/connection parts of the vehicle body skeleton model, so as to create a mass-set vehicle body skelton model; and a rigidity analysis step S3 of performing the rigidity analysis on the mass-set vehicle body skelton model in consideration of inertia force acting during traveling of the vehicle.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vehicle body stiffness analysis method, and more particularly, to a vehicle body stiffness analysis method that performs a vehicle body skeleton stiffness analysis in consideration of the influence of an inertial force acting in a running state of an automobile.

In recent years, in the automobile industry, weight reduction of vehicle bodies due to environmental problems has been promoted, and CAE analysis has become an indispensable technology for vehicle body design. In this CAE analysis, rigidity analysis, collision analysis, vibration analysis, etc. are carried out, which greatly contributes to the improvement of vehicle body performance. In addition to evaluating vehicle body performance by CAE analysis, the analysis results obtained by CAE analysis are used to perform optimization analysis such as mathematical optimization, plate thickness optimization, shape optimization, topology optimization, etc. It is known that various vehicle performances can be improved and the vehicle weight can be reduced.
Patent Document 1 discloses a rigidity evaluation support method for evaluating the rigidity of a vehicle in a running state by numerical analysis.

Japanese Patent No. 5203851

Considering the state in which the vehicle is actually traveling, for example, when the vehicle body behavior changes due to a lane change or the like, the inertial force acting on the fitting or lid disposed away from the center position of the vehicle is It greatly affects the deformation of the skeleton. Even if this is a fitting or lid, the mass of a component (ASSY) that is a combination of multiple parts may be 10 kg or more, and it cannot be ignored for a body skeleton with a mass of about 100 to 300 kg. Because. Therefore, when evaluating the performance of the vehicle body skeleton, it is desirable to evaluate in a state in which the inertial force acting on the fitting or the lid is taken into consideration during actual traveling.
In the present invention, the fittings collectively refer to engines, transmissions, seats, and the like, and the lids collectively refer to doors, trunks, hoods, and the like.

  The vehicle stiffness evaluation support method disclosed in Patent Document 1 evaluates the vehicle stiffness in a free support state in which the vehicle body is supported by an absorber or a soft bush, and the vehicle is equipped with a fitting or a lid. It is a thing. However, in general, the appearance and design of the vehicle are not decided at the initial stage of the body frame design, and lids and fittings that are greatly influenced by the appearance and design of the vehicle are finally decided at the latter stage of design. Many.

  Therefore, in the stage before the shape of the fitting or lid is determined by the vehicle stiffness evaluation support method disclosed in Patent Document 1, the inertial force acting on the fitting or lid in the actual running state is taken into consideration. Therefore, it is difficult to evaluate the performance of the body frame. Furthermore, assuming that the fittings and lids were finally determined in the late design stage, CAE analysis was performed on the vehicle (full body) with the fittings and lids installed to evaluate the performance of the vehicle body skeleton and return There is no time to correct the design of the body frame. For this reason, in the past, performance evaluation and design of the vehicle body skeleton were forced by CAE analysis only for the vehicle skeleton.

  The present invention has been made in order to solve the above-described problems, and in a vehicle body skeleton model, these fittings or lids can be substituted for these fittings or lids even before the fittings or lids are determined. It is an object of the present invention to provide a vehicle body rigidity analysis method in which the mass corresponding to is set and the rigidity analysis is performed with high accuracy in consideration of the inertial force acting when the vehicle is running.

(1) The vehicle body rigidity analysis method according to the present invention uses a vehicle body skeleton model having a fixed connecting portion for fixing or connecting a fitting or a lid, and configured using planar elements and / or three-dimensional elements. A vehicle body stiffness analysis method in which a computer performs a stiffness analysis, wherein a fitting or lid is equivalent to a mass of the fitting or lid at a predetermined position in a region where the fitting or lid is coupled to a fixed coupling portion of the vehicle body skeleton model. A mass setting vehicle body skeleton model generation step for generating a mass setting vehicle body skeleton model by setting a mass, and a stiffness analysis step for performing rigidity analysis for the mass setting vehicle body skeleton model in consideration of an inertial force acting when the vehicle is running It is characterized by comprising.

(2) In the device described in (1) above, the predetermined position in the mass setting vehicle body skeleton model generation step is set on a straight line or a curve connecting the fixed connecting portions.

(3) In the above (2), in the case where the fitting or the lid is a rotatable movable part, the predetermined position is on a rotationally movable central axis when the fitting or the lid is rotationally movable. It is characterized by excluding.

(4) In the device described in (1) above, the predetermined position in the mass setting vehicle body skeleton model generation step is set on a plane or curved surface surrounded by a straight line or a curve connecting the fixed connecting portions (the straight line or the curved line). (Except on the line).

(5) In the device according to any one of (1) to (4), the mass setting vehicle body skeleton model generation step includes a mass element and a mass element corresponding to a mass of the fitting or the lid. And a rigid element that connects the fixed connecting portion.

(6) In the device according to any one of (1) to (4), the mass setting vehicle body skeleton model generation step is set using a mass element and a beam element, and the mass element and the mass of the beam element Is equivalent to the mass of the fitting or lid fixed or connected to the fixed connecting portion.

(7) In the device according to any one of (1) to (4), the mass setting vehicle body skeleton model generation step is set using a beam element having a mass corresponding to the mass of the fitting or the lid. It is characterized by this.

  In the present invention, in a vehicle body skeleton model of an automobile having a fixed connecting portion for fixing or connecting a fitting or a lid, and using a planar element and / or a three-dimensional element, the fitting or lid is the body skeleton model. A mass setting vehicle body skeleton model generating step for generating a mass setting vehicle body skeleton model by setting a mass corresponding to the mass of the fitting or lid at a predetermined position in a region fixed or connected to the fixed connection portion of The vehicle body skeleton model is provided with a stiffness analysis step for performing a stiffness analysis in consideration of the inertial force that acts when the vehicle is traveling, so that the inertial force that acts on the fitting or lid when the vehicle is traveling is taken into account. Thus, the rigidity of the body frame can be evaluated.

It is a flowchart which shows the flow of a process of the rigidity analysis method of the vehicle body which concerns on embodiment of this invention. It is explanatory drawing of the vehicle body frame | skeleton model used by embodiment of this invention. It is explanatory drawing of the mass setting vehicle body frame | skeleton model made into analysis object by the rigidity analysis method of the vehicle body which concerns on embodiment of this invention. 1 is a block diagram of an analysis apparatus that performs a vehicle body rigidity analysis method according to an embodiment of the present invention. It is explanatory drawing explaining the predetermined position where mass is set in the mass setting vehicle body skeleton model production | generation step which concerns on embodiment of this invention. It is explanatory drawing explaining the mass setting vehicle body skeleton model in which the mass was set in the mass setting vehicle body skeleton model production | generation step which concerns on embodiment of this invention. It is explanatory drawing explaining the mass setting method in the mass setting vehicle body frame | skeleton model production | generation step which concerns on embodiment of this invention. It is explanatory drawing explaining the load constraint conditions in the rigidity analysis of the static torsion of a vehicle body in an Example. It is a figure which shows the result of the load direction displacement obtained by the rigidity analysis of the static torsion of the vehicle body in the Example. It is a figure which shows the comparison with the example of this invention of the rigidity analysis result of the static torsion of the vehicle body in an Example, and a comparative example. In an Example, it is explanatory drawing explaining the load conditions supposing lane change. In an Example, it is a figure which shows the result of the displacement of the load point A and the rigidity change rate in the rigidity analysis supposing the lane change. In an Example, it is a figure explaining the load conditions given to the vehicle body front side. In an Example, it is a figure which shows the result of the load direction displacement in each load condition given to the vehicle body front side. In an Example, it is a figure which shows the result of the rigidity change rate in each load condition given to the vehicle body front side. In an Example, it is a figure which shows the correlation of the rigidity value and rigidity change rate of the example of this invention and the comparative example 2 in each load condition given to the vehicle body front side. In an Example, it is a figure explaining the load conditions given to the vehicle body rear side. In an Example, it is a figure which shows the result of the load direction displacement in each load condition given to the vehicle body rear side. In an Example, it is a figure which shows the result of the rigidity change rate in each load condition given to the vehicle body rear side. In an Example, it is a figure which shows the correlation of the rigidity value and rigidity change rate of the example of this invention and the comparative example 2 in each load condition given to the vehicle body rear side.

Embodiments of the present invention will be described below with reference to the drawings.
The vehicle body rigidity analysis method according to the present embodiment includes a fixed connection portion 3 for fixing or connecting a fitting or a lid, and is configured using a planar element and / or a three-dimensional element. 2), the stiffness analysis is performed using the mass setting vehicle body skeleton model 21 (see FIG. 3) generated by setting the mass corresponding to the fitting or the lid as shown in FIG. The vehicle body rigidity analyzer 41 (hereinafter simply referred to as “stiffness analyzer”) configured as described above can be used.
Hereinafter, after describing each structure of the vehicle body skeleton model 1 and the stiffness analysis apparatus 41 targeted in the present invention, each step in the vehicle body stiffness analysis method according to the present embodiment will be described.

<Body frame model>
As shown in FIG. 2, the vehicle body skeleton model 1 used in the present invention is composed only of skeleton parts such as a chassis, and has a fixed connecting portion 3 for fixing or connecting a fitting or a lid.
The vehicle body skeleton model 1 is configured using plane elements and / or solid elements, and element information and the like are stored in the vehicle body skeleton model file 60.

  As an example of the fixed connection portion 3 of the vehicle body skeleton model 1, there are a hinge 3a, a hinge 3b, and a striker 3c for fixing or connecting the revolving door as shown in FIG. 2, but the fixed connection portion 3 is not limited thereto. It includes not only those that fix equipment such as engine mounts that fix the engine, but also those that fix or connect lids such as sliding doors and bonnets other than revolving doors.

<Analyzer>
A stiffness analysis device 41 used in the vehicle body stiffness analysis method according to the present embodiment is a device that performs stiffness analysis using the mass setting vehicle body skeleton model 21 shown in FIG. 3 as an analysis target, such as a PC (personal computer). As shown in FIG. 4, the computer includes a display device 43, an input device 45, a storage device 47, a work data memory 49, and an arithmetic processing unit 50. In addition, a display device 43, an input device 45, a storage device 47, and a work data memory 49 are connected to the arithmetic processing unit 50, and each function is executed according to instructions from the arithmetic processing unit 50.

≪Display device≫
The display device 43 is used for displaying calculation results, and is composed of a liquid crystal monitor or the like.

≪Input device≫
The input device 45 is used by an operator to display the body skeleton model 1 and the mass setting body skeleton model 21 and input analysis conditions, and includes a keyboard, a mouse, and the like.

≪Storage device≫
The storage device 47 is used for storing files and is configured by a hard disk or the like, and stores at least various files such as the vehicle body skeleton model file 60, programs executed by the arithmetic processing unit 50, and the like.

≪Work data memory≫
The work data memory 49 is used for temporary storage and calculation of data used by the arithmetic processing unit 50, and includes a RAM or the like.

≪Operation processing part≫
The arithmetic processing unit 50 is configured by a CPU (Central Processing Unit) such as a PC, and includes a mass setting vehicle body skeleton model generation unit 51 and a stiffness analysis unit 53. Each of the above units is realized by the CPU executing a predetermined program.
Hereinafter, the structure of each part in the arithmetic processing part 50 is demonstrated in detail based on FIG.

≪Mass setting car body skeleton model generation part≫
The mass setting body skeleton model generation unit 51 sets a mass corresponding to the mass of the equipment or lid at a predetermined position in a region where the equipment or lid is fixed or connected to the fixed connection portion 3 of the body skeleton model 1. Thus, the mass setting vehicle body skeleton model 21 is generated.

≪Rigidity analysis part≫
The stiffness analysis unit 53 analyzes the stiffness of the mass setting vehicle body skeleton model 21 generated by setting the mass of the vehicle body skeleton model 1 by the mass setting vehicle body skeleton model generation unit 51 in consideration of the inertial force acting when the vehicle is running. Is to do.

<Car body stiffness analysis method>
As shown in FIG. 1, the vehicle body stiffness analysis method according to the present embodiment includes a mass setting vehicle body skeleton model generation step S1 for setting a mass corresponding to a fitting or a lid in the vehicle body skeleton model 1, A stiffness analysis step S3 for performing a stiffness analysis in consideration of the acting inertial force.
Hereinafter, each step will be described. Note that each step is executed by the computer in accordance with an instruction from the operator.

≪Mass setting body frame model generation step≫
In the mass setting vehicle body skeleton model generation step S1, a mass corresponding to the mass of the equipment or lid is set at a predetermined position in a region where the equipment or lid is fixed or connected to the fixed connection portion 3 of the vehicle body skeleton model 1. The mass setting vehicle body skeleton model 21 is generated by the mass setting vehicle body skeleton model generation unit 51 in the stiffness analyzer 41.

  In the mass setting vehicle body skeleton model generation step S1, as shown in FIG. 5, the mass element 11 is set at a predetermined position in a region where the fitting or the lid is fixed or connected, whereby the mass of the fitting or the lid is set. The mass corresponding to can be set.

  That is, the predetermined position for setting the mass element 11 is, as shown in FIG. 5, on a straight line L connecting a plurality of fixed connecting portions 3 (3a and 3c, 3b and 3c, 3a and 3b) (FIG. 5A). ) Or on a curve connecting the fixed connecting portions 3 along the shape of the vehicle body to which a lid or the like is attached.

In a rotationally movable part in which a fitting or a lid is rotationally movable like the rotational door shown in FIG. 2, there is a rotationally movable central axis when the rotational door is rotationally movable on a line connecting the hinges 3a and 3b of the rotational door. .
The rotationally movable central axis is substantially at the same position as the boundary of the region where the revolving door is fixed or connected to the vehicle body skeleton model 1.

  On the other hand, the straight line connecting the hinge 3a and the striker 3c of the revolving door and the straight line connecting the hinge 3b and the striker 3c are located inside the region where the door is fixed or connected to the vehicle body skeleton model 1.

In setting the mass corresponding to the fitting or lid in the vehicle body skeleton model 1, it is more rigid to be described later that the inside of the vehicle body skeleton model 1 is inside the boundary of the region where the fitting or lid is fixed or connected. This is preferable in consideration of the inertial force acting on the fitting or lid in the analysis step S3.
Therefore, the predetermined position for setting the mass corresponding to the fitting or lid is a center of rotation when the fitting or lid is rotationally movable on a straight line L connecting the plurality of fixed connecting portions 3 or on the curve. It is desirable to set the position excluding the axis.

Furthermore, the predetermined position for setting the mass corresponding to the fitting or the lid is not limited to the straight line L or the curved line, but on the plane P surrounded by the straight line L (FIG. 5B), Or it is good also on the curved surface enclosed by the said curve.
Here, since the straight line L or the curved line is a boundary of the plane P or the curved surface, it is desirable to set a mass corresponding to the fitting or the lid inside the boundary. Therefore, it is more preferable to set the predetermined position for setting the mass corresponding to the fitting or the lid on the plane P excluding the straight line L or the curved line or on the curved surface.

  When the fitting is fixed or connected by the four fixed connection parts 3, the fixed connection parts 3 are connected by a straight line so that two straight lines intersect each other, and the mass element 11 is set on the straight line. It is preferable. Also in this case, the fixed connecting portion 3 may be connected by a curve in accordance with the curvature of the vehicle body, and the mass element 11 may be set on the curve.

  Specific mass setting methods for setting the mass at the predetermined position include, for example, the following (1), (2), and (3).

(1) The mass element 11 having a mass corresponding to the mass of the fitting or lid is set at the predetermined position, and the mass element 11 and the fixed connecting portion 3 are connected using the rigid element 15 (see FIG. 6).
FIG. 6A is an example in which one mass element 11 is set on the center of the straight line L connecting the fixed connecting portions 3, but the straight line L is equally divided as shown in FIG. 6B. A plurality of mass elements 11 may be set on the top. When a plurality of mass elements 11 are set, the mass of each mass element 11 may be determined such that the total mass of each mass element 11 corresponds to the mass of the fitting or the lid.

(2) The mass element 11 having a mass corresponding to the mass of the fitting or the lid is set at the predetermined position, and the mass element 11 and the fixed connecting portion 3 are connected using the beam element 17 (see FIG. 7A). ). The sum of the mass of each of the mass element 11 and the beam element 17 is set so as to correspond to the mass of the fitting or lid fixed or connected to the fixed connecting portion 3.

  The mass of the beam element 17 is determined by the cross-sectional area given as the cross-sectional characteristic of the beam element 17 and the material density given as the material characteristic. The cross-sectional area of the beam element 17 is determined, for example, by giving the radius of the beam element 17.

  Further, in rigidity analysis step S3 described later, the cross-sectional characteristics and material characteristics necessary for transmitting the load due to the inertial force acting on the mass element 11 and the beam element 17 to the mass setting vehicle body skeleton model 21 are appropriately set in the beam element 17. There is a need to.

  The beam element 17 is a linear element and may be a rod element (bar element) as long as it can transmit a tensile and compressive load acting in the axial direction of the element, and the mass of the rod element is , Similarly to the beam element 17, the cross-sectional area (or radius) given as a cross-sectional characteristic and the material density given as a material characteristic are set.

(3) It sets using the beam element 17 which has the mass corresponded to the mass of a fitting or a cover (refer FIG.7 (b)).
The mass of the beam element 17 is determined by the cross-sectional area given as the cross-sectional characteristic of the beam element 17 and the material density given as the material characteristic. For example, the cross-sectional area is determined by giving the radius of the beam element 17.

≪Rigidity analysis step≫
In the stiffness analysis step S3, the stiffness analysis is performed on the mass setting vehicle body skeleton model 21 or 23 (FIG. 6) in which the mass is set in the mass setting vehicle body skeleton model generation step S1 in consideration of the inertial force acting when the vehicle is running. It is a step.
In performing the rigidity analysis, a load condition is set for the mass setting vehicle body skeleton model 21 or 23 as an analysis condition, and an inertial force that is applied when the automobile is running is considered using an inertia relief method.

  The inertia relief method is an analysis method for obtaining stress and strain from the force acting on an object in constant acceleration motion in a state where the object is supported (free support state) at the support point that becomes the reference of the coordinate of inertia force, It is used for static analysis of moving airplanes and ships (see Patent Document 1).

  By executing the stiffness analysis in the stiffness analysis step S3, results such as displacement and stress in the mass setting vehicle body skeleton model 21 are obtained, and the stiffness of the mass setting vehicle body skeleton model 21 is calculated from these results.

Hereinafter, an experiment for confirming the effect of the present invention was performed, which will be described.
In the experiment, a mass setting in which a mass corresponding to the rotating door component is set at a predetermined position in a region where the rotating door component as a lid is fixed or connected to the fixed connecting portion 3 of the vehicle body skeleton model 1 shown in FIG. Rigidity analysis was performed with the body skeleton model as the analysis target.

In this embodiment, the mass of the vehicle body skeleton model 1 is about 300 kg, and the mass of the rotating door component set in the vehicle body skeleton model 1 is 10 kg per piece.
Therefore, as an example of the invention, in the vehicle body skeleton model 1, ten mass elements 11 are evenly arranged on a straight line connecting the upper hinge 3a and the striker 3c, and the mass element 11, the hinge 3a and the striker 3c are rigid elements 15 The mass setting vehicle body skeleton model 23 (see FIG. 6B) connected in the above is the object of analysis, and the mass of each mass element 11 (= 1 kg) so that the total mass of the mass elements 11 becomes the mass of the rotating door components. ) Was set (example of the present invention).

  On the other hand, as a comparative example, the case where only the vehicle body skeleton model 1 is analyzed without setting the mass corresponding to the rotary door component (comparative example 1) and the vehicle door skeleton model 1 are combined with the rotary door component model. Rigidity analysis was also performed for a case where a vehicle body model (not shown) was an analysis target (Comparative Example 2).

  In this example, first, rigidity analysis was performed for static torsion, and the influence of the mass set in the mass setting vehicle body skeleton model 23 was examined. FIG. 8 shows load constraint conditions. A load point (A in FIG. 8) is a mounting position of the front suspension of the vehicle body, and a vertically upward load (= 1000 N) is applied. On the other hand, the restraint points were the front suspension mounting position (B in FIG. 8) and the rear suspension mounting position (C and D in FIG. 8).

The rigidity in static torsion was evaluated based on the average torsional rigidity determined as follows.
First, the straight line connecting the subframe mounting positions (C and D in FIG. 8) at the rear of the vehicle body is used as a reference (angle 0 degree), and viewed from the front of the vehicle body when a load is applied to the load point (A in FIG. 8) An average inclination angle is obtained by averaging the inclination angle of the vehicle body in the longitudinal direction of the vehicle body. Then, the average torsional rigidity is obtained by dividing the load applied to the load point by the average inclination angle.

FIG. 9 shows the result of displacement of the mass setting vehicle body skeleton model 23 in the present invention.
FIG. 10 shows the average torsional stiffness and the rate of change of stiffness obtained from the displacement obtained from the result of the stiffness analysis. Here, the stiffness change rate is a relative change in the average torsional stiffness obtained with reference to the stiffness of the vehicle body skeleton model 1 (Comparative Example 1). For example, the stiffness change rate in the present invention example was obtained from the following equation.
Stiffness change rate (%) = (average torsional rigidity of the present invention example−average torsional rigidity of comparative example 1) / average torsional rigidity of comparative example 1 × 100

  In the rigidity analysis for static torsion, since a restraint point is set as a load restraint condition, inertia force does not act on the mass element 11 or the rotating door component, and both the present invention example and the comparative example 2 have the vehicle body skeleton. As a result, the average torsional rigidity was almost the same as that of Comparative Example 1 in which model 1 was analyzed, and the rate of change in rigidity was slight.

Next, in the stiffness analysis that assumed the automobile in the running state, the effect on the rigidity of the vehicle body by considering the inertial force was verified.
Here, assuming that the vehicle in a running state changes lanes, as shown in FIG. 11, four load points are set at the subframe mounting position on the rear side of the vehicle body (before RH in FIG. Before LH, after RH, and after LH), a rigidity analysis was performed by applying a load of 1000 N to each load point in the vehicle width direction, and a value obtained by dividing the load by the displacement at each load point was obtained as the rigidity of the vehicle body.

  Similar to the static torsion described above, when a mass corresponding to the mass of the rotating door component is set (example of the present invention), when only the vehicle body skeleton model 1 is analyzed (comparative example 1), the rotating door component model A case (comparative example 2) was studied in which a vehicle body model combining the above was used as an analysis target.

  In FIG. 12, the result of the displacement and rigidity change rate in this invention example, the comparative example 1, and the comparative example 2 is shown. The stiffness change rate was obtained on the basis of the stiffness (Comparative Example 1) obtained by analyzing the vehicle body skeleton model 1 as the analysis target, similarly to the stiffness change rate in the static torsion described above.

  In the example of the present invention, an inertial force acts on the mass element 11 having a mass corresponding to the mass of the rotating door component, and the inertial force is transmitted to the mass setting vehicle body skeleton model 23 via the rigid element 15. Therefore, the displacement of the example of the present invention is about 30% larger than that of Comparative Example 1 in which the rotating door components are not considered, and as a result, the rigidity is reduced by about 20%. Furthermore, the example of the present invention shows a result that generally matches the displacement and the rate of change in rigidity in Comparative Example 2 in which the revolving door component model is considered as it is, and it can be seen that the result of the example of the present invention is appropriate.

Furthermore, the vehicle body rigidity analysis method according to the present invention was applied to load conditions corresponding to various driving conditions of the automobile.
Here, when applying a load to the front side or the rear side of the vehicle body and setting the mass corresponding to the mass of the rotating door component as in the rigidity analysis assuming the static torsion and lane change described above (example of the present invention), The case where only the vehicle body skeleton model 1 is analyzed (Comparative Example 1), and the case where the vehicle body model combined with the revolving door component model (Comparative Example 2) is analyzed using the rigidity analysis method according to the present invention. Analysis was performed.

FIG. 13 shows a load condition in which a load is applied to the front side of the vehicle body.
The front bend shown in FIG. 13A applies a vertically upward load to both the right and left front suspension attachment positions (RH and LH in FIG. 13A) of the vehicle body.
In the front torsion shown in FIG. 13B, a vertical upward load is applied to one of the right and left front suspension mounting positions (RH and LH in FIG. 13B), and a vertical downward load is applied to the other. Given.
The front single wheel torsion shown in FIG. 13 (c) applies a vertically upward load to one of the front suspension mounting positions (RH or LH in FIG. 13 (c)) on the right and left sides of the vehicle body. .
The front lateral bending shown in FIG. 13 (d) applies a load leftward or rightward in the vehicle width direction at the sub-frame mounting position (before RH, before LH, after RH and after LH in FIG. 13 (d)) on the front side of the vehicle body. Given.

FIG. 14 shows the displacement results obtained by the rigidity analysis in the present invention example, and FIG. 15 shows the rigidity change rates of the present invention example and the comparative example 2.
The bending and lateral bending in FIG. 15 correspond to the load conditions shown in FIGS. 13 (a) and 13 (d), respectively, and the rate of change in rigidity is calculated by dividing the displacement at each load point by the load at each load point. The obtained rigidity is obtained on the basis of the rigidity in Comparative Example 1 by dividing the difference between the rigidity and the rigidity of Comparative Example 1 by the rigidity of Comparative Example 1.

Further, the torsion and one-wheel torsion in FIG. 15 correspond to the load conditions shown in FIGS. 13 (b) and 13 (c), respectively, and the rigidity change rate under each load condition was obtained as follows.
First, the inclination angle of the vehicle body as viewed from the front side of the vehicle body when a load is applied to the load point (RH and / or LH in FIG. 13) with the straight line connecting the subframe mounting positions at the rear of the vehicle body as a reference (angle 0 degree). Is averaged over the longitudinal direction of the vehicle body to obtain an average inclination angle. Then, the average torsional rigidity is obtained by dividing the load applied to the load point by the average inclination angle.
Further, by dividing the difference between the average torsional rigidity and the average torsional rigidity of Comparative Example 1 by the average torsional rigidity of Comparative Example 1, the rigidity change rate is obtained based on the average torsional rigidity in Comparative Example 1.

  Further, in FIG. 15, torsion (reverse direction) is the result when a load is applied in the direction opposite to the load direction given to the load points (RH and LH) shown in FIG. 13B. Similarly, the lateral bending (reverse direction) in FIG. 15 applied a load in the direction opposite to the load direction given to the load points (before RH, before LH, after RH, and after LH) shown in FIG. Is the result of the case.

  FIG. 16 shows the correlation between the stiffness values obtained by the present invention example and the comparative example 2 under the respective load conditions shown in FIG. 13 and the correlation between the stiffness change rates obtained by the present invention example and the comparative example 2. In FIG. 16, the x-axis is the stiffness value or stiffness change rate obtained by the example of the present invention, and the y-axis is the stiffness value or stiffness change rate obtained by the comparative example 2.

The rigidity value and the rigidity change rate in the example of the present invention both have a high correlation (R ² = 1.000 and R ¹ = 1.000) with the rigidity value and the rigidity change rate in Comparative Example 2 in which the rotating door components are directly modeled and the rigidity analysis is performed. 0.993).

  15 and 16, it was shown that in each load condition, the example of the present invention satisfactorily matched the rigidity change rate of Comparative Example 2 in which the rotating door components were directly modeled.

Next, rigidity analysis was also performed when a load was applied to the rear side of the vehicle body. FIG. 17 shows a load condition when a load is applied to the rear side of the vehicle body.
The rear bending shown in FIG. 17 (a) applies a vertically upward load to both the right and left rear suspension mounting positions (RH and LH in FIG. 17 (a)) of the vehicle body.
In the rear torsion shown in FIG. 17 (b), a vertical upward load is applied to one of the right and left rear suspension mounting positions (RH and LH in FIG. 17 (b)), and a vertical downward load is applied to the other. Given.
The rear single wheel torsion shown in FIG. 17 (c) applies a vertically upward load to one of the right and left rear suspension mounting positions (RH or LH in FIG. 17 (c)). .
The rear lateral bending shown in FIG. 17 (d) applies a load leftward or rightward in the vehicle width direction at the subframe attachment position (before RH, before LH, after RH and after LH in FIG. 17 (d)) on the rear side of the vehicle body. Given.

FIG. 18 shows the displacement results obtained by the rigidity analysis in the present invention example, and FIG. 19 shows the rigidity change rates of the present invention example and the comparative example 2 with the comparative example 1 as a reference.
The bending and lateral bending in FIG. 19 correspond to the load conditions shown in FIGS. 17 (a) and 17 (d), respectively. The rate of change in rigidity is calculated by dividing the displacement at each load point by the load at each load point. The obtained rigidity is obtained on the basis of the rigidity in Comparative Example 1 by dividing the difference between the rigidity and the rigidity of Comparative Example 1 by the rigidity of Comparative Example 1.

Further, the torsion and single wheel torsion in FIG. 19 correspond to the load conditions shown in FIGS. 17B and 17C, respectively, and the rate of change in rigidity under each load condition was obtained as follows.
First, the inclination angle of the vehicle body as viewed from the front side of the vehicle body when a load is applied to the load point (RH and / or LH in FIG. 17) with the straight line connecting the front suspension mounting position of the vehicle body as a reference (angle 0 degree). An average inclination angle is obtained by averaging over the longitudinal direction of the vehicle body. Then, the average torsional rigidity is obtained by dividing the load applied to the load point by the average inclination angle.
Further, by dividing the difference between the average torsional rigidity and the average torsional rigidity of Comparative Example 1 by the average torsional rigidity of Comparative Example 1, the rigidity change rate is obtained based on the average torsional rigidity in Comparative Example 1.

  Further, in FIG. 19, torsion (reverse direction) is a result when a load is applied in the direction opposite to the load direction given to the load points (RH and LH) shown in FIG. Similarly, the lateral bending (reverse direction) in FIG. 19 applied a load in the direction opposite to the load direction given to the load points (before RH, before LH, after RH, and after LH) shown in FIG. Is the result of the case.

  FIG. 20 shows the correlation between the stiffness values obtained by the present invention example and the comparative example 2 and the correlation between the stiffness change rates obtained by the present invention example and the comparative example 2 under each load condition shown in FIG. In FIG. 20, the x-axis is the stiffness value or stiffness change rate obtained by the example of the present invention, and the y-axis is the stiffness value or stiffness change rate obtained by the comparative example 2.

The rigidity value and the rigidity change rate in the example of the present invention both have a high correlation (R ² = 0.9998 and R ² = 0.9998) with the rigidity value and the rigidity change rate in the comparative example 2 in which the rotating door components are directly modeled and the rigidity analysis is performed. 0.993).
19 and 20, it is shown that the example of the present invention matches well with the comparative example 2 in which the rotating door components are directly modeled under each load condition, and the rigidity analysis method according to the present invention is effective. It was shown that there is.

  As described above, in the vehicle body skeleton model having a fixed connecting portion for fixing or connecting the automobile fitting or lid, the mass corresponding to the fitting or lid is set by the vehicle body rigidity analysis method according to the present invention. It was proved that the rigidity of the vehicle body skeleton in the traveling state can be obtained with high accuracy by performing the rigidity analysis in consideration of the inertial force acting on the fitting or the lid during the traveling.

1 Car body skeleton model 3 Fixed connecting part 3a Hinge (upper side)
3b Hinge (lower side)
3c Striker 11 Mass element 15 Rigid element 17 Beam element 21 Mass setting vehicle body skeleton model 23 Mass setting vehicle body skeleton model 41 Stiffness analysis device 43 Display device 45 Input device 47 Storage device 49 Work data memory 50 Arithmetic processing unit 51 Mass setting vehicle body skeleton Model generation unit 53 Stiffness analysis unit 60 Body frame model file

Claims (7)

A vehicle body stiffness analysis method in which a computer performs a stiffness analysis using a vehicle body skeleton model having a fixed connection portion for fixing or connecting a fitting or a lid and using a plane element and / or a three-dimensional element. There,
Mass setting for generating a mass setting vehicle skeleton model by setting a mass corresponding to the mass of the rigging or lid at a predetermined position in a region where the fitting or lid is fixed or connected to the fixed connection portion of the vehicle skeleton model Body skeleton model generation step,
A stiffness analysis method for a vehicle body, comprising: a stiffness analysis step for performing a stiffness analysis for the mass-set vehicle body skeleton model in consideration of an inertial force acting when the vehicle is running.   2. The vehicle body rigidity analysis method according to claim 1, wherein the predetermined position in the mass setting vehicle body skeleton model generation step is set on a straight line or a curve connecting the fixed connecting portions.   In the case where the fitting or the lid is a rotationally movable part that is rotatable, the predetermined position is set to a position excluding a rotationally movable central axis when the fitting or the lid is rotationally movable. Item 2. The vehicle body rigidity analysis method according to Item 2.   The predetermined position in the mass setting vehicle body skeleton model generation step is set on a plane or a curved surface (except on the straight line or curved line) surrounded by a straight line or a curve connecting the fixed connecting portions. The vehicle body rigidity analysis method according to claim 1.   In the mass setting vehicle body skeleton model generation step, a mass corresponding to a mass of the fitting or the lid is set using a mass element and a rigid element that connects the mass element and the fixed coupling portion. The vehicle body rigidity analysis method according to any one of claims 1 to 4.   The mass setting vehicle body skeleton model generation step is set using a mass element and a beam element, and a sum of masses of the mass element and the beam element is a mass of a fitting or a lid fixed or connected to the fixed connection portion. The vehicle body stiffness analysis method according to claim 1, wherein the vehicle body stiffness analysis method corresponds to the vehicle body stiffness analysis method according to claim 1.   5. The vehicle body skeleton model generation step according to claim 1, wherein the mass setting vehicle body skeleton model generation step is set using a beam element having a mass corresponding to a mass of the fitting or the lid. Stiffness analysis method.