JP2011053807A - Device and method for collision analysis - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To analyze collision between an impact absorber and a vehicle by reproducing the collision naturally with high accuracy using a finite element model, without producing drag characteristics, deformation portion, deformation sequence and deformation shape (deformation type (break, crushed destruction)) which are different from actual characteristics in a wide characteristic range of a stress-distortion characteristic. <P>SOLUTION: An impact absorber 12 formed of integrated cylinder-shaped bodies, having axial lines mutually disposed in parallel, is modeled with a shell element by the finite element method. A collision analysis device 1 performs collision analysis by making collision in a predetermined manner between the impact absorber 12 and a collision object vehicle 21 which is modeled by the finite element method. To each element of the modeled impact absorber 12, a damage characteristic having a decreased stress accompanying an increased distortion is set in a predetermined first distortion area, as a characteristic between stress and distortion at compression. Also, a characteristic in which the element itself becomes extinct is set in a predetermined second distortion area. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a collision analysis apparatus for analyzing a collision between a vehicle collision test barrier (moving barrier, fixed barrier, etc.) including a shock absorber having a honeycomb structure and a vehicle by modeling with a shell element by a finite element method, and a collision It relates to the analysis method.

  Conventionally, various crash tests have been performed on vehicles, and in recent years, not only a crash test using an actual vehicle but also modeling and analysis by a finite element method has been performed.

  For example, in Japanese Patent Application Laid-Open No. 2007-102537 (hereinafter referred to as Patent Document 1), a shock absorber made of an aluminum honeycomb that is an aggregate of a large number of honeycomb lattices formed in a cylindrical shape having mutually parallel axes is limited. When modeling with the element method, the virtual dimensions of the honeycomb lattice are set to be larger than the actual honeycomb lattice dimensions, and the same compressive stress as the actual product is generated when the same compressive load is applied. A technique for modeling the thickness different from the actual plate thickness is disclosed.

JP 2007-102537 A

  By the way, in an actual collision, the shock absorber (actual machine) generally takes a form of gradually collapsing from the collision side. There is a problem that it is very difficult to analyze the drag characteristics together with the scale factor. In the finite element method, there are problems such as element locking. For example, as shown by the one-dot broken line in FIG. A drag (increase in stress) different from the stress-strain characteristic (shown by a solid line in FIG. 9) is generated, and the reproducibility is deteriorated. Therefore, when the plate thickness and the like are virtually set as disclosed in Patent Document 1 described above, there is a problem that more complicated adjustment is required in consideration of the deformation mode and the like.

  The present invention has been made in view of the above circumstances, and the collision between the shock absorber and the vehicle is based on the finite element model, the drag characteristics, the deformation site, the deformation order, and the different characteristics from the actual characteristics in a wide characteristic region of the stress-strain characteristics. An object of the present invention is to provide a collision analysis apparatus and a collision analysis method capable of reproducing and analyzing a collision naturally and accurately without generating a deformed shape (deformation type (folding / crushing)).

  The present invention is a collision analysis in which a shock absorber formed by collecting cylindrical bodies in parallel with each other in an axis is modeled by the finite element method, and is collided with a collision target modeled by the finite element method to perform a collision analysis. In the device, a correction characteristic that suppresses an increase in stress is set in a region where the entire drag characteristic indicated by the relationship between stress and strain at the time of compression of the above modeled shock absorber exceeds a preset strain value. It is characterized by that.

  According to the collision analysis apparatus and the collision analysis method according to the present invention, the collision between the shock absorber and the vehicle is based on the finite element model, and the drag characteristics, the deformation part, and the deformation order that are different from the actual characteristics in a wide characteristic region of the stress-strain characteristics. In addition, it is possible to reproduce and analyze the collision naturally and accurately without generating a deformation shape (deformation type (breaking / crushing)).

1 is a schematic configuration diagram of a collision analysis apparatus according to an embodiment of the present invention. It is a flowchart of the collision analysis program which concerns on one Embodiment of this invention. It is a flowchart of the moving barrier modeling process which concerns on one Embodiment of this invention. It is a perspective view of the moving barrier concerning one embodiment of the present invention. It is explanatory drawing of the shock absorber which concerns on one Embodiment of this invention. It is explanatory drawing of the shock absorber modeled with the shell element by the finite element method which concerns on one Embodiment of this invention. It is explanatory drawing which shows an example of the crash test to analyze which concerns on one Embodiment of this invention. It is explanatory drawing of the stress-strain characteristic set to each element which concerns on one Embodiment of this invention. It is explanatory drawing of the whole stress-strain characteristic at the time of compression of the shock absorber which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the present embodiment, a collision analysis analysis of a vehicle collision test barrier (moving barrier) including a shock absorber having a honeycomb structure and a vehicle will be described later in a computer system such as a personal computer (hereinafter abbreviated as PC). This is done by executing a collision analysis program.

  As shown in FIG. 1, a PC 1 as a collision analysis device is connected to a computer main body 2 having a central processing unit (hereinafter abbreviated as CPU) and a storage device for storing various data and programs, and to the computer main body 2. The keyboard 3 that is a key input device, a mouse 4 that is a pointing device, and a monitor 5 that is a display device are mainly configured.

  In the computer 2, data to be analyzed such as drawings and drawings of moving barriers and vehicles, etc. are recorded on recording media such as FD (flexible disk), CD (Compact Disc), DVD (Digital Versatile Disk), etc. And is recorded in an HD (Hard Disk) built in the computer main body 2, and the collision analysis between the moving barrier and the vehicle by the finite element model is executed according to a collision analysis program described later.

Here, the actual machine of the moving barrier to be analyzed in this embodiment will be described.
In FIG. 4, reference numeral 10 denotes a moving barrier. The moving barrier 10 is configured as a deformable barrier in which a shock absorber 12 is attached to the front end of a carriage (four-wheeled vehicle) 11.

  The shock absorber 12 is formed to resemble the shape of an actual vehicle, and a lower absorber 12a positioned at a height corresponding to the height of a bumper of the actual vehicle is formed to protrude forward from the upper absorber 12b. .

  As shown in FIG. 5, the impact absorber 12 has an aluminum honeycomb structure in which both the lower absorber 12a and the upper absorber 12b are configured to be deformable by collision. An aluminum honeycomb is formed by arranging a large number of regular hexagonal honeycomb lattices in parallel as a cylindrical body in which the respective axial directions coincide with the front-rear direction (collision direction). Each honeycomb lattice has a hollow structure in which each cylindrical wall is shared with adjacent different honeycomb lattices, so that there is no gap between them and spaces are formed only within each honeycomb lattice.

  Next, the collision analysis executed by the present embodiment will be described with reference to the flowchart of FIG. First, in step (hereinafter abbreviated as “S”) 101, various information necessary for analysis, the shape of the moving barrier 10 (including the external dimensions of the shock absorber 12), the shape of the vehicle to be collided, the weight, etc. Input the collision type such as original, side collision, and rear collision, collision conditions (collision speed, collision angle), analysis conditions, etc.

  Next, in S102, modeling of the moving barrier 10 by the finite element method is executed according to a flowchart of the moving barrier modeling process described later.

  Next, the process proceeds to S103, and the collision vehicle is modeled by the finite element method.

  Then, the process proceeds to S104, and a structural analysis is performed after the moving barrier 10 modeled by the finite element method collides with the vehicle to be collided modeled by the finite element method. For example, when the collision mode is a side collision, as shown in FIG. 7, the moving vehicle modeled by the finite element method is compared with the collision target vehicle 21 modeled by the finite element method in accordance with a known side collision test standard. The barrier 10 is collided with the side surface of the vehicle, and the structural analysis after the collision is performed. The collision mode is not limited to a side collision, and may be a front collision, a rear collision, an offset collision, or the like.

  Next, modeling of the moving barrier 10 by the finite element method executed in S102 described above will be described with reference to the flowchart of FIG.

First, in S201, an analysis calculation time is determined.
Next, proceeding to S202, the step time of each process in the analysis is determined from the constraint of the calculation time of S201, and the total number of elements is determined. Thereby, the minimum element size is determined, and the minimum core size (virtual dimension different from the actual machine dimension) of the honeycomb lattice is determined. In this way, the core size of the honeycomb lattice (virtual dimension different from the actual machine dimension: Sc in FIG. 5B) is determined.

Next, when proceeding to S203, the plate thickness is virtually determined.
Next, the process proceeds to S204, for example, referring to data obtained in advance through experiments or the like, using (sheet thickness / length of one side of honeycomb) as a parameter, the stress-strain characteristics at the time of compression of the actual machine, It is determined as a stress-strain characteristic serving as a reference for each element (determination of the characteristic of the solid line in FIG. 8).

  Next, the process proceeds to S205, and a correction characteristic based on a preset experiment, calculation, or the like is set for the stress-strain characteristic serving as a reference for each element determined in S204. This correction characteristic is, for example, a characteristic indicated by a broken line in FIG. 8. In this example, in the region where the strain ε exceeds ε1 (first strain region), the stress σ decreases as the strain ε increases. Damage characteristics. Further, in the present embodiment, in addition to the damage characteristics indicated by the above-described broken line as the correction characteristics of each element, for example, in an area where the strain ε exceeds a preset value (second distortion area), the element itself is A characteristic that disappears is set.

  Next, in S206, the shock absorber 12 having a honeycomb structure is modeled by a shell element by a finite element method as shown in FIG. The stress-strain characteristics of S204 and S205 are set.

  In step S207, the moving barrier 10 is modeled as a shell element by the finite element method, and the routine is exited.

  As described above, according to the present embodiment, the impact absorber 12 formed by assembling the cylindrical body with the axis lines set in parallel to each other is modeled by the shell element by the finite element method, and the collision target modeled by the finite element method is used. In the collision analysis apparatus 1 that performs collision analysis with a vehicle 21 in a predetermined collision, each element of the modeled shock absorber 12 is distorted in a first strain region that is predetermined as stress and strain characteristics during compression. In addition to setting a damage characteristic in which the stress decreases with an increase in the value, a characteristic in which the element itself disappears in a predetermined second strain region is set. This reliably suppresses an increase in stress in a region where the overall stress-strain characteristic during compression of the modeled shock absorber 12 exceeds a preset strain value. That is, as shown in FIG. 9, when the strain exceeds a predetermined strain value, the stress tends to increase beyond the actual characteristic (one-dot broken line), but by setting the damage characteristic including the stress drop, This increase in stress is prevented so as to approach the actual stress-strain characteristic (broken line). In addition, by setting the characteristic that the element itself disappears in the second strain region, the element whose strain is increased and the stress is increased is erased, so that this also approaches the actual stress-strain characteristic. (Stress-strain characteristics including erasure correction). As described above, the shock absorber modeled by the finite element method according to the embodiment of the present invention can be analyzed with substantially the same characteristics as actual characteristics in a wide characteristic region of stress-strain characteristics. It is possible to reproduce and analyze the collision naturally and accurately.

  In the present embodiment, as characteristics for correcting the stress-strain characteristics, correction for setting a damage characteristic in which stress decreases with increasing strain is set in the first strain area, and elements themselves are set in the second strain area. Although two corrections for setting the characteristic of disappearance are set, only one of the corrections may be set.

  Furthermore, in the present embodiment, a regular hexagonal tubular aluminum honeycomb has been described as an example of the shock absorber cylindrical body. However, it is needless to say that other shapes such as a regular rectangular tubular body may be used. .

  Further, in the present embodiment, the moving barrier 10 provided with the shock absorber having the honeycomb structure is described as an example, but the present analysis is similarly applied to the fixed barrier provided with the shock absorber having the honeycomb structure. It goes without saying that the method can be applied.

  Furthermore, in the present embodiment, an example in which the shock absorber is modeled with a shell element by the finite element method has been described. However, the present analysis method can be applied even when modeling and analyzing with an element other than the shell element. Needless to say.

DESCRIPTION OF SYMBOLS 1 Collision analyzer 2 Computer main body 3 Keyboard 4 Mouse 5 Monitor 10 Moving barrier 11 Cart 12 Shock absorber 12a Lower absorber 12b Upper absorber 21 Impacted vehicle

Claims (6)

In a collision analysis device that analyzes a collision by modeling a shock absorber formed by collecting cylindrical bodies parallel to each other by a finite element method and colliding with a collision target modeled by a finite element method.
The above-mentioned modeled shock absorber has a correction characteristic that suppresses the rise of stress in the region where the overall drag characteristic indicated by the relationship between stress and strain during compression exceeds the preset strain value. A collision analysis device.   The correction characteristic is that, for each element of the shock absorber modeled by the finite element method, the stress decreases as the strain increases in the first strain region that is predetermined as the stress and strain characteristics during compression. The collision analysis apparatus according to claim 1, wherein a damage characteristic to be set is set.   The correction characteristic is set such that each element of the shock absorber modeled by the finite element method is extinguished in a second strain region predetermined as a stress and strain characteristic during compression. The collision analysis apparatus according to claim 1, wherein the collision analysis apparatus is formed.   The correction characteristic is that, for each element of the shock absorber modeled by the finite element method, the stress decreases as the strain increases in the first strain region that is predetermined as the stress and strain characteristics during compression. The collision analysis apparatus according to claim 1, wherein a damage characteristic to be set is set and a characteristic in which the element itself disappears is set in a predetermined second strain region. In a collision analysis method in which a shock absorber formed by collecting cylindrical bodies parallel to each other in an axis is modeled by the finite element method, and a collision is performed by colliding with a collision target modeled by the finite element method.
Set and analyze a correction characteristic that suppresses the rise of stress in the region where the overall drag characteristic indicated by the relationship between stress and strain during compression of the modeled shock absorber exceeds the preset strain value. A collision analysis method characterized by the above.   The correction characteristic is that, for each element of the shock absorber modeled by the finite element method, the stress decreases as the strain increases in the first strain region that is predetermined as the stress and strain characteristics during compression. 6. The collision according to claim 5, wherein the collision characteristic is formed by setting at least one of setting a damage characteristic to be performed and setting a characteristic that the element itself disappears in a predetermined second strain region. analysis method.

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