JP5527243B2 - Calculation method of material anisotropy considering material movement by molding - Google Patents

Description

  The present invention relates to a method for calculating material anisotropy in consideration of material movement due to molding, and more specifically, a finite element method is applied to an anisotropic material whose mechanical properties are in-plane anisotropy. Material anisotropy that takes into account material movement due to molding, which can properly reflect the influence of in-plane anisotropy in CAE (Computer Aided Engineering) analysis, which mainly performs deformation simulation such as stiffness analysis and impact analysis by (FEM) calculation It relates to the calculation method of sex. Here, the rigidity analysis is a simulation calculation of a rigidity test, and the collision analysis is a simulation calculation of a collision test.

  In recent years, especially in the automobile industry, weight reduction of vehicle bodies due to environmental problems has been promoted, and CAE analysis has become an indispensable technique for vehicle body design (for example, Patent Document 1). In addition, it is known that the mechanical property value of the input material (metal plate, eg, steel plate) greatly affects the CAE analysis result. In the forming analysis, YS (yield strength), TS (tensile strength) are mainly used. R) (Rankford value) contributes, in stiffness analysis, elasticity values such as Young's modulus contribute in proportion to the displacement obtained in the analysis, and in impact analysis, material strength values such as YS and TS contribute greatly. To do.

On the other hand, there are materials whose mechanical properties have large in-plane anisotropy (this is called anisotropic material), especially those manufactured by rolling are in the rolling direction (L direction) and in the direction perpendicular thereto. It is known that there is a characteristic change of 2 to 50% in the (C direction) and 45 ° direction (D direction) in terms of the characteristic change width calculated by (maximum−minimum) / maximum × 100.
In the case of CAE analysis, if the object to be analyzed is a material (isotropic material) whose mechanical properties are constant regardless of the in-plane direction, the problem of directionality does not occur, but it is an anisotropic material When a mechanical property value in a direction different from the main deformation direction of the material is input, a calculated shape different from the deformed shape without anisotropy is obtained. Therefore, in the anisotropic material, it is necessary to set information on in-plane anisotropy of mechanical characteristics (this is called anisotropic information) for each element obtained by dividing the analysis target into a plurality of elements. This anisotropy information is a reference direction (for example, the L direction or the C direction or these directions) related to the in-plane anisotropy of the mechanical characteristic to give a mechanical characteristic value corresponding to the direction according to the main deformation. Information on the correspondence between the azimuth angle and the mechanical characteristics with respect to the direction between them, and can be stored in the form of a table or a functional expression in advance. The reference direction is displayed by one arrow in each element on the analysis screen (see, for example, FIG. 4). The direction indicated by the arrow is the reference direction, and the reference direction is fixed to each element. If each element moves and rotates, it moves and rotates in the same manner.

JP 2004-171144 A

However, since each element of the analysis target product faces various directions by molding, it is difficult to reflect the information on the movement and rotation of each element accompanying the molding analysis by CAE analysis in anisotropy. It was.
In other words, conventionally, with the input that relies on the human intuition for the change in the angle of the material, it is not possible to accurately calculate the rotational movement due to molding, and it is possible to input only the shape of the shape along the original LC direction in a linear shape. An actual molded product has a complicated shape consisting of a curved surface, and a human intuition cannot accurately represent movement and rotation. In addition, the number of elements used in the current vehicle body is about 300,000 to 500,000, and it is extremely difficult to manually input all the elements. Since the reference direction set for the molded product depends on human intuition, it is far from the actual, and the subsequent stiffness analysis results are the results of the corresponding actual molded product stiffness test and impact test. There were many cases that did not fit. Furthermore, the number of elements used for CAE analysis of the current car body is about 300,000 to 500,000. Even if multiple elements can be combined into a smaller number of blocks and input can be made in units of blocks, all are input manually. It is extremely difficult to do.

  In order to solve the above problems, the inventor has eagerly studied the setting method of the reference direction, which can accurately reduce the calculation time, without relying on manual input, and as a result, forming the three-dimensional shape into a planar shape. By using analysis software, the reference direction can be automatically set, and the present invention has been obtained with the knowledge that the results of rigidity analysis and collision analysis after molding analysis will match well with the experimental results. .

  The error is extremely large in the rotational movement of the material by human intuition. For this reason, a deformation | transformation of material can be calculated using shaping | molding analysis, and a subject is solved by using the result of this shaping | molding calculation. In the forming analysis, each element has coordinate information of the node before and after the deformation. The angle formed by the coordinate information in the blank state and the LC direction is kept constant even when moving and rotating. Even when an element is deformed by molding, the angle formed with the LC direction can be calculated by taking the deformation amount into account. By using these and reflecting the angle formed by the blank for each element in the molded product, the angle can be accurately set over the entire molded product.

That is, the present invention is as follows.
(1)
A calculation method of the material anisotropy of definitive to CAE analysis performing deformation simulation by a finite element method calculation using the computer against anisotropic material, the computer automatically, the target solid comprising the anisotropic material A first step of developing a shaped molded article into a planar blank as an analysis object, and then the computer automatically blanks the blank with respect to a specific direction in the base plate from which the blank was collected or a direction perpendicular thereto. A second step of moving and rotating the plate, and then the computer automatically sets the blank element and the surface of the mechanical characteristics set in the blank according to the blank coordinate information obtained in the second step. The angle formed with the reference direction related to the internal anisotropy is calculated, and the reference direction related to the in-plane anisotropy of the mechanical characteristics already set in the base plate is set in the blank. A third calculation method considers material anisotropic material movement by molding, characterized by a step of setting the reference direction in each element by collectively transferred to all elements.
(2)
The mechanical property related to the in-plane anisotropy of the mechanical property is one or more of Young's modulus, yield strength, tensile strength, r value, and stress-strain curve. A method for calculating material anisotropy taking into account material movement by molding as described in (1).
(3)
In (2), the material anisotropy calculation method considering material movement by molding, wherein rigidity analysis or collision analysis is performed on the molded product after the third step as an analysis target.

  According to the present invention, the reference direction relating to the in-plane anisotropy of the mechanical characteristics set for each element in the analysis target correctly reflects the fact, and the automatic input can be performed, so that the creation time is greatly increased. Shorten. Moreover, when the rigidity analysis and the collision analysis were performed on the obtained molded product of the calculated shape, the calculated values were in good agreement with the experimental values, and high accuracy of the deformation simulation was achieved.

It is explanatory drawing which shows one example of embodiment of this invention. It is explanatory drawing which shows an example of the shaping | molding analysis result by this invention. It is explanatory drawing which shows an example of the shaping | molding analysis result by this invention. It is explanatory drawing which shows an example of the conventional shaping | molding analysis result. It is a graph which shows the rigidity analysis result of this invention example and a comparative example compared with an experimental value.

FIG. 1 is an explanatory diagram showing an example of an embodiment of the present invention. 1 is a molded article, its shape is a target three-dimensional shape, the material is anisotropic materials. The anisotropy information of the material is correspondence information between the azimuth angle with respect to the reference direction and the mechanical characteristics, and is stored in the form of a table here. As the reference direction, a direction rotated counterclockwise from the C direction by an angle θ (this angle θ is also referred to as a C direction angle with respect to the reference direction) is used. The table has mechanical characteristic values corresponding to each of three angles of θ = 0 °, 45 °, and 90 °, and setting or changing the reference direction can be performed by designating θ on the table. it can. If θ = 0 ° is designated, the C direction becomes the reference direction, if θ = 45 ° is designated, the direction rotated 45 ° counterclockwise from the C direction becomes the reference direction, and if θ = 90 ° is designated. A direction rotated counterclockwise by 90 ° from the C direction (= L direction) is a reference direction. The mechanical property values in the table are data of Young's modulus, yield strength, tensile strength, r value, and stress-strain curve. Those necessary for the analysis are selected and used according to the type of analysis to be performed (the above-described stiffness analysis and collision analysis).

In the CAE analysis, the molded product 1 is divided into a plurality of regions by mesh as shown in the figure. Each of the plurality of divided areas is an element.
In the first step [1] (the following (a) and (b)), the molded product 1 is set as an analysis target, and this is developed on a planar blank 2. The molding analysis software used to develop the solid figure into a plane figure is “Onestep” (trade name).

In 2nd step [2] (following (c)), the blank 2 returns to the state before extract | collecting from the base plate 3 by moving and rotating the blank 2. FIG. The base plate 3 and the blank collection figure 4 in the base plate 3 are input in advance. In this example, the base plate 3 is a rolled steel strip, and its C direction is known. Based on this known C direction, the reference direction is already set for the base plate 3.
Therefore, in the third step [3] (the following (d) and (e)), the set reference direction in the base plate 3 is collectively transferred to all the elements in the blank 2. Thus, the reference direction is automatically set for each element in the blank 2 in a very short time. The reference direction set for each element is fixed to the element and performs the same movement as the movement and rotation of the element accompanying molding.

Record
(a) Obtaining information about the original molded product:
Get node number 1 and node number 2 of the element to be calculated.
(b) Return the original part to the blank:
Using molding analysis such as Onestep, turn a product with a 3D shape into a 2D flat plate.
(c) Blank placement:
The blank is moved and rotated with respect to the LC direction.
(d) Angle measurement with blank:
From the X and Y coordinates of node number 1 and node number 2 acquired in (a), the angle between the straight line connecting node1 and node2 and the L or C direction is calculated by the outer product.
(e) Setting the angle on the molded product:
The angle calculated in (d) is input to the material angle information of the element of the original molded product.

2 and 3 show a molded product 5 having a final calculated shape obtained by molding analysis according to the present invention. 2 and 3, (a), (b), and (c) are cases where the reference direction C-direction angle θ is 0 °, 45 °, and 90 °, respectively. It can be seen that the arrow indicating the reference direction is collectively transferred from the base plate and set in a form suitable for all elements of the molded product 5.
On the other hand, FIG. 4 shows a molded product 5 having a final calculated shape obtained by conventional molding analysis for the same target three-dimensional shape. The C direction angle θ of the reference direction is 0 °. However, since the arrows indicating the reference direction are input to each element of the three-dimensional shape depending on human intuition, the linear portion (FIG. 4 (a)) There are places where elements are adjacent to each other in the opposite direction, and the curved portion (FIG. 4 (b)) is set so as not to match the actual situation because it is input for each large block.

  Table 1 shows an example in which the time required for setting the reference direction (arrow input) is compared between the present invention and the conventional case when a molded article having a target solid shape different from the examples of FIGS. Show. From Table 1, according to the present invention, the reference direction setting time is 1/3 of the conventional even when the number of elements is as small as 1000, and 1/27 of the conventional when the number of elements is as large as 10,000. It can be seen that it is significantly shortened.

  For the molded product 5 having the final calculated shape according to the present invention in the case of θ = 0 °, 45 °, and 90 ° illustrated in FIGS. On the other hand, actual molded products corresponding to these were produced, and a rigidity test (rigidity confirmation experiment) corresponding to rigidity analysis was performed to obtain a rigidity value. Also, for the same target solid shape, the final calculated shape molded product 5 obtained by the conventional molding analysis method (shown in FIG. 4 when θ = 0 °, not shown when θ = 45 ° and 90 °) ) Was similarly analyzed to calculate a stiffness value. These results are shown in Table 2 and graphically shown in FIG.

From FIG. 5, in the example of the present invention, the calculated value is very close to the experimental value even if the reference direction C-direction angle θ changes. On the other hand, in the conventional example, when θ = 0 °, the calculated value is close to the experimental value, but when θ = 45 ° and 90 °, the calculated value is significantly different from the experimental value.
That is, according to the present invention, it can be seen that the rigidity value prediction accuracy by the deformation simulation of the rigidity analysis is remarkably improved as compared with the conventional case.

  It should be noted that in the above case, the collision analysis is performed instead of the rigidity analysis, and the same result is obtained.

1 Molded product (target solid shape)
2 blank 3 base plate (base plate from which the blank was collected)
4 Blank sampling figure in base plate 5 Molded product (final calculation shape)

Claims (3)

A calculation method of the material anisotropy of definitive to CAE analysis performing deformation simulation by a finite element method calculation using the computer against anisotropic material, the computer automatically, the target solid comprising the anisotropic material A first step of developing a shaped molded article into a planar blank as an analysis object, and then the computer automatically blanks the blank with respect to a specific direction in the base plate from which the blank was collected or a direction perpendicular thereto. A second step of moving and rotating the plate, and then the computer automatically sets the blank element and the surface of the mechanical characteristics set in the blank according to the blank coordinate information obtained in the second step. The angle formed with the reference direction related to the internal anisotropy is calculated, and the reference direction related to the in-plane anisotropy of the mechanical characteristics already set in the base plate is set in the blank. A third calculation method considers material anisotropic material movement by molding, characterized by a step of setting the reference direction in each element by collectively transferred to all elements.   The mechanical property related to the in-plane anisotropy of the mechanical property is one or more of Young's modulus, yield strength, tensile strength, r value, and stress-strain curve. The material anisotropy calculation method considering material movement by molding according to claim 1.   3. The material anisotropy calculation method according to claim 2, wherein the rigidity analysis or the collision analysis is performed on the molded product after the third step as an analysis target.

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