JP6597339B2 - Evaluation method for structural member and evaluation member used therefor - Google Patents

Description

  The present invention relates to a method for evaluating a structural member that receives bending and tension, and an evaluation member used for the method. The evaluation method and the evaluation member of the present invention are particularly suitable for evaluation of a structural member made of a high-strength steel plate.

  In order to achieve both vehicle crash performance and fuel efficiency, a high-strength and lightweight vehicle structure is required. To design the optimal vehicle body structure, it is necessary to create an evaluation member that can accurately reproduce the bending moment and tensile / compressive stress acting on the actual structural member of an automobile, and set this in a test device for evaluation. .

  As a general structural member evaluation method, there is a three-point or four-point bending test method. In this method, bending moment and axial force (axial tensile / compressive force) are generated at the same time in the cross section to be evaluated. I can't let you. Therefore, in order to solve this problem, the present applicant has previously developed a “lever bending evaluation method” and proposed it as Patent Document 1.

  As shown in FIG. 1, this “lever bending evaluation method” includes an application arm 2 having an application point 3 offset from the axis of the evaluation member 1 at the end of the evaluation member 1 that is a structural member to be evaluated. Is attached, and a tensile or compressive test force is applied to the force application point 3 in a state where the force application point 3 at the tip of the force application arm 2 is supported by a pivotable support point to cause buckling at a predetermined portion of the evaluation member 1. It is an evaluation method of a structural member. In this example, the structural member has a structure in which an inner member 6 is welded to a flange portion 5 of a hat member 4 having a hat-shaped cross section as shown in FIG. At the opposite ends in the axial direction, the force applying arms 2 are welded to the end portions via end plates 7.

  According to this “lever bending evaluation method”, since a bending moment and an axial force can be simultaneously applied to a predetermined portion of the evaluation member 1, unlike a general bending test method, There is an advantage that the working bending moment and tensile / compressive stress can be accurately reproduced.

  However, when the material of the evaluation member 1 is a high-strength steel plate, before the deformation such as buckling is generated at a predetermined portion of the evaluation member 1, as shown in FIG. The welded portion with the plate 7 was broken, and there was a problem that correct evaluation could not be performed.

Japanese Patent Laying-Open No. 2015-108585

  Accordingly, an object of the present invention is to solve the above-described conventional problems, and in a lever bending evaluation method in which a bending moment and an axial force are simultaneously applied to a predetermined portion of an evaluation member, the welded portion between the end portion of the evaluation member and the end plate An object of the present invention is to provide a structural member evaluation method capable of avoiding breakage and stably generating buckling at a predetermined portion of the evaluation member, and an evaluation member used therefor.

  As a result of examining the cause of the breakage of the evaluation member described above, the inventor has a softened portion at the end portion of the evaluation member because the heat input to the base material (high strength steel plate) of the evaluation member is large when welding the end plate. It was found that the fracture occurred from the weakest softened part due to the axial force generated and uniformly generated in the longitudinal direction of the evaluation member during the test.

  The present invention has been completed on the basis of the above knowledge, and an attachment arm having an application point offset with respect to the axis of the evaluation member is attached to the end of the evaluation member which is a structural member to be evaluated. A method of evaluating a structural member in which a tensile or compressive test force is applied to an applied point while the point is supported by a supporting point, and a bending moment and an axial force are simultaneously applied to the evaluation member. The flange portion of the hat member and the end portion of the inner member opposite to the hat member have a butterfly shape with a curve, and a structure in which these hat member and the inner member are welded is used. It is characterized by this.

  The attachment arm is attached to only one end portion of the evaluation member, is attached to both ends of the evaluation member by being offset in the same direction, is attached to be offset in a non-parallel manner in a plane including the axis of the evaluation member, and evaluation It can be attached by being offset in a direction away from the plane including the axis of the member. In addition, a rolling bearing can be used for the support point.

The evaluation member of the present invention is an evaluation member in which an attachment arm having an application point offset with respect to the axis of the evaluation member is attached to the end of the evaluation member, which is a structural member to be evaluated. It consists of a hat member and an inner member of the mold, and the flange portion of the hat member and the end portion of the inner member corresponding to the hat member are curved butterfly shapes, and the hat member and the inner member are welded. It is characterized by this. In addition, it is preferable to make it the structure which made the both ends of the said inner member thicker than a center part, and welded the mild steel plate .

  According to the present invention, the evaluation member includes a hat member having a cross-sectional hat shape and an inner member, and the flange portion of the hat member and the end portion of the inner member corresponding to the hat member are butterfly shapes with curves, and these hats Since a member having a structure in which a member and a flat inner member are welded is used, the cross-section at the center remains the same as the evaluation cross-section, and the width of the flange at both ends is widened to alleviate the stress generated at the end welds. Can do. Thereby, the fracture of the welded portion between the end portion of the evaluation member and the end plate can be avoided, and buckling can be stably generated at a predetermined portion of the evaluation member.

It is explanatory drawing of the conventional lever bending evaluation method. It is a disassembled perspective view of the evaluation member of the conventional lever bending evaluation method. It is explanatory drawing of the conventional problem. It is explanatory drawing of the lever bending evaluation method of this invention. It is explanatory drawing of the assembly process of an evaluation member. It is a side view which shows the state which offset and attached the attachment arm to the both ends of the evaluation member in the same direction. It is a side view which shows the state which attached the attachment arm to the end of the evaluation member. It is a side view which shows the state which offset the non-parallel offset arm in the plane containing the axis line of an evaluation member, and was attached.

  Embodiments of the present invention will be described below. In the present invention, the structural member to be evaluated is a cross-sectional hat-shaped member made of a high-strength steel plate.

  As shown in FIG. 4, the structural member evaluation method of the present invention also attaches an attachment arm 11 having an application point offset with respect to its axis to the end of the evaluation member 10, and uses the application point at the tip as a support point 12. As in the conventional case, a tensile or compressive test force is applied to the applied force point in a state where it is supported by, and a bending moment and an axial force are simultaneously applied to the evaluation member 10. However, as will be described below, the structure of the evaluation member 10 is different from the conventional one.

  As shown in FIGS. 4 and 5, the structural member to be evaluated is composed of a hat-shaped hat member 13 and an inner member 14, but the flange portion 15 of the hat member 13 is constricted at the center. It has a butterfly shape with a gentle curve. Similarly to the shape of the flange portion 15, the inner member 14 has a butterfly shape with a constricted central portion, and the hat member 13 and the inner member 14 are welded. The end plates 16 are welded to both ends of the evaluation member 1 having such a shape, and the attaching arm 11 is attached to the outside of the end plates 16.

  By making the evaluation member 10 in such a shape, the cross section at the center of the evaluation member 10 can be left as it is, and the flange width at the end can be widened to relieve the stress at the end weld. Furthermore, by making the evaluation member 10 in such a shape, the bending position of the evaluation member 10 can be stably buckled with the center of the section coefficient being the smallest.

  Further, as in the present embodiment, it is preferable that both end portions of the inner member 14 are thicker than the center portion. In FIG. 5, reinforcing plates 17 having a plate thickness of about 3 mm, for example, are welded to both ends of the inner member 14. The welding can be butt welding with a laser or the like. Such a technique of butt-welding steel plates having different thicknesses is known as a tailored blank welding technique.

  By using a soft metal such as a mild steel plate as the reinforcing plate 17, softening due to a thermal effect during welding of the reinforcing plate 17 and the end plate 16 is prevented. Since both ends of the hat member 13 made of a high-strength steel plate are directly welded to the end plate 16, softened portions are generated. During the test, the reinforcing plate 17 welded to the flange portion 15 is passed through the welded portion. Therefore, the stress generated in the softened portion is relieved.

  Thus, if the lever bending evaluation method is implemented using the evaluation member 10 of the present invention, the stress generated in the welded portion between the end portion of the evaluation member 10 and the end plate 16 can be relaxed. Therefore, it is possible to avoid breakage of the welded portion between the end portion of the evaluation member 10 and the end plate 16 as in the prior art, and to stably generate buckling in the central portion of the evaluation member 10. This is shown in FIG.

  As shown in FIG. 6, it is preferable to use a rolling bearing having a low frictional resistance at the support point 12 at the tip of the force arm 11. As a result, the test force F can be transmitted to the applied arm 11 without being affected by friction, and a highly accurate evaluation test can be performed.

  In FIG. 4 and FIG. 6, the attachment arm 11 is attached to both sides of the evaluation member 10. However, the attachment arm 11 can be attached only to one end of the evaluation member 10 as shown in FIG. 7.

  Further, as shown in FIG. 6, the attachment arm 11 is attached to both ends of the evaluation member 10 while being offset in the same direction.

  Further, as shown in FIG. 8, it is possible to attach the attachment arm 11 by offsetting it in a non-parallel manner in a plane including the axis of the evaluation member 10, or by attaching it in a direction deviating from the plane including the axis of the evaluation member 10. It is.

  As described above, by changing the attachment method of the arm 11 in various ways, the bending moment applied to the test section of the evaluation member 10 and the magnitude and direction of the axial force can be changed in various ways. It is possible to set optimum evaluation conditions according to the mounting position of each. In any case, the structure of the evaluation member 10 is as described above.

  As described above, according to the present invention, the fracture of the welded portion between the end portion of the evaluation member 10 and the end plate 16 is avoided, and a predetermined portion of the evaluation member 10 having the evaluation cross section, that is, the center of the evaluation member 10 There exists an advantage which can generate buckling stably in a site | part.

DESCRIPTION OF SYMBOLS 1 Conventional evaluation member 2 Applying arm 3 Applying point 4 Hat member 5 Flange part 6 Inner member 7 End plate 10 Evaluation member 11 of the present invention 11 Applying arm 12 Supporting point 13 Hat member 14 Inner member 15 Flange part 16 End plate 17 Reinforcing plate

Claims (8)

An attachment arm having an application point offset from the axis of the evaluation member is attached to the end of the evaluation member, which is the structural member to be evaluated, and the application point is pulled or compressed to the application point while the application point is supported by the support point. A method for evaluating a structural member in which a test force is applied and a bending moment and an axial force are simultaneously applied to the evaluation member,
The evaluation member includes a hat-shaped hat member and an inner member, and the flange portion of the hat member and the end portion of the inner member corresponding to the hat member have a butterfly shape with a curve, and the hat member and the inner member A method for evaluating a structural member, characterized by using a structure welded to each other. The structural member evaluation method according to claim 1, wherein the attachment arm is attached only to one end of the evaluation member . The structural member evaluation method according to claim 1 , wherein the attachment arm is attached to both ends of the evaluation member while being offset in the same direction . The structural member evaluation method according to claim 3 , wherein the attachment arm is attached by being offset non-parallelly in a plane including an axis of the evaluation member. 4. The structural member evaluation method according to claim 3 , wherein the attachment arm is attached by being offset in a direction deviating from a plane including the axis of the evaluation member. 6. A method for evaluating a structural member according to claim 1, wherein a rolling bearing is used as the support point . An evaluation member comprising an attachment arm having an application point offset with respect to the axis of the evaluation member at the end of the evaluation member, which is a structural member to be evaluated,
  Consists of a hat-shaped hat member and an inner member, and a flange portion of the hat member and an end portion of the inner member opposite to the hat member have a butterfly shape with a curve, and the hat member and the inner member are welded The evaluation member characterized by being. The evaluation member according to claim 7, wherein both end portions of the inner member are thicker than the central portion, and a mild steel plate is welded .