JP2009286351A - Collision-proof reinforcing member for vehicle with superior buckling resistance and manufacturing method for it - Google Patents

Abstract

An object of the present invention is to provide a collision-resistant reinforcing material for vehicles excellent in buckling resistance and a method for manufacturing the same.
A collision-resistant reinforcing material for vehicles 1a and 1b made of a thin plate that is molded, and includes a main body 2 and a main body 2 via bent portions 3 provided on both sides of the main body 2 in the width direction. The main body 2 is provided with a concave bead 8 extending in the center in the width direction of the main body 2 along the longitudinal direction, and the concave bead 8 and the bent portion are provided. 3, the concave bead 8 is provided so that the effective width c ′ satisfies a predetermined formula, when the distance to the effective width c ′ is defined as the effective width c ′. Material 1 is provided.
[Selection] Figure 1

Description

  The present invention relates to a vehicle impact-resistant reinforcing material having excellent buckling resistance and a method for manufacturing the same.

  In order to reduce carbon dioxide emissions from automobiles, the weight of automobile bodies is being reduced using high-strength steel sheets. In addition, in order to ensure the safety of passengers, studies are being made in the direction of using high-strength steel plates in addition to mild steel plates for automobile bodies.

  As a part using a high-strength steel plate, there is a collision-resistant reinforcing material for a center pillar. This collision-resistant reinforcing material is a long reinforcing material having a closed cross-sectional structure formed by superposing and welding a steel plate having a cross-sectional shape formed into a hat shape and a flat steel plate. is there. In the automobile body, the collision reinforcing material is housed inside the center pillar, and is laid between the side sill and the side roof rail constituting the body.

  When another car collides with the side of the car, the collision part becomes a part below the door waist of the center pillar, and the lower part of the collision-resistant reinforcing material corresponding to this collision part is crushed by the collision energy. And pushed inside the car. For this reason, the shape of the collision-resistant reinforcing material for the center pillar is wide at the lower part of the lower side of the door waist and has a wide width along the full length direction of the vehicle and is directed toward the inside of the vehicle in order to ensure the collision-resistant strength. The shape becomes thick. On the other hand, in the upper part above the door waist part, from the viewpoint of design, the width along the full length direction of the automobile is narrow and the shape becomes thinner toward the inside of the car. For this reason, in the upper part of a collision-resistant reinforcement material, the buckling resistance with respect to a compressive stress may fall.

  For this reason, when an external force due to a collision is applied to the side surface of the automobile, the collision energy is absorbed in the lower part of the collision-resistant reinforcing material, while a compressive stress is applied to the upper part of the center pillar including the collision-resistant reinforcing material, resulting in collision-resistant reinforcement. The upper part of the center pillar including the material is bent toward the inside of the vehicle, and there is a possibility that the safety of the passenger cannot be sufficiently ensured. In order to solve this problem, Patent Document 1 discloses a vehicle body structure in which an intensity change point is provided between the upper end and the lower end of the pillar, and the strength of the portion above the strength change point is higher than the strength of the lower portion. ing.

In addition to the center pillar, various types of collision-resistant reinforcing materials having a closed cross-sectional structure are used for the automobile body. For example, a cross member is installed between the floor tunnel and the side sill. Further, on both sides of the front part of the vehicle body, extension parts of the front member are installed so as to sandwich the engine. In these collision-resistant reinforcing materials, since compressive stress is applied at the time of collision, improvement of buckling resistance has been desired as in the case of the collision-resistant reinforcing material for center pillars.
JP 2001-163257 A

  This invention is made | formed in view of the said situation, Comprising: It aims at providing the impact-resistant reinforcement material for vehicles excellent in buckling resistance, and its manufacturing method.

  Conventionally, it has been considered that when a concave beat is provided in a collision-resistant reinforcing material having a closed cross-sectional structure, the secondary moment of cross-section is reduced under the action of a static load, thereby leading to an increase in deformation. Therefore, it has not been performed to provide a concave bead in the collision-resistant reinforcing material. However, as a result of diligent research by the present inventors, it has been found that, in the case of collision deformation in which deformation of the collision-resistant reinforcing member occurs, the deformation of the collision-resistant reinforcing material can be reduced by providing a concave bead.

  So far, when a compressive load is applied to a collision-resistant reinforcing material that has been processed into a closed cross-section structure by processing a thin plate, the entire cross-section does not share the load, but a part of the cross-section actually shares the load. There is already a theoretical formula for calculating the effective width, which is known as the effective width. However, although the conventional theoretical formula for the effective width incorporates the elastic modulus, yield strength, thickness and Poisson's ratio of the thin plate, no consideration has been given to the width of the impact-resistant reinforcing material. The present inventors derived the effective width of a new concept by paying attention to the width of the impact-resistant reinforcing material, and applied this new effective width concept to the design of the impact-resistant reinforcing material. This has led to a dramatic increase in buckling resistance. And this inventor came to solve said subject by employ | adopting the following structures.

  The collision-resistant reinforcing material for vehicles excellent in buckling resistance of the present invention is a collision-resistant reinforcing material for vehicles made of a molded thin plate, and the collision-resistant reinforcing material for vehicles includes a main body portion and the main body. At least a pair of side wall portions integrated with the main body portion via bent portions provided on both sides in the width direction of the main portion, and the main body portion has a longitudinal direction at the center in the width direction of the main body portion. An extending concave bead is provided, and when the distance between the concave bead and the bent portion is an effective width c ′, the concave bead is configured so that the effective width c ′ satisfies the following formula (1). It is provided.

However, in Formula (1), h is the thickness of the said thin plate, b is the width | variety of the said main-body part before providing a concave bead, E is the elasticity modulus of the said thin plate, (sigma) _YP is the yield of the said thin plate. Stress, A and B are constants, A is 1.90, and B is -1.00.

  Moreover, in the collision-resistant reinforcement material for vehicles excellent in buckling resistance of the present invention, it is preferable that the depth of the concave bead is 5 mm or more.

  Furthermore, in the collision-resistant reinforcing material for a vehicle excellent in buckling resistance according to the present invention, the concave bead is composed of a bottom surface portion and bead side wall portions erected at both ends in the width direction of the bottom surface portion. Is preferred.

Furthermore, it is preferable that the collision-resistant reinforcing material for a vehicle excellent in buckling resistance of the present invention is a reinforcing material for a pillar of an automobile.
Moreover, it is preferable that the collision-resistant reinforcing material for vehicles excellent in buckling resistance of the present invention is a cross member of an automobile.
Furthermore, the collision-resistant reinforcing material for a vehicle having excellent buckling resistance according to the present invention is preferably an extension portion of a front member of an automobile.

  Next, a method for manufacturing a collision-resistant reinforcing material for a vehicle excellent in buckling resistance according to the present invention is a method for manufacturing a collision-resistant reinforcing material for a vehicle made of a molded thin plate, and includes a main body portion and the main body. Forming the thin plate so as to include at least a bent portion located on both sides in the width direction of the portion and a pair of side wall portions integrated with the main body portion via the bent portion; A step of providing a concave bead at the center in the width direction of the main body along the longitudinal direction, and when the distance between the concave bead and the bent portion is an effective width c ′, the effective width c ′ is The concave bead is provided so as to satisfy the following formula (2).

However, in Formula (2), h is the thickness of the said thin plate, b is the width | variety of the said main-body part before providing a concave bead, E is the elasticity modulus of the said thin plate, (sigma) _YP is the yield of the said thin plate. Stress, A and B are constants, A is 1.90, and B is -1.00.

  Moreover, in the manufacturing method of the collision-resistant reinforcement material for vehicles excellent in buckling resistance of this invention, it is preferable that the depth of the said concave bead shall be 5 mm or more.

  Furthermore, in the method for manufacturing a collision-resistant reinforcing material for a vehicle having excellent buckling resistance according to the present invention, the concave bead is configured with a bottom surface portion and bead side wall portions erected at both ends in the width direction of the bottom surface portion. It is preferable to do.

  ADVANTAGE OF THE INVENTION According to this invention, the collision-resistant reinforcement material for vehicles excellent in buckling resistance, and its manufacturing method can be provided.

Hereinafter, a collision-resistant reinforcing material for a vehicle excellent in buckling resistance, which is an embodiment of the present invention, will be described with reference to the drawings.
The collision reinforcing member for a vehicle according to the present embodiment is preferably disposed at a location that receives a compressive force at the time of collision deformation. The concave bead according to the present invention contributes to the improvement of the shock absorption capacity by two actions, that is, the improvement of the buckling load when buckling by receiving the compressive force and the small decrease in load after buckling. Therefore, it does not buckle greatly with parts connected to these parts, such as the front side member and the lower part of the center pillar, etc., which absorb energy by being greatly deformed, and transmits the load to other parts. Application to the parts to be handled is desirable from the viewpoint of overall energy absorption characteristics and weight reduction.

  In the case of a side collision, there are an upper part of the center pillar part, a roof center, a cross member, and the like as such parts when considering an automobile. In the case of a frontal collision, there is a front side member extension that is connected to the front side member and disposed in the cabin.

In the present embodiment, application to the center pillar portion will be described as an example.
A center pillar portion of a vehicle such as an automobile is generally composed of a body side outer panel and a center pillar reinforcing material (collision resistant reinforcing material for a vehicle) located therein. The center pillar reinforcing material is further composed of two parts: an outer side reinforcing material and an inner side reinforcing material. The body side outer panel located on the outermost side is made mainly of low-strength mild steel and hardly contributes to absorption of impact load. Therefore, the impact energy at the time of a side collision is mainly absorbed by the center pillar reinforcing material. An example of the center pillar reinforcing material of the present embodiment is shown in FIG.

  FIG. 1 is a view showing a form in which the vehicle collision-resistant reinforcing material of the present embodiment is applied to a vehicle center pillar reinforcing material, and (a) shows a center pillar reinforcing material for the right side of the vehicle. It is a perspective view, (b) is a perspective view which shows the reinforcement material for center pillars for the left side of a vehicle, (c) is a cross-sectional schematic diagram corresponding to the AA 'line of (a) or (b). is there.

A center pillar reinforcing material 1a, 1b (vehicle collision resistant reinforcing material) shown in FIG. 1 is formed by pressing a thin plate into a convex shape, for example, and has a main body 2 extending in the vertical direction, A bent portion 3 provided on both sides in the width direction of the main body 2, a pair of side walls 4, 4 integrated with the main body 2 via the bent portion 3, and welding provided on the side walls 4, 4 It is roughly comprised from the flange part 5 used as a part.
Further, an upper coupling portion 6 welded to the side roof rail of the vehicle is provided on the upper end side of the main body portion 2, while a lower coupling portion 7 welded to the side sill of the vehicle is disposed on the lower end side of the main body portion 2. Is provided.

  The main body 2 is provided with a concave bead 8. The concave bead 8 extends substantially in the center in the width direction of the main body 2 along the longitudinal direction of the main body 2. Moreover, the concave bead 8 is comprised by the bead side wall part 8b standingly arranged by the width direction both ends of the bottom face part 8a and the bottom face part 8a, for example. The concave bead 8 is formed at the upper part of the main body part 2, and more preferably, when the lower part of the center pillar part absorbs energy while being greatly deformed, the load at that time is efficiently transmitted to the side roof rail. It is desirable to provide it at a position corresponding to the upper part of the center pillar portion that can be. In general, the upper portion of the center pillar portion has a smaller cross section than the lower portion, and it is difficult to have sufficient deformation resistance so that the upper portion does not buckle when the lower portion is deformed. However, the concave beads according to the present invention are effective for the purpose of providing a difference in deformation strength.

  More specifically, the concave bead 8 is formed by evaluating the secondary moment of the cross section of the center pillar reinforcing members 1a and 1b, and secondarily differentiating the secondary moment of the cross section by the position (height direction coordinate). It is desirable to set the upper side (side roof rail side) above the part where the derivative is zero, that is, the part where the change rate of the moment of inertia of the cross section takes the extreme value.

  The center pillar reinforcing members 1a and 1b shown in FIG. 1 are arranged so that the main body 2 faces the outside of the vehicle, and are used as outer center pillar reinforcing members. The outer side center pillar reinforcing members 1a and 1b are welded with an inner side center pillar reinforcing member 10 so as to span between the flange portions 5 and 5, as shown by a one-dot chain line in FIG. Has been.

  The inner-side center pillar reinforcing member 10 may be formed by punching or cutting a thin plate into a predetermined shape and welding it to the outer-side center pillar reinforcing members 1a and 1b in a plate shape. Further, the inner side center pillar reinforcing member 10 may be formed by pressing a thin plate and forming a cross-sectional shape into a hat shape, and welding it to the outer side center pillar reinforcing members 1a and 1b. As shown in FIG. 1C, a center pillar reinforcing material having a closed cross-sectional structure can be configured by joining the outer side center pillar reinforcing materials 1a and 1b and the inner side center pillar reinforcing material 10.

  The concave bead 8 provided in the main body 2 extends substantially in the center in the width direction of the main body 2 along the longitudinal direction of the main body 2, and in the upper portion of the main body 2, more specifically, in the evaluation of the secondary moment of section. It is provided above the part where the second derivative is zero when the second moment of the cross section is second-order differentiated by the position (height direction coordinate). The upper part of the main body 2 is positioned at the upper part of the vehicle when the center pillar reinforcing members 1a and 1b are incorporated into the vehicle, and receives a compressive load from the lower part of the main body when a side collision occurs. It is a part that is easily deformed. Therefore, a concave bead is not provided in the lower part of the main body to which an impact is directly applied in a side collision, and a concave bead is provided only in the upper part to which a compressive load is applied. It is preferable in that it can be performed. If a concave bead is also provided at the lower part of the main body part, the shock absorption at the time of collision is reduced, the lower part of the main body part enters the inside of the vehicle and the space for the passenger is narrowed, and on the contrary, the safety is lowered.

  In the center pillar reinforcing material 1a, 1b (vehicle collision resistant reinforcing material) of the present invention, when the shortest distance between the bead side wall 8b of the concave bead 8 and the bent portion 3 is the effective width c ', the effective width The concave bead 8 is preferably provided so that c ′ satisfies the following formula (3).

However, in Equation (3), h is the thickness of the thin plate, b is the width of the main body before providing the concave bead, E is the elastic modulus of the thin plate, σ _YP is the yield stress of the thin plate, A and B are constants, A is 1.90, and B is -1.00.

  The center pillar reinforcing materials 1a and 1b of the present embodiment are prepared by, for example, preparing a thin plate (steel plate) such as a solid solution strengthened steel having a tensile strength of 440 MPa or higher, DP steel, or hardened steel, and press-molding the thin plate. . The press molding includes a main body 2, bent portions 3 and 3 located on both sides in the width direction of the main body 2, and a pair of side wall portions 4 integrated with the main body 2 via the bent portions 3 and 3. 4, and a concave bead 8 is provided at the center in the width direction of the main body 2 along the longitudinal direction of the main body 2. When the concave bead 8 is provided, when the distance between the concave bead 8 and the bent portions 3 and 3 is the effective width c ′, the concave bead 8 is set so that the effective width c ′ satisfies the above formula (3). What is necessary is just to provide.

  The depth of the concave bead 8 may be 5 mm or more. The concave bead 8 may be configured by the bottom surface portion 8a and the bead side wall portions 8b provided upright at both ends in the width direction of the bottom surface portion 8a.

Hereinafter, Formula (3) will be described in detail. It has been known that the entire cross section does not work effectively when a thin plate is buckled under compression (Theory of Elastic Stability / Brain Books Publishing Co., Ltd., co-authored by Timoshenko Gear). The cross section that works effectively during buckling is a region of a certain width from the end, and this is called the effective width c. The buckling _limit load P _ult is obtained using this effective width c, and is given by equation (4), where h is the thickness of the thin plate and σ _YP is the yield stress of the thin plate.

  Here, the effective width c can be obtained by Expression (5) using the elastic modulus E and Poisson's ratio ν of the thin plate.

  The present inventors have found that the concept of the effective width c is used as the arrangement position of the concave beads 8. It has been found that the improvement of the impact absorption characteristics by the concave bead 8 is effective when it is disposed on a surface that receives a compressive load at the time of collision deformation. That is, the area of the effective width c from the end part (the bent part 3) effectively shares the load, but the central area between the bent parts 3 and 3 excluding it effectively shares the load. However, it is considered that by providing the concave bead 8 in this central region, deformation restraint occurs, and as a result, the entire cross section works effectively.

  Therefore, the effective width was calculated using the above formula (5), but the calculated value of the effective width c based on the formula (5) is a relatively large value, and the member width (the width of the main body 2) b, As a result, within the range of the plate thickness h, almost the entire cross section of the main body 2 is an effective cross section (b≈2c). Further, the expression (5) does not include the influence of the width b of the main body 2. Therefore, it is apparent that this conventional concept of effective width cannot be used as a basic value for the method of arranging the concave beads 8.

  Therefore, the present inventors try to improve the concept of the effective width using the buckling limit load given by the equation (4) as a medium. Substituting equation (5) into equation (4) yields equation (6) below.

  In Equation (6), K is a proportionality constant. When this equation (6) is placed equally with equation (4) and arranged with respect to c, the following equation (7) is obtained.

The present inventors have measured the buckling limit load using various materials. A schematic diagram of the test method is shown in FIGS. A steel or aluminum thin plate 21 was used as a test material, and the length in the longitudinal direction of compression was set to 300 mm. The width b was changed to 50, 100, 150, and 200 (mm). The lower end 21a of the thin plate 21 was constrained, and the left and right ends 21b and 21b were constrained by forming a V-shaped jig 22 so as not to restrain rotation (see FIG. 3). In this state, the upper end 21c of the thin plate 21 was pushed in and tested. With respect to the buckling limit load, the load at that time was measured with respect to the pushing amount of the upper end 21c, and the load deviating from the proportional relationship was determined as the buckling _limit load (P _ult ).

Table 1 shows materials used as test materials. Various steel plates (thin plates) having different strengths and thicknesses from mild steel to quenched steel plates (hot press materials) and 5000 series aluminum plates (thin plates) were used. The elastic modulus E of the material shown in Table 1 was obtained from literature values, and the yield stress and tensile strength were obtained by conducting a tensile test using a JIS No. 5 test piece in which the longitudinal direction was perpendicular to the rolling direction. Using these values and the buckling limit load (P _ult ), the proportionality constant K was calculated according to the equation (6). The values are also shown in Table 1. It has been found that the proportionality constant K is not a constant value, but changes according to the material characteristics, the thickness and width of the thin plate. In order to quantify these effects, a multivariate analysis was performed on the proportionality constant K. As a result, it was found that the following formula (8) is appropriate as the expression.

Here, A and B are proportional constants, and A = 1.90 and B = −1.00. FIG. 4 shows an approximation by this equation. FIG. 4 is a graph showing the relationship between K and (E / σ _YP ) ^0.5 · (h / b). By setting A = 1.90 and B = −1.00, it can be seen that the experimental results are reproduced relatively well.

  The effective width c represented by the equation (5) cannot consider the influence of the member width b (the width of the main body) b. Therefore, the improved effective width c ′ is defined using the equations (7) and (8) obtained from the buckling limit load. By substituting equation (8) into equation (7), the following equation (9) (same as equation (2) above) is obtained.

By using this equation (9) (equation (2)), an improved effective width c ′ incorporating the influence of the member width can be calculated. FIG. 5 shows a result of comparison between the conventional effective width c and the improved effective width c ′. Whereas the conventional effective width c cannot consider the influence of the member width, the improved effective width c ′ can consider the influence of the member width.
Furthermore, with regard to the arrangement of the concave beads 8 according to the present invention, it is effective to arrange the concave beads 8 in a region excluding the improved effective width c ′ calculated by the equation (9) from both ends of the member surface receiving the compressive force. It has been confirmed that. Therefore, it is possible to determine a region where the bead is surely arranged with respect to a member having any member width, member plate thickness, member strength, and elastic modulus.

Hereinafter, the present invention will be described in more detail with reference to examples.
[Example 1]
As described above, the center pillar portion for a vehicle includes a body side outer panel and a center pillar reinforcing material (collision resistant reinforcing material for vehicle) located therein. The shape of the center pillar portion of an automobile varies depending on the vehicle type. Therefore, in the present Example, it examined using the model member.

  FIG. 6 shows an outer side center pillar reinforcing member having a concave bead used in this example. 6A is a schematic plan view of the center pillar reinforcing material, and FIGS. 6B to 6E correspond to the AA ′ to DD ′ lines in FIG. 6A, respectively. It is a cross-sectional schematic diagram to do. The thin plate used as the material of the reinforcing material was 780 MPa class DP steel having a thickness of 1.8 mm (yield stress: 490 MPa, tensile strength: 820 MPa, elongation: 24%). Further, the center pillar reinforcing material 11 shown in FIG. 6 has a shape in which the width of the main body portion 16 gradually narrows toward the top. For example, the width of the main body portion is 105 mm in the D-D ′ section, whereas the width is 49 mm in the A-A ′ section. The outer side center pillar reinforcing member 11 shown in FIG. 6 receives a compression force at the time of side collision deformation. On the other hand, the inner side center pillar reinforcing member receives a tensile force. Therefore, it is desirable that the concave bead 18 is disposed on the outer side center pillar reinforcing member that receives the compression force.

  At the position of the concave bead 18 in each cross section, the improved effective width c ′ was calculated using the above equation (3). FIG. 6B to FIG. 6E show values of the improved effective width c ′, respectively. Within the range from the bent portion 13 to the effective width c ′, it effectively works against the compressive force. Therefore, a bead 18 having a depth of 5 mm is arranged in the other central portion to smoothly connect the cross sections. A concave bead shape was provided. Further, the height of the concave bead 18 is set at the upper part of the center pillar part in order to efficiently transmit the load at that time to the side roof rail when absorbing the energy while the lower part of the center pillar part is largely deformed. Arranged.

  The upper part of the center pillar reinforcing member has a smaller cross section than the lower part as shown in FIG. 6, and it is difficult to provide sufficient deformation resistance so that the upper part does not buckle when the lower part is deformed. However, the concave bead 18 according to the present invention is effectively arranged for the purpose of providing a difference in deformation strength.

  The method of determining the arrangement was determined based on the evaluation result of the cross-sectional secondary moment of the center pillar reinforcing member 11 shown in FIG. FIG. 7 is a schematic side view of the center pillar reinforcing member 11, and FIG. 8 is a graph showing the relationship between the cross-sectional second moment and the second derivative of the center pillar reinforcing member 11 in the height direction. .

  The vertical axis | shaft of FIG. 8 has shown the coordinate of the height direction of the center pillar reinforcing material 11 shown in FIG. As shown in FIG. 7, the coordinate in the height direction has the position of the lowermost end portion of the center pillar reinforcing member 11 as the origin (0 mm). As shown in FIG. 8, the cross-sectional secondary moment calculated at intervals of 100 mm is small at the upper part of the center pillar reinforcing material 11 and increases as it approaches the lower part, indicating that the upper part is more likely to bend than the lower part. .

  FIG. 8 shows the result of second-order differentiation of the moment of inertia of the cross section with respect to the position (height direction coordinates). It can be seen that the second derivative of the sectional second moment becomes 0 at a position where the height is about 700 mm, and the rate of change of the sectional second moment takes an extreme value at this portion. That is, when this part is viewed in the longitudinal direction, the ease of bending changes most steeply. Therefore, in the present invention, it is more desirable to dispose the concave bead 18 above the position where the second derivative of the sectional second moment is zero. The bead shown in FIG. 6 is determined in the height direction from such a study, and the concave portion is arranged over a range of about 750 mm to 1100 mm as the height position.

  Next, model members used in the collision test are shown in FIGS. Similar to the actual member, this model member has a roof side rail on the upper side and a member having a uniform cross section simulating the side sill on the lower side, and an outer side center pillar reinforcing member shown in FIG. Two parts of the inner side center pillar reinforcing member were arranged. The inner side center pillar reinforcing member was made of 780 MPa class DP steel with a plate thickness of 1.2 mm. The roof side rail and the side sill were all made of a 590 MPa grade steel plate (JSH590Y) having a thickness of 3.2 mm. The members were joined by spot welding with an interval of about 50 mm.

  Table 2 shows a list of center pillar reinforcing members manufactured this time. No. 1 is a comparative example in which no beads are provided. No. Reference numeral 2 denotes a concave bead shown in FIG. 6 having a depth of 5 mm. No. 3 is No.3. 2 and the concave bead are arranged in the same position, but the bead depth is 3 mm. These were all produced using the same material (plate thickness 1.8 mm, 780 MPa class DP steel).

  The experiment simulated actual side-impact deformation. First, the right and left ends of the roof side rail and the side sill were restrained by a jig. Thereafter, a hemispherical jig (R = 1000 mm, 125 kg) was collided from the outer side at a speed of 15 m / s from the side with the apex positioned at a height of 500 mm in the coordinates shown in FIG.

  At this time, the reaction force generated in the hemispherical jig was measured, and the positions of marks provided at intervals of about 100 mm on the ridge line of the inner side center pillar reinforcing member were sequentially measured and used as an index of intrusion amount. As an index of the side collision performance, the average reaction force obtained by averaging the reaction force generated in the hemispherical jig in a certain section (0-20 msec and 10-20 msec) and the penetration amount at 20 msec (the mark position of the inner side member) ).

  FIG. 11 shows a modified form at 20 msec. 11 is a comparative example in which no concave bead is provided. 1 and the present invention examples (No. 2, No. 3) are compared. In 1, the deformation was concentrated on the upper portion where the cross-sectional strength was relatively small, and the member was broken at the upper portion (near position 1100 mm). On the other hand, no. In No. 2, the buckling of the upper part is suppressed by the effect of the concave bead. Compared to 1, the shape was nearly vertical, which was preferable. In addition, a No. 3 bead depth of 3 mm. No. 3 also has a no. Although the deformation of the upper part was suppressed as compared with 1, it was slightly bent.

  The concave bead suppresses the load drop after buckling due to the compressive force. Although it is considered that the high effect as shown in FIG. 2 is exhibited, when the bead depth is shallow, it is likely that the effect is reduced because the transition to a form close to a flat plate is likely due to buckling. Therefore, when considering a member having a size close to the center pillar, the bead depth is more preferably 5 mm or more.

  Also, as an index of the buckling form, the horizontal difference between the position of the uppermost mark at 20 msec and the position of each lower mark at 20 msec is calculated and squared to evaluate the verticality of the member. And the square root was calculated (a numerical value with a dimension of mm). As a result, if the horizontal position of each mark is the same, this value is 0, indicating that the shape of the inner side reinforcement is vertical after the collision. The value is shown in Table 2 as the vertical degree. The smaller this value is, the more desirable as the center pillar reinforcing material. 2, no. No. 3 is No.3. It became a value smaller than 1 and it turned out that the effect of a concave bead is high.

  For the average reaction force (average value of 0-20 msec) indicating the impact absorbing ability of the member, No. No. 1 2, no. All 3 were high values. This difference becomes more prominent at the average load (10-20 msec) in the latter half, and it was found that the impact absorbing characteristic is greatly improved especially in the latter half by suppressing the buckling of the concave beads.

[Example 2]
In Example 1, with respect to the model member of the center pillar, the concave bead was arranged based on the above formula (3) and the effect was verified by the experiment simulating the collision. However, the concave bead should be appropriately arranged on the actual part. Therefore, it is important to use numerical analysis techniques. In simple cases such as a flat plate or a member with a uniform cross-section, it is sufficient to consider the arrangement based on Equation (3). However, considering the actual member, the cross-section changes in the longitudinal direction or the entire member is curved. It is difficult to perform proper arrangement when there are complicated cases. Then, numerical analysis technology of the placement method was examined.

  FIG. 12 shows the outer shape of the model member used for the study. The straight member shown in FIG. 12A is a so-called cross-sectional hat-shaped member in which a convex portion is provided at the center in the width direction, and the convex portion has a constant cross-sectional width of 60 mm along the longitudinal direction. is there. On the other hand, the widening member shown in FIG. 12B is a so-called cross-sectional hat-shaped member provided with a convex portion at the center in the width direction, and the width of the convex portion at one end is 60 mm and the width of the convex portion at the other end. It is a member whose width of the convex portion changes between one end and the other end at 100 mm.

  For these two types of model members, No. 1 shown in Table 3 was obtained. 4-No. Nineteen members were assumed. The cross-sectional shape of the straight member is shown in FIG. As shown in FIG. 4, no. No. 12 having a concave bead width of 20 mm as shown in FIG. 5, no. No. 13 having a concave bead width of 40 mm as shown in FIG. 6, no. It was set to 14.

  For the widening member, as shown in FIG. 14, there are two types of shapes, one in which the shape of the concave bead does not change in the longitudinal direction (equal width) and the other in which the shape expands in accordance with the width of the convex portion (widening). It was investigated. These member shapes are assumed to be front side member extensions and cross members.

  The assumed material property value was 980 MPa class DP steel, and the yield stress was considered to be 650 MPa. When the effective width c ′ of the improved type is calculated using the above equation (3), c ′ is 16.5 mm when the plate thickness is 1.2 mm and the member width is 60 mm, and c ′ is 18 when the member width is 100 mm. 0.0 mm. When the member width was 60 mm, c ′ was 21.9 mm, and when the member width was 100 mm, c ′ was 25.3 mm.

  Therefore, among the members having the bead disposed, the concave bead is disposed at a place other than the effective width in the member having a width of 20 mm, and the concave bead forming region is within the effective width in the member having a width of 40 mm.

  First, the bending characteristic performed when evaluating the cross-sectional performance of a straight member was evaluated. The analysis software used was NASTRAN, which is a general-purpose structural analysis finite element method code of the static implicit method. The analysis was performed by constraining the central part of the member and applying a force of 600 N to both ends of the member to apply a compressive force to the bead arrangement surface. The displacement of the edge part which applied force with each member was measured. The results are shown in Table 3.

  As shown in Table 3, it was found that when the concave beads were arranged, the displacement in the load direction was larger when the beads were arranged than those without the beads. This is considered to mean that in the static bending deformation, the secondary moment of the cross section is lowered by the concave bead, and the bending becomes easy.

  However, in actual collision deformation, the concave bead has been found to be effective in preventing buckling and preventing a decrease in load after buckling, and such evaluation cannot be correlated with actual performance. Therefore, we evaluated by buckling mode analysis in consideration of local deformation at the time of collision.

  As the analysis software, NASTRAN was used as in the bending analysis. In the buckling mode analysis, the analysis up to the higher order mode was performed based on the boundary condition given in the bending analysis, and the result was evaluated by the deformation mode and the buckling eigenvalue.

  The buckling load in this mode can be calculated by the product of the load given as a boundary condition (600N in this case) and the buckling eigenvalue, and the higher the buckling eigenvalue, the higher the buckling load and therefore the less buckling. In this analysis, we performed calculations up to higher order, searched for a buckling mode that was almost equivalent to local buckling in impact deformation, and found the buckling eigenvalue in that mode.

  The member considered this time has a simple shape, and the mode corresponding to local buckling is the secondary mode. The values are shown in Table 3. As shown in Table 3, the bead effect was not seen in the static bending analysis, but when evaluated by the buckling eigenvalue, the buckling eigenvalue was given with a concave bead. Was found to be higher. Further, when comparing the members having a width of 20 mm and a width of 40 mm, it was found that the buckling eigenvalue was high in the member having a width of 20 mm arranged in addition to the effective width.

  The examination by the collision experiment as in the first embodiment is enormous in time and cost, and when evaluating a certain part, information on other members that support it is also required. However, the buckling mode analysis described above can be examined for a single component, and is suitable for optimizing the arrangement of concave beads, whose effect is difficult to be examined by ordinary bending analysis. In addition, if the buckling mode can be specified when considering the actual member, it is possible to obtain the desired buckling mode according to the boundary conditions such as the restraint position, and then consider the arrangement of the concave beads. do it. Even when information on surrounding members cannot be obtained by such a method, it is possible to examine the arrangement of the concave beads, which is a particularly effective means in the initial stage of design.

  In order to confirm the effectiveness of this method, members were actually fabricated and the initial peak load was evaluated by a drop weight test. The material used was 980 MPa grade DP steel as in the above examination, and the plate thickness was 1.2 mm and 1.8 mm. The back plate of the member used the same material as the other member. The spot welding interval was 30 mm. This member was supported with a span of 800 mm, and the center portion was bent by the falling weight of R50. The results are also shown in Table 3. It was found that the initial peak load was high with the beads. In addition, a good correspondence was found in the buckling eigenvalues obtained by buckling mode analysis and those with the same member outline. Therefore, it was confirmed that the impact absorption characteristics were improved by the concave bead and the numerical analysis method using the buckling mode analysis was effective.

  Among the members targeted this time, the distance from the bent part to the concave bead is 10 mm. 6, no. In FIG. 14, beads are arranged within the effective width c ′ calculated by Expression (3). As summarized in Table 3, it was found that even with these members, the buckling eigenvalue and the initial peak load exhibited characteristics superior to those without a bead. Therefore, the arrangement of the concave beads within the effective width c 'is also a proposal. However, when trying to maximize the effect of the concave bead, no. 5, no. It is better to dispose the concave bead outside the effective width c ′ as shown in FIG. Further, when the concave bead cannot be disposed due to some constraint condition, it is within the scope of the idea of the present invention and is effective to dispose only a single step outside the effective width.

FIG. 1 is a view showing a form in which a vehicle collision-resistant reinforcing material according to an embodiment of the present invention is applied to a center pillar reinforcing material, wherein (a) shows a center pillar reinforcing material for the right side of the vehicle. It is a perspective view, (b) is a perspective view which shows the reinforcement material for center pillars for the left side of a vehicle, (c) is a cross-sectional schematic diagram corresponding to the AA 'line of (a) or (b). is there. FIG. 2 is a schematic front view illustrating a method for testing a buckling limit load. FIG. 3 is a schematic plan view for explaining a test method for a buckling limit load. FIG. 4 is a graph showing the relationship between K and (E / σ _YP ) ^0.5 · (h / b). FIG. 5 is a graph showing the relationship between the plate thickness and the effective width of the thin plate constituting the center pillar reinforcing material. FIG. 6 is a view showing the outer side center pillar reinforcing material used in Example 1, wherein (a) is a schematic plan view of the center pillar reinforcing material, and (b) to (e) are respectively ( It is a cross-sectional schematic diagram corresponding to the AA 'line-DD' line of a). FIG. 7 is a view showing the center pillar reinforcing material used for the evaluation of the moment of inertia of the cross section, and is a schematic side view showing the height coordinates. FIG. 8 is a graph showing the evaluation results of the cross-sectional secondary moment, and is a graph showing the relationship between the height position, the cross-sectional secondary moment and its secondary differential coefficient. FIG. 9 is a schematic plan view illustrating a model member used for a collision test in Example 2. FIG. 10 is a schematic side view showing a model member used in the collision test in Example 2. FIG. 11 is a graph showing the relationship between the amount of displacement of the model member at the time of collision and the height position. 12A and 12B are diagrams showing another model member used in the collision test used in the examination in Example 2, wherein FIG. 12A is a perspective view of a straight member, and FIG. 12B is a perspective view of a widening member. is there. 13A and 13B are cross-sectional schematic views showing the cross-sectional shape of the straight member of FIG. 12A, where FIG. 13A is an example without a concave bead, and FIG. 13B is an example with a concave bead width of 20 mm. (C) is an example in which the width of the concave bead is 40 mm. FIG. 14 is a diagram illustrating a straight member and a widening member used in the study in Example 2.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1a, 1b ... Center-pillar reinforcement (vehicle collision-resistant reinforcement), 2 ... Main-body part, 3 ... Bending part, 4 ... Side wall part, 8 ... Concave bead, 8a ... Bottom part, 8b ... Bead side wall part

Claims (9)

A collision-resistant reinforcing material for vehicles consisting of a molded thin plate,
The vehicle collision-resistant reinforcing material includes at least a main body portion and a pair of side wall portions integrated with the main body portion via bent portions provided on both sides in the width direction of the main body portion. Is provided with a concave bead extending in the center in the width direction of the main body along its longitudinal direction,
The seat-resistant seat, wherein the concave bead is provided so that the effective width c ′ satisfies the following formula (1) when the distance between the concave bead and the bent portion is an effective width c ′. Anti-collision reinforcement for vehicles with excellent flexibility.

However, in Formula (1), h is the thickness of the said thin plate, b is the width | variety of the said main-body part before providing a concave bead, E is the elasticity modulus of the said thin plate, (sigma) _YP is the yield of the said thin plate. Stress, A and B are constants, A is 1.90, and B is -1.00.   The collision-resistant reinforcing material for a vehicle excellent in buckling resistance according to claim 1, wherein the depth of the concave bead is 5 mm or more.   The said concave bead is comprised from the bead side wall part standingly arranged by the width direction both ends of the bottom face part and the said bottom face part, It was excellent in the buckling resistance of Claim 1 or Claim 2 characterized by the above-mentioned. Anti-collision reinforcement for vehicles.   The collision-resistant reinforcing material for a vehicle excellent in buckling resistance according to any one of claims 1 to 3, wherein the collision-resistant material for a vehicle is a reinforcing material for a pillar of an automobile.   The collision-resistant reinforcing material for a vehicle having excellent buckling resistance according to any one of claims 1 to 3, wherein the vehicle-made collision reinforcing material is a cross member of an automobile.   The collision-resistant reinforcing material for a vehicle having excellent buckling resistance according to any one of claims 1 to 3, wherein the vehicle-made collision reinforcing material is an extension portion of a front member of an automobile. A method of manufacturing a collision-resistant reinforcing material for a vehicle made of a molded thin plate,
The thin plate is molded so as to include at least a main body part, a bent part located on both sides in the width direction of the main body part, and a pair of side wall parts integrated with the main body part via the bent part. And a step of providing a concave bead at the center in the width direction of the main body along the longitudinal direction of the main body.
When the distance between the concave bead and the bent portion is an effective width c ′, the concave bead is provided so that the effective width c ′ satisfies the following formula (2). A method for producing an excellent collision-resistant reinforcing material for vehicles.

However, in Formula (2), h is the thickness of the said thin plate, b is the width | variety of the said main-body part before providing a concave bead, E is the elasticity modulus of the said thin plate, (sigma) _YP is the yield of the said thin plate. Stress, A and B are constants, A is 1.90, and B is -1.00.   The depth of the concave bead is 5 mm or more, and the method for producing a collision-resistant reinforcing material for a vehicle having excellent buckling resistance according to claim 7.   The vehicle having excellent buckling resistance according to claim 7 or 8, wherein the concave bead is constituted by a bottom surface portion and bead side wall portions erected at both ends in the width direction of the bottom surface portion. Of manufacturing anti-collision reinforcement material.

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