JP7178286B2 - automotive bumper beam - Google Patents

Description

The present invention relates to a bumper beam for motor vehicles.

Bumper beams made of fiber-reinforced resin are known, which are effective for reducing the weight of automobiles. Patent Document 1 discloses a bumper beam made of a fiber-reinforced thermoplastic resin stampable sheet in which discontinuous fibers are oriented in one direction. The discontinuous fibers are oriented in the longitudinal direction of the bumper.

In Patent Document 2, a unidirectional fiber reinforced resin sheet in which continuous reinforcing fibers are arranged in parallel in one direction is attached to the top and bottom of a hat-shaped thermoplastic resin molded product, and the hat-shaped side surface of the molded product is attached. discloses a bumper beam to which the sheet is not applied.

Patent Document 3 discloses a bumper beam having a Θ-shaped cross section, in which a cloth material in which reinforcing fibers are woven is used on the entire surface, and a unidirectional material in which continuous reinforcing fibers are aligned in one direction is attached to the bottom surface of the vehicle body. A bumper beam is disclosed for use in

JP-A-6-155495 JP 2013-184630 A WO2014/136858

The bumper beam of Patent Document 1 may break when a large load is applied because the reinforcing fibers are discontinuous fibers. That is, this bumper beam may not provide excellent energy absorption.

When the bumper beam of Patent Document 2 was subjected to a center pole collision test, the unreinforced standing surface (hat-shaped side surface) was opened and stretched in the longitudinal direction, and the bumper beam was broken. Energy absorption may not be obtained.

In Patent Literature 3, an attempt is made to improve the energy absorbability by positively compressing and destroying the cloth material of the standing surface. However, the cloth material is difficult to press-form, and it is very difficult to cover the entire surface of the complicated shape with the cloth material as in Patent Document 3. In addition, the cloth material has a lower mechanical strength than a unidirectionally oriented continuous fiber material (UD material), and the energy absorption using this low compressive strength is not high.

SUMMARY OF THE INVENTION An object of the present invention is to provide an automobile bumper beam made of fiber-reinforced resin, which can be easily press-molded and has excellent energy absorption properties.

The gist of the present invention resides in the following (1) to (6).

(1) For automobiles comprising a laminate of a carbon fiber reinforced portion comprising at least two carbon fiber reinforced resin layers (A) and a glass fiber reinforced portion comprising at least one glass fiber reinforced resin layer (B) a bumper beam,
Each of the carbon fiber reinforced resin layers (A) is made of a thermoplastic resin and continuous carbon fibers oriented in one direction,
At least one of the carbon fiber reinforced resin layers (A) is a carbon fiber reinforced resin layer (A ^α ) having an orientation angle α, and at least one of the remaining carbon fiber reinforced resin layers (A) The layer is a carbon fiber reinforced resin layer (A ^−α ) having an orientation angle of −α, where the orientation angle is the angle formed by the orientation direction of the continuous carbon fibers with respect to the longitudinal direction of the bumper beam, 30°≦α≦90°,
The glass fiber reinforced resin layer (B) is made of a thermoplastic resin and discontinuous glass fibers,
One surface of the two surfaces in the stacking direction of the laminate is formed by the glass fiber reinforced portion, and the other surface is formed by the other glass fiber reinforced portion,
The orientation angles of all the carbon fiber reinforced resin layers (A) are in the range of -90° or more and less than -15° or in the range of more than 15° and 90° or less.
Automotive bumper beam.

(2) The automotive bumper beam according to (1) above, wherein all the carbon fiber reinforced resin layers (A) have an orientation angle of α or −α.

(3) In the carbon fiber reinforced portion, a carbon fiber reinforced resin layer (A ^α ) having an orientation angle of α and a carbon fiber reinforced resin layer (A ^−α ) having an orientation angle of −α are adjacent to each other. The automotive bumper beam according to (2) above, comprising at least one pair arranged in parallel.

(4) the carbon fiber reinforced portion consists of a first portion consisting of n said pairs and a second portion consisting of another n said pairs, where n represents a positive integer;
The automotive bumper beam according to (3) above, wherein the lamination structure of the first portion and the lamination structure of the second portion are symmetrical in the lamination direction.

(5) The thermoplastic resin constituting the carbon fiber reinforced resin layer (A) and the thermoplastic resin constituting the glass fiber reinforced resin layer (B) may be polyamide, polycarbonate, and modified, respectively. The automobile bumper beam according to any one of (1) to (4) above, which is selected from polypropylene.

(6) The above (5), wherein the thermoplastic resin constituting the carbon fiber reinforced resin layer (A) and the thermoplastic resin constituting the glass fiber reinforced resin layer (B) are the same type of resin. ) for automotive bumper beams.

According to the present invention, it is possible to provide an automotive bumper beam made of fiber-reinforced resin, which is easy to press-mold and has excellent energy absorption properties.

It is a cross-sectional schematic diagram which shows the example of a bumper beam. It is a cross-sectional schematic diagram which shows the example of a carbon fiber reinforcement part. It is a schematic diagram for demonstrating an orientation angle. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the model used for the simulation in the Example, The figure (a) is a front view of the whole model, The figure (b) is a side view of a test member. 4 is a graph showing displacement-load curves obtained in Examples.

The present inventors have found that laminating a continuous carbon fiber layer having high mechanical strength and orientation in one direction and a discontinuous fiber layer that is easy to mold is easy to press mold and has excellent energy absorption. We have found that this is effective for obtaining a bumper beam for automobiles made of fiber-reinforced resin. The present invention has been made based on such findings.

An automotive bumper beam according to the present invention comprises a carbon fiber reinforced portion comprising at least two carbon fiber reinforced resin layers (A) and a glass fiber reinforced portion comprising at least one glass fiber reinforced resin layer (B). It consists of a laminate. That is, in the carbon fiber reinforced portion, at least two carbon fiber reinforced resin layers (A) are laminated. Moreover, when the glass fiber reinforced part is composed of two or more glass fiber reinforced resin layers (B), the glass fiber reinforced resin layers (B) are laminated.

・Carbon fiber reinforced resin layer (A)
Each carbon fiber reinforced resin layer (A) is composed of a thermoplastic resin and continuous carbon fibers oriented in one direction. That is, each carbon fiber reinforced resin layer (A) is formed of a unidirectional material in which continuous carbon fibers are oriented in one direction.

At least one of the carbon fiber reinforced resin layers (A) is a carbon fiber reinforced resin layer (A ^α ) having an orientation angle α, and at least one of the remaining carbon fiber reinforced resin layers (A) has It is a carbon fiber reinforced resin layer (A ^−α ) having an orientation angle of −α. Here, the orientation angle is the angle formed by the orientation direction of the continuous carbon fibers with respect to the longitudinal direction of the bumper beam in each carbon fiber reinforced resin layer (A). And 30°≦α≦90°. Hereinafter, the carbon fiber reinforced resin layer (A ^α ) having an orientation angle α is referred to as “A ^α layer”, and the carbon fiber reinforced resin layer (A ^−α ) having an orientation angle −α is referred to as “A ^−α It is sometimes called a layer. When there are a plurality of A ^α layers, all the A ^α layers have the same orientation angle (α). When there are a plurality of A 1 ^-α layers, all the A ^{1 -α} layers have the same orientation angle (−α).

・Glass fiber reinforced resin layer (B)
The glass fiber reinforced resin layer (B) consists of a thermoplastic resin and discontinuous glass fibers. The average fiber length of the discontinuous glass fibers is, for example, 5 mm or more and 100 mm or less.

The glass fibers of the glass fiber reinforced resin layer (B) do not have to be oriented. That is, in the glass fiber reinforced resin layer (B), the glass fibers may be arranged in random directions. Alternatively, the glass fibers may have orientation. In that case, from the viewpoint of reducing anisotropy, it is preferable that the orientation angles of all the glass fiber reinforced resin layers (B) are substantially 0° or 90°. The orientation angle of the glass fiber reinforced resin layer (B) is the angle formed by the glass fibers with respect to the longitudinal direction of the bumper beam.

Laminated structure In this specification, when the bumper beam is attached to the vehicle body, the direction facing the vehicle body is "rearward", the direction opposite to the rear is "forward", and the upward direction is "upper". The downward direction is called "downward," the rightward direction is called "rightward," and the leftward direction is called "leftward."

One of the two surfaces in the stacking direction of the laminate constituting the bumper beam is formed by a glass fiber reinforced portion, and the other surface is formed by another glass fiber reinforced portion.

FIG. 1 schematically shows a cross section of an example of the bumper beam (a cross section perpendicular to the longitudinal direction of the bumper beam). A laminate 1 forming a bumper beam has a hat-shaped cross section. The stacking direction is the front-to-rear direction of the vehicle body at the portion forming the hat-shaped top surface (the most forward surface). Glass fiber reinforced portions 20 are arranged on both the rear side and the front side with the carbon fiber reinforced portion 10 interposed therebetween.

An example of the laminated structure of the carbon fiber reinforced portion 10 will be described with reference to FIG. In this carbon fiber reinforced portion 10, two carbon fiber reinforced resin layers (A) are laminated in the longitudinal direction of the vehicle body. For example, in the carbon fiber reinforced portion 10, the A ^α layer 11 is arranged on the rear side and the A 1 ^-α layer 12 is arranged on the front side.

FIGS. 3A and 3B are schematic views of the hat-shaped top surfaces of the A ^α layer 11 and the A 1 ^-α layer 12, respectively, viewed from the rear side to the front side. The carbon fibers are oriented at an orientation angle α or −α in a plane extending in the longitudinal direction of the bumper beam and in the vertical direction of the vehicle body.

The laminate 1 can include a carbon fiber reinforced resin layer whose orientation angle is neither α nor −α. However, from the viewpoint of energy absorption of the bumper beam, the orientation angle of all the carbon fiber reinforced resin layers (A) contained in the laminate 1 is in the range of -90° or more and less than -15° or exceeds 15°, It is in the range of 90° or less. The orientation is the same when the orientation angle is 90° and when the orientation angle is −90°. Further, it is more preferable that the orientation angle of all the carbon fiber reinforced resin layers (A) is α or -α.

From the viewpoint of energy absorption of the bumper beam, it is preferable that the carbon fiber reinforced portion 10 consist of at least one pair in which one A ^α layer 11 and one A 1 ^-α layer 12 are arranged adjacent to each other.

The carbon fiber reinforced portion 10 includes a first portion consisting of n pairs (a pair of one A ^α layer and one A ^-α layer) and a second portion consisting of another n pairs. (n represents a positive integer). In this case, it is more preferable that the lamination structure of the first portion and the lamination structure of the second portion are symmetrical in the lamination direction of the laminate 1 .

For example, in Example 1 described later, α = 30 °, the third, fifth, eighth and tenth layers are A ^α layers, and the fourth, sixth, seventh and ninth layers are A - ^α layer. There is a 3rd and 4th layer pair, a 5th and 6th layer pair, an 8th and 7th layer pair, and a 10th and 9th layer pair. In Example 1, n=4, the 3rd to 6th layers form the first portion, and the 7th to 10th layers form the second portion. The lamination structure of the first portion and the lamination structure of the second portion are symmetrical in the lamination direction with respect to the interface between the sixth layer and the seventh layer. Note that the first and second layers form a glass fiber reinforced portion 20 and the eleventh and twelfth layers form another glass fiber reinforced portion 20 .

In Example 5, which will be described later, the orientation angles of the third to tenth layers are all 90°. However, since the orientation angle of 90° and the orientation angle of −90° mean the same orientation, the 4th, 6th, 7th and 9th layers are A- ^α layers (layers with an orientation angle of −90°). can be regarded as Therefore, in Example 5 as well, the pair of the third and fourth layers, the pair of the fifth and sixth layers, the pair of the eighth and seventh layers, and the tenth and ninth layers A pair exists. Also, n=4, the third to sixth layers form the first portion, and the seventh to tenth layers form the second portion. The lamination structure of the first portion and the lamination structure of the second portion are symmetrical in the lamination direction with respect to the interface between the sixth layer and the seventh layer.

The glass fiber reinforced portion 20 is composed of one or more glass fiber reinforced resin layers (B).

・Thermoplastic resin The thermoplastic resin constituting the carbon fiber reinforced resin layer (A) and the thermoplastic resin constituting the glass fiber reinforced resin layer (B) are not particularly limited, but for example, nylon 6, nylon 66, nylon 12 Polyolefins such as low-density polyethylene, high-density polyethylene, and polypropylene (which may be modified with acids, etc.); polyesters such as polyethylene terephthalate and polybutylene terephthalate; polycarbonate; polyamideimide; polyphenylene oxide; polyether sulfone; polyether ether ketone; polyether imide; polystyrene; ABS resin; polyphenylene sulfide; liquid crystal polyester; . Modified polyolefin is, for example, acid-modified polyolefin obtained by modifying polyolefin with an acid such as maleic acid. Each of the thermoplastic resin constituting the carbon fiber reinforced resin layer (A) and the thermoplastic resin constituting the glass fiber reinforced resin layer (B) may be used singly or in combination of two or more. good too.

From the viewpoint of energy absorption and press moldability of the bumper beam, the thermoplastic resin constituting the carbon fiber reinforced resin layer (A) and the thermoplastic resin constituting the glass fiber reinforced resin layer (B) are polypropylene (acid etc.), polyamides and polycarbonates.

Furthermore, from the viewpoint of adhesiveness, it is preferable that the thermoplastic resin constituting the carbon fiber reinforced resin layer (A) and the thermoplastic resin constituting the glass fiber reinforced resin layer (B) are the same type of resin. . The fact that a plurality of resins are the same system means that the main components of the resins have common monomer units, or that the monomers of the main components of the resins are bonded to each other by the same functional group. For example, the thermoplastic resin constituting the carbon fiber reinforced resin layer (A) and the thermoplastic resin constituting the fiber reinforced resin layer (B) are each polypropylene (one or both of which may be modified with an acid or the like). Preferably. Moreover, each of these resins is preferably one selected from the group consisting of nylon 6 and nylon 66.

- Manufacturing method of bumper beam A carbon fiber reinforced resin sheet can be used to form the carbon fiber reinforced resin layer (A). A glass fiber reinforced resin sheet can be used to form the glass fiber reinforced resin layer (B). For example, the laminate 1 can be obtained by appropriately stacking a carbon fiber reinforced resin sheet and a glass fiber reinforced resin sheet and subjecting them to heat and pressure molding. The resulting laminate can be used as a bumper beam for automobiles. The carbon fiber reinforced portion can consist of a plurality of identical carbon fiber reinforced resin sheets. The glass fiber reinforced portion can consist of a plurality of identical glass fiber reinforced resin sheets. A unidirectional material is used as the carbon fiber reinforced resin sheet, the unidirectional material is arranged so that the orientation angle is α to form the ^{Aα layer, and the unidirectional material is arranged to form the A-α layer} . It can be arranged so that the orientation angle is −α.

The automobile bumper beam according to the present invention does not use a cloth material, so it can be easily manufactured by hot pressing.

- Shape of bumper beam The shape of the bumper beam is not particularly limited. For example, the cross section of the bumper beam may be a hat shape, a shape in which hat-shaped flanges are glued together, or a Θ shape.

[Example 1]
Simulation software (trade name: LS-DYNA, manufactured by LSTC) was used to evaluate the bumper beam composed of the laminate by simulation.

In the simulation, a model simulating a three-point bending test was created (see FIG. 4). The indenter 31 for the three-point bending test had an R (corner radius) of 75 mm, the two supports 32 had an R of 15 mm, and the distance between the fulcrums was 350 mm.

The test member was a hat channel (laminate 1) with a length of 400 mm. The hat shape was as follows (see FIG. 4(b)).
Width: 72mm,
height: 25mm,
thickness: 2mm,
Hat shape side taper: 93°,
Corner R: 4 mm,
Width of hat-shaped top surface (flat portion): 40 mm.

The indenter 31 and the support portion 32 were set as rigid bodies, and the hat channel (laminate 1) was set as a fiber-reinforced resin composite material. This fiber reinforced resin material is a laminate of a carbon fiber reinforced resin layer (A) and a glass fiber reinforced resin layer (B) using the material physical property database "Material 58 (*MAT_LAMINATED_COMPOSITE_FABRIC)" for anisotropic laminates. defined to be

The glass fiber reinforced resin layer (B) is assumed to be a composite material using real discontinuous glass fibers (trade name: Unisheet P4038, made by Quadrant Plastic Composite Japan, thermoplastic resin: polypropylene). was set as an isotropic material (indicated as "GMT" in the table) with a modulus of elasticity of 6,400 MPa and a modulus of elasticity perpendicular to the fiber of 6,400 MPa, and no fracture occurred.

The carbon fiber reinforced resin layer (A) assumes an existing unidirectional continuous fiber composite material (manufactured by Production Example 1 described later; thermoplastic resin: acid-modified polypropylene), and has an elastic modulus in the fiber direction of 101, 000 MPa and an elastic modulus in the direction perpendicular to the fiber of 4,600 MPa (indicated as "CFUD" in the table) as an anisotropic material. The compressive strength was set to 460 MPa and the tensile strength to 1570 MPa in the fiber direction, and the compressive strength was set to 70 MPa, the tensile strength to 21 MPa, and the shear strength to 207 MPa in the fiber orthogonal direction. In the simulation, the element was set to be removed when stress exceeding the above strength occurred in each element.

In the simulation, the contact between the indenter 31 and the hat channel (laminate 1) and the contact between the support 32 and the hat channel were defined as contact without restraint. Further, the indenter was set to move 40 mm in the stacking direction (direction from front to back) at a constant speed of 100 mm/s. As a result of the simulation, the amount of movement of the indenter and the reaction force received by the indenter are read, and by making a graph of the movement amount and reaction force at the same time, the relationship between displacement and load as confirmed in the three-point bending test can be obtained. reproduced (see FIG. 5).

As an index representing the energy absorbability of the bumper beam, the load at the maximum displacement (40 mm) in the displacement-load curve thus obtained was evaluated. It can be said that the larger the load at the maximum displacement (40 mm), the better the energy absorption.

The lamination structure of the hat channel was as shown in the table below from the support portion 32 side toward the indenter 31 side. The first layer is closest to the support portion 32 (most rearward side), and the twelfth layer is closest to the indenter 31 (most forward side). All carbon fiber reinforced resin layers (A) are made of the same material (they are the same except for the orientation angle). All the glass fiber reinforced resin layers (B) are made of the same material (they are the same except for the orientation angle). Note that there is a portion where a plurality of glass fiber reinforced resin layers (B) each having a thickness of 0.25 mm are superimposed, but this is merely for convenience of simulation. For example, the first and second layers may actually be one glass fiber reinforced resin layer (B) layer with a thickness of 0.5 mm. The same applies to other examples.

The load at maximum displacement was 1240N.

・Manufacturing example 1
The unidirectional continuous fiber composite material assumed here as the carbon fiber reinforced resin layer (A) was produced as follows. Carbon fibers (trade name: Pyrofil TR 50S, manufactured by Mitsubishi Chemical Co., Ltd., carbon fiber diameter 7 μm) were aligned in one direction and flat to form a fiber sheet having a basis weight of 72 g/m ² . The fiber sheet was sandwiched from both sides by films having a basis weight of 36 g/m ² made of acid-modified polypropylene resin (trade name: Modic P958V, manufactured by Mitsubishi Chemical). These were passed through calender rolls multiple times to be heated and pressurized to impregnate the fiber sheet with the resin to produce a unidirectional continuous fiber composite material having a fiber volume content (Vf) of 33% by volume and a thickness of 125 μm.

[Example 2]
Evaluation was performed in the same manner as in Example 1, except that the laminated structure was as shown in the table below. The load at maximum displacement was 1290N.

[Example 3]
Evaluation was performed in the same manner as in Example 1, except that the laminated structure was as shown in the table below. The load at maximum displacement was 1450N.

[Example 4]
Evaluation was performed in the same manner as in Example 1, except that the laminated structure was as shown in the table below. The load at maximum displacement was 1540N.

[Example 5]
Evaluation was performed in the same manner as in Example 1, except that the laminated structure was as shown in the table below. The load at maximum displacement was 1590N.

[Comparative Example 1]
Evaluation was performed in the same manner as in Example 1, except that the laminated structure was as shown in the table below. The load at maximum displacement was 930N.

[Comparative Example 2]
Evaluation was performed in the same manner as in Example 1, except that the laminated structure was as shown in the table below. The load at maximum displacement was 610N.

[Comparative Example 3]
Evaluation was performed in the same manner as in Example 1, except that the laminated structure was as shown in the table below. The load at maximum displacement was 840N.

[Comparative Example 4]
Evaluation was performed in the same manner as in Example 1, except that the laminated structure was as shown in the table below. The load at maximum displacement was 1190N.

[Comparative Example 5]
Evaluation was performed in the same manner as in Example 1, except that the laminated structure was as shown in the table below. The load at maximum displacement was 1090N.

The above results are summarized in the table below. In these tables, conventional notation is used to abbreviate the stacking configurations, but the stacking configuration for each example is detailed above. In addition, "s" in the said abbreviation means "symmetrical."

FIG. 5 shows displacement-load curves obtained in some examples and comparative examples. The load at maximum displacement (40 mm) mentioned above is read from such a curve.

1 Laminated body constituting a bumper beam 10 Carbon fiber reinforced part 11 Carbon fiber reinforced resin layer 12 with an orientation angle of α Carbon fiber reinforced resin layer 20 with an orientation angle of -α Fiber reinforced part

Claims (6)

An automotive bumper beam comprising a laminate of a carbon fiber reinforced portion comprising at least two carbon fiber reinforced resin layers (A) and a glass fiber reinforced portion comprising at least one glass fiber reinforced resin layer (B). There is
Each of the carbon fiber reinforced resin layers (A) is made of a thermoplastic resin and continuous carbon fibers oriented in one direction,
At least one of the carbon fiber reinforced resin layers (A) is a carbon fiber reinforced resin layer (A ^α ) having an orientation angle α, and at least one of the remaining carbon fiber reinforced resin layers (A) The layer is a carbon fiber reinforced resin layer (A ^−α ) having an orientation angle of −α, where the orientation angle is the angle formed by the orientation direction of the continuous carbon fibers with respect to the longitudinal direction of the bumper beam, 30°≦α≦90°,
The glass fiber reinforced resin layer (B) is made of a thermoplastic resin and discontinuous glass fibers,
One surface of the two surfaces in the stacking direction of the laminate is formed by the glass fiber reinforced portion, and the other surface is formed by the other glass fiber reinforced portion,
The orientation angles of all the carbon fiber reinforced resin layers (A) are in the range of -90° or more and less than -15° or in the range of more than 15° and 90° or less.
Automotive bumper beam. 2. The automotive bumper beam according to claim 1, wherein the orientation angle of all said carbon fiber reinforced resin layers (A) is α or -α. In the carbon fiber reinforced portion, a carbon fiber reinforced resin layer (A ^α ) having an orientation angle of α and a carbon fiber reinforced resin layer (A ^−α ) having an orientation angle of −α are arranged adjacent to each other. 3. The automotive bumper beam of claim 2, comprising at least one pair. said carbon fiber reinforcement consists of a first portion of n said pairs and a second portion of another n said pairs, where n represents a positive integer;
4. A bumper beam for a motor vehicle according to claim 3, wherein the lamination arrangement in the first portion and the lamination arrangement in the second portion are symmetrical in the lamination direction. The thermoplastic resin constituting the carbon fiber reinforced resin layer (A) and the thermoplastic resin constituting the glass fiber reinforced resin layer (B) are each selected from polyamide, polycarbonate, and optionally modified polypropylene. 5. A bumper beam for a motor vehicle according to any one of claims 1 to 4, wherein the bumper beam is 6. The method according to claim 5, wherein the thermoplastic resin forming the carbon fiber reinforced resin layer (A) and the thermoplastic resin forming the glass fiber reinforced resin layer (B) are the same type of resin. Automotive bumper beam.

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