JP2017100375A - Bonded structure of metallic member and frp member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress rupture of an adhesive layer through decreasing the peak value of the stress in the adhesive layer that bonds a metallic member and an FRP member.SOLUTION: A bonded structure 11 of a metallic member 12 and an FRP member 13 is configured with: the metallic member 12 having a first flat face 12a sandwiched between two first ridgelines 12b; the FRP member 13 having a second flat face 13a; and an adhesive layer 14 which joins the first flat face 12a of the metallic member 12 and the second flat face 13a of the FRP member 13. An edge 14a of the adhesive layer 14 has a tip part 14b extended to a direction substantially orthogonal to the two first ridgelines 12b and a notch part 14c cut into a triangle shape from at least one of the first ridgelines 12b by going over the tip part 14b, so that the stress is dispersed to the notch part 14c of the edge 14a of the adhesive layer 14 when a load is imposed upon the bonded structure 11. This makes it possible to increase the strength of the bonded structure 11 by preventing the adhesive layer 14 from being ruptured from a corner part of the edge 14 where the stress tends to be concentrated.SELECTED DRAWING: Figure 1

Description

  The present invention provides a metal member having a first flat surface sandwiched between two first ridge lines, an FRP member having a second flat surface, a first flat surface of the metal member, and a second flat surface of the FRP member. The present invention relates to an adhesive structure of a metal member and an FRP member made of an adhesive layer that joins.

  In a structural material in which an FRP material is bonded to the surface of a light metal member through an adhesive layer having a thickness of 10 μm or more and 500 μm or less, the volume resistivity of the adhesive layer is set to a predetermined value or more, and the adhesive strength at room temperature is set to a predetermined value Thus, it is known from Patent Document 1 below that the structural material is reduced in weight and the electric corrosion resistance, strength, and impact energy absorption performance are improved.

WO099 / 10168

  By the way, as shown in FIG. 9, the longitudinal end of the flat plate 01a of the flat surface 01a of the metal member 01 having a hollow quadrangular cross section is overlapped with the longitudinal end of the strip-like FRP member 02, and the rectangular shape overlaps both. An adhesive structure 04 is assumed in which these areas are bonded by the adhesive layer 03. When a tensile load F in a direction away from each other is applied to the metal member 01 and the FRP member 02 of the bonding structure 04, the maximum is applied to the edge 03a of the adhesive layer 03 positioned at the edge of the flat surface 01a of the metal member 01. Shear stress and tensile stress act. The sum of the maximum shear stress and the tensile stress (hereinafter referred to as “stress”) varies along the direction along the edge 03a of the adhesive layer 03, and becomes maximum at both ends of the edge 03a. Minimal at the center.

  The reason is that there are ridge lines 01b and 01b bent at right angles on both sides of the flat surface 01a of the metal member 01, and the ridge lines 01b and 01b are more rigid than the flat surface 01a. Due to the tensile load F, the amount of elongation of the ridge lines 01b and 01b of the metal member 01 is reduced, and the amount of extension of the portion of the flat surface 01a of the metal member 01 is increased. The Young's modulus of the adhesive layer 03 is smaller than the Young's modulus of the metal member 01 and the Young's modulus of the FRP member 02. Since the adhesive layer 03 expands in accordance with the expansion of the metal member 01, the edge of the adhesive layer 03 The stress at 03a is maximized at both ends of the edge 03a and is minimized at the center of the edge 03a.

  As described above, when the stress is locally maximized at both ends of the edge 03a of the adhesive layer 03, the adhesive layer 03 is easily broken at the portion where the stress is maximized. There is a problem that the strength of the bonding structure 04 is lowered due to the entire 03 being broken.

  This invention is made | formed in view of the above-mentioned situation, and it aims at reducing the peak value of the stress of the adhesive bond layer which adhere | attaches a metal member and a FRP member, and suppressing a fracture | rupture of an adhesive bond layer.

  In order to achieve the above object, according to the invention described in claim 1, a metal member having a first flat surface sandwiched between two first ridge lines, an FRP member having a second flat surface, An adhesive structure of a metal member and an FRP member comprising a first flat surface of the metal member and an adhesive layer that joins the second flat surface of the FRP member, and an edge of the adhesive layer has the two edges A tip end portion extending in a direction substantially orthogonal to the first ridge line and a notch portion cut out in a triangular shape so as to straddle the tip end portion from at least one of the first ridge lines are provided. An adhesion structure of a metal member and an FRP member is proposed.

  According to a second aspect of the present invention, in addition to the structure of the first aspect, the angle formed by the tip portion and the notch portion is in the range of at least 45 ° to 65 °. And an adhesion structure of FRP members is proposed.

  According to a third aspect of the present invention, in addition to the structure of the second aspect, the angle formed by the tip portion and the notch portion is in the range of at least 45 ° to 55 °. And an adhesion structure of FRP members is proposed.

  According to a fourth aspect of the present invention, in addition to the configuration of any one of the first to third aspects, the edge of the adhesive layer has two edges corresponding to the two first ridge lines. A bonding structure of a metal member and an FRP member is proposed, which has two notches, and the length of the two notches along the direction of the tip is equal to the length of the tip.

  According to the invention described in claim 5, in addition to the configuration of any one of claims 1 to 4, the metal member continues to the first flat surface via the first ridgeline. The FRP member has a fourth flat surface that continues to the second flat surface via a second ridge line, and the first and third flat surfaces are the second and fourth flat surfaces. The edge of the adhesive layer to be joined to a surface is cut out into two triangular shapes extending from the first and second ridge lines to the first and third flat surfaces and the second and fourth flat surfaces. An adhesion structure of a metal member and an FRP member is provided, which is provided with the notched portion.

  The flat surfaces 12a, 12c, 13a, and 13c of the embodiment correspond to the first flat surface, the third flat surface, the second flat surface, and the fourth flat surface of the present invention, respectively, and the ridge lines 12b and 13b corresponds to the first ridge line and the second ridge line of the present invention, respectively, and the CFRP member 13 of the embodiment corresponds to the FRP member of the present invention.

  According to the configuration of claim 1, the bonded structure of the metal member and the FRP member includes a metal member having a first flat surface sandwiched between two first ridge lines, an FRP member having a second flat surface, and a metal It consists of an adhesive layer that joins the first flat surface of the member and the second flat surface of the FRP member. The edge of the adhesive layer has a tip portion extending in a direction substantially orthogonal to the two first ridge lines, and a notch portion cut out in a triangular shape so as to straddle the tip portion from at least one of the first ridge lines. Therefore, when the load is input to the adhesive structure, the adhesive layer breaks starting from the corner of the edge where stress tends to concentrate by dispersing the stress in the notch on the edge of the adhesive layer. It is possible to increase the strength of the bonded structure.

  According to the second aspect of the present invention, the angle formed by the tip portion and the notch portion is at least in the range of 45 ° to 65 °. Therefore, the stress distribution in the notch portion can be made uniform and the maximum stress can be reduced.

  According to the third aspect of the present invention, the angle formed by the tip and the notch is at least in the range of 45 ° to 55 °. Therefore, the stress distribution in the notch is further uniformed to further reduce the maximum stress, and the tip Stress concentration at the part can be avoided.

  According to the configuration of claim 4, the edge of the adhesive layer includes two notches corresponding to the two first ridge lines, and the length along the direction of the tips of the two notches is the length of the tips. Since it is equal to the length, the maximum stress at the edge of the adhesive layer can be minimized.

  According to the fifth aspect of the present invention, the metal member has a third flat surface that continues to the first flat surface via the first ridge line, and the FRP member continues to the second flat surface via the second ridge line. The edge of the adhesive layer that has the fourth flat surface and joins the first and third flat surfaces to the second and fourth flat surfaces extends from the first and second ridge lines to the first, third flat surface, and the second flat surface. 2. Since it is provided with two triangular cutouts straddling the fourth flat surface, the maximum stress caused by the cutouts while ensuring the strength and rigidity of the bonded structure by the FRP member having no cutouts It is possible to prevent the adhesive layer from being broken by the effect of reducing the above.

The perspective view of the adhesion structure (θ = 45 °). (First embodiment) FIG. 2 is a two-direction arrow view of FIG. 1. (First embodiment) The figure corresponding to FIG. 1 (θ = 55 °). (First embodiment) The figure corresponding to FIG. 1 (θ = 65 °). (First embodiment) The graph which shows the relationship between the angle of a notch part, and the maximum shear stress. (First embodiment) The graph which shows the relationship between the length of a notch part, and the maximum shear stress. (First embodiment) The perspective view which looked at the center pillar outer from the vehicle body inside. (Second Embodiment) The perspective view (arc-shaped edge) of an adhesion structure. (Third embodiment) The perspective view of an adhesion structure. (Conventional example)

First embodiment

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIGS. 1 and 2, the bonding structure 11 of the present embodiment is made of a steel plate having a plate thickness of 2 mm and a strength of 590 MPa, and a metal member 12 having a square constant hollow cross section with a side of 70 mm. And a CFRP member 13 made of a flat plate made of CFRP (carbon fiber reinforced resin), which is a kind of FRP having a width of 60 mm and a plate thickness of 1 mm, and the CFRP member 13 on one flat surface 12 a of the metal member 12. And an adhesive layer 14 made of a thermosetting epoxy resin adhesive having a thickness of 1 mm to be bonded.

  The CFRP member 13 overlaps with one flat surface 12a of the metal member 12 in a rectangular region having a length of 80 mm so as to follow the two ridge lines 12b and 12b of the metal member 12, but the adhesive layer 14 is The metal member 12 and the CFRP member 13 are bonded together in a small hexagonal region. That is, one edge 14a of the adhesive layer 14 includes a linear tip portion 14b that overlaps the end portion of the metal member 12, and two cutout portions 14c and 14c in which both ends of the tip portion 14b are cut out in a triangular shape. Consists of. In the present embodiment, the angle θ formed by the notches 14c and 14c with respect to the tip portion 14b is 45 °, the width L1 of the tip portion 14b, and the width L2 of the notches 14c and 14c along the direction of the tip portion 14b. Both are 20 mm.

  FIG. 1 shows the distribution of stress acting on the adhesive layer 14 when the metal member 12 and the CFRP member 13 are pulled with a load F. The dark colored portion is a portion where the stress is high. A thin part is a part with low stress. The portion with the highest stress is distributed substantially evenly along the cutout portions 14c and 14c of the end edge 14a, and no stress concentration occurs at the tip end portion 14b of the end edge 14a.

  Thus, according to the present embodiment, by removing the corners (a portion in FIG. 2) of the edge 14a where stress is most likely to concentrate in the adhesive layer 14 by the notches 14c and 14c, It is possible to avoid the concentration of local stress that becomes the starting point of the fracture of the adhesive layer 14 and to increase the strength of the adhesive structure 11 with respect to the load F.

  The graph of FIG. 5 shows the relationship between the angle θ of the notches 14c and 14c of the adhesive layer 14 and the maximum shear stress generated in the notches 14c and 14c, and the angle θ is in the range of 45 ° to 65 °. It can be seen that the maximum stress can be effectively reduced by making the stress distribution in the notches 14c, 14c substantially uniform (see FIGS. 1, 3 and 4).

  However, when the angle θ of the notches 14c and 14c of the adhesive layer 14 exceeds 55 °, stress concentration tends to occur in the vicinity of the tip 14b. FIG. 4 shows the stress distribution when the angle θ of the notches 14c, 14c is 65 °, and it can be seen that a slight stress concentration occurs in the vicinity of the tip 14b. Therefore, if the angle θ of the notches 14c and 14c is set in the range of 45 ° to 55 °, the stress distribution in the notches 14c and 14c can be made uniform while avoiding stress concentration at the tip 14b.

  The graph of FIG. 6 shows the relationship between the length L2 of the notches 14c and 14c along the direction of the tip 14b of the adhesive layer 14 and the maximum shear stress generated in the notches 14c and 14c. It can be seen that the maximum shear stress decreases as the length L2 of 14c, 14c increases from zero, and the maximum shear stress is minimized when it coincides with the length L1 (20 mm) of the tip portion 14b. That is, the maximum shear stress of the notches 14c and 14c can be reduced by dividing the width of the adhesive layer 14 into three equal parts and disposing the tip 14b and the pair of notches 14c and 14c there.

Second embodiment

  Next, a second embodiment of the present invention will be described with reference to FIG.

  In the second embodiment, the present invention is applied to a center pillar 15 of an automobile. The center pillar 15 is constituted by a steel plate center pillar outer 12 having a hat-shaped cross-section, which is a metal member of the present invention, and a steel plate center pillar inner 16 having a hat-shaped cross-section to form a closed cross-section. A stiffener 13 having a U-shaped cross section, which is a CFRP member 13 of the present invention, is integrally bonded to the inner surface of the center pillar outer 12 by an adhesive layer 14 of the present invention.

  The center pillar outer 12 includes a first flat surface 12a and a third flat surface 12c continuous to the first flat surface 12a via a first ridge line 12b. The stiffener 13 is a first flat surface 12a of the center pillar outer 12. The second ridgeline 13b, the second ridgeline 13b, and the fourth flat surface 13c are attached to the first ridgeline 12b and the third flat surface 12c via the adhesive layer 14. The first flat surface 12a, the adhesive layer 14 and the second flat surface 13a constitute one adhesive structure 11, and the third flat surface 12c, the adhesive layer 14 and the fourth flat surface 13c are another adhesive. The structure 11 is configured.

  Two triangular cutouts 14 c are formed at the lower end of the ridge line 14 d of the adhesive layer 14, and part of the cutouts 14 c is the first flat surface 12 a of the center pillar outer 12 and the second flat surface 13 a of the stiffener 13. The other part of the notch 14 c is interposed between the third flat surface 12 c of the center pillar outer 12 and the fourth flat surface 13 c of the stiffener 13.

  When the center pillar 15 is bent to the inside of the vehicle body due to a side collision, a tensile load acts on the center pillar outer 12, but stress concentration occurs at the edge 14a of the adhesive layer 14 due to the action of the notch 14c. Can be prevented, and the strength reduction of the center pillar 15 due to the fracture of the adhesive layer 14 can be prevented.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, the FRP of the present invention includes GFRP (glass fiber reinforced resin) in addition to the CFRP of the embodiment. GFRP has a lower tensile strength than CFRP, but has the advantage of being inexpensive and free from corrosion even when used in combination with metals.

  In the first and second embodiments, the tip 14b and the notch 14c of the edge 14a of the adhesive layer 14 are straight, but as shown in the third embodiment of FIG. 8, the adhesive layer The distal end portion 14b and the cutout portion 14c of the 14 end edges 14a may be curved.

12 metal member 12a flat surface (first flat surface)
12b Ridge line (first ridge line)
12c Flat surface (third flat surface)
13 CFRP member (FRP member)
13a Flat surface (second flat surface)
13b Ridge line (second ridge line)
13c flat surface (fourth flat surface)
14 Adhesive Layer 14a Edge 14b Tip 14c Notch L1 Tip Length L2 Length θ along Notch Tip Direction Angle between Tip and Notch

Claims (5)

A metal member (12) having a first flat surface (12a) sandwiched between two first ridge lines (12b), an FRP member (13) having a second flat surface (13a), and the metal member (12) An adhesive structure of a metal member and an FRP member composed of an adhesive layer (14) for joining the first flat surface (12a) and the second flat surface (13a) of the FRP member (13),
The edge (14a) of the adhesive layer (14) includes a tip end portion (14b) extending in a direction substantially orthogonal to the two first ridge lines (12b), and at least one of the first ridge lines (12b). A metal member and FRP member bonding structure, comprising: a notch portion (14c) cut out in a triangular shape so as to straddle the tip portion (14b).   The metal member and FRP member bonding structure according to claim 1, wherein an angle (θ) formed by the tip portion (14b) and the notch portion (14c) is at least 45 ° to 65 °. body.   The metal member and FRP member bonding structure according to claim 2, wherein the angle (θ) formed by the tip portion (14b) and the notch portion (14c) is at least in the range of 45 ° to 55 °. body.   The edge (14a) of the adhesive layer (14) includes two notches (14c) corresponding to the two first ridge lines (12b), and the tip portions (14c) of the two notches (14c) ( The length (L2) along the direction of 14b) is equal to the length (L1) of the said front-end | tip part (14b), The metal member in any one of Claims 1-3 characterized by the above-mentioned. And an FRP member bonding structure. The metal member (12) has a third flat surface (12c) continuous to the first flat surface (12a) via the first ridge line (12b), and the FRP member (13) is the second flat surface. The surface (13a) has a fourth flat surface (13c) continuous through the second ridge line (13b), and the first and third flat surfaces (12a, 12c) are the second and fourth flat surfaces ( The edge (14a) of the adhesive layer (14) joined to the 13a, 13c) extends from the first and second ridge lines (12b, 13b) to the first and third flat surfaces (12a, 12c) and The said notch part (14c) notched in the shape of two triangles straddling said 2nd, 4th flat surface (13a, 13c) is provided, The any one of Claims 1-4 characterized by the above-mentioned. The adhesion structure of the metal member and FRP member of Claim 1.