Impact absorbing structure of automobile

1 . An impact absorbing structure of an automobile, comprising:

a first member composed of a metallic material; and

a second member joined to an outer surface or an inner surface of the first member, and extending in an axial direction of the first member, wherein:

a shape of the first member is a cylindrical shape;

a length of the second member in the axial direction of the first member is a length of 15 to 75% of a length in the axial direction of the first member;

the first member and the second member overlap each other over an overall length of the second member in the axial direction,

when a distance between end portions of the first member and the second member in the axial direction of the first member is set as D, a maximum curvature radius of the first member in a cross section perpendicular to the axial direction of the first member is set as R, and a sheet thickness of the first member is set as t, 0≤D<0.40Rt is satisfied; and

a joint line, extending along a direction different from a circumferential direction of the first member, of the first member and the second member is present.

2 . The impact absorbing structure of the automobile according to claim 1 , wherein a shape of the second member is a cylindrical shape.

3 . The impact absorbing structure of the automobile according to claim 1 , wherein an area of a region divided by the joint line in the second member is 60% or less of a total area of the regions.

4 . An impact absorbing structure of an automobile, comprising:

a first member composed of a metallic material; and

a second member joined to an outer surface or an inner surface of the first member, and extending in an axial direction of the first member, wherein:

a shape of the first member is a square tube shape;

a length of the second member in the axial direction of the first member is a length of 15 to 75% of a length in the axial direction of the first member;

the first member and the second member overlap each other over an overall length of the second member in the axial direction,

when a distance between end portions of the first member and the second member in the axial direction of the first member is set as D, a width of a flat surface portion of the first member is set as W p , and a sheet thickness of the first member is set as t, 0≤D<1.11W p t is satisfied; and

a joint line, extending along a direction different from a circumferential direction of the first member, of the first member and the second member is present.

5 . The impact absorbing structure of the automobile according to claim 4 , wherein the second member is joined to the flat surface portion of the first member.

6 . The impact absorbing structure of the automobile according to claim 4 , wherein the second member is joined to a ridge line portion of the first member.

7 . The impact absorbing structure of the automobile according to claim 1 , wherein the joint line extends along the axial direction of the first member.

8 . The impact absorbing structure of the automobile according to claim 1 , wherein the joint line extends in a direction inclined to the axial direction of the first member.

9 . The impact absorbing structure of the automobile according to claim 1 , wherein another joint line extending along the circumferential direction of the first member is present.

10 . The impact absorbing structure of the automobile according to claim 1 , wherein a thickness ratio t/t′ between the sheet thickness t of the first member and a sheet thickness t′ of the second member is 0.25 to 4.0.

11 . The impact absorbing structure of the automobile according to claim 1 used for a crash box, a side member, an extension of a subframe, or a reinforcement disposed in a hollow crushing member.

12 . An impact absorbing structure of an automobile, comprising:

a first member comprising a metallic material; and

a second member joined to an outer surface or an inner surface of the first member, and extending in an axial direction of the first member, wherein:

a shape of the first member is a cylindrical shape;

a length of the second member in the axial direction of the first member is a length of 15 to 75% of a length in the axial direction of the first member;

the first member and the second member overlap each other over an overall length of the second member in the axial direction,

when a distance between end portions of the first member and the second member in the axial direction of the first member is set as D, a maximum curvature radius of the first member in a cross section perpendicular to the axial direction of the first member is set as R, and a sheet thickness of the first member is set as t, 0≤D<0.40Rt is satisfied; and

a joint line, extending along a direction different from a circumferential direction of the first member, of the first member and the second member is present.

13 . An impact absorbing structure of an automobile, comprising:

a first member comprising a metallic material; and

a second member joined to an outer surface or an inner surface of the first member, and extending in an axial direction of the first member, wherein:

a shape of the first member is a square tube shape;

a length of the second member in the axial direction of the first member is a length of 15 to 75% of a length in the axial direction of the first member;

the first member and the second member overlap each other over an overall length of the second member in the axial direction,

when a distance between end portions of the first member and the second member in the axial direction of the first member is set as D, a width of a flat surface portion of the first member is set as W p , and a sheet thickness of the first member is set as t, 0≤D<1.11W p t is satisfied; and

a joint line, extending along a direction different from a circumferential direction of the first member, of the first member and the second member is present.