Tubular beam of an automotive structure having an improved impact behavior

摘要

Bumper crossbeam (10, 10′), having a plane of symmetry (Y) and globally oriented in a direction (T) perpendicular to the plane of symmetry (Y), comprising two attachment areas (12a, 12b) symmetrically arranged with respect to the plane of symmetry (Y) and distant from each other by a distance D, said beam being designed to absorb the energy dissipated by a shock generated by a force substantially horizontal and oriented in a direction (L) perpendicular to said direction (T), made from a globally tubular body (11) with a monotonically varying nominal cross-section (Sn) over most of its length between said attachment areas (12a, 12b), except in two weakened areas (15a, 15b), which are symmetrical with respect to the plane of symmetry (Y), which are remote from the said plane of symmetry by a distance of between 0.10*D and 0.40*D, wherein the second moment of area about the axis (Z) perpendicular to the plane (L, T) is lower in the said weakened areas than expected from the nominal cross-section.

主权项

1. A vehicle bumper comprising:
a crossbeam having a tubular body, a nominal cross section Sn, a first end, and a second end; wherein said crossbeam is substantially symmetrical with respect to a plane of symmetry Y, and globally oriented in a direction T that is perpendicular to the plane of symmetry Y; wherein said crossbeam is configured to absorb the energy dissipated by a shock generated by a concentrated or substantially horizontal distributed force oriented in a direction L perpendicular to said direction T; first and second attachment areas on the crossbeam, said first and second attachment areas being configured to attach the crossbeam to the vehicle; wherein the first and second attachment areas are symmetrically arranged with respect to the plane of symmetry Y of the crossbeam; wherein said first and said second attachment areas are separated by a distance D; wherein the nominal cross section Sn of said crossbeam varies progressively according to a monotonic function of the distance d to the plane of symmetry Y over most of a length of the crossbeam and between said first and second attachment areas; first and second weakened areas in the crossbeam, said first and second weakened areas both having a cross section Sw; wherein said first and second weakened areas are arranged symmetrically with respect to the plane of symmetry Y of the crossbeam; wherein a distance dw of the first and second weakened areas from the plane of symmetry is between 0.10*D and 0.40*D; wherein the nominal cross section Sn of the crossbeam is different from the cross section Sw of the first and second weakened areas; and wherein a second moment of area about an axis Z, perpendicular to a plane defined by L and T, is lower in said first and second weakened areas than a second moment of area of the nominal cross section Sn; wherein said first attachment area is located between said first weakened area and said first end of said crossbeam; and wherein said second attachment area is located between said second weakened area and said second end of said crossbeam.