Bumper Beam High-Strength Portion Impact Design
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Solution Overview
Problem
Bumper beams used in automotive applications face challenges in achieving both reduced weight and increased yield strength while preventing breakage during impact tests, particularly in pole front crash testing, where the top plate of inverted-hat constructions with high-strength materials may fracture due to concentrated loads.
Innovation Solution
A bumper beam design featuring a hat member with a high-strength portion and a low-strength portion, where the high-strength portion has a tensile strength of at least 1.5 GPa and extends 250 mm along the longitudinal direction, and the low-strength portion has a lower tensile strength, located outward from the high-strength portion, to absorb and distribute impact loads effectively, preventing breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the wall thicknesses of the bumper beam are increased to improve yield strength, then the yield strength against impact is improved, but the weight of the bumper beam increases
Solution Approach 1:
The bumper beam applies local quality by differentiating material strength across different regions. The high-strength portion (tensile strength ≥1.5 GPa) is positioned at the longitudinal center where impact loads are most severe, while low-strength portions are located at both ends. This spatial differentiation of material properties allows the beam to provide maximum strength where needed without uniformly increasing weight throughout the entire structure.
2Strength
If the size of the bumper beam is increased to improve yield strength, then the yield strength against impact is improved, but the weight of the bumper beam increases
Solution Approach 1:
Rather than uniformly increasing the size of the entire bumper beam, the invention increases size selectively. The high-strength portion has specific dimensional requirements (length ≥250 mm, wall height ≥15 mm) concentrated at the impact zone, while the low-strength portions at the ends can have reduced dimensions. This localized sizing approach improves yield strength at critical locations without proportionally increasing overall weight.
3Strength
If a high-strength material with tensile strength not lower than 1.5 GPa is used throughout the bumper beam to improve yield strength, then the yield strength is improved, but the top plate may break due to lack of ductility during impact
Solution Approach 1:
The invention applies local quality by using different material strengths in different regions. The high-strength material (tensile strength ≥1.5 GPa) is used only in the longitudinally middle portion where maximum load bearing is critical, while the low-strength material with higher ductility is used in the portions at both ends. This spatial differentiation allows the high-strength region to prevent breakage through superior strength, while the low-strength regions provide ductility and energy absorption through deformation.
Solution Approach 2:
The invention changes the material parameter (tensile strength) spatially along the longitudinal direction of the bumper beam. The high-strength portion has tensile strength ≥1.5 GPa, while the low-strength portions have lower tensile strength but higher ductility. This parameter differentiation enables the beam to exhibit both high strength (preventing breakage) and high ductility (allowing deformation) at different locations, resolving the contradiction between strength and reliability.
Data Source
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AI summary
A bumper beam 100 includes a closing plate 2 and a hat member 1. The hat member 1 includes a top plate 1a, two flanges 1c, and two walls 1b. The hat member 1 includes a high-strength portion 10H and low-strength portions 10L. The high-strength portion 10H includes a longitudinally middle portion of each of the two walls 1a and extends a length of at least 250 mm. The high-strength portion 10H has a tensile strength not lower than 1.5 GPa. The low-strength portions 10L are located outward of the high-strength portion and extends a length not smaller than the height of the walls. The low-strength portions have a tensile strength lower than the tensile strength of the longitudinally middle portion of the two walls.