Bumper Cross Beam Flange Radius Variation for Crash Load Management
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Solution Overview
Problem
Existing bumpers experience high peak loads during crash tests like the AZT crash test due to sudden impact, leading to undesirable deformation patterns and potential buckling of crash boxes, and they often lack optimal weight reduction while maintaining constant load over time.
Innovation Solution
A bumper with a hat-shaped cross beam featuring bent longitudinal upper and lower flanges, where specific portions have a larger inner radius at the mounting site to crash boxes, reducing peak loads and allowing for weight reduction while maintaining stiffness, with radii ranging from 10 to 16 mm for the larger sections and 5 to 9 mm for the rest.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cross beam uses uniform material and standard flange design, then manufacturing is simple, but high peak loads occur during crash tests causing crash box buckling
Solution Approach 1:
The patent applies local quality by varying the inner radius of the flanges at specific locations. The first portion (at the crash box mounting site) has a larger inner radius (10-16 mm) to reduce peak loads and prevent buckling, while the second portion has a smaller inner radius (5-9 mm) to maintain stiffness. This localized geometric modification optimizes crash performance without requiring complete redesign of the entire cross beam structure.
2Reliability
If the cross beam uses larger flange radius at mounting site, then peak load is reduced and crash box buckling is prevented, but weight increases
Solution Approach 1:
The patent applies local quality by varying the inner radius of the flanges at specific locations. The first portion (at the crash box mounting site) has a larger inner radius (10-16 mm) to reduce peak loads and prevent buckling, while the second portion has a smaller inner radius (5-9 mm) to maintain stiffness. This localized geometric modification optimizes crash performance without requiring complete redesign of the entire cross beam structure.
3Weight of moving object
If the cross beam uses smaller flange radius throughout, then weight is reduced, but peak load increases causing crash box buckling
Solution Approach 1:
The patent applies local quality by varying the inner radius of the flanges at specific locations. The first portion (at the crash box mounting site) has a larger inner radius (10-16 mm) to reduce peak loads and prevent buckling, while the second portion has a smaller inner radius (5-9 mm) to maintain stiffness. This localized geometric modification optimizes crash performance without requiring complete redesign of the entire cross beam structure.
4Reliability
If the cross beam uses uniform flange design, then manufacturing is simple, but constant load over time cannot be achieved during crash test
Solution Approach 1:
The patent applies local quality by varying the inner radius of the flanges at specific locations. The first portion (at the crash box mounting site) has a larger inner radius (10-16 mm) to reduce peak loads and prevent buckling, while the second portion has a smaller inner radius (5-9 mm) to maintain stiffness. This localized geometric modification optimizes crash performance without requiring complete redesign of the entire cross beam structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively cushions initial peak loads during crash tests, reducing the likelihood of crash box buckling and achieving a constant load over time, while also minimizing weight through optimized radius design, as demonstrated by load curve measurements.
Implementation Method 1
the cross beam of the bumper should deform and 'cushion' the initial peak load before the crash box/boxes of the bumper starts to buckle
Implementation Method 2
the bent longitudinal upper and lower flanges have each a portion with a large inner radius (R) at least at the mounting site of the cross beam to respective crash box
Data Source
Figure 1
Figure 2
Figure 3a
AI summary
A bumper (B), comprising an elongated hat-shaped cross beam (1) mounted to at least two crash boxes (2) which are attached to a vehicle, said cross beam (1) having a primary contact face in the form of bent longitudinal upper and lower flanges (3,4). The bent longitudinal upper and lower flanges being arranged in the direction of the cross beam (1), and said primary contact face is facing away from the vehicle. Said bent longitudinal upper and lower flanges (3,4) have each a portion (5) with a large inner radius (R) at least at the mounting site of the cross beam (1) to respective crash box (2) compared to a small inner radius (r) of the rest of each of the bent longitudinal upper and lower flanges (3,4).