Vehicle Bumper Beam Varied Strength Zones
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Solution Overview
Problem
Existing vehicle bumper beam assemblies with uniform microstructures exhibit undesirable impact deformation characteristics and challenges in securing components together, limiting their crash performance and fuel efficiency.
Innovation Solution
A bumper assembly with varied strength zones is created by thermally treating the bumper beam to have a middle portion with a fully martensitic structure and ends with medium strength zones, allowing for controlled deformation and energy absorption during impacts, while also facilitating secure attachment to crush cans.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a bumper beam assembly has uniform microstructure throughout, then manufacturing is simplified, but impact deformation characteristics are undesirable and energy absorption is reduced
Solution Approach 1:
The bumper beam is designed with non-uniform microstructure where different regions have different tensile strengths. The middle portion has higher tensile strength (1000-1900 MPa) for structural integrity, while the ends have lower tensile strength (600-900 MPa) for controlled deformation and energy absorption during impact. This local differentiation resolves the contradiction by optimizing each region's properties for its specific function.
Solution Approach 2:
The patent changes the tensile strength parameter along the length of the bumper beam by controlling the microstructure during manufacturing. By varying the tensile strength from high in the middle portion to low at the ends, the beam achieves both structural integrity and desirable impact deformation characteristics, resolving the contradiction between uniform manufacturing and performance optimization.
2Strength
If the ends of the bumper beam have high tensile strength, then structural integrity is improved, but controlled deformation and energy absorption are reduced
Solution Approach 1:
The ends of the bumper beam are designed with lower tensile strength (600-900 MPa) compared to the middle portion (1000-1900 MPa). This local quality differentiation allows the ends to deform controllably during impact, absorbing energy through deformation, while the high-strength middle portion maintains structural integrity and prevents catastrophic failure.
3Weight of moving object
If the bumper beam is made lighter, then fuel consumption is reduced, but crash performance may be compromised
Solution Approach 1:
By changing the tensile strength parameter along the bumper beam length, the design achieves optimal weight utilization. The high-strength middle portion provides necessary crash protection, while the lower-strength ends deform to absorb energy. This parameter variation allows the beam to be lighter than a uniformly high-strength beam would be, while maintaining or improving crash performance through controlled deformation and energy absorption.
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 enables the bumper beam to deform appropriately under impact forces, absorbing energy and maintaining structural integrity, thereby enhancing crash performance and reducing vehicle weight and overhang length.
Implementation Method 1
The bumper beam is thermally treated to provide the first and second ends with less tensile strength than the middle portion
Implementation Method 2
The middle portion may have a tensile strength between 1000 MPa and 1900 MPa. Each of the first and second ends may have a tensile strength between 600 MPa and 900 MPa
Data Source
AI summary
A bumper assembly may include a pair of crush cans and a bumper beam. The pair of crush cans are for securing to a vehicle body. The bumper beam is secured to the crush cans and includes a first end and a second end each extending outboard of one of the crush cans, and a middle portion extending between the first and second ends. The bumper beam is thermally treated to provide the first and second ends with less tensile strength than the middle portion. The middle portion may have a tensile strength between 1000 MPa and 1900 MPa. Each of the first and second ends may have a tensile strength between 600 MPa and 900 MPa.