Cross-Shaped Crash Box Offset Impact Absorption
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Solution Overview
Problem
Conventional crash boxes in vehicles exhibit insufficient impact energy absorption when subjected to offset loads due to reduced section modulus and transverse rigidity, leading to unstable deformation and inefficient energy transmission to the vehicle frame.
Innovation Solution
A vehicle structure featuring a crash box with a substantially cross-shaped section, connected to a bumper beam and vehicle frame via fasteners, with protrusions extending in both vertical and transverse directions to enhance rigidity and prevent falling deformation, ensuring stable buckling and deformation regardless of impact angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional crash box with a flat polygonal section and a trench is used, then the crash box can absorb impact energy from front loads through buckling deformation, but the section modulus and transverse rigidity are reduced causing the crash box to fall and deform under offset loads
Solution Approach 1:
The crash box transitions from a conventional flat polygonal section to a cross-shaped section with four protrusions extending in vertical and transverse directions. This dimensional change adds structural complexity that simultaneously provides buckling deformation capability for energy absorption and enhanced transverse rigidity to prevent falling deformation under offset loads.
Solution Approach 2:
The cross-shaped crash box can be formed by overlaying a plurality of members and spot-welding their wall faces. This composite construction method allows the integration of multiple structural elements that work together to provide both energy absorption through controlled deformation and sufficient rigidity to maintain structural integrity under various loading conditions.
2Reliability
If the crash box is designed to buckle and deform definitely under front loads, then impact energy absorption is ensured, but the deformation mode becomes unstable under offset loads leading to insufficient energy absorption
Solution Approach 1:
The cross-shaped crash box with four protrusions is designed to perform multiple functions: it can undergo stable buckling deformation under front loads for energy absorption, and simultaneously resist falling deformation under offset loads due to enhanced transverse rigidity. This universal design ensures reliable energy absorption performance across different impact scenarios.
Solution Approach 2:
The invention changes the geometric parameters of the crash box section from a simple flat polygon to a complex cross-shape with specific protrusion dimensions and orientations. This parameter change fundamentally alters the deformation characteristics, enabling stable buckling under compression while maintaining rigidity against lateral displacement under offset loading conditions.
3Strength
If a cross-shaped crash box with four protrusions is used, then rigidity and section modulus are enhanced to prevent falling deformation, but the structural complexity increases
Solution Approach 1:
The cross-shaped crash box is segmented into four distinct protrusions that extend in vertical and transverse directions. Each protrusion can be independently formed and positioned, allowing for modular construction and assembly. The segmentation enables the complex shape to be manufactured efficiently by overlaying and spot-welding multiple members, reducing the practical complexity despite the enhanced geometric complexity.
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 enhanced rigidity and section modulus of the crash box allow for effective impact energy absorption both from front and offset loads, providing stable and consistent performance by ensuring the crash box is buckled and deformed definitively, thus improving vehicle design and safety.
Implementation Method 1
the crash box is buckled and deformed definitely, thus allowing the crash box to absorb the impact energy
Data Source
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AI summary
In a vehicle structure for an automobile including a crash box 3 at a distal end of a vehicle frame 1 extending in the longitudinal direction of the automobile, the crash box 3 has a substantially cross shape (a substantially boxed cross shape) in closed section. Specifically, four substantially rectangular protrusions 35, 36, 37, 38 extend upward, downward, rightward, and leftward. The lengths of the sides of the protrusions 35, 36, 37, 38 are almost equal to each other. Each angle α of the corners 39, 40 between the sides is substantially a right angle (90 degrees). Hence, the crash box 3 can definitely exhibit impact energy absorbing performance not only upon receipt of a load from the front but also upon receipt of a load offset in the car width direction by being buckled and deformed definitely.