Metallic Cross Member Bumper with Deformable Connections
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Solution Overview
Problem
Existing bumper structures with polymeric crash boxes often fail to effectively absorb angled crash forces, leading to sudden rear portion deformation and compromised functionality during crashes, which can result in increased damage and risk to passengers.
Innovation Solution
A bumper structure featuring a metallic cross member and plastically deformable connection means, such as tie rod elements, that absorb and distribute crash forces, preventing direct transmission to the vehicle frame and maximizing energy absorption by the polymeric crash boxes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polymeric cross member is used in the bumper structure, then the structure achieves adequate strength for normal operation, but the cross member breaks under angled crash forces causing sudden rear portion deformation and failure
Solution Approach 1:
The cross member material is changed from polymeric to metallic, fundamentally altering the mechanical properties to achieve both high strength and reliability under angled crash conditions. The metallic material provides the necessary yield strength to prevent breaking while maintaining the ability to absorb energy through controlled deformation.
Solution Approach 2:
The bumper structure becomes a composite system combining metallic cross member with polymeric crash boxes. This composite approach allows each material to perform its optimal function: the metallic cross member provides structural strength and stability under angled loads, while the polymeric crash boxes absorb energy through controlled collapse during frontal impacts.
2Stability of the object's composition
If connection means are made rigid to prevent deformation, then structural stability is improved, but crash forces are directly transmitted to the vehicle frame increasing damage risk
Solution Approach 1:
The connection means are designed with controlled deformation characteristics, allowing them to change their mechanical response under different load conditions. They maintain rigidity for stability during normal operation but enable controlled energy absorption during crashes by deforming in a predetermined manner, preventing direct transmission of full crash forces to the frame.
Solution Approach 2:
The connection means incorporate predetermined deformation zones that act as pre-positioned energy absorption mechanisms. These zones are designed to deform controllably during crashes, cushioning the transmission of kinetic energy to the vehicle frame before the forces reach critical levels that would cause damage.
3Use of energy by moving object
If polymeric crash boxes are designed for complete collapse during crash, then maximum energy absorption is achieved, but rear portion deformation occurs when cross member breaks compromising crash box functionality
Solution Approach 1:
The cross member's material parameter is changed from polymeric to metallic, fundamentally altering its deformation characteristics. This change ensures the cross member maintains structural integrity during angled crashes, preventing the sudden failure that would otherwise cause premature rear portion deformation of the crash boxes and compromise their energy absorption functionality.
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
This design reduces the likelihood of rear portion collapse and minimizes kinetic energy transfer to the vehicle frame and passengers, enhancing safety by ensuring that the crash is absorbed by the polymeric crash boxes before it reaches the frame, thereby reducing damage and injury risk.
Implementation Method 1
said cross member is a metallic cross member (20) and it is able to resist to a compression force greater than 60000 N, in particular greater than 80000 N, applied along a longitudinal direction (97) of said motor vehicle
Implementation Method 2
Said connection means (40) are plastically deformable under compression with a compression force greater than 500 N, and in particular greater than 1000 N, applied along said longitudinal direction (97), avoiding advantageously therefore to transmit said compression stresses to said frame
Implementation Method 3
Each polymeric crash box is designed for having in case of crash a permanent plastic deformation and a programmed collapse starting from a frontal portion towards a second rear portion of the same, consequently determining a plurality of folding starting from said frontal portion towards said second rear portion
Implementation Method 4
Each polymeric crash box shows in particular a substantially alveolar structure which permit to absorb a portion of kinetic energy due to a crash of the motor vehicle against an obstacle fixed or mobile
Data Source
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AI summary
Bumper structure 10 for a motor vehicle comprising at least two polymeric crash boxes 30 having preferably an alveolar structure, and comprising a cross member 20 which extends between the at least two polymeric crash boxes 30, in which the cross member 20 is a metallic cross member 20. The bumper structure 10 comprises connection means 40 which extend between the metallic cross member 20 and a frame of the motor vehicle, and besides which are positioned in proximity of the at least two polymeric crash boxes 30. The connection means 40 are plastically deformable and are unable to resist to compression stresses avoiding advantageously to transmit the compression stresses to the frame.