Hybrid Side Rail Assembly for Lightweight Side-Impact Energy Absorption
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Solution Overview
Problem
Existing side rails in vehicles do not effectively absorb energy from side impacts while minimizing weight, particularly in side pole impacts, which can damage critical components like electric vehicle battery boxes.
Innovation Solution
A hybrid energy absorbing side rail assembly comprising a metal inner and outer rail with a plastic energy absorber array, optimized through roll forming and injection molding, respectively, to provide tailored geometry and weight reduction, and coated with electrostatic paint for enhanced protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional solid metal side rails are used, then strength and impact resistance are improved, but weight increases
Solution Approach 1:
The side rail employs a composite structure combining metal rails (inner and outer) with a plastic energy absorber material filled within the cavity. This composite approach allows the metal components to provide structural strength and attachment points, while the plastic filler absorbs impact energy, achieving both high strength and weight reduction compared to solid metal rails
Solution Approach 2:
The side rail is divided into multiple functional segments: inner metal rail for structural support, outer metal rail for protection and attachment, and plastic energy absorber material filling the cavity. This segmentation allows each component to be optimized for its specific function, with the plastic material providing lightweight energy absorption while metal components provide strength
2Weight of moving object
If lighter materials are used for side rails, then weight is reduced, but energy absorption capability deteriorates
Solution Approach 1:
The plastic energy absorber material is selected specifically for its high energy absorption properties per unit weight. When filled within the metal rail cavity, this lightweight material provides superior specific energy absorption compared to traditional solid metal structures, achieving both weight reduction and improved energy absorption capability
Solution Approach 2:
The plastic energy absorber material's properties (density, strength, ductility) are optimized to maximize energy absorption during impact. The material parameters are selected and tuned to provide optimal crashworthiness while maintaining lightweight characteristics, allowing the structure to deform and absorb energy efficiently
3Loss of energy
If complex energy absorption structures are implemented, then energy absorption is improved, but manufacturing complexity increases
Solution Approach 1:
The manufacturing process merges multiple operations into integrated steps: the inner and outer metal rails are formed using roll forming, the plastic energy absorber is molded in one piece using injection molding, and the components are assembled by filling the cavity. This consolidation of processes reduces manufacturing complexity compared to assembling multiple complex energy absorption components
Solution Approach 2:
The plastic energy absorber's geometry and material properties are optimized through parameter adjustment during injection molding to achieve the desired energy absorption performance. By controlling mold design, injection parameters, and material formulation, the complex energy absorption function is achieved through a relatively simple single-piece molded component rather than multiple assembled parts
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 assembly efficiently absorbs energy during side impacts, protecting vehicle components while maintaining a lightweight design, meeting safety standards and reducing manufacturing costs.
Implementation Method 1
at least one energy absorber housed in the cavity. The at least one energy absorber is positioned in-line with the triggers
Implementation Method 2
coating the energy absorbing side rail includes electrostatic coating
Data Source
AI summary
An energy absorbing side rail including an inner rail, an outer rail fixedly coupled to the inner rail defining a cavity, the outer rail defining triggers extending along at least a portion of the outer rail, and at least one energy absorber housed in the cavity, wherein at least one energy absorber is positioned in-line with the triggers.