Nested Side Sill Profiles for EV Side Impact Energy Dissipation
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Solution Overview
Problem
In electric vehicles, the increased weight of battery packs enhances kinetic energy during side impacts, necessitating improved energy absorption in side sill parts to prevent damage and ensure occupant safety in crash tests like EuroNCAP Pole Side Impact and AE-MDB Side Impact.
Innovation Solution
A side sill part design featuring a first profile with high crushability between rigid members, a second profile with lower crushability, and an external profile with even lower crushability, arranged to sequentially deform and absorb energy during a side impact, utilizing press-hardened and martensitic steel components with specific thicknesses and geometries to optimize energy absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single hollow tubular side sill part is used, then the structure is simple, but the energy absorption is insufficient for electric vehicles with battery packs
Solution Approach 1:
The side sill part is divided into multiple profile parts (first profile part, second profile part, external profile part) with different crushability levels, arranged in a hierarchical structure. Each profile part deforms sequentially during impact, creating multiple energy absorption stages that significantly increase total energy absorption capacity while maintaining a relatively compact integrated structure.
Solution Approach 2:
Different profile parts are assigned different local qualities in terms of crushability - the first profile part has higher crushability, the second has intermediate crushability, and the external profile part has lower crushability. This gradient structure ensures optimal energy absorption at each deformation stage while protecting critical components like the battery pack.
2Loss of energy
If multiple profile parts with different crushability are used, then the energy absorption is optimized, but the device complexity increases
Solution Approach 1:
The profile parts are arranged in a nested configuration where the first profile part is positioned inside the second, which is in turn positioned inside the external profile part. This nested arrangement allows multiple energy absorption mechanisms to be packed into a compact space, maximizing energy absorption while minimizing the increase in structural complexity.
Solution Approach 2:
The profile parts are pre-configured with specific crushability characteristics and geometric features (joining walls, contact portions) that determine their deformation sequence. During impact, this preliminary configuration ensures that the first profile part deforms first, followed by the second, and finally the external profile part, creating a controlled progressive energy absorption process.
3Reliability
If the side sill part is made more rigid to protect the battery pack, then the protection is improved, but the energy absorption capacity decreases
Solution Approach 1:
The structure uses parameter changes in crushability across different profile parts - the first profile part has higher crushability for initial energy absorption, while the external profile part has lower crushability for final protection. This gradient of parameters allows the structure to absorb energy progressively while maintaining adequate protection for the battery pack.
Solution Approach 2:
The side sill part functions as a composite structure combining multiple profile parts with different mechanical properties (different crushability levels). This composite approach allows the system to exhibit both energy absorption capabilities (through the more crushable inner profiles) and protection capabilities (through the rigid outer profile), resolving the contradiction between these two functions.
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 ensures efficient energy absorption and deformation of all profile parts, preventing intrusion into the vehicle compartment and protecting the battery pack by optimizing the sequence of deformation and energy dissipation during side impacts, thus enhancing safety and structural integrity.
Implementation Method 1
the first profile part having a higher crushability... a second profile part having a lower crushability... arranged to be crushed during the side impact in order to dissipate energy
Data Source
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AI summary
The side sill part (6) comprises at least: - an outer sill member (10) and an inner sill member (12), and defining between them an outer volume (47), - an external profile part (68), defining with the inner sill member (12) an inner volume (74), - a first profile part (48) extending in the outer volume (47), comprising at least one outer contact portion (50), at least one inner contact portion (52), and at least one joining wall (54) joining the outer contact portion (50) and the inner contact portion (52), - a second profile part (88) extending in the inner volume (74), comprising at least one outer contact portion (90), at least one inner contact portion (92), and at least one joining wall (94) joining the outer contact portion (90) and the inner contact portion (92).