Triple-Layer Compressible Helmet Liner for Oblique Impact Protection
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Solution Overview
Problem
Existing compressible liners in helmets and other applications fail to effectively manage oblique impacts, which can cause significant rotational acceleration and deceleration, leading to increased energy transfer to the head or body, and do not efficiently absorb different levels of impact forces.
Innovation Solution
A compressible liner comprising three layers with varying densities and interlocking cone-like protuberances and recesses, where the intermediate layer has a different compressibility or density than the inner and outer layers, acting as a decoupling zone to reduce impact energy transfer and provide a compression gradient, thereby minimizing rotational acceleration and absorbing impact forces more efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer compressible liner is used, then the structure is simple and manufacturing is easy, but it cannot effectively manage oblique impacts and rotational acceleration
Solution Approach 1:
The liner is divided into three distinct layers with different compressibility characteristics (first layer: high compressibility, second layer: medium compressibility, third layer: low compressibility). This segmentation allows each layer to handle different aspects of impact forces, with the intermediate layer acting as a decoupling zone to reduce rotational acceleration while the outer layers manage translational deceleration.
Solution Approach 2:
Each layer is assigned specific local properties: the first layer has high compressibility for initial impact absorption, the second layer has medium compressibility to act as a decoupling zone, and the third layer has low compressibility for final energy dissipation. This local differentiation of material properties enables the liner to effectively manage both translational and rotational impact forces.
2Loss of energy
If dual-layer compressible liners are used, then some impact absorption is improved, but rotational acceleration and oblique impact management are still insufficient
Solution Approach 1:
The second intermediate layer acts as a mediator or decoupling zone between the first and third layers. This intermediate layer with medium compressibility reduces the transfer of rotational acceleration between the high-compressibility and low-compressibility layers, thereby minimizing the harmful rotational effects while maintaining effective impact energy absorption.
Solution Approach 2:
The liner employs a composite structure with three layers of different compressibility characteristics. This composite approach combines materials with varying mechanical properties to simultaneously achieve high impact energy absorption and effective reduction of rotational acceleration, addressing both requirements that a single material cannot satisfy.
3Ease of manufacture
If uniform density foam is used throughout the liner, then manufacturing is simpler, but the liner cannot provide compression gradient or decoupling effect
Solution Approach 1:
The liner utilizes systematic changes in material parameters (compressibility and density) across the three layers. The first layer has high compressibility, the second layer has medium compressibility, and the third layer has low compressibility. This parameter gradient enables the liner to provide both decoupling effect and compression gradient, effectively managing different levels of impact forces while maintaining manufacturability.
4Loss of energy
If higher density foam is used to improve impact absorption, then energy absorption improves, but the liner weight increases
Solution Approach 1:
The liner employs a dynamic, gradient-based compressibility structure rather than uniform high-density foam. The three layers with progressively different compressibility levels (high, medium, low) create a compression gradient that optimizes impact energy absorption at different stages of deformation, achieving effective protection without the excessive weight that would result from using uniformly high-density material throughout.
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 three-layered liner effectively reduces the risk of concussion and severe head injuries by directing impact energy sideways and reducing g-forces, while maintaining a lighter weight and preventing shearing effects during oblique impacts.
Implementation Method 1
compressible liner for impact protection... comprising three substantially co-extensive layers... the intermediate layer having a different compressibility to that of an adjacent layer
Implementation Method 2
layers comprise foam materials of different compressibility... absorb impact forces more efficiently
Implementation Method 3
intermediate layer... acting as a decoupling zone to reduce impact energy transfer... minimizing rotational acceleration
Data Source
AI summary
A compressible liner for a helmet or other apparatus subject to shock loading comprises three substantially co-extensive layers mutually engaged by respective cone-like protuberances and cone-like recesses. The intermediate layer is of a different compressibility and provides for de-coupling of the layers in an oblique impact.