Multi-Stage Helmet Liner for Off-Axis Impact Management
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Solution Overview
Problem
Current helmet energy absorbing systems are inadequate for both linear and non-linear impacts, particularly failing to effectively manage off-angle hits due to their rigidity and lack of adaptability to varying impact energies, leading to insufficient energy absorption and increased rotational forces on the brain.
Innovation Solution
A multi-stage energy absorber system comprising a compliant membrane as the first stage and stiffer energy absorbing units as the second stage, designed to absorb impact energy progressively, with the second stage being 2-10 times stiffer than the first, allowing for efficient energy dissipation in both normal and off-axis impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If homogeneous energy absorbing materials tuned for linear impacts are used, then linear impact protection is improved, but non-linear impact performance deteriorates due to excessive rigidity and failure to stroke
Solution Approach 1:
The energy absorber is divided into multiple stages with different stiffness characteristics. The first stage has lower stiffness to allow substantial stroking and stroke-induced rotation reduction during non-linear impacts, while the second stage has higher stiffness to provide protection during linear impacts. This segmentation resolves the contradiction by enabling each stage to specialize in different impact types.
Solution Approach 2:
Different regions of the energy absorber have different local stiffness properties. The first stage is designed with compliant characteristics for non-linear impact absorption, while the second stage is designed with rigid characteristics for linear impact protection. This local differentiation allows the system to adapt to varying impact conditions without compromising overall performance.
2Device complexity
If single-stage energy absorbing systems are used, then device complexity is reduced, but energy absorption efficiency deteriorates due to inability to optimize for multiple impact scenarios
Solution Approach 1:
The energy absorption process is segmented into two distinct stages, each optimized for specific impact conditions. The first stage absorbs energy through compliant deformation and stroking, while the second stage absorbs remaining energy through rigid deformation. This segmentation enables superior energy absorption efficiency compared to single-stage systems while maintaining reasonable structural complexity.
Solution Approach 2:
The multi-stage energy absorber combines multiple energy absorption mechanisms (compliant stroking, rigid deformation) into a single integrated system. This merging of different absorption modes within one structure achieves high energy absorption efficiency across multiple impact scenarios without requiring separate systems for each impact type.
3Object-affected harmful factors
If helmet liner is decoupled from the head to reduce rotational forces, then non-linear impact protection is improved, but energy absorption capability deteriorates due to reduced stroke effectiveness
Solution Approach 1:
The energy absorber incorporates dynamic stroking capability in the first stage, allowing the system to adapt its response based on impact conditions. During non-linear impacts, the first stage can stroke and induce controlled rotation reduction, while maintaining energy absorption capability. This dynamic behavior resolves the contradiction between rotational force reduction and energy absorption.
Solution Approach 2:
The system changes its mechanical parameters (stiffness, stroke length) between stages. The first stage operates with lower stiffness and longer stroke for non-linear impacts with rotation control, while the second stage operates with higher stiffness for linear impacts. This parameter variation enables simultaneous achievement of rotational force reduction and energy absorption.
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 multi-stage system enhances impact protection by maximizing energy absorption at lower loads, reducing rotational forces, and enabling the helmet to be reused after impacts, while providing superior comfort, durability, and cost-effectiveness compared to traditional systems.
Implementation Method 1
the first stage of the energy absorber (termed herein as a 'membrane') bends and/or collapses to absorb an initial portion of the impact energy
Implementation Method 2
one or more subsequent stages (termed herein as 'energy absorbing units') deflect and absorb at least some of the remaining impact energy
Data Source
AI summary
An energy absorbing liner system that offers a multi-stage reaction to impact and is positioned inside a member that receives an impact. The energy absorbing liner system has one or more interconnected energy absorbing modules that rebound after one or more impacts. At least some of the modules in the layer have a basal portion with multiple levels of reaction to impact. For example, a first stage has one or more membranes. A second stage has energy absorbing units with bendable walls. The membranes extend between the walls of adjacent energy absorbing units. The membranes alone or in combination with the side walls of the units at least partially cushion the blow in multiple stages of reaction by progressively absorbing energy imparted by an object that impacts the outer shell.