Flexible Energy-Absorbing Layers With Re-Entrant Impact Geometry
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing impact protection systems are either uncomfortable due to rigid exteriors or provide inadequate protection due to the use of foam or foam laminate pads.
Innovation Solution
A flexible energy absorbing system comprising multiple layers with strain rate sensitive materials and re-entrant geometries, allowing for efficient absorption and dissipation of shock loads while maintaining comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rigid exterior shell is used for impact protection, then protection level is improved, but comfort is worsened
Solution Approach 1:
The protective system is divided into multiple layers with different functions: an outer layer with re-entrant geometry for initial impact absorption, a middle layer with protrusions for interlocking and friction-based energy dissipation, and an inner layer for comfort. This segmentation allows each layer to contribute differently to protection and comfort.
Solution Approach 2:
The system uses composite structure combining rigid re-entrant geometry elements with softer strain rate sensitive materials. The outer layer provides rigid structural integrity while the inner layers with strain rate sensitive materials provide comfort and additional energy absorption, creating a composite protective system.
2Ease of operation
If foam or foam laminate pads are used for impact protection, then comfort is improved, but protection level is worsened
Solution Approach 1:
Different regions of the protective system have different properties: the outer layer has rigid re-entrant geometry for high-protection zones, while inner layers use softer strain rate sensitive materials for comfort. This local differentiation allows the system to provide both comfort and high-level protection simultaneously.
Solution Approach 2:
The system transitions from static foam materials to dynamic strain rate sensitive materials that change their mechanical properties in response to impact conditions. Under normal conditions, the materials remain soft and comfortable; under impact, they become stiffer to provide enhanced protection.
3Device complexity
If single layer structure is used, then device complexity is reduced, but energy absorbency is worsened
Solution Approach 1:
The energy absorbing system is segmented into multiple layers, each with specific geometric features (re-entrant cells in outer layer, protrusions in middle layer). This segmentation creates multiple mechanisms for energy dissipation: buckling of re-entrant cells, interlocking of protrusions, and friction between layers, significantly enhancing energy absorbency.
Solution Approach 2:
The system adds the dimensional aspect of layering with inter-layer interactions. The protrusions extend in one dimension while friction acts between layers in another dimension, creating a three-dimensional energy dissipation mechanism that greatly enhances energy absorbency compared to single-layer structures.
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 system achieves significant improvements in energy absorbency and comfort by utilizing frictional components between layers and strain rate sensitive materials, providing more effective protection against impact.
Implementation Method 1
The system achieves significant improvements in energy absorbency and comfort by utilizing frictional components between layers and strain rate sensitive materials
Implementation Method 2
the geometry lends itself to buckling or folding inwards during impact, improving the impact energy absorbing properties
Data Source
AI summary
Disclosed herein are flexible energy absorbing systems and methods of manufacturing flexible energy absorbing systems. The systems include one or more cells of a strain rate sensitive material and having a re-entrant geometry. Some of the systems have an anisotropic geometry to provide a different response to impacts from different directions.