Auxetic Structure Impact Energy Absorption
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Solution Overview
Problem
Conventional materials used in aircraft construction for protecting against high-energy impacts, such as Propeller Blade Release and Uncontained Engine Rotor Failure, result in significant weight penalties due to their positive Poisson ratio, which requires thick and heavy shielding to absorb impact energy effectively.
Innovation Solution
A three-dimensional auxetic structure composed of interconnected cells with a re-entrant hexagonal pattern, which exhibits negative Poisson ratio behavior, allowing the material to concentrate around impact areas and absorb energy in multiple directions, thereby reducing the need for thick ceramic and aramid layers and minimizing weight while maintaining high impact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional materials with positive Poisson ratio are used for impact protection, then impact resistance is achieved, but weight increases significantly due to required thickness
Solution Approach 1:
The patent changes the fundamental Poisson ratio parameter from positive (conventional materials) to negative (auxetic materials). This parameter change enables the material to exhibit opposite deformation behavior: expanding laterally under tension and contracting laterally under compression, which allows for thinner protective structures that maintain or enhance impact resistance
Solution Approach 2:
The patent employs composite structures combining auxetic materials with traditional protective materials. The auxetic layer works synergistically with ceramic, aramid, or other ballistic materials to achieve superior impact protection at reduced weight, utilizing the unique negative Poisson ratio behavior to improve energy absorption and distribution
2Reliability
If thick shielding layers are used to absorb impact energy, then protection effectiveness improves, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent extracts the essential protective function from thick, complex multi-layer shields and concentrates it in a thinner configuration. By utilizing the auxetic effect, the design removes the need for excessive thickness while maintaining protection effectiveness, simplifying the overall shielding structure
Solution Approach 2:
The patent inverts the conventional approach to impact protection. Instead of relying on thickness and mass to absorb impact energy, it uses materials that actively respond to compression by contracting laterally, creating a more efficient energy absorption mechanism that reduces structural complexity
3Weight of moving object
If conventional honeycomb structures are used for lightweight protection, then weight is reduced, but impact energy absorption in multiple directions is insufficient
Solution Approach 1:
The patent changes the Poisson ratio parameter to negative values, enabling the material to contract laterally under compression. This creates a mechanism where impact energy is absorbed more effectively in multiple directions, as the material responds dynamically to compressive loads from any angle, enhancing multi-directional protection without increasing weight
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 auxetic structure effectively absorbs impact energy by condensing material around the impact zone in multiple directions, enhancing ballistic performance with reduced weight compared to conventional solutions, making it suitable for lightweight protection in aircraft applications.
Implementation Method 1
auxetic, having a negative Poisson ratio and when stretched, they become wider on the transversal directions to the applied force, and thinner when compressed
Implementation Method 2
There are materials or structure geometries configurations that exhibit opposite behavior, that are called auxetic
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
Deformable auxetic structure for absorbing energy of an impact that comprises a plurality of interconnected adjoining tridimensional auxetic cells (1) where each tridimensional auxetic cell (1) comprises at least a surface element (3) and a plurality of legs (5) extending from said surface (3), the plurality of legs (5) and the surface element (3) being configured such that the section cut of the structure in at least two planes perpendicular to said surface element (3) follows an auxetic pattern.