Poisson's Ratio Layered Energy Absorbing Structure
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Solution Overview
Problem
Current solutions for structures in the aerospace industry to withstand mechanical and acoustic impacts are distinct and lack a unified approach for energy absorption from both sources.
Innovation Solution
A deformable energy-absorbing structure composed of layers with positive and negative Poisson's ratios, combined with an elastomeric material, arranged in various configurations such as rod-type, membrane-type, plate-type, and sandwich-type to absorb energy through shear and compression forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional single-material structures are used to withstand mechanical impacts, then structural strength is maintained, but energy absorption capability is limited
Solution Approach 1:
The patent employs a composite structure consisting of alternating layers of positive Poisson's ratio material and negative Poisson's ratio material. This composite arrangement enables the structure to simultaneously maintain structural strength and enhance energy absorption capability. The positive Poisson's ratio layers provide structural integrity while the negative Poisson's ratio layers expand laterally under compression to absorb impact energy, creating a synergistic effect that resolves the contradiction between strength and energy absorption.
Solution Approach 2:
The patent utilizes materials with fundamentally different Poisson's ratio parameters (positive versus negative) to create distinct deformation behaviors. When subjected to mechanical impact, the positive Poisson's ratio layers contract laterally while the negative Poisson's ratio layers expand laterally, creating differential deformation that enhances energy dissipation through shear forces in the intermediate layers while maintaining overall structural strength.
2Loss of energy
If elastomeric material is used for energy absorption, then energy attenuation is improved, but structural strength is limited by the elastomeric material
Solution Approach 1:
The patent creates a composite system where rigid layers (positive and negative Poisson's ratio materials) alternate with elastomeric intermediate layers. The rigid layers maintain structural strength and load-bearing capacity, while the elastomeric layers provide energy attenuation through shear deformation. This composite arrangement allows the structure to achieve both high energy attenuation and adequate structural strength, overcoming the limitation of using elastomeric material alone.
Solution Approach 2:
The elastomeric material serves as an intermediate layer between the rigid positive and negative Poisson's ratio layers. This intermediary position allows the elastomeric material to absorb energy through shear forces generated by the differential deformation of the adjacent rigid layers, while the rigid layers continue to provide the primary structural strength. The elastomeric intermediate layers act as energy-dissipating elements without becoming the load-bearing components.
3Reliability
If separate solutions are used for mechanical and acoustic impact protection, then specific performance requirements are met, but structural complexity increases
Solution Approach 1:
The patent creates a universal energy-absorbing structure that simultaneously protects against both mechanical impacts and acoustic vibrations. The alternating layers of positive and negative Poisson's ratio materials with elastomeric intermediates provide a unified mechanism for energy absorption that is effective against various types of energy sources. This multi-functional design eliminates the need for separate protection systems for different impact types, thereby reducing overall structural complexity while maintaining comprehensive protection performance.
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 structure effectively attenuates energy from mechanical and acoustic impacts by differential deformation of layers, providing enhanced energy absorption and durability without limiting strength by the elastomeric material, and can be tailored for specific applications.
Implementation Method 1
absorbing at least part of the energy through the shear forces or the combinations of traction and compression forces applied by the first and second layers as a consequence of their differential deformation
Implementation Method 2
one or more first layers of a material having a positive Poisson's ratio, one or more second layers of a material having a negative Poisson's ratio
Implementation Method 3
absorbing at least part of the energy through the shear forces or the combinations of traction and compression forces applied by the first and second layers
Implementation Method 4
absorbing at least part of the energy through the shear forces or the combinations of traction and compression forces applied by the first and second layers
Data Source
AI summary
An energy absorbing structure for attenuating energy received from an energy source. The structure comprises a deformable structure formed by an ensemble of one or more first layers of a material having a positive Poisson's ratio, one or more second layers of a material having a negative Poisson's ratio and one or more third layers of an elastomeric material placed between a first layer and a second layer. The ensemble is arranged with the one or more third layers joined to the first and second layers for absorbing at least part of the energy through shear forces or a combination of traction and compression forces applied to the ensemble by the first and second layers as a consequence of their differential deformation after receiving the energy.