Auxetic Bi-Stable Curved Shell for Controlled Deformation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional curved shells with positive Poisson ratio exhibit undesirable buckling and sudden deformation under compression, limiting their controlled shape change and energy absorption capabilities.
Innovation Solution
A curved shell made of auxetic material combined with a rigid element, allowing for controlled deformation from concave to convex geometry by utilizing negative Poisson ratio properties, which enables smooth shape transition and increased energy absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional material with positive Poisson ratio is used in curved shell, then structural strength is maintained, but sudden buckling and stiffening occur under compression
Solution Approach 1:
The patent changes the Poisson ratio parameter from positive (conventional materials) to negative (auxetic materials). This fundamental parameter change alters the deformation behavior of the curved shell, enabling progressive deformation without sudden buckling while maintaining structural strength.
Solution Approach 2:
The patent employs composite structures combining auxetic materials with specific geometrical configurations (re-entrant hexagonal patterns, chiral structures). These composite configurations enhance the material's ability to absorb energy progressively while maintaining overall structural integrity under compressive loads.
2Use of energy by moving object
If conventional material is used in curved shell, then initial structural rigidity is maintained, but energy absorption capability is limited
Solution Approach 1:
By changing the Poisson ratio to negative values through auxetic materials, the patent enables the structure to expand laterally when stretched and contract laterally when compressed. This parameter change allows progressive deformation that absorbs significant energy while controlling the resistance force evolution throughout the deformation process.
Solution Approach 2:
The patent creates dynamically adaptable structures that change their mechanical properties during deformation. The auxetic materials enable the curved shell to transition from initial rigidity to progressive deformation, optimizing energy absorption while managing resistance forces through controlled geometric transformation.
3Adaptability or versatility
If auxetic material with negative Poisson ratio is used, then controlled deformation and energy absorption are improved, but manufacturing complexity increases
Solution Approach 1:
The patent divides the curved shell into discrete auxetic unit cells (re-entrant hexagons, chiral structures) that can be manufactured independently and then assembled. This segmentation approach enables controlled deformation at the unit cell level while simplifying the overall manufacturing process through modular construction.
Solution Approach 2:
The patent utilizes porous auxetic structures with specific cellular geometries that provide controlled deformation pathways. These porous configurations enable predictable mechanical behavior while being amenable to various manufacturing techniques including additive manufacturing, foam processing, and cellular material fabrication.
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 curved shell achieves reversible deformation with reduced stiffness, allowing for significant energy absorption and controlled shape change, avoiding sudden buckling and stiffening effects, making it suitable for applications requiring progressive deformation and energy management.
Implementation Method 1
auxetic material with negative Poisson ratio instead of a conventional material, it is possible to control the deformation behavior of curved shells or domes
Implementation Method 2
the influence of young modulus and Poisson ratio on the deformation is even higher as they drive both the stable strength deformation and also the buckling or unstable behavior
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
Auxetic bi-stable structure that comprises: - an auxetic curved shell (2) movable between a first and a second stable position, and - a rigid element (1) wherein at least part of the surface the auxetic curved shell (2) is joined to the rigid element (1) such that the curved shell (2) is movable with respect to said rigid element (1) between said first and second stable positions.