Honeycomb Crush Structure With Controlled Multi-Phase Buckling
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Solution Overview
Problem
Standard honeycomb structures exhibit non-linear compressive stiffness with an initial stiffness peak that decreases after cell buckling, making it difficult to control crumpling within a defined location along the cell axis, and they are challenging to conform to curved surfaces due to anticlastic behavior.
Innovation Solution
The introduction of geometric perturbations on cell sidewalls, not parallel to the longitudinal axis, reduces stiffness and crush strength in a controlled manner, allowing for multi-phasic compressive stiffness and improved formability through reentrant geometries, enabling controlled buckling and conformability to curved shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If pre-crushing is applied to eliminate the initial stiffness peak, then the compressive stiffness is improved, but the location of crumpling cannot be controlled within a defined location along the cell axis
Solution Approach 1:
The patent introduces geometric perturbations at specific local regions of the cell walls (not uniform pre-crushing throughout) to create controlled weak points. These localized modifications allow buckling to initiate at predetermined locations along the cell axis while maintaining the desired compressive stiffness characteristics.
Solution Approach 2:
The geometric perturbations are pre-formed during manufacturing to predetermined locations on the cell walls. This preliminary action creates predetermined buckling initiation sites that control where crumpling occurs during impact, eliminating the randomness of conventional pre-crushing methods.
2Device complexity
If standard honeycomb structure is used, then the structure is simple and lightweight, but it exhibits non-linear compressive stiffness with an initial stiffness peak that is difficult to control
Solution Approach 1:
Instead of modifying the entire honeycomb structure uniformly, the patent applies geometric perturbations only at specific locations on cell walls. This localized modification approach maintains the overall simplicity and lightness of the honeycomb structure while achieving controlled compressive stiffness characteristics through targeted local changes.
3Strength
If geometric perturbations are introduced on cell sidewalls, then the stiffness and crush strength are reduced in a controlled manner, but the structure becomes more complex
Solution Approach 1:
The geometric perturbations are applied locally at specific positions on cell sidewalls rather than throughout the entire structure. This localized approach achieves controlled stiffness and crush strength reduction while minimizing the overall geometric complexity of the honeycomb structure.
Solution Approach 2:
The geometric perturbations introduce asymmetric features at specific locations on otherwise symmetric cell walls. This controlled asymmetry creates predetermined buckling initiation sites and allows for controlled stiffness reduction without requiring complex overall structural redesign.
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
This approach eliminates the initial stiffness peak, provides predictable and reproducible compressive and shear stiffness, and allows honeycomb structures to absorb impacts effectively while conforming to complex shapes, such as helmets, by reducing the load required for plastic deformation and enhancing formability.
Implementation Method 1
honeycomb structures undergo mainly plastic, non-recoverable deformation by controlled buckling during impact
Implementation Method 2
controlled buckling of interconnected cells by plastic deformation
Implementation Method 3
The introduction of geometric perturbations on cell sidewalls, not parallel to the longitudinal axis, reduces stiffness and crush strength in a controlled manner
Data Source
AI summary
An impact-absorbing structure that includes a plurality of interconnected cells forming a sheet, each cell having a sidewall and a longitudinal axis. Each cell may be configured to absorb energy through plastic deformation in response to an applied load, and a sidewall of at least one cell may include a geometric perturbation that is oriented in a direction that is not parallel to the longitudinal axis of the cell. The geometric perturbation may reduce the load required to cause plastic deformation of the cell.