Tubular Array Energy Absorbing Cells for Curved Body Protection
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Solution Overview
Problem
Existing body protecting devices, such as safety helmets and pads, face challenges in achieving large curvature shapes due to the limitations of honeycomb structures, which are rigid and inflexible, leading to discomfort and inefficient energy absorption, especially when forming complex curved shapes like spheroidal helmets or pads that require significant deformation.
Innovation Solution
A body protecting device comprising an array of energy-absorbing cells with tubular structures that are connected or in close proximity, allowing for isotropic and non-anticlastic properties, enabling efficient energy absorption and deformation to large curvatures, using materials like polycarbonate and polyetherimide with a thermoplastic adhesive for bonding and thermoforming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a honeycomb structure is used for body protecting devices, then energy absorption capability is improved, but the device becomes rigid and inflexible, making it difficult to form large curvature shapes
Solution Approach 1:
The honeycomb structure is segmented into individual cells that can rotate independently about their longitudinal axes. This segmentation allows each cell to adapt to curvature while maintaining the overall energy absorption capability of the honeycomb structure.
Solution Approach 2:
The honeycomb cells are designed to be dynamically rotatable about their longitudinal axes, transforming the static rigid structure into a dynamic one that can adapt to large curvature shapes while maintaining structural integrity and energy absorption properties.
2Loss of energy
If a hexagonal honeycomb structure is used, then energy absorption is improved, but the structure becomes anticlastic, creating difficulties in forming spheroidal shapes
Solution Approach 1:
The patent modifies the symmetric hexagonal honeycomb structure by allowing asymmetric rotation of individual cells about their longitudinal axes. This controlled asymmetry enables the structure to conform to spheroidal shapes while maintaining energy absorption capabilities.
Solution Approach 2:
By making the honeycomb cells dynamically rotatable, the structure can transition from a static anticlastic form to a dynamic configuration that accommodates positive curvature required for spheroidal helmet shapes.
3Ease of manufacture
If traditional hand lay-up methods are used to form helmets, then manufacturing flexibility is maintained, but the process becomes complex and expensive
Solution Approach 1:
The honeycomb structure is pre-formed with rotatable cells before final assembly, allowing the complex energy absorption structure to be manufactured separately and then integrated into the helmet, simplifying the overall forming process while maintaining manufacturing flexibility.
Solution Approach 2:
The helmet manufacturing process is segmented into separate stages: pre-forming the honeycomb core with rotatable cells, preparing the outer shell, and then assembling them together. This segmentation reduces the complexity of the overall process while maintaining flexibility.
4Shape
If the outer and inner skins are inserted separately into the mould, then the necessary slippage during bending is achieved, but the bonding process becomes complex
Solution Approach 1:
The rotatable honeycomb cells act as an intermediary layer between the outer and inner skins, allowing relative movement and slippage during forming while maintaining structural integrity, thereby simplifying the bonding process compared to direct skin-to-skin bonding.
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 tubular array structure achieves efficient energy absorption with a high efficiency of over 80% and improved comfort by maintaining tube orientation under load, avoiding global buckling failures and allowing for easier shaping and reduced material mass.
Implementation Method 1
a first material bonded to a second material using an adhesive, wherein the adhesive has a melt temperature which is lower than the melt temperature of the first and second material
Implementation Method 2
the adhesive has a melt temperature which is lower than the melt temperature of the first and second material
Implementation Method 3
Axially loaded columns of various cross sectional shapes have been used for some time to improve the structural crashworthiness
Implementation Method 4
a global buckling failure mode (or a local failure which leads to failure of the whole column) is to be avoided as this does not efficiently absorb impact energy
Implementation Method 5
the adhesive has a melt temperature which is lower than the melt temperature of the first and second material
Implementation Method 6
the first material is bonded to the second material using an adhesive, wherein the adhesive has a melt temperature which is lower than the melt temperature of the first and second material
Data Source
AI summary
A body protecting device for wearing by a user comprising an array of energy absorbing cells, wherein each cell comprises a tube, and wherein substantially each tube has a side wall which is near or adjacent to the side wall of at least another tube, and wherein substantially each tube is configured such that the orientation of the tube is substantially maintained when a load is applied parallel to the axis of the tube.