Pseudo-Spherical Helmet Liners for Rotational Impact Attenuation
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Solution Overview
Problem
Conventional helmets with spherical symmetry energy management liners face issues such as larger size, undesirable length to width ratio, and decreased effectiveness due to insufficient material, and those with continuous interfaces are not suitable for helmets requiring air flow openings, while deformation-based energy absorption is inefficient for rotational acceleration attenuation.
Innovation Solution
A helmet design featuring pseudo-spherical energy management liners with an outer liner and an inner liner composed of elastically deformable material, slidably coupled to facilitate rotation and absorb rotational energy through elastic deformation, maintaining a desirable form factor and effective thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spherical symmetry energy management liners are used to facilitate rotation, then rotational energy absorption is improved, but helmet size increases and length to width ratio becomes undesirable
Solution Approach 1:
The patent applies asymmetry by transitioning from spherical symmetry to pseudo-spherical symmetry in the energy management liner design. The pseudo-spherical shape maintains the rotational facilitation benefits while reducing overall helmet volume and improving the length to width ratio, thereby resolving the contradiction between rotational energy absorption and helmet size.
Solution Approach 2:
The patent changes the geometric parameters of the energy management liner from a perfect sphere to a pseudo-sphere with modified curvature radii. This parameter change allows the liner to maintain its rotational energy absorption function while reducing the helmet's overall size and improving its dimensional proportions.
2Ease of manufacture
If continuous interface surface between liners is used, then manufacturing is simplified, but air flow openings are blocked and ventilation is reduced
Solution Approach 1:
The patent applies segmentation by dividing the continuous interface surface into discrete segments that accommodate air flow openings. This segmentation allows the liners to be manufactured with ventilation channels while maintaining the sliding interface functionality, thus resolving the contradiction between manufacturing simplicity and ventilation capability.
3Loss of energy
If projection structures are used to bridge energy liners, then energy absorption occurs, but rotational acceleration attenuation is insufficient due to short deformation time
Solution Approach 1:
The patent applies dynamics by enabling the energy management liners to rotate and deform in a controlled manner during impact. The pseudo-spherical interface facilitates gradual rotational movement and elastic deformation, extending the duration of energy absorption and improving rotational acceleration attenuation compared to rigid projection structures.
Solution Approach 2:
The patent changes the mechanical parameters of the interface from rigid projection contact to pseudo-spherical sliding contact. This parameter change allows for extended deformation time and more effective attenuation of rotational accelerations while maintaining energy absorption capabilities.
4Reliability
If inner liner is made elastically deformable, then rotational energy is attenuated through deformation, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies spheroidality by using a pseudo-spherical curved interface between the inner and outer liners. This curved geometry naturally guides the rotational movement and deformation, reducing the sensitivity to manufacturing precision variations while maintaining effective rotational energy attenuation.
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 pseudo-spherical design effectively attenuates rotational energy by elastic deformation, improving protection without increasing helmet size or sacrificing thickness, and enhances ventilation and manufacturability.
Implementation Method 1
the inner liner being elastically deformable along the interior surface of the outer liner in response to rotation of the outer liner relative to the inner liner caused by an impact to the helmet
Data Source
AI summary
A helmet comprising an outer liner and an inner liner slidably coupled to an interior surface of the outer liner is disclosed. The outer liner comprises an interior surface and the inner liner comprises an exterior surface. The inner liner is composed of an elastically deformable material. A majority of the interior surface of the outer liner and a majority of the exterior surface of the inner liner are both substantially parallel to a pseudo-spherical surface having a coronal cross section that is circular with a first radius and a sagittal cross section that is circular with a second radius different from the first radius. The inner liner is elastically deformable along the interior surface of the outer liner in response to rotation of the outer liner relative to the inner liner caused by an impact to the helmet.