Helmet Fit System With Elastomeric Connectors
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Solution Overview
Problem
Conventional protective helmets, such as bicycle helmets, can fail to adequately absorb and dissipate impact energy due to their rigid nature, leading to potential injuries even with impact attenuating materials, and may be removed from the user's head during an impact due to their design.
Innovation Solution
The helmet design incorporates an outer liner and an inner liner with a slip plane and elastomeric straps that allow relative movement between the two, providing a range of 0-30 mm of deformation to absorb impact energy and prevent complete removal from the head, using materials like expanded polystyrene, polypropylene, or polyolefin, and featuring a low-friction thermoplastic slip plane and spherical or ellipsoid mating surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid materials and structures are used in helmet design, then structural integrity is maintained, but impact energy absorption is reduced and the helmet may be removed from the user's head during impact
Solution Approach 1:
The helmet is divided into multiple segments including an outer shell, intermediate layer, and inner liner that can move independently. This segmentation allows each layer to perform its specific function - the outer shell maintains structural integrity while the intermediate and inner layers deform to absorb impact energy, resolving the contradiction between strength and energy absorption.
Solution Approach 2:
The helmet incorporates dynamic elements such as the movable inner liner that can shift relative to the outer shell during impact. This dynamic behavior allows the helmet to adapt to impact forces, absorbing energy through controlled movement while maintaining overall structural integrity, thus resolving the contradiction between rigidity and energy absorption.
2Reliability
If rigid straps are used to secure the helmet, then the helmet remains fixed to the head, but the helmet may be completely removed during impact due to the rigid nature of the helmet and straps
Solution Approach 1:
The straps incorporate elastomeric materials that change their mechanical properties during impact. These elastomeric straps can stretch and deform under impact forces, allowing the helmet to remain securely attached to the head while accommodating the sudden forces that would otherwise cause removal, thus resolving the contradiction between reliable retention and preventing impact removal.
3Loss of energy
If impact attenuating materials are used, then energy absorption is improved, but the helmet may still fail to prevent injury due to rigid construction
Solution Approach 1:
The inner liner is designed as a dynamic component that can move independently within the helmet shell. During impact, this movable inner liner deforms and shifts to absorb impact energy, while the elastomeric straps allow controlled movement. This dynamic response complements the impact attenuating materials to effectively reduce injury risk, resolving the contradiction between energy absorption and injury prevention.
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 design enhances energy management during impacts by allowing the helmet to rotate and deform, reducing the force of the impact on the user's head and improving the retention of the helmet during crashes, thereby limiting injuries.
Implementation Method 1
An elastomeric strap may comprise an inner end and an outer end opposite the inner end. The outer end of the elastomeric strap may be coupled to an inner surface of the outer liner, the outer end of the elastomeric strap comprising a recess and a fastener that extends through the recess of the outer end of the elastomeric strap to couple the elastomeric strap to the outer liner. The inner end of the elastomeric strap may be coupled to the fit belt. The elastomeric strap may provide relative movement between the outer liner and the inner liner in a range of 0-30 millimeters (mm).
Implementation Method 2
The helmet may further include a slip plane disposed between an inner surface of the outer liner and an outer surface of the inner liner. The slip plane may comprise mating surfaces of the inner liner and the outer liner and further comprise a low friction thermoplastic material.
Implementation Method 3
One or more of the outer liner and the inner liner may be formed of expanded polystyrene (EPS), expanded polypropylene (EPP), or expanded polyolefin (EPO).
Data Source
AI summary
A helmet may include an outer liner and an inner liner disposed inward from the outer liner, the inner liner comprising an inner surface with at least one hole. A fit belt may comprise at least one pin coupled to an inner surface of the inner liner with the at least one hole mateably coupled with the at least one pin. An elastomeric strap may comprise an inner end and an outer end opposite the inner end. The outer end of the elastomeric strap may be coupled to an inner surface of the outer liner. The outer end of the elastomeric strap may comprise a recess and a fastener that extends through the recess of the outer end of the elastomeric strap to couple the elastomeric strap to the outer liner. The inner end of the elastomeric strap may be coupled to the fit belt.