Rate-Sensitive Impact Absorbing Structures for Concussion Mitigation
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Solution Overview
Problem
Existing helmets are ineffective in preventing concussions from collisions, as they primarily focus on preventing skull fractures and do not adequately absorb the energy from impacts, especially from high-velocity collisions.
Innovation Solution
A helmet design featuring two concentric shells with impact-absorbing structures between them, incorporating rate-sensitive materials (RSMs) that change resistance based on the rate of force application, allowing for deformation and energy dissipation during impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard shell is used to prevent skull fractures, then skull fracture protection is improved, but concussion protection deteriorates because the hard shell transmits impact forces to the brain
Solution Approach 1:
The helmet is divided into multiple functional layers: a hard outer shell for skull fracture protection, an intermediate impact-absorbing layer with deformable structures, and an inner liner. This segmentation allows each layer to address different aspects of impact protection - the hard shell prevents penetration while the intermediate layer absorbs energy to reduce concussion risk.
Solution Approach 2:
The impact-absorbing intermediate layer is pre-configured with deformable structures (such as expandable beads or collapsible cells) that are designed to activate and absorb energy before the impact force reaches the inner shell and brain, providing beforehand cushioning against concussion forces.
2Object-affected harmful factors
If cushioning materials are added to dissipate energy, then concussion protection is improved, but the helmet becomes less effective at preventing skull fractures because the cushioning compresses under high impact
Solution Approach 1:
Different regions of the helmet have different material properties optimized for their specific functions. The outer shell maintains high strength and rigidity for skull fracture protection, while the intermediate impact-absorbing layer uses softer, deformable materials locally where energy dissipation is needed, and the inner liner provides additional cushioning near the head.
Solution Approach 2:
The helmet combines multiple materials with different mechanical properties: a rigid outer shell material (such as polycarbonate or composite), an intermediate impact-absorbing material (such as expanded polypropylene beads or collapsible foam cells), and an inner liner material. This composite structure allows simultaneous achievement of skull fracture protection and concussion mitigation.
3Object-affected harmful factors
If rate sensitive materials are used to resist high-velocity impacts, then concussion protection is improved, but the helmet becomes stiffer and transmits more force during low-velocity impacts
Solution Approach 1:
The impact-absorbing intermediate layer uses rate-sensitive materials or structures that dynamically change their mechanical properties based on impact velocity. During high-velocity impacts, the material stiffens to resist and absorb the large forces, while during low-velocity impacts, it remains compliant to allow controlled deformation and energy dissipation without transmitting excessive force to the head.
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 helmet design significantly reduces the incidence and severity of concussions by effectively absorbing and dissipating impact energy, while also providing protection against skull fractures.
Implementation Method 1
A RSM is a material that changes its resistance to force based on a rate at which the material is loaded. Hence, a RSM provides greater resistance to an impact force that is more quickly applied to the RSM.
Implementation Method 2
the impact absorbing structures undergo deformation (e.g., buckling, bending, crushing, crumpling) when subjected to forces from a sufficiently strong impact force. As a result of the deformation, the impact absorbing structures reduce energy transmitted from the outer shell to the inner shell
Implementation Method 3
the impact absorbing structures reduce energy transmitted from the outer shell to the inner shell, thereby reducing forces on the wearer's skull and brain
Implementation Method 4
the outer shell may also somewhat rigid to spread impact forces over a wider area of the impact absorbing structures positioned inside the outer shell
Implementation Method 5
the outer shell may be more flexible such that impact forces locally deform the outer shell to transmit forces to a smaller, more localized section of the impact absorbing structures positioned inside the outer shell
Data Source
AI summary
A garment worn by a wearer has an exterior shell and an interior shell with various impact absorbing material between the exterior shell and the interior shell. The impact absorbing material includes multiple structures, such as rods or filaments, capable of deforming when force is applied then returning to its state prior to application of the force. In various embodiments, a rate sensitive material (RSM) is positioned in one or more locations relative to the exterior shell and the interior shell of the garment to further attenuate impacts to the garment. The RSM changes its resistance to force based on a rate at which the material is loaded.