Porous Unit-Cell Padding to Limit High-Rate Impact Stiffening
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current padding materials, including second skin products, are inadequate in absorbing energy during high-strain-rate impacts common in sporting activities, as they rapidly stiffen and fail to attenuate impact energy effectively.
Innovation Solution
A padding material comprising a base with an array of raised unit cells formed from cured polymeric material, embedded with a breathable textile substrate, which allows for improved shock absorption and adhesion to the skin, and can be produced using a method involving a two-part mold and vacuum curing to create fine porosity and spaced unit cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional foam cell materials or gel-like substances are used for padding, then the padding can attenuate impact energy at low strain rates, but at high strain rates the materials rapidly stiffen and fail to absorb impact energy effectively
Solution Approach 1:
The padding material is divided into an array of discrete, spaced-apart unit cells rather than a continuous foam structure. Each unit cell independently deforms during impact, preventing the rapid stress propagation and stiffening that occurs in continuous foam materials at high strain rates. This segmentation allows progressive energy absorption as each cell collapses sequentially.
Solution Approach 2:
The unit cells are constructed with controlled porosity, creating a hierarchical pore structure that enables progressive collapse mechanisms. The porous architecture allows air to escape during compression, preventing pressure buildup that would cause rapid stiffening, while still providing effective energy absorption through controlled cell wall deformation and buckling.
2Ease of operation
If a substrate is embedded in the polymeric material to provide adhesion to skin, then the padding can be affixed without compression layers, but the substrate may reduce breathability
Solution Approach 1:
The substrate is designed with a porous structure that allows air and moisture vapor to pass through while maintaining adequate skin adhesion. The porosity creates channels for breathability, preventing the suffocating effect that would occur with solid, non-porous adhesive materials. The adhesive properties are distributed throughout the porous matrix rather than forming a continuous blocking layer.
Solution Approach 2:
The padding material forms a composite structure combining the polymeric unit cells with the porous substrate material. This composite architecture integrates the adhesive function of the substrate with the shock-absorbing function of the unit cells, while the porous nature of the substrate maintains breathability. The two materials work synergistically rather than the substrate merely covering the unit cells.
3Loss of energy
If the unit cells are spaced apart rather than continuous, then the padding can reduce high-strain-rate stiffening, but the spacing may create gaps that reduce protective coverage
Solution Approach 1:
The spacing between unit cells is optimized to specific parameters that balance energy absorption with coverage. The gaps are sized and distributed to allow progressive collapse mechanisms while maintaining sufficient protective coverage. The unit cell density, individual cell size, and spacing pattern are carefully controlled to ensure that the combined protective effect of all cells provides adequate coverage even with spacing between them.
Solution Approach 2:
The segmented array of unit cells creates a distributed protective system where multiple discrete elements work together to provide comprehensive protection. The spacing between cells allows independent deformation of each unit, preventing stress concentration and rapid stiffening, while the collective arrangement of numerous cells ensures that impact forces are distributed across the entire protected area.
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 padding material demonstrates enhanced shock absorption capabilities compared to conventional products, with reduced high-strain-rate stiffening, allowing for better impact energy management and breathability, and can be integrated into various protective products for improved safety.
Implementation Method 1
materials capable of energy absorption to offer protection from impacts
Implementation Method 2
padding materials that include an array of shock absorbing surface features
Implementation Method 3
The base and the unit cells are formed of a cured polymeric material that contains fine porosity
Implementation Method 4
generating a vacuum through the second component such that a first portion of the uncured polymer material is siphoned from the recesses
Implementation Method 5
a first portion of the uncured polymer material is siphoned from the recesses in the first component and through the substrate
Implementation Method 6
curing the uncured polymer material to form a cured polymeric material that is integrated into and permeates the substrate
Data Source
AI summary
Padding materials capable of use as or incorporation into protective products, and methods of producing such padding materials. The padding material includes a base and an array of raised unit cells that individually protrude from a surface of the base so that the unit cells are spaced apart from each other. The base and the unit cells are formed of a cured polymeric material that contains fine porosity, and a substrate formed of a textile or fabric material is embedded in the base and permeated by the cured polymeric material.