Footwear Midsole with Variable Density Foam Zones
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Solution Overview
Problem
Conventional athletic footwear midsoles lack customizable density distribution and flexibility to effectively attenuate ground reaction forces and control foot motions across various athletic activities.
Innovation Solution
A sole structure with support elements featuring a polymer foam core of varying densities, integrated within a shell with flexion indentations that allow for independent compression and flexibility, enhancing cushioning and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polymer foam material is used throughout the midsole with uniform density, then manufacturing is simple, but the ability to attenuate ground reaction forces and control foot motions is insufficient
Solution Approach 1:
The patent applies local quality by varying the density of polymer foam material at different locations within the midsole. Specifically, the midsole includes a heel region with higher density foam and a forefoot region with lower density foam, allowing each region to be optimized for its specific function (cushioning in heel, flexibility in forefoot) while maintaining overall structural integrity
Solution Approach 2:
The patent segments the midsole into multiple regions with different foam densities, creating distinct functional zones. The midsole is divided into a heel portion, midfoot portion, and forefoot portion, each with tailored density characteristics to address specific biomechanical requirements during the gait cycle
2Stability of the object's composition
If the midsole is made uniformly stiff for stability, then foot motion control is improved, but cushioning comfort is reduced
Solution Approach 1:
The patent implements local quality by creating regions of varying stiffness within the midsole through differential foam density. The higher density heel region provides stability and motion control during impact, while the lower density forefoot region maintains flexibility and comfort during toe-off, resolving the contradiction between overall stability and localized comfort
3Reliability
If fluid-filled chambers are added to the midsole for cushioning, then ground reaction force attenuation is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies parameter changes by modifying the density parameter of the polymer foam material rather than introducing separate fluid-filled chambers. By varying foam density through controlled expansion ratios and material formulation, the patent achieves enhanced ground reaction force attenuation while maintaining the simplicity of monolithic foam construction
Solution Approach 2:
The patent utilizes composite materials by combining polymer foam with different density characteristics in specific regions. The midsole incorporates a composite structure where high-density foam regions provide structural support and low-density foam regions provide cushioning, creating a multi-functional material system without requiring separate fluid chambers
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 solution provides improved cushioning, stability, and motion control by varying foam density and flexibility, accommodating different foot strike phases and reducing pronation, thus enhancing athletic performance.
Implementation Method 1
The core has a shape of the void and is located within the void, with at least a portion of the core being a polymer foam material. The polymer foam material of at least two of the support elements may have different densities.
Implementation Method 2
The properties of the polymer foam material in the midsole are primarily dependent upon factors that include the dimensional configuration of the midsole and the specific characteristics of the material selected for the polymer foam, including the density of the polymer foam material.
Data Source
AI summary
An article of footwear may have an upper and a sole structure secured to the upper. The sole structure has a plurality of support elements, and each of the support elements include a shell and a core. The shell defines an interior void and is formed from a polymer material that extends around substantially all of the void. The core has a shape of the void and is located within the void, with at least a portion of the core being a polymer foam material. The polymer foam material of at least two of the support elements may have different densities.