Variable Stiffness Footwear Midsole for Pressure Management

Solution Overview

Problem

Current footwear midsoles with uniform hardness fail to simultaneously provide adequate support under high plantar pressure regions and comfort for areas under less pressure, compromising support and comfort during various physical activities.

Innovation Solution

A midsole with variable stiffness, featuring firmer foam material at high-pressure regions and softer foam at lower-pressure areas, dynamically adjusting to reduce peak plantar pressures and pressure gradients, utilizing a combination of firm and soft foam materials with different Asker C hardness levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a harder foam material is used for the midsole, then support under high plantar pressure is improved, but comfort for areas under less pressure deteriorates

Engineering Contradiction:

ImprovesupportVSAvoidcomfort

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The midsole is divided into multiple regions with different foam densities: a first region (heel area) with first foam material having a first density, a second region (midfoot area) with second foam material having a second density, and a third region (forefoot area) with third foam material having a third density. This allows each region to provide locally optimized characteristics - harder foam where support is needed and softer foam where comfort is prioritized.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The midsole structure is segmented into distinct zones with different material properties. The segmentation creates independent functional regions that can be optimized separately, with transition regions between the first, second, and third regions that smoothly connect the different density materials.

Inventive Principle:

Principle #1Segmentation

2Object-affected harmful factors

If a softer foam material is used for the midsole, then comfort for areas under less pressure is improved, but support under high plantar pressure deteriorates

Engineering Contradiction:

ImprovecomfortVSAvoidsupport

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The midsole is divided into multiple regions with different foam densities: a first region (heel area) with first foam material having a first density, a second region (midfoot area) with second foam material having a second density, and a third region (forefoot area) with third foam material having a third density. This allows each region to provide locally optimized characteristics - harder foam where support is needed and softer foam where comfort is prioritized.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If a single-density foam is used for the midsole, then manufacturing simplicity is improved, but ability to provide both support and comfort simultaneously deteriorates

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidability to provide support and comfort

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The midsole is divided into multiple regions with different foam densities: a first region (heel area) with first foam material having a first density, a second region (midfoot area) with second foam material having a second density, and a third region (forefoot area) with third foam material having a third density. This allows each region to provide locally optimized characteristics - harder foam where support is needed and softer foam where comfort is prioritized.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The midsole utilizes composite foam materials with different densities arranged in specific regions. The first foam material, second foam material, and third foam material are combined to create a multi-density structure that provides both support and comfort functionalities within a single integrated component.

Inventive Principle:

Principle #40Composite materials

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 midsole effectively reduces peak plantar pressures and pressure gradients, providing stability and comfort during activities like walking and golfing by optimizing foam stiffness distribution based on plantar pressure contours.

Implementation Method 1

a midsole having a variable stiffness configured to provide pressure gradients based on the applied load or pressure. The midsole may have a stiffness that dynamically varies and may be predetermined based on the distribution of plantar pressure across the midsole

Methodology Applied

Scientific EffectVariable stiffness:

Implementation Method 2

A single-density foam of a particular Asker C hardness is most commonly used as a midsole to provide a structure that merely compresses under walking loads

Methodology Applied

Scientific EffectFoam material compression: Compression

Data Source

PatentUS20240381972A1Article of footwear with midsole having variable stiffness

Publication Date: 2024.11.21 ACUSHNET CO

AI summary

An article of footwear comprising an upper and a sole assembly connected to the upper. The sole assembly may comprise a midsole with a variable stiffness that provides different stiffness gradients in different regions of the sole assembly. The midsole may comprise a core piece and a perimeter piece surrounding the core piece. The perimeter piece may include a recess for receiving the core piece. In some cases, the recess may not or need not extend into a medial midfoot region of the midsole.