Dual-Layer Footwear Sole Assembly for Heel Support and Cushioning
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Solution Overview
Problem
Existing footwear lacks adequate heel support and cushioning, particularly in sandal-type footwear, which compromises stability and comfort, and existing orthotic solutions require additional inserts and significant modifications.
Innovation Solution
A dual-layer sole assembly with a firmer upper layer and softer lower layer, featuring a concave-convex design and integrated rolling element, providing enhanced heel support, stability, and cushioning without altering the shoe's appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a softer upper sole element is used to provide cushioning comfort, then user comfort is improved, but stability is reduced
Solution Approach 1:
The sole is divided into two distinct layers: an upper layer and a lower layer, each with different material properties. The upper layer provides cushioning comfort while the lower layer provides stability, resolving the contradiction by separating these functions into different segments of the sole structure.
Solution Approach 2:
Different regions of the sole have different material properties - the upper layer is softer for comfort while the lower layer is harder for stability. This local differentiation of material quality allows each layer to perform its specific function optimally without compromising the other.
2Object-affected harmful factors
If a single density foam with soft durometer is used throughout the sole, then cushioning feel is improved, but foot support is reduced
Solution Approach 1:
The sole is segmented into two layers with different foam densities. The upper layer uses softer foam for cushioning feel, while the lower layer uses denser foam for foot support, eliminating the need for additional orthotic inserts while providing both comfort and support.
Solution Approach 2:
The sole uses a composite structure combining two different foam materials with different durometers and densities. This composite approach allows the softer upper layer to provide cushioning while the denser lower layer provides structural support, achieving both comfort and orthopedic support functions.
3Strength
If orthotic stabilizers are added to existing footwear, then foot support is improved, but device complexity is increased
Solution Approach 1:
The orthotic support function is merged into the sole structure itself through the two-layer design. The lower dense layer provides inherent orthotic support and stabilization without requiring separate inserts, counters, or additional shoe upper components, simplifying the overall device while maintaining foot support functionality.
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 dual-layer sole assembly promotes a natural rolling gait, enhances stability and cushioning, and supports the foot through the stride phases, addressing heel strike, midstance, and toe-off, while maintaining comfort and support.
Implementation Method 1
the lower layer provides a cushion for the more rigid upper layer, specifically where the rigid upper layer presents a thin section directly under the heel
Implementation Method 2
The material of the upper layer is harder or more resilient than the material of the lower layer
Implementation Method 3
The footbed of the upper layer is thin in the center of the heel region and thickens toward the medial and lateral sides. The change in thickness in the upper layer provides support to the foot at the heel during heel strike, by creating a cantilever.
Implementation Method 4
The rolling element is made at least partially of an elastic material, for example an elastomer such as rubber or polyurethane. The rolling element provides enhanced heel-to-toe motion during a stride, from heel strike to toe off.
Data Source
AI summary
A footwear sole assembly with upper and lower layers, where the upper layer has a firmer durometer than the lower layer. Upon a user's heel strike, the difference in resilience between the upper and lower layers causes the upper layer to compress the lower layer. Sidewalls in the upper layer are urged toward each other on the heel strike, providing cradling support for the user's heel. The rigidness of the sidewalls of the upper layer also encourages the foot to propel through the stride, especially with the addition of a rolling element along the side of the footwear.