Composite Plate Sole Assembly with Varying Stiffness
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Solution Overview
Problem
Current composite plates in footwear sole assemblies are uniformly rigid, which can inhibit upward bendability during activities like climbing, and may not provide adequate support on uneven terrain, while also being prone to wear and flexibility issues.
Innovation Solution
The footwear construction includes a sole assembly with a spring plate between two midsoles and an outsole, featuring an upward curving, multi-radii transition portion, lateral and medial arms in the forefoot region, and varying bending stiffness to enhance energy return and gait efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the composite plate is made uniformly rigid to provide stability and support, then stability and support are improved, but upward bendability during toe off is inhibited
Solution Approach 1:
The plate is designed with non-uniform thickness varying along its longitudinal axis, creating different local stiffness characteristics. The thicker portion provides enhanced rigidity for stability during weight bearing, while the thinner portion enables flexible upward bending during toe off, thus resolving the contradiction between uniform stability and localized flexibility needs
2Strength
If the composite plate is made uniformly rigid to provide support on hard terrain, then support on hard terrain is improved, but energy return during gait cycle is reduced
Solution Approach 1:
The plate incorporates varying thickness along its length, with specific regions optimized for different functions. The thicker sections provide structural support on hard terrain, while the thinner sections near the toe area enable energy-efficient flexing during the gait cycle, thereby reducing energy loss and improving overall energy return
3Strength
If the plate extends fully under all toes to provide support, then support is improved, but the tips become worn out and crack
Solution Approach 1:
The plate design incorporates gaps or interruptions in the toe region, extracting the plate material from the areas most susceptible to wear. This prevents direct contact between the plate tips and the ground during toe off, thereby eliminating the wear and cracking issue while maintaining support in the heel and midfoot regions
4Stability of the object's composition
If the slit is made narrower to maintain plate rigidity, then rigidity is improved, but side to side flexibility is reduced
Solution Approach 1:
The plate is segmented into multiple sections with strategic gaps or interruptions, particularly in the forefoot region. This segmentation allows the plate to maintain overall rigidity for stability while creating localized flexible zones that enable side-to-side movement and adaptation to terrain variations
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 energy return and gait efficiency by decreasing energy loss at the metatarsophalangeal joint, increasing energy transfer during toe off, and enhancing overall performance in running activities, while also offering stability and support on various terrains.
Implementation Method 1
a spring plate between the first and second midsoles... configured to provide a bias so as to return energy to the wearer's foot
Data Source
AI summary
A footwear construction includes a sole assembly including a first midsole, a second midsole, a spring plate between the first and second midsoles, and an outsole. The plate can include an upward curving, multi-radii transition portion extending from a lowermost portion to a forward most portion of the plate so as to roll a wearer's foot forward into a next stride in a gait cycle of the wearer. The plate can include a lateral arm and a medial arm in the forefoot region separated by a plate slot extending rearward from the forwardmost portion of the plate toward the lowermost portion. The medial arm can be longer than the lateral arm. The plate can have a first bending stiffness during bending in a first direction, and a second bending stiffness greater than the first bending stiffness during bending in a second direction.