Adjustable Sandal Sole With Rigid Strap Inserts and EVA Cushioning
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Solution Overview
Problem
Conventional sandal constructions face challenges with heavy and firm materials that allow for lengthwise movement of straps relative to the sole, leading to a need for improvements in adjustability and cushioning.
Innovation Solution
A sandal construction featuring a multilayer sole with a rubber outsole and EVA midsole, incorporating strap inserts made of rigid polymeric material to facilitate strap movement through the midsole, and a heel assembly for enhanced adjustability and cushioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If firm and heavy material is used for the sole to permit lengthwise movement of the strap relative to the sole, then the strap adjustment function is improved, but the weight and comfort of the sandal deteriorate
Solution Approach 1:
The sole is divided into multiple functional layers: a lightweight cushioning layer (EVA or similar) for comfort and weight reduction, and a separate rigid strap insert component for strap guidance. This segmentation allows each layer to perform its specialized function without compromising the other, resolving the contradiction between weight and strap adjustability.
Solution Approach 2:
A rigid strap insert acts as an intermediary component between the lightweight sole material and the strap. This insert provides the necessary structural support for strap movement while the lightweight sole material provides cushioning and reduces overall weight. The intermediary element resolves the contradiction by decoupling the structural support function from the cushioning function.
2Strength
If firm material is used for the sole to maintain structural integrity, then the sole strength is improved, but the cushioning comfort deteriorates
Solution Approach 1:
The sole is segmented into distinct functional layers: a lightweight cushioning layer (EVA or similar) for comfort and weight reduction, and a separate rigid strap insert component for structural support during strap adjustment. This segmentation allows each layer to perform its specialized function without compromising the other.
Solution Approach 2:
The sole assembly uses composite construction combining lightweight cushioning material (EVA) with rigid strap inserts. This composite approach allows the cushioning material to provide comfort while the rigid inserts provide structural integrity where needed, resolving the contradiction between strength and cushioning.
3Weight of moving object
If lightweight and cushioning material is used for the midsole, then the comfort and weight are improved, but the ability to facilitate strap movement deteriorates
Solution Approach 1:
A rigid strap insert acts as an intermediary component between the lightweight sole material and the strap. This insert provides the necessary structural support for strap movement while the lightweight sole material provides cushioning and reduces overall weight. The intermediary element resolves the contradiction by decoupling the structural support function from the cushioning function.
Solution Approach 2:
The sole is divided into multiple functional layers: a rubber outsole configured to engage the ground, an EVA midsole configured to receive the wearer's foot, and strap inserts embedded in the midsole to define passages. This segmentation allows the midsole to remain lightweight and cushioning while the strap inserts provide the structural support needed for strap movement.
Data Source
AI summary
A sandal construction providing lightweight, highly adjustable sandals. The sandal includes an EVA midsole configured to receive the wearers footwear and an outsole configured to engage the ground. The sandal includes an upper having a heel assembly that seats the heel of the wearer's foot and a strap that retains the forward portion of the wearer's foot. The forefoot strap is a single, adjustable length strap that passes over the wearer's foot and is slidably threaded through passages in the sole. The midsole includes embedded strap inserts that define portions of the passages to receive and facilitate lengthwise movement of the strap. The strap inserts are substantially more rigid than the EVA. Each strap insert may include a web shepherding the strap across the bottom of the midsole and a pair of upright sleeves that shepherd the strap through at least a portion of the thickness of the midsole.