Shoe with Shape Memory Polymer for Automatic Tensioning
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Solution Overview
Problem
Conventional shoe lacing methods, such as using shoelaces or tension wires, are not comfortable and require manual tightening to secure the shoe on the foot effectively.
Innovation Solution
A shoe design incorporating a second material section made of thermoplastic polyurethane with shape memory effect, which changes clamping force based on temperature, allowing for automatic tensioning by heating the material with an electrically conductive layer and a battery-powered heating system, eliminating the need for shoelaces or wires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional shoelaces or tension wires are used to secure the shoe, then the shoe can be adequately secured to the wearer's foot, but the lacing process is uncomfortable and requires manual tightening
Solution Approach 1:
The shoe upper performs the lacing function automatically through temperature-dependent material properties. The second material section with shape memory effect autonomously adjusts tension based on temperature changes, eliminating the need for manual lacing operations by the user.
Solution Approach 2:
The mechanical lacing system (shoelaces or tension wires) is replaced with a thermally-responsive material system. The tensioning force is generated through temperature-induced shape memory effects rather than manual mechanical tightening, substituting a passive mechanical system with an active thermal-mechanical system.
2Reliability
If the second material section exerts high tensioning force at high temperature, then secure fitting is achieved, but at low temperature the clamping force is insufficient to hold the shoe
Solution Approach 1:
The material properties of the second material section are designed to change with temperature. At low temperature (below 25°C), the material exhibits low clamping force for comfortable wearing, while at high temperature (above 35°C), it transitions to high tensioning force for secure fitting, achieving both comfort and security through temperature-dependent parameter changes.
Solution Approach 2:
The shape memory effect material undergoes a phase transition between crystalline and amorphous states at different temperatures. Below the transition temperature, the material is soft and compliant; above the transition temperature, it becomes rigid and exerts high tensioning force, enabling automatic adjustment of clamping force based on thermal conditions.
3Extent of automation
If shape memory material is used for the second material section, then automatic tensioning is enabled, but the device complexity increases due to heating system requirements
Solution Approach 1:
The shape memory material serves multiple functions simultaneously: it provides the structural component (second material section) and the actuation mechanism (thermal response). The material itself performs the work of tensioning when heated, eliminating the need for separate actuators, motors, or complex control systems, thereby achieving automation without proportionally increasing device complexity.
Solution Approach 2:
The second material section is constructed as a composite incorporating shape memory polymer or alloy with heating elements. This composite structure integrates the functional material properties with the heating capability in a single component, reducing overall system complexity compared to using separate materials and separate heating systems.
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 shoe provides comfortable and secure fitting by automatically adjusting tension based on temperature, ensuring even pressure distribution and eliminating the need for manual lacing.
Implementation Method 1
the second material section consisting of a plastic material with a shape memory effect (memory effect)
Implementation Method 2
the electrically conductive material of the second material section is connected to a battery, with which the electrically conductive material can be charged with or flow through the electrically conductive material via a switching element. This results in heating of the second material section
Data Source
Figure 1
AI summary
The invention relates to a shoe (1), in particular a sports shoe, comprising a sole (2) and an upper (3), wherein the upper (3) has a first material section (4), which at least partially extends around the foot of the wearer of the shoe (1). To enable the tying of the shoe on the foot of the wearer in a comfortable manner, a second material section (5), according to the invention, is arranged on the outside of the first material section (4), which second material section at least partially covers the first material section (4), wherein the second material section (5) consists of a plastic material having a shape memory effect. The invention further relates to a method for tying such a shoe.