Releasable Fastener With Shape Memory Polymer Retainer
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Solution Overview
Problem
Traditional fasteners often require tools for removal, which may not be available, leading to delays, and can cause damage to surface coatings or be difficult to remove due to increased tightening force, corrosion, or material stress, especially in restricted access situations.
Innovation Solution
A fastening system comprising two opposing plates and a retainer material that can change flexibility, allowing the plates to move apart and together, with a pin having a tapered and flared portion to facilitate easy insertion and removal, and an activation mechanism to control the retainer material's rigidity for locking and unlocking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional fasteners are used with greater tightening force to create a more robust attachment, then the attachment reliability increases and vibration between members decreases, but the force required to remove the fastener increases and tools or equipment not immediately available are required
Solution Approach 1:
The retainer material transitions from a rigid state during installation to a flexible state during removal, dynamically changing its mechanical properties to facilitate easy removal after secure attachment. This is achieved through temperature-dependent phase transition of the polymer material.
Solution Approach 2:
The mechanical properties of the retainer material are changed by altering the temperature parameter. Heating the material above its glass transition temperature transforms it from rigid to flexible, enabling removal without tools even after high-force attachment.
2Reliability
If traditional fasteners are used that require tools for removal, then secure attachment is achieved, but delays occur when tools are not available at the time and location
Solution Approach 1:
The mechanical tool-based removal system is replaced with a thermal activation system. Instead of using wrenches or screwdrivers to overcome friction and corrosion, heat activates the shape memory polymer to enable tool-free removal.
Solution Approach 2:
The retainer material undergoes a phase transition from glassy (rigid) to rubbery (flexible) state through temperature change, enabling the fastener to be removed without tools by simply heating the retainer material above its glass transition temperature.
3Reliability
If traditional fasteners are used that require special tools for corrosion-resistant fasteners, then corrosion protection is maintained, but special tools may not be immediately available causing delays
Solution Approach 1:
The mechanical tool-based removal approach is replaced with thermal activation. Corrosion-resistant fasteners with shape memory polymer retainers can be removed by heating, eliminating the need for specialized corrosion-resistant tools while maintaining corrosion protection.
4Reliability
If traditional fasteners are used that may damage surface coatings during removal, then secure attachment is achieved, but surface coating damage occurs requiring repair
Solution Approach 1:
The mechanical prying and twisting actions that damage surface coatings are replaced with thermal activation. Heating the retainer material uniformly softens it, allowing the fastener to be removed cleanly without damaging adjacent surface coatings.
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
Enables quick and tool-free removal and installation of fasteners, reduces damage to surface coatings, and maintains secure attachment without the need for excessive force, even in corrosive environments, by using a shape memory polymer or elastic materials to control the retainer's flexibility.
Implementation Method 1
The retainer material may be made from a shape memory polymer or other suitable material that is rigid in an unactivated state and flexible in an activated state
Implementation Method 2
The material may become elastic when activated to allow the first plate to move between engaged and disengaged positions
Implementation Method 3
The pin includes a first tapered portion configured to separate the plates as the pin is inserted in the opening via a pushing force
Implementation Method 4
The retainer material becoming rigid when deactivated to lock the pin between the plates
Data Source
AI summary
In some embodiments, a fastening system includes two opposing plates, and a retainer material that is activated to increase the flexibility of the retainer material. The retainer material surrounds at least a portion of two opposing plates, the plates and the retainer material mounted to allow the plates to move apart and back together when the retainer material is flexible. A pin is insertable through an opening between the plates. The pin includes a first tapered portion configured to separate the plates as the pin is inserted in the opening via a pushing force. The retainer material becomes rigid when deactivated to lock the pin between the plates.