Auxetic Locking Pin for Secure Assembly Serviceability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional pin structures fail to operate effectively under extreme environmental conditions and are difficult to repair, especially when consumers attempt to disassemble them, potentially damaging the product and invalidating warranties.
Innovation Solution
A novel locking pin with a negative Poisson's ratio is developed, featuring void structures that reduce in diameter under axial force, allowing insertion into a bore and subsequent expansion for locking engagement, enabling serviceability without damaging the part.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional pin structure is used to secure members together, then the assembly is strongly held together, but the pin cannot be removed or repaired without damaging the product
Solution Approach 1:
The pin transitions from a static traditional design to a dynamic auxetic structure that changes its mechanical properties under load. When axial force is applied, the pin's diameter changes due to negative Poisson's ratio, enabling it to be inserted into the bore and then expand to lock securely. This dynamic behavior allows the pin to be serviceable when force is applied while providing strong locking when engaged.
Solution Approach 2:
The pin utilizes negative Poisson's ratio as a key parameter change mechanism. This causes the pin to contract laterally when stretched axially, allowing insertion, and expand laterally when compressed axially, providing locking engagement. This parameter change enables both easy installation and secure locking while maintaining serviceability.
2Reliability
If a pin is designed to be strongly locked in place, then the assembly integrity is maintained, but unauthorized disassembly attempts cannot be detected or prevented
Solution Approach 1:
The pin incorporates a visual indicator mechanism that changes the appearance or state of the pin when axial force is applied during unauthorized removal attempts. This allows authorized personnel to detect whether the pin has been subjected to removal forces, even if the pin remains in place, thereby detecting unauthorized modification attempts while maintaining assembly integrity.
3Reliability
If traditional materials are used for pin construction, then the pin performs under predetermined environmental conditions, but it cannot operate under extreme environmental conditions
Solution Approach 1:
The pin is constructed from composite or specially engineered materials that exhibit negative Poisson's ratio, combining properties that enable operation under extreme environmental conditions. This material innovation allows the pin to maintain its unique mechanical behavior and locking functionality across a broader range of temperatures, pressures, and environmental stresses compared to traditional pin materials.
4Strength
If a solid pin construct is used, then the pin provides high shear strength, but the pin cannot be inserted into a tightly fitted bore without damage
Solution Approach 1:
The auxetic pin provides a dynamic solution where the solid construct maintains high shear strength when engaged, but the negative Poisson's ratio effect allows the diameter to change under axial load. This enables the pin to be inserted into a tightly fitted bore when axial force is applied, then expand to provide strong shear resistance when the load is removed and the pin locks in place.
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 auxetic locking pin provides a secure, serviceable, and damage-resistant solution by contracting to fit into a bore and expanding for locking, preventing unauthorized disassembly and allowing authorized personnel to service the assembly without compromising the integrity of the system.
Implementation Method 1
The pin exhibits a negative Poisson's ratio and is made of a material and construct that reduces its diameter when an axial force is exerted on the longitudinal axis
Implementation Method 2
Once the axial force is removed, the diameter of the pin expands thusly engaging the bore of the part causing a locking engagement between the pin and the part
Implementation Method 3
void configurations are generated in the material directly in a stress free state, whereby the pin like structure can then undergo a loaded condition resulting in a negative Poisson's ratio behavior
Data Source
Figure 1~2
Figure 3A~4C
Figure 5
AI summary
An auxetic locking structure can be used as a mechanism for securing two or more members in an assembly or other system. The locking structure has void patterns on its exterior surface which permit the locking structure to reduce its outer diameter upon loading in an axial direction. Once the structure has been sufficiently loaded and the diameter has been sufficiently reduced, the locking structure may be positioned within a bore of an article, the axial load is then reduced, thus causing the locking structure to expand and engage the bore of the article. The locking structure and article are now secured to one another creating an improved assembly.