Hybrid Joint Pin Geometry for Peel Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hybrid joints between metal and composite materials face challenges in resisting peel loads due to the ease of pin pull-out and fiber disruption, leading to poor mechanical performance and sudden catastrophic failure, especially when using simple cylindrical pins.
Innovation Solution
Modifying the geometry of the pins after initial placement by adding retaining means such as metal mesh or deforming pin heads to create an interference fit, which constrains the composite material and enhances resistance to peel loads, allowing for improved joint performance and increased constraint against peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If simple cylindrical pins are used for mechanical interlocking, then the joint is easy to manufacture and assemble, but the resistance to peel loads is poor due to easy pin pull-out
Solution Approach 1:
The pin geometry is transformed from a static simple cylindrical shape to a dynamic configuration where the head shape changes during assembly. The pin head is initially narrow to facilitate easy insertion through composite fibers, then deforms under compression to create a bulbous enlarged head that provides superior peel resistance. This dynamic transformation allows the same pin to satisfy both ease of manufacture and high strength requirements.
Solution Approach 2:
The pin head geometry parameters are changed from fixed to variable. The pin head transitions from a narrow initial diameter (for easy insertion) to an enlarged final diameter (for peel resistance) through controlled deformation during the assembly process. This parameter change enables the pin to overcome the trade-off between ease of manufacture and peel load resistance.
2Strength
If bulbous-headed pins are used to resist peel loads, then the resistance to peel loads is improved, but the composite fabric is disrupted and damaged during manufacturing
Solution Approach 1:
The pin is prepared in advance with a narrow head geometry that is optimized for easy insertion through composite fibers without disruption. Only after the pin is successfully inserted does the head deform to its bulbous shape. This preliminary action with the narrow head prevents fiber disruption while achieving the final peel-resistant configuration.
Solution Approach 2:
The pin head geometry is made dynamic, transitioning from a narrow insertion-friendly shape to an enlarged peel-resistant shape only after successful insertion. This dynamic transformation ensures that the composite fabric is not disrupted during the critical insertion phase, while still achieving the desired peel resistance in the final assembled state.
3Object-affected harmful factors
If adhesive bonding is used to join metal and composite, then the joint avoids mechanical fasteners and notches, but the joint is sensitive to surface preparation and environmental conditions
Solution Approach 1:
The solution merges mechanical interlocking (pins) with adhesive bonding in a hybrid joint. The pins provide immediate mechanical strength and resistance to peel loads, while the adhesive bonding fills gaps and provides environmental sealing. This combination reduces sensitivity to surface preparation compared to pure adhesive bonding, while avoiding the notch sensitivity and fastener weight of pure mechanical joints.
Solution Approach 2:
The hybrid joint combines two different joining mechanisms (mechanical pin interlocking and chemical adhesive bonding) into a composite joining system. This composite approach leverages the strengths of both methods: the pins provide structural integrity and peel resistance, while the adhesive provides gap filling and environmental protection, resulting in a joint that is more reliable and less sensitive to surface preparation variations than either method alone.
Data Source
Figure 1~3
Figure 4~7
Figure 8~10
AI summary
A method for forming a joint between a fibre reinforced composite component and a metallic component and a joint are provided. The metallic component and the composite component each define a joint surface for mating with the joint surface of the other to join the two components together and the composite component defines a free surface opposed to the joint surface thereof. The joint surface of the metallic component defines an array of pins extending therefrom with each pin defining a pin head at an end distal from the joint surface. The method includes the steps of pressing together the joint surfaces of the two components whereby to cause the array of pins to penetrate through the fibre reinforcing material, and modifying the effective cross sectional shape of the pin heads whereby to increase the constraint applied to the composite component against peeling of the composite component from the joint surface of the metallic component.