Self-Aligning Shear-Out Joint for Lower Flap Fusing Loads
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Solution Overview
Problem
Existing aircraft flap systems with auxiliary support tracks face issues of high fusing loads due to fuse pins sized for high deployment loads, leading to increased weight and cost, and potential mechanical jams that affect aerodynamic efficiency.
Innovation Solution
A self-aligning support system with a rotatable pin assembly and fuse pins that accommodate varying load directions, allowing the primary load pin to rotate relative to the attachment claws, reducing shear loading and enabling controlled separation of the auxiliary track from the flap, thus minimizing fusing loads and preventing jams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If fuse pins are sized for high deployment loads, then the structure can withstand high loads, but the fusing loads increase significantly impacting overall design weight and cost
Solution Approach 1:
The pin assembly is made rotatable relative to the attachment fitting, allowing it to dynamically adjust its orientation to accommodate variations in load direction during flap deployment and retraction. This dynamic adaptation prevents excessive shear loads on the fuse pins by aligning the pin assembly with the actual load vector, thereby reducing the required fusing load capacity and enabling lighter structure design
Solution Approach 2:
The eccentric positioning of the primary load pin axis relative to the rotational axis of the attachment claws creates a mechanical advantage that changes the effective load path. This parameter change allows the system to accommodate load direction variations and reduces the shear loading on fuse pins, enabling them to be sized for lower fusing loads while maintaining structural integrity
2Reliability
If fuse pins are sized for high deployment loads, then controlled separation can be achieved, but the surrounding structure must be sufficiently strong and rigid increasing complexity
Solution Approach 1:
The rotatable pin assembly dynamically adapts to load direction changes during operation, maintaining optimal alignment between the fuse pins and the actual shear load vector. This dynamic adjustment ensures that controlled separation occurs reliably at the intended lower fusing load level without requiring the surrounding structure to be designed for much higher loads, thereby reducing structural complexity
Solution Approach 2:
The rotatable pin assembly acts as an intermediary mechanism between the attachment fitting and the fuse pins. It accommodates load direction variations and protects the fuse pins from excessive shear loads by redirecting the force path, thereby enabling reliable controlled separation without requiring complex reinforcement of the surrounding structure
3Stability of the object's composition
If auxiliary support tracks are used to balance loads, then flap stability is improved, but they may cause inadvertent mechanical jams
Solution Approach 1:
The fuse pins are extracted as separate, sacrificial elements that can fail independently to protect the main auxiliary support track system. When a jam occurs, the fuse pins shear off at their designed lower load level, allowing the track to separate from the flap without dragging or causing mechanical damage, thereby maintaining both stability during normal operation and reliability during abnormal conditions
Solution Approach 2:
The fuse pins provide beforehand cushioning by being pre-designed to fail at a specific lower load level. This protective measure is built into the system in advance, so that if a jam occurs during flap operation, the fuse pins will shear off to prevent excessive forces from being transmitted to the auxiliary support track and flap structure, ensuring jam-free operation
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
This solution reduces the overall weight and cost of the flap and support structure by allowing fuse pins to fracture at lower shear loads, ensuring optimal flap performance and reducing the risk of mechanical jams during deployment and retraction.
Implementation Method 1
at least one fuse pin extends through the primary load pin to limit translation of the primary load pin relative to the inboard and outboard claws
Implementation Method 2
allowing the main support tracks and actuators to operate the flap
Data Source
AI summary
A self-aligning support incorporates a support attachment fitting and a rotatable pin assembly having a primary load pin coupling the support attachment fitting to an attachment support, and inboard and outboard attachment claws engaged to end portions of the primary load pin. The rotatable pin assembly is configured to rotate relative to the support attachment fitting. At least one fuse pin extends through the primary load pin to limit translation of the primary load pin relative to the inboard and outboard claws.