Aircraft Nacelle Linking Device Shear Stress Management
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Solution Overview
Problem
Existing connection devices for aircraft nacelles face challenges in reducing on-board mass while effectively managing shear stresses during blade breakage, leading to increased energy consumption and material usage.
Innovation Solution
The connection device features passage holes with a flared shape and adjusted sections to reduce shear forces, allowing connecting elements to deform and absorb energy, thereby minimizing the number and size of connecting elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the connecting device uses a large number of bolts or rivets with large diameter to resist shear stresses during blade breakage, then the reliability and strength of the connection is improved, but the on-board mass increases leading to greater energy consumption
Solution Approach 1:
The invention changes the geometric parameters of the passage holes from cylindrical to flared shape with specific radius of curvature R1 at the junction plane. This parameter change reduces shear forces on connecting elements by a factor of 2 to 5, allowing reduction in the number and/or diameter of bolts or rivets while maintaining connection strength during blade breakage incidents
Solution Approach 2:
The invention applies curvature by designing passage holes with a flared shape and a specific radius of curvature R1 at the level of the junction plane. This curved geometry redistributes stresses and reduces shear forces on connecting elements, enabling lighter connection devices that still provide adequate strength and reliability during incident conditions
2Ease of manufacture
If the passage holes are cylindrical with sharp edges, then the manufacturing precision and ease of manufacture are improved, but the shear stresses on connecting elements increase during deformation
Solution Approach 1:
The invention replaces sharp-edged cylindrical passage holes with flared passage holes having a radius of curvature R1 at the junction plane. This curvature eliminates stress concentration at sharp edges, reducing shear stresses on connecting elements during deformation while remaining manufacturable through standard aerospace fabrication processes
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 design reduces shear stresses and allows for a lighter aircraft by enabling the connection device to absorb energy through plastic and elastic deformation, thereby lowering the overall mass and energy consumption.
Implementation Method 1
The connecting device can absorb part of the energy produced when the blade breaks, for example by plastic and elastic deformation of said connecting device
Implementation Method 2
The connecting device can absorb part of the energy produced when the blade breaks, for example by plastic and elastic deformation of said connecting device
Data Source
Figure 1~3B
Figure 4A~5B
Figure 6A~7B
AI summary
The device has connection elements (46) e.g. bolts or rivets, housed in passage holes (38, 44) formed in cylindrical parts to be connected, respectively. Each element comprises a rod (48) having ends provided with supports (50, 52) for holding the parts in a plated manner. Each hole includes a reduced section adjusted to a section of the rod near the corresponding support, and another section with a large clearance at a junction plane (42), such that the rod is subjected to weak shearing forces at the junction plane during relative deformation of the connected parts.