Pin and Bolt Shear-Axial Load Interface
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Solution Overview
Problem
Conventional rotary wing aircrafts face challenges in assembling highly loaded connections between components with different coefficients of thermal expansion, especially when temperature differentials exist, making it difficult to form secure connections outside standard room and machining temperatures.
Innovation Solution
A connection system utilizing a pin and bolt configuration with a clearance fit, where the pin absorbs shear loads and the bolt absorbs axial loads, allowing for separate load application and accommodating different thermal expansion coefficients, enabling assembly over a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional large bolts are used to form highly loaded connections, then the connection can handle high loads, but the assembly becomes difficult when components have different coefficients of thermal expansion and temperature differentials exist
Solution Approach 1:
The connection system is segmented into two distinct functional elements: a pin that handles shear loads and a bolt that handles axial loads. This segmentation allows each component to be optimized for its specific function, with the pin accommodating thermal expansion differences through clearance fits while the bolt provides secure axial fastening, thereby resolving the assembly difficulty without compromising load carrying capability.
Solution Approach 2:
The pin acts as an intermediary element between the two components with different coefficients of thermal expansion. By introducing the pin with clearance fits, the system mediates the thermal expansion differences, allowing the components to expand and contract independently while maintaining the connection integrity, thus enabling assembly across temperature ranges.
2Manufacturing precision
If close tolerances are used to distribute loads effectively, then the load distribution improves, but assembly becomes impossible when temperature differentials exist between components
Solution Approach 1:
Different levels of precision are applied to different parts of the connection system. The pin fits tightly in the shear direction to ensure proper load distribution, while providing clearance in the axial direction to accommodate thermal expansion. This local differentiation of fit quality allows the system to achieve both effective load distribution and temperature range adaptability.
Solution Approach 2:
The clearance fit parameters of the pin are specifically designed to change with temperature. The clearance allows for thermal expansion and contraction of the connected components, enabling the connection to function across a wide temperature range while maintaining proper load distribution through the pin's shear resistance.
3Device complexity
If a single bolt is used to handle both shear and axial loads, then the connection is simpler, but the bolt is more prone to damage from shear stresses
Solution Approach 1:
The load handling function is segmented between the pin and bolt. The pin is specifically designed to handle shear loads, while the bolt handles axial loads. This segmentation protects the bolt from shear stresses that would cause damage, while maintaining relative simplicity through the use of standard fastener components.
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 connection system effectively isolates shear and axial loads, facilitating assembly of components with different thermal expansion coefficients and reducing bolt damage by not requiring it to react to shear loads, thus ensuring reliable connections across varying temperatures.
Implementation Method 1
The pin is configured to absorb a shear load applied to the connection
Implementation Method 2
The bolt is configured to absorb an axial load applied to the connection
Implementation Method 3
the new component may have a different coefficient of thermal expansion than the part the new component is being coupled to
Data Source
AI summary
A connection between a first component and a second component is provided including a first hole formed in a portion of the first component and a second hole formed in a portion of the second component. The second hole is aligned with the first hole. A pin includes a through hole having a pin hole diameter. The pin extends through a portion of the first hole and into a first portion of the second hole. The pin is configured to absorb a shear load applied to the connection. A bolt extends through the second hole and the pin such that a clearance fit is formed between the bolt and the pin. The bolt is configured to absorb an axial load applied to the connection. A nut connected to the free end of the bolt limits movement of the bolt relative to the first and second component.