Propeller Blade Retention Assembly with Adhesive Coupling
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Solution Overview
Problem
Modern lightweight propeller blades face reduced bending moment capacity due to lower centrifugal loads, leading to potential unloading of the interface between the composite blade and outer ring bearing race, which can shorten the life of the blade and outer ring.
Innovation Solution
A propeller blade assembly with an extended outer ring and adhesive coupling between the outer ring and the root portion, providing enhanced retention capacity by preventing separation at the bearing race interface and directing bending loads to the bearings, thus improving the blade's ability to withstand high bending moments at lower centrifugal loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If lightweight composite materials are used for propeller blades, then weight is reduced and performance is enhanced, but bending moment capacity of the retention assembly is reduced due to lower centrifugal load
Solution Approach 1:
The retention assembly is segmented into multiple functional components: bearing races for radial support, adhesive layers for shear load transfer, and mechanical interlocks for positioning. This segmentation allows each component to specialize in handling specific load types, collectively achieving high bending moment capacity despite lightweight construction.
Solution Approach 2:
The retention assembly uses composite construction combining metallic bearing races with polymer adhesive materials. The metallic races handle centrifugal loads while the adhesive composite handles bending moment loads, creating a hybrid system that maintains strength while supporting lightweight blades.
2Strength
If bearing races are sized for bearings that can withstand bending moments, then bending moment capacity is improved, but the interface between the composite blade and outer ring bearing race becomes unloaded due to insufficient centrifugal loading
Solution Approach 1:
An adhesive layer is introduced as an intermediary between the outer ring bearing race and the composite blade root. This adhesive mediator transfers bending moment loads through shear stress, ensuring that the bearing race interface remains loaded and functional even when centrifugal loads are insufficient.
Solution Approach 2:
The patent replaces reliance on pure mechanical contact at the bearing race interface with a combination of adhesive bonding and mechanical support. The adhesive system substitutes for the missing centrifugal load by providing alternative load transfer paths through shear stress.
3Weight of moving object
If the propeller blade is made lightweight, then weight reduction is achieved, but the centrifugal load decreases leading to potential unloading of the bearing race interface
Solution Approach 1:
The adhesive bonding is established in advance during assembly, creating pre-loaded shear stress paths that are independent of centrifugal loading. This preliminary action ensures load transfer capability exists before the blade enters service, compensating for the inherently lower centrifugal loads from lightweight construction.
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 solution significantly increases the bending moment capacity of lightweight propeller blades, preventing unloading and extending the life of both the blade and outer ring by ensuring secure retention even under lower centrifugal loads.
Implementation Method 1
adhesive coupling between the outer ring and the root portion, providing enhanced retention capacity by preventing separation at the bearing race interface
Data Source
Figure 1
Figure 2
AI summary
A retention assembly (32) for a propeller blade (30) includes an inner ring (40) that is conformally shaped to a bore (41) of an annular loop (38), the annular loop (38) being associated with a root portion (36) of the propeller blade (30); a base (44) that is configured to be immediately adjacent the annular loop (38); an outer ring (42) that includes an extended tapered portion (72) which decreases in radial thickness from an inboard end (74) to an outboard end (76); and an adhesive that adhesively connects complementary surfaces of the outer ring (42) and the annular loop (38). Also, a propeller blade assembly (22) includes a propeller blade (30) having a blade portion (34) and a root portion (36) and the retention assembly (32) configured to be attached to the propeller blade (30).