Marine Propeller Dovetail Stress Reduction via Composite Gaps
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Solution Overview
Problem
Existing marine propeller assemblies face sub-optimal flow characteristics due to shape limitations, leading to decreased efficiency and the need for more powerful drive systems, which increases costs and complexity.
Innovation Solution
The use of a composite marine propeller assembly with separable blades retained in dovetail grooves and wedges, featuring gaps between the blade dovetail and hub to reduce stress concentrations and facilitate a direct load path, while being formed from a composite material shell with an internal structural frame and filler material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If propeller blades are retained in dovetail grooves without gaps, then the connection strength between blades and hub is improved, but stress concentrations increase at the interface
Solution Approach 1:
The patent extracts the stress concentration problem by removing material at the dovetail interface to create gaps. These gaps eliminate the stress concentration zones that would otherwise exist at the sharp corners of a tight dovetail fit, while the connection strength is maintained through alternative load paths and structural design of the blade-root and hub interface.
2Ease of manufacture
If composite material shell with internal structural frame is used, then manufacturing flexibility and hydrodynamic shape are improved, but structural complexity increases
Solution Approach 1:
The patent employs composite materials with an internal structural frame within a composite shell to create propeller blades with complex hydrodynamic shapes. This composite construction allows for high manufacturing flexibility and optimized hydrodynamic performance while managing structural complexity through integrated design of the composite laminates and internal framing structures.
Data Source
AI summary
An apparatus and system for a marine propeller assembly are provided. In one aspect, the marine propeller assembly includes a plurality of circumferentially-spaced blades that each include a dovetail having a radial inner surface. The marine propeller assembly also includes a hub including a plurality of circumferentially-spaced dovetail receiving portions configured to receive a corresponding dovetail of the plurality of blades. At least one gap is formed between the radial inner surface and at least a portion of the dovetail receiving portion.