Radial Prestressing Device Wear Reduction
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Solution Overview
Problem
Existing prestressing devices in mechanical assemblies, such as turbine engines, experience excessive wear due to high vibration levels, leading to reduced component lifespan.
Innovation Solution
A prestressing device with two annular bodies and radially extending tabs, providing surface contact and optimized force distribution between pieces, comprising a first inner annular body with outward tabs and a second outer annular body with inward tabs, ensuring even stress distribution and minimizing wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conical prestressing washers are used to generate permanent stress, then the prestressing force is applied, but the contact surfaces cause excessive wear under high vibration
Solution Approach 1:
The prestressing device is segmented into two separate annular bodies (first and second annular bodies) with distinct contact surfaces. The first annular body provides a first contact surface while the second annular body provides a second contact surface, distributing the prestressing force across multiple surfaces rather than concentrating it on a single conical interface, thereby reducing wear.
Solution Approach 2:
The invention transitions from a single-point or line contact (conical washer) to a multi-surface contact system. The contact surfaces are arranged in different spatial dimensions and orientations, creating distributed contact zones that reduce stress concentration and wear at any single location.
2Device complexity
If a single conical washer is used for prestressing, then the structure is simple, but the stress distribution is concentrated causing wear
Solution Approach 1:
The prestressing device is divided into two annular bodies with multiple contact surfaces each, segmenting the stress distribution across multiple interfaces rather than concentrating it in a single conical contact zone, thereby reducing wear while maintaining structural efficiency.
Solution Approach 2:
The first and second annular bodies are combined in a stacked configuration, merging their prestressing functions to create a distributed multi-surface contact system that reduces wear compared to a single washer, while the overall structure remains relatively simple.
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 reduces wear and increases the lifespan of components subjected to prestress by distributing the prestressing force more evenly, preventing stress concentration and facilitating deformation through rounded transition zones.
Implementation Method 1
Each of the tabs advantageously comprises an inclined zone connecting the annular body to the planar surface. This inclined zone is displaced as a function of the stress applied.
Data Source
AI summary
A prestressing device extending about an axis between a first plane that is substantially perpendicular to the axis and a second plane that is substantially parallel to the first plane and axially offset relative to the latter. The device includes a first annular body extending in the first plane, and a first series of at least three tabs, each of which is connected to the first body and extending in an essentially radial direction, each of the tabs of the first series including a planar surface extending in the second plane. This arrangement ensures surface contact between the parts of the elements to be subjected to prestressing. The device can be used for example for a rotor, and for example for a rotor of an unducted propeller for a turbine engine.