Thread Guard Assembly for Aircraft Bolt Shear Load Protection

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Solution Overview

Problem

Existing bolt assemblies in aircraft engines face reduced strength and longevity due to shear forces causing contact between bolt threads and inner surfaces of openings, leading to thread wear and joint degradation.

Innovation Solution

A bolt assembly that includes a shaft with external threads, a guard with internal threads mating to the bolt threads, and a nut secured to the bolt, where the guard distributes shear loads across its uniform outer surface, preventing contact between the bolt threads and the opening surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a bolt assembly is used to connect flanged components, then the joint provides structural connection, but shear forces cause contact between bolt threads and inner surfaces of openings, reducing strength and longevity

Engineering Contradiction:

Improvejoint strengthVSAvoidconnection longevity

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

A thread guard is introduced as an intermediary component between the bolt threads and the opening inner surfaces. The guard includes a body with an outer surface and an inner surface that defines a passage, allowing the bolt to pass through while preventing direct contact between the threads and the opening surfaces. This mediator protects the threads from wear and damage caused by shear forces, thereby improving both joint strength and connection longevity

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If bolt threads are exposed to shear forces in flanged connections, then the bolt provides threading engagement, but thread wear reduces connection durability

Engineering Contradiction:

Improvethread engagementVSAvoidconnection durability

Core Design Contradiction:

Ease of operationVSDuration of action of stationary object

Solution Approach 1:

The thread guard acts as a protective intermediary that allows the bolt to maintain its threading engagement function while preventing the threads from直接接触 with the opening surfaces. The guard's inner surface defines a passage through which the bolt passes, enabling thread engagement without exposing the threads to shear forces, thus preserving connection durability

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of manufacture

If the bolt shaft extends directly through the openings, then installation is simple, but the threads contact the inner surfaces causing wear

Engineering Contradiction:

Improveinstallation simplicityVSAvoidthread wear from shear forces

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The thread guard is designed as a simple tubular component that slides onto the bolt shaft, providing protection without complicating the installation process. The guard's body with passage through it allows the bolt to pass through the flanged components while the outer surface of the guard contacts the opening surfaces instead of the threads, eliminating thread wear while maintaining installation simplicity

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20250102010A1Thread guard

Publication Date: 2025.03.27 PRATT & WHITNEY CANADA CORP

AI summary

A bolt assembly for connecting component sections of an aircraft component is disclosed and includes a guard that is assembled onto threads of a bolt. The guard includes a first end, a second end and an outer surface having a uniform diameter between the first end and the second end. The bolt assembly further includes a nut including internal threads securable to the external threads of the bolt.