Frangible Composite Airfoil for Foreign Object Impact Mitigation

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Solution Overview

Problem

Conventional rotary machine blades and propellers lack frangibility to manage the release of damaged portions caused by foreign object ingestion, leading to potential secondary impacts and damage to adjacent components or aircraft structures.

Innovation Solution

A composite blade with integrated energy dissipating members, such as strands and damage initiators, that are co-cured with the blade to dissipate kinetic energy and alter the trajectory of released portions, enabling self-shredding and reducing the size and impact of released fragments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional single rotation turboprop gas turbine engines are used, then high efficiency is achieved at low cruise speeds (Mach numbers up to about 0.7), but the blades lack frangibility to manage foreign object ingestion damage, leading to potential secondary impacts and damage to adjacent components

Engineering Contradiction:

Improveblade integrity under foreign object ingestionVSAvoidsecondary impact damage to adjacent components

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The blade is segmented into multiple layers with different material properties and failure characteristics. The composite structure includes frangible sections that can separate upon impact, preventing catastrophic failure and secondary damage to adjacent components while maintaining overall blade functionality

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The blade incorporates sections with altered mechanical parameters, including reduced strength zones and modified material properties, that enable controlled frangibility. These parameter changes allow the blade to absorb impact energy through controlled separation rather than rigid failure

Inventive Principle:

Principle #35Parameter changes

2Speed

If ducted fan gas turbine engines are used to achieve high cruise speeds (Mach 0.7 to 0.9), then high thrust is produced, but the blades still lack frangibility and can release damaging portions that impact adjacent structures

Engineering Contradiction:

Improvecruise speedVSAvoiddamage from released blade portions

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The high-speed blade is divided into frangible sections that can separate upon foreign object impact. This segmentation allows the blade to dissipate impact energy through controlled separation, preventing large portions from detaching and causing secondary damage to adjacent engine components

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The blade design converts the harmful effect of foreign object impact into a beneficial controlled separation mechanism. The impact energy that would otherwise cause catastrophic failure is instead used to activate predetermined frangible sections, which separate in a controlled manner to protect adjacent components

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Productivity

If unducted counter-rotating propeller gas turbine engines are used, then high thrust with higher efficiency is delivered at high cruise speeds, but the blades have certain integrity to foreign object debris yet still can lead to releasing damaging portions

Engineering Contradiction:

Improvethrust efficiencyVSAvoidblade frangibility under foreign object ingestion

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The blade utilizes composite materials with tailored mechanical properties to achieve both strength for productivity and controlled frangibility. The composite structure includes layers with different failure characteristics that enable the blade to maintain integrity during normal operation but separate controllably upon foreign object impact

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The blade incorporates dynamic characteristics that allow it to respond differently to normal operational loads versus impact loads. Under normal conditions, the blade maintains structural integrity for high thrust efficiency, but under impact conditions, predetermined frangible sections activate to enable controlled separation

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS9828862B2Frangible airfoil

Publication Date: 2017.11.28 GENERAL ELECTRIC CO

AI summary

A frangible airfoil that mitigates adverse conditions associated with release of material resulting from impact damage to the composite blade is provided, the airfoil having provisions for dissipating energy, self-shredding, and predetermined release trajectory.