Composite Vane Reinforcement Separation by Cryogenic Stress

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Solution Overview

Problem

Existing methods for separating metal reinforcements from composite material turbomachine vanes are either inefficient, risk damaging the composite material, or require complex and costly equipment, such as inductive heating causing overheating or chemical dissolution that degrades the vane or is not recyclable.

Innovation Solution

A method involving simultaneous cooling of the metal reinforcement to a negative temperature using liquid nitrogen and applying mechanical stress through ultrasonic hammering to break the adhesive film, leveraging the higher thermal conductivity of the reinforcement to minimize material degradation and simplify the process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If inductive heating is used to separate the metal reinforcement from the composite vane, then the adhesive film is softened and separation is achieved, but the composite material is overheated and degraded

Engineering Contradiction:

Improveseparation effectivenessVSAvoidoverheating damage to composite material

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Instead of heating the assembly to soften the adhesive, the patent inverts the approach by cooling the metal reinforcement to negative temperatures. This causes the adhesive to become brittle and fracture under subsequent mechanical stress, achieving separation without thermal damage to the composite material.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the temperature parameter from positive (heating) to negative (cooling), transforming the adhesive's mechanical properties from ductile to brittle state, which enables clean fracture during stress application without degrading the composite substrate.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If chemical dissolution is used to separate the metal reinforcement, then separation is achieved, but the process requires bulky equipment and long processing time

Engineering Contradiction:

Improveseparation effectivenessVSAvoidequipment complexity and processing time

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the complex chemical dissolution system with a simpler thermomechanical system. By cooling the metal reinforcement and applying mechanical stress, separation is achieved through adhesive fracture rather than chemical dissolution, eliminating the need for bulky chemical treatment equipment and lengthy processing times.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If the metal reinforcement is cooled to negative temperature and mechanical stress is applied, then the adhesive film breaks and separation is achieved, but the process requires precise temperature and stress control

Engineering Contradiction:

Improveseparation effectivenessVSAvoidprocess control complexity

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent applies preliminary cooling to the metal reinforcement before mechanical stress is applied. This pre-cooling step transforms the adhesive into a brittle state, so that when mechanical stress is subsequently applied, the adhesive fractures easily and separation occurs with minimal force and simple equipment.

Inventive Principle:

Principle #10Preliminary action

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

Effectively separates the metal reinforcement from the composite vane without damaging it, reducing the risk of overheating and processing time, while allowing for efficient recycling of the metal reinforcement.

Implementation Method 1

the second mechanical part having a second thermal conductivity that is higher than the first thermal conductivity

Methodology Applied

Scientific EffectThermal conductivity: Conduction (thermal)

Implementation Method 2

at least one cooling step during which only the second mechanical part is cooled to a negative temperature

Methodology Applied

Scientific EffectThermal shock: Thermal Shock

Implementation Method 3

at least one stressing step during which the second mechanical part is subjected to a mechanical stress in order to cause the adhesive film to break

Methodology Applied

Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Data Source

PatentUS11731221B2Method for separating a first mechanical part from a second mechanical part

Publication Date: 2023.08.22 SAFRAN AIRCRAFT ENGINES SAS

AI summary

A method for separating a first mechanical part from a second mechanical part is described, wherein the second mechanical part is bonded to the first mechanical part by an adhesive film along a connecting area, the first mechanical part having a first specific thermal conductivity and the second mechanical part having a second thermal conductivity that is higher than the first thermal conductivity. The method includes at least one cooling step during which the second mechanical part is cooled to a negative temperature and at least one stressing step during which the second mechanical part is subjected to mechanical stress in order to cause the adhesive film to break.