Segmented Connector Structure for CMC-Metal Thermal Mismatch

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Solution Overview

Problem

The thermal expansion mismatch between ceramic matrix composite (CMC) turbine outer annular components and metal components in gas turbine engines leads to high contact stress and potential strength failure due to differing thermal expansion coefficients, which existing technologies fail to adequately address.

Innovation Solution

A connector with a subtractive hollow section and anti-thermal mismatch connecting device, featuring a central shaft, supporting rib plates, and outer annular plates, which allows for radial elastic deformation and alleviates thermal deformation mismatch through a combination of close contact and sliding mechanisms, ensuring accurate installation and positioning while minimizing contact stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If close fit installation is used to avoid vibration and collision between metal pin and CMC connecting hole, then installation precision is improved, but thermal deformation mismatch causes high contact stress leading to strength failure

Engineering Contradiction:

Improveinstallation precisionVSAvoidstrength of CMC structure

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The connector is divided into multiple segments including a metal cylindrical section, intermediate section, and CMC section. Each section can deform independently to accommodate thermal expansion differences, eliminating the need for close fit installation while preventing strength failure through controlled thermal deformation in each segment

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The connector uses materials with different thermal expansion coefficients in different sections (metal with high expansion coefficient, CMC with low expansion coefficient). This parameter change allows each section to expand differently during heating, matching the thermal expansion characteristics of the connected components and reducing contact stress

Inventive Principle:

Principle #35Parameter changes

2Temperature

If CMC material is used to improve high temperature performance, then service temperature limit is improved, but thermal expansion mismatch with metal components causes deformation incompatibility

Engineering Contradiction:

Improveservice temperature limitVSAvoidthermal deformation compatibility

Core Design Contradiction:

TemperatureVSStability of the object's composition

Solution Approach 1:

The connector is constructed as a composite structure combining metal materials (for high thermal expansion and strength) and CMC materials (for low thermal expansion and high temperature resistance). This composite design allows the connector to exhibit both high temperature performance and thermal expansion characteristics that match the connected components

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

Different sections of the connector have different material properties tailored to their specific functions. The CMC section provides thermal stability matching the CMC turbine component, while the metal section provides strength and thermal expansion matching the metal intermediate casing, achieving local optimization of thermal deformation compatibility

Inventive Principle:

Principle #3Local quality

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 effectively alleviates thermal deformation mismatch, preventing strength failure and ensuring structural integrity, while allowing for accurate installation and positioning of CMC turbine outer annular components, thus enhancing the operational reliability and efficiency of gas turbine engines.

Implementation Method 1

the outer surface of the subtractive hollow section has a small radial deformation stiffness and is prone to radial elastic deformation

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

since thermal expansion coefficient of metal material is greater than that of ceramic matrix composite, the thermal expansion of a CMC turbine outer annular component in a temperature change process, is different from that of a metal pin and a metal intermediate casing component

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS11692460B2Connector and an anti thermal mismatch connecting device

Publication Date: 2023.07.04 AECC COMML AIRCRAFT ENGINE CO LTD

AI summary

In order to alleviate a mismatch problem of thermal deformation, in all directions, of a connecting and installing structure between a CMC turbine outer annular component and a metal intermediate casing, a connector and an anti thermal mismatch connecting device are provided. The rod part of the connector comprises a subtractive hollow section and a cylindrical section. The subtractive hollow section is composed of a central shaft, a plurality of supporting rib plates extending outwards from a peripheral surface of the central shaft and inclined radially relative to the central shaft, and a plurality of outer annular plates arranged around the central shaft, with a circumferential gap between adjacent outer annular plates. The supporting rib plate is connected with the central shaft and the outer annular plate, and the central shaft is connected with the cylindrical section. The anti thermal mismatch connecting device the connector.