Stiffening Rib Design for Gas Turbine Fan Casing

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Solution Overview

Problem

Traditional metal brackets used in gas turbine engines for load-bearing applications add weight while offering limited flexibility in performance characteristics and are not optimized for multiple clipping locations, necessitating a lightweight, high-strength solution with improved manufacturing processes.

Innovation Solution

The use of injection-molded clipping members with I-shaped or C-shaped stiffening ribs, which can be tuned by modifying their dimensions or material thickness to meet specific natural frequency requirements, providing structural rigidity and enhanced load-carrying capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If metal brackets are used for load-bearing applications, then structural strength is improved, but weight increases

Engineering Contradiction:
Improvestructural strengthVSAvoidweight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent employs composite materials, specifically fiber-reinforced plastics, to manufacture load-bearing clipping members. This allows the structure to achieve high strength-to-weight ratio by combining the strength benefits of fibers (such as carbon fiber, glass fiber, or aramid fiber) with the lightweight characteristics of plastic matrices, thereby reducing overall weight while maintaining or improving structural strength compared to traditional metal brackets.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The clipping member is divided into functional segments including a mounting portion with stiffening ribs and a body portion with clipping features. The stiffening ribs are specifically designed as separate structural elements that can be optimized independently to provide localized reinforcement without requiring the entire component to be made of heavy material, thus achieving weight reduction while maintaining structural integrity.

Inventive Principle:
Principle #1Segmentation

2Strength

If traditional metal brackets are used, then load-carrying capacity is provided, but flexibility in tuning performance characteristics is limited

Engineering Contradiction:
Improveload-carrying capacityVSAvoidflexibility in tuning performance
Core Design Contradiction:
StrengthVSAdaptability or versatility

Solution Approach 1:

The patent utilizes the ability to vary multiple design parameters of the clipping member including rib thickness, rib spacing, fiber orientation, material composition, and geometric dimensions. These parameters can be adjusted during the injection molding process to tune the natural frequency, stiffness, and load-carrying capacity of the bracket, providing flexibility to optimize performance for different clipping locations and application requirements.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The stiffening ribs are designed with varying thicknesses and dimensions at different locations to provide localized reinforcement where needed. This allows the structure to have different mechanical properties in different regions, enabling optimization of load-carrying capacity at critical areas while maintaining flexibility to adjust performance characteristics for specific application requirements.

Inventive Principle:
Principle #3Local quality

3Productivity

If injection molding process is used, then manufacturing capacity and weight reduction are improved, but manufacturing precision requirements increase

Engineering Contradiction:
Improvemanufacturing capacityVSAvoidmanufacturing precision
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The injection molding process incorporates preliminary actions such as pre-heating the mold, pre-positioning inserts or嵌件, and pre-programming the injection parameters before production begins. This ensures consistent manufacturing precision across high-volume production by establishing optimal conditions in advance, allowing the process to achieve both high productivity and precise dimensional control without requiring post-processing adjustments.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The injection molding process allows for dynamic adjustment of parameters such as injection pressure, temperature, and cooling rates during production. These parameters can be precisely controlled and modified to achieve the required manufacturing precision for the stiffening ribs and overall component geometry, enabling high-volume production while maintaining tight tolerances through process optimization.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3048271B1Stiffening rib
Publication Date: 2020.05.27 ROLLS ROYCE CORP
  • EP3048271B1 patent drawingFigure 1
  • EP3048271B1 patent drawingFigure 2~3
  • EP3048271B1 patent drawingFigure 4~6

AI summary

A fan casing (46) for a gas turbine engine (10) includes an improved clipping member (150, 300, 400) for attaching various fan case externals and units. The clipping member (150, 300, 400) may include I-Shaped (186) or C-shaped (322) cross sectional stiffened rib sections (160, 202, 204, 322) that afford enhanced load carrying capabilities while providing mounting surfaces for being connected to structures of the fan case (46). The I-Shaped or C-Shaped cross sectional stiffened rib (186, 322) also affords an enhanced natural frequency tuning characteristic. Hardware may be formed within the clipping member (150, 300, 400) and become an integral part of the structure which may be tuned to specific design preferences.