Alternating CFRP and GFRP Fan Casing Blocks for Impact Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing fan casing designs for aircraft engines face a challenge in balancing the need for debris retention and impact absorption while minimizing weight, as heavier casings increase operational costs.
Innovation Solution
A fan casing design featuring a main impact region with alternating carbon-fibre reinforced polymer (CFRP) and glass-fibre reinforced polymer (GFRP) blocks, arranged to provide high strength for debris containment and varying stiffness for enhanced energy dispersion, with a neutral axis positioning and specific thickness configurations to optimize energy absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fan casing is made heavier to improve debris retention and impact absorption, then safety performance is improved, but operational cost increases
Solution Approach 1:
The fan casing employs a composite structure combining CFRP (carbon-fibre reinforced polymer) and GFRP (glass-fibre reinforced polymer) blocks in alternating layers within the main impact region. This composite material approach enables the casing to achieve high strength and debris retention capability while maintaining lightweight properties, directly resolving the contradiction between safety performance and weight.
Solution Approach 2:
The patent applies different material properties to different regions of the fan casing. The main impact region contains alternating CFRP and GFRP blocks with specific thickness variations, while other regions may have different configurations. This local differentiation allows optimal strength and weight balance in the critical impact zone without unnecessarily increasing overall casing weight.
2Loss of energy
If the fan casing is made heavier to improve impact absorption, then energy absorption capacity is improved, but flight cost increases
Solution Approach 1:
The alternating CFRP and GFRP block structure provides superior energy absorption capacity compared to homogeneous materials. The combination of stiff CFRP blocks and more compliant GFRP blocks creates a laminate that dissipates impact energy through multiple mechanisms including elastic deformation, fiber-matrix bonding, and progressive failure, achieving high energy absorption with reduced weight.
Solution Approach 2:
The patent varies the thickness parameters of CFRP and GFRP blocks within the main impact region to optimize energy absorption. By adjusting the thickness distribution of different material blocks, the casing can be tuned to absorb specific energy levels while maintaining minimal weight, resolving the contradiction between energy absorption capacity and weight.
3Strength
If CFRP blocks are used throughout the impact region, then strength is maximized, but energy dispersion is reduced
Solution Approach 1:
The alternating CFRP and GFRP block configuration creates a composite laminate where CFRP blocks provide high strength and stiffness for debris containment, while GFRP blocks provide lower stiffness and higher ductility for energy dispersion. This material combination resolves the contradiction by leveraging the complementary properties of the two materials.
Solution Approach 2:
Different regions of the main impact region have different material compositions optimized for specific functions. CFRP blocks are positioned where maximum strength is required for debris containment, while GFRP blocks are positioned where energy dispersion and shock absorption are critical, achieving both strength and energy dispersion simultaneously.
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 design achieves improved debris retention and energy dispersion, ensuring effective containment of fan blade fragments while maintaining a lightweight structure, thereby enhancing safety and reducing operational costs.
Implementation Method 1
the different thicknesses of GFRP blocks within the region provide lower stiffnesses but allow increased deflection when impacted by debris
Implementation Method 2
A fan case having a combination of such features can exhibit improved energy dispersion within the impact region
Implementation Method 3
Having CFRP blocks at the bounds of the region provides high strength blocks which prevent any debris that impacts on the case from exiting the case
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A fan casing (100) for an engine having a fan (13) with fan blades that each have a centre of gravity (CoG) that lies on a fan blade CoG plane (420), the fan casing having a central axis (11) and comprising a main impact region (106) comprising carbon-fibre reinforced polymer (CFRP) blocks (200) and glass-fibre reinforced polymer (GFRP) blocks (300) having a constant thickness throughout the axial extent of the main impact region, wherein the total depth of the main impact region is equal to the sum of the thicknesses of the CFRP blocks (200) and GFRP blocks (300), each of the GFRP blocks is positioned between two CFRP blocks, and the thickness of at least one of the GFRP blocks is different to the thickness of another of the GFRP blocks.