Composite Fan Case Load Distribution Devices for Blade Out Protection
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Solution Overview
Problem
Current composite structures for aircraft turbine engine fan cases, such as those designed to withstand fan blade out events, face challenges in balancing weight efficiency with the need to withstand extreme loading conditions, as additional reinforcement materials can increase mass unacceptably.
Innovation Solution
The implementation of locally strengthened areas within a reinforcement region using load distribution devices composed of composite fibers, where fibers are oriented within a range of plus or minus 30 degrees from perpendicular to the main fiber axis, covering no more than 50% of the region, to redistribute and manage load effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If additional layers of metal or composite materials are added to reinforce the fan case, then the strength and damage tolerance are improved, but the mass and weight of the composite structure increase unacceptably
Solution Approach 1:
The patent applies local quality by placing load distribution devices only in specific reinforcement regions where damage is most likely to occur and propagate, rather than uniformly reinforcing the entire fan case. The LDDs are positioned at circumferential locations corresponding to fan blade spacing, creating locally strengthened areas that provide damage tolerance only where needed, thus avoiding unnecessary weight addition in other regions.
Solution Approach 2:
The reinforcement strategy is segmented by dividing the fan case into multiple reinforcement regions, each containing one or more load distribution devices. These devices are discrete, localized elements rather than continuous reinforcement, allowing the structure to be strengthened at specific critical points while maintaining lighter weight in non-critical areas.
2Reliability
If the LDD covers a larger portion of the reinforcement region, then the load distribution and damage tolerance are improved, but the weight and material usage increase
Solution Approach 1:
The patent implements partial action by designing LDDs that cover only specific portions of the reinforcement region rather than the entire area. The LDDs are sized and positioned to provide sufficient load distribution and damage propagation resistance at critical locations, using just enough material to achieve the required reliability without excessive coverage that would increase weight.
Data Source
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AI summary
An improved composite structure and method for making same has been provided. The provided improved composite structure (100) has locally strengthened areas within a reinforcement region (110). The locally strengthened areas within the reinforcement region have load distribution devices (116) to redistribute load in order to (i) locally strengthen an area around damage induced by an initial momentary and direct transmitted load, and (ii) limit growth and propagation of damage induced by an initial momentary and direct transmitted load during a subsequent unbalance load. The improved composite structure reduces the impact of the fan blade out phenomenon in a weight efficient manner.