Segmented Nacelle Inlet Attachment for Lightweight FBO Load Handling
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Solution Overview
Problem
The aft bulkhead of an engine nacelle is large, expensive, and contributes significantly to weight, due to the use of expensive materials and complex structural designs for flight loads and Fan Blade Out (FBO) loading, which complicates manufacturing and assembly.
Innovation Solution
A segmented attach flange with discrete fittings and triangular attachment brackets replace the traditional continuous bulkhead, forming a truss structure that reduces material usage and weight, while maintaining structural integrity for flight loads and allowing energy absorption during FBO events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a continuous bulkhead with stiffening ribs is used, then structural strength and stiffness are improved, but weight and manufacturing cost increase significantly
Solution Approach 1:
The continuous bulkhead is divided into multiple discrete attachment brackets that are distributed around the circumference. Each bracket is a separate component that can be independently manufactured and attached, replacing the monolithic continuous structure while maintaining overall structural strength through the distributed arrangement of multiple segments.
Solution Approach 2:
The attachment brackets utilize composite construction combining aluminum alloy extrusions for the main bracket body with titanium alloy fittings for high-stress connection points. This composite material approach optimizes the strength-to-weight ratio by using lightweight aluminum for the structural framework and high-strength titanium only where mechanically necessary for load transfer.
2Reliability
If expensive materials and complex structural designs are used for the aft bulkhead, then structural integrity under flight loads and FBO loading is improved, but manufacturing cost and assembly complexity increase
Solution Approach 1:
The bulkhead system is segmented into standardized attachment brackets that can be manufactured using conventional aluminum extrusion processes, avoiding the need for expensive custom-machined titanium bulkheads. Each bracket is a repeatable component with standardized interfaces, simplifying manufacturing while maintaining structural integrity through the distributed multi-point attachment architecture.
Solution Approach 2:
The design changes the material parameter from expensive titanium alloy to lighter aluminum alloy for the main bracket structure, combined with optimized geometric parameters of the bracket configuration and attachment fitting arrangement. This parameter optimization achieves the required structural integrity through intelligent design rather than relying solely on expensive materials.
3Stability of the object's composition
If a continuous bulkhead structure is used, then structural stability is maintained, but weight reduction opportunities are lost
Solution Approach 1:
The continuous bulkhead is replaced by multiple discrete attachment brackets positioned circumferentially around the nacelle. This segmentation allows each bracket to be optimized as a lightweight truss structure while the distributed arrangement across multiple locations maintains the overall structural stability and load distribution characteristics of a continuous bulkhead.
Solution Approach 2:
The attachment brackets utilize thin-walled aluminum extrusions with optimized cross-sectional geometries that provide high stiffness-to-weight ratios. The thin-walled structural members maintain structural stability through intelligent geometric design rather than relying on thick, heavy material sections.
Data Source
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AI summary
An engine nacelle inlet is provided. The inlet comprises an inner barrel having a leading edge and a trailing edge. A segmented attach flange is connected to an outer circumference of the trailing edge of the inner barrel, wherein the segmented attach flange comprises a number of discrete attach flange fittings. An outer barrel having a leading edge and a trailing edge surrounds the inner barrel. A number of attachment brackets connect the outer barrel to the segmented attach flange. Each attachment bracket comprises two struts connected at a common point on the trailing edge of the outer barrel and connected at separate points on one of the attach flange fittings to form a truss. Each attachment bracket is connected to a separate respective attach flange fitting.