Rigid-Flexible Air Inlet Bulkhead for Bird-Strike Resistance

Solution Overview

Problem

Aircraft propulsion systems are susceptible to high-velocity impacts from bird strikes, and existing propulsion system housings lack sufficient resistance to such impacts, necessitating improved structural integrity and impact resistance.

Innovation Solution

The air inlet for an aircraft propulsion system nacelle incorporates a forward bulkhead assembly comprising a rigid first bulkhead portion made of thermoplastic composite material and a flexible second bulkhead portion made of woven fabric layers embedded in a thermoplastic matrix, which provides structural support and absorbs impact energy from bird strikes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a rigid bulkhead structure is used to maintain structural integrity, then strength is improved, but weight increases and impact energy absorption is reduced

Engineering Contradiction:

Improvestructural integrityVSAvoidbulkhead weight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The bulkhead transitions from a completely rigid structure to a semi-rigid structure with controlled flexibility. The rigid portion maintains structural integrity while the flexible portion can deform to absorb impact energy, effectively changing the mechanical properties parameter of the bulkhead material and structure.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The bulkhead is constructed as a composite structure with two distinct portions: a rigid portion providing structural support and a flexible portion for energy absorption. This composite approach combines materials or structures with different mechanical properties to achieve both strength and weight reduction.

Inventive Principle:

Principle #40Composite materials

2Strength

If a rigid bulkhead structure is used to maintain structural integrity, then strength is improved, but impact energy absorption is reduced

Engineering Contradiction:

Improvestructural integrityVSAvoidimpact energy absorption

Core Design Contradiction:

StrengthVSLoss of energy

Solution Approach 1:

The flexible portion of the bulkhead is designed in advance to deform and absorb impact energy during bird strikes. This pre-designed flexibility acts as a cushioning mechanism that activates during impact events, protecting the rigid portion and overall structure from excessive forces.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The bulkhead transitions from a completely rigid structure to a semi-rigid structure with controlled flexibility. The rigid portion maintains structural integrity while the flexible portion can deform to absorb impact energy, effectively changing the mechanical properties parameter of the bulkhead material and structure.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If traditional bulkhead materials are used, then ease of manufacture is improved, but bird strike resistance is insufficient

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidbird strike resistance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The bulkhead is divided into two distinct segments: a rigid portion and a flexible portion. Each segment can be manufactured using different processes and materials optimized for its specific function, then assembled together. This segmentation allows traditional manufacturing methods to be used for each portion while achieving superior overall bird strike resistance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The bulkhead is constructed as a composite structure with two distinct portions: a rigid portion providing structural support and a flexible portion for energy absorption. This composite approach combines materials or structures with different mechanical properties to achieve both strength and weight reduction.

Inventive Principle:

Principle #40Composite materials

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 bulkhead assembly enhances the air inlet's resistance to bird strikes by absorbing impact energy, maintaining structural integrity, and reducing the transmission of force to the outer and inner skins while using lightweight materials.

Implementation Method 1

The second bulkhead portion includes a flexible body material and is configured to facilitate resistance to bird strike impacts

Methodology Applied

Scientific EffectEnergy absorption through material deformation: Deformation

Data Source

PatentUS12441478B2Air inlet bulkhead assembly for an aircraft propulsion system

Publication Date: 2025.10.14 ROHR INC

AI summary

An air inlet for an aircraft propulsion system nacelle includes an outer skin, an inner skin, a lip skin, and a forward bulkhead. The lip skin extends between and to an outer end and an inner end. The outer end is disposed at the outer skin. The inner end is disposed at the inner skin. The forward bulkhead includes a first bulkhead portion and a second bulkhead portion. The first bulkhead portion and the second bulkhead portion are mounted to the outer skin. The first bulkhead portion and the second bulkhead portion are mounted to the inner skin. The first bulkhead portion includes a rigid body material and the second bulkhead portion includes a flexible body material.