Aircraft Cabin Door Beams with Variable Cross-Section

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Solution Overview

Problem

Existing pressurized aircraft cabin doors are difficult and costly to manufacture due to complex intersections of beams, which increase mass and complicate the use of composite materials, while also requiring high rigidity to maintain pressure differences and support additional equipment.

Innovation Solution

A pressurized aircraft cabin door design featuring circumferential and longitudinal beams with open cross sections, where longitudinal beams have a variable cross-section that increases from ends to middle, providing reinforcement and simplified assembly, allowing for reduced thickness and weight without intersecting beams, suitable for composite materials and various manufacturing techniques.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If beams with intersections are used to form a rigid door structure, then the rigidity and strength are improved, but the manufacturing complexity and cost increase

Engineering Contradiction:

Improvedoor structure rigidityVSAvoidbeam intersection complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The door structure is divided into separate longitudinal beams and circumferential beams that do not intersect, eliminating the need for complex connection joints. Each beam is an independent structural element that can be manufactured separately and assembled without intersecting connections.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The longitudinal beams are positioned within the circumferential beams in a nested arrangement where the ends of longitudinal beams rest on the inner surface of circumferential beams, creating a rigid structure without requiring the beams to intersect or complex fastening systems.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Strength

If intersecting beams are used to ensure door rigidity, then the structural strength is improved, but the mass of the door structure increases

Engineering Contradiction:

Improvedoor structure rigidityVSAvoiddoor structure mass

Core Design Contradiction:

StrengthVSWeight of stationary object

Solution Approach 1:

The structure is segmented into non-intersecting beams, eliminating the need for additional fasteners, joints, and connection hardware that would increase mass. The simplified assembly requires fewer parts and less material overall.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cross-sectional dimensions of the longitudinal beams are optimized to provide adequate rigidity without excessive mass. The beam parameters are carefully selected to achieve the minimum required structural strength while minimizing weight.

Inventive Principle:

Principle #35Parameter changes

3Strength

If complex beam intersections are used to achieve high rigidity, then the door strength is improved, but the ease of manufacture decreases

Engineering Contradiction:

Improvedoor structure rigidityVSAvoiddoor structure manufacturability

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The door structure is segmented into separate longitudinal and circumferential beams that can be manufactured independently using standard fabrication processes. This eliminates the need for complex multi-step assembly operations required by intersecting beam structures.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of having beams intersect and require complex joint fabrication, the invention inverts the approach by having beams terminate and rest on each other, simplifying the manufacturing process to basic cutting and assembly operations.

Inventive Principle:

Principle #13The other way round (Inversion)

4Reliability

If thick door panels and structures are used to maintain pressure difference, then the pressure integrity is improved, but the mass and production cost increase

Engineering Contradiction:

Improvepressure difference maintenanceVSAvoiddoor mass

Core Design Contradiction:

ReliabilityVSWeight of stationary object

Solution Approach 1:

The beam cross-sectional parameters are optimized to provide the minimum thickness required for pressure integrity. The longitudinal and circumferential beams are dimensioned to achieve adequate rigidity and strength while minimizing material usage and overall door mass.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11919618B2Aircraft pressurized cabin door with a structure formed by beams having a varying cross-section

Publication Date: 2024.03.05 LATECOERE

AI summary

An aircraft pressurized cabin door (1) having an outer panel (2) and a door structure (3) including: two circumferential beams (4) fastened to the lateral edges of the door; a plurality of longitudinal beams (5a, 5b) which are arranged substantially perpendicularly between the circumferential beams (4) and are fastened to the outer panel (2), each longitudinal beam (5a, 5b) extending from one circumferential beam (4) to the other. At least one longitudinal beam (5b) is a beam that has a variable cross-section which increases from the ends (B, M) of the beam to the center (H, L) of the beam, with two bent support bars.