Aircraft Fuselage Frame Energy Absorbing Device

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Solution Overview

Problem

Aircraft fuselages made of composite materials struggle to absorb energy during crashes due to the lack of intrinsic plastic deformation capacity, which is essential for crash resistance, unlike metallic materials.

Innovation Solution

Incorporating a mechanically weakened area in the circumferential reinforcing frames with an energy-absorbing device comprising effector members and a central core that deforms under compressive forces, allowing for localized buckling and energy dissipation during impacts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If composite materials are used for circumferential reinforcing frames to reduce mass and improve mechanical performance, then weight decreases and fatigue resistance improves, but energy absorption capacity during crash decreases

Engineering Contradiction:

Improvefuselage massVSAvoidenergy absorption capacity

Core Design Contradiction:

Weight of moving objectVSLoss of energy

Solution Approach 1:

The frame is divided into a regular portion and a mechanically weakened area. The weakened area acts as a dedicated energy absorption zone that segments the overall structure, allowing localized buckling and deformation to absorb crash energy while the rest of the frame maintains its load-bearing function.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The mechanical properties of the frame are changed by creating a weakened area with modified geometry (reduced thickness or cross-sectional area). This parameter change allows the frame to undergo controlled plastic deformation in the weakened zone during impact, enabling energy absorption that would not be possible with uniform composite structure.

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If metallic frames with plastic deformation capacity are used, then energy absorption during crash improves, but mass increases compared to composite materials

Engineering Contradiction:

Improveenergy absorption capacityVSAvoidfuselage mass

Core Design Contradiction:

Loss of energyVSWeight of moving object

Solution Approach 1:

Instead of making the entire frame from heavy metallic material, only a localized weakened area is designed to undergo plastic deformation for energy absorption. The majority of the frame can remain as lightweight composite material, achieving energy absorption functionality without the penalty of overall mass increase.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention combines composite material frame structure with a mechanically weakened area that provides metal-like energy absorption characteristics. This composite approach allows the frame to benefit from both the low weight of composites and the energy absorption capacity traditionally associated with metallic plastic deformation.

Inventive Principle:

Principle #40Composite materials

3Strength

If the frame structure is designed for static load resistance, then structural integrity under normal operation is maintained, but energy absorption during crash impact is insufficient

Engineering Contradiction:

Improvestatic load resistanceVSAvoidcrash energy absorption

Core Design Contradiction:

StrengthVSLoss of energy

Solution Approach 1:

The frame is pre-designed with a mechanically weakened area that is prepared in advance to undergo controlled buckling and deformation. This preliminary design feature ensures that during crash impact, the frame will automatically activate its energy absorption mechanism through localized buckling in the pre-weakened zone, without requiring active control or additional components.

Inventive Principle:

Principle #10Preliminary action

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 solution effectively absorbs kinetic energy during crashes by deforming the central core, enhancing the crash resistance of composite material fuselages while maintaining structural integrity under standard loads.

Implementation Method 1

a central core maintained between the effector members such that a reduction in the distance between the effector members produces a deformation of said central core. The central core is able to absorb the energy under the effect of said deformation.

Methodology Applied

Scientific EffectDeformation: Deformation

Implementation Method 2

the frame comprises a mechanically weakened area able to cause a localized buckling of the frame under the effect of a compressive force exerted circumferentially on the frame

Methodology Applied

Scientific EffectBuckling:

Data Source

PatentUS9545989B2Aircraft fuselage structure comprising an energy absorbing device

Publication Date: 2017.01.17 EURON AERONAUTIC DEFENCE & SPACE

AI summary

An aircraft fuselage structure, includes a circumferential reinforcing frame (2) and a plurality of stringers (3) substantially perpendicular to the frame. The frame includes a mechanically weakened area able to cause its localized buckling under the effect of a compressive force exerted circumferentially thereon. The structure includes an energy absorbing device (5) having two effector members (52) secured to the frame respectively on either side of the weakened area, and a central core (51) maintained between the effector members such that a reduction in the distance between the effector members produces a deformation of the central core, which is able to absorb energy under the effect of the deformation.