transportation research institute the george washington university

Application of Finite Element Dynamic Simulation to Airplane Cabin in

Air Turbulence

Vahid Motevalli and Ahmad NoureddineVahid Motevalli and Ahmad Noureddine

Transportation Research InstituteThe George Washington University

International Aircraft Fire and Cabin Safety ResearchNov. 16 - 20, 1998

AcknowledgementAcknowledgement

Robert L. Frantz , AirLine Pilots Association (ALPA)

Dhafer Marzogui of the National Crash Analysis Center (NCAC) at GW

The GW Aviation InstituteThe GW Aviation Institute

Established in March of 1998 Three collaborating institute

– The GW Transportation Research Institute– Institute for Crisis, Disaster & Risk Management– International Institute for Travel and Tourism

Research in all aspects of Aviation Safety and Security

Certificate Program in Aviation Safety and Security Management

BackgroundBackground Between 1980-1997, there has been 3 fatalities and 629

injuries due to turbulence (ATA) Competing and contributing phenomena:

– Increased flights, passenger loads– Reducing fatal accident rates of the first kind (CFIT,

in-flight Human Errors, …)– High on-time performance pressures (hub & spoke

operations, competitions, etc.)– Increased need for commuter flights (smaller jets

and turbo-props and jets) Increase in low-fatality (non-haul loss) accident rate,

e.g. turbulence, crash landings. More attention must be paid to injuries to passengers and flight attendants.

Candidate Airplane Incident Categories Candidate Airplane Incident Categories for Computer Simulationsfor Computer Simulations

In-Flight* Fire and Explosion * Structural Failure* Turbulence

Bomb

Mechanical/ElectricalComponent Failure

Crash/Post-crash* Occupant survivability (impact)* Crashworthiness - Component failure (fuel tank,

seats, over-head bins, etc..)* Fire/explosion

Hull breach Occupant injuries and egress

Predictive Analytical/Computational Predictive Analytical/Computational Tools Needed to Solve these ProblemsTools Needed to Solve these Problems

Current Capabilities– Component structural analysis (many tools, accepted)– Composites analysis (limited)– Computational Fluid Dynamics, (CFX4.2, KIVA3V,

acceptable?)– Dynamic structural analysis (LS-DYNA3D, etc.,

acceptable) Future Vision: 21st Century

Coupled structural/fluid/combustion modeling capability to perform comprehensive simulation of incidents, tests and performance evaluation for Enhancement of Airplane Safety/Survivability/Airwothiness /Crashworthiness

Airplane SimulationsAirplane Simulations

Structural Construction of a “Generic” Wide-Body Commercial Passenger Airplane

“Virtual Reality” View of the Entire Plane

Incident and Test Simulation Landing gear failure

Finite Element Model of the PlaneFinite Element Model of the Plane



“Virtual Reality” View of the Entire Plane Incident and Test Simulation

Landing gear failure Impact landing - obstructed runway (similar to CIDE)

CIDE FE Simulation DemonstrationCIDE FE Simulation Demonstration



“Virtual Reality” View of the Entire Plane Incident and Test Simulation

Landing gear failure Impact landing - obstructed runway (similar to CIDE) Fuselage drop tests with “occupants”

FE Model of Fuselage Section with FE Model of Fuselage Section with Hybrid III DummiesHybrid III Dummies

Airplane SimulationsAirplane SimulationsFE Model SpecificationsFE Model Specifications

Model 1 Model 2 Model 3Number of Parts 33 187 255Number of Nodes 25,000 85,000 280,000Number of Elements 26,000 70,000 250,000Total Simulation Time 1.0 sec 0.5 sec -Number of Processors(SGI Power Challenge)

4 4 -

Total CPU Time 12 hr. 4 hr. -

Demonstration of Finite Element Demonstration of Finite Element Simulation of Air TurbulenceSimulation of Air Turbulence

Actual Wide-body passenger airplane geometry Generic structural elements and connections Detailed Finite Element model of the fuselage

section Hybrid III dummy models with and without

restrain Sample turbulence data, 3-axis acceleration,

pitch, yaw and roll

Simulation of Air TurbulenceSimulation of Air Turbulence

Simulation of Air TurbulenceSimulation of Air TurbulenceTotal Number of Elements: 50,000

2 Hybrid III Dummy models: 14,000 elements each

Turbulence duration simulated: 2.5 seconds

Input: longitudinal, lateral, and vertical acceleration plus pitch and roll

Total run time: 30 hours (multiple processors)

Most dummy parts in this model are rigid except for the head skin and the neck to reduce the run time. Airplane cabin parts were also rigidized for the same reason. Time step was maximized.


-1

0

1

2

0 20 40 60 80 100 120

Time (seconds)

Acce

lerat

ion (g

)

-10-505101520

Roll

and

Pitch

(d

egre

es)

G's Normal_Accel G's Longitudinal_Accel G's Lateral_Accel

degrees Pitch degrees Roll

Simulation of Air TurbulenceSimulation of Air Turbulence(Results)(Results)

-20

-19

-18

-17

-16

-15

-14

0.00 0.40 0.80 1.20 1.60 2.00 2.40

time (s)

dum

my

vert

ical

vel

ocity

(m/s

)

unrestraineddummy

belted dummy


-20

-15

-10

-5

0

5

10

1.70 1.75 1.80 1.85 1.90

time (s)

head

acc

eler

atio

n (g

's)

unrestrained dummy

belted dummy

Potential uses of Finite Element Potential uses of Finite Element Simulation of Aircraft in TurbulenceSimulation of Aircraft in Turbulence

Passenger education for in-flight seat-belt use to avoid turbulence-induced injuries

Structural Evaluation of overhead bins during severe turbulence and dynamic impact

Evaluation of interior panel integrity Evaluation of Bulk-head occupant injury

reduction approaches Occupant safety issues (falling luggage, child

safety, seat design, etc.)

ConclusionsConclusions HIC number may not be a right measure for

this type of head impact scenario Force of impact is certain to cause neck

injuries. Tremendous potential to use finite element

simulation for aircraft occupant safety issue A large number of issues such as:

– passenger compliance with seatbelt use– child safety in turbulence– overhead bin performance– unsecured objects.

transportation research institute the george washington university

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