CRAHVI CRashworthiness of Aircraft for High Velocity Impact Tim Brown (Airbus UK) Aeronautics Days 19th - 21st June, 2006
Overview of CRAHVI Project OVERVIEW Background The Consortium Overall Project Objectives Simulation of Aircraft Response to High Velocity Impact Scenarios Simulation of Transport Aircraft Crashworthiness Environment Results
Background CRAHVI is an RTD project (FW5), partly funded by the EU CRAHVI is a follow up of two previous Brite Euram projects Design for Crash Survivability (CRASURV) (Sept. 96 / 42 Months) HICAS (High Velocity Impact of Composite Aircraft Structures) ended 30.04.200 CRAHVI started on 1.02.01 and finsihed 1.04.04
The Consortium: 20 Partners from 8 EU Countries UK France Germany Italy Spain Holland Greece Ireland
CRAHVI: The Consortium CRANFIELD IMPACT CENTRE MECALOG
Overview of CRAHVI Project Overall Project Objectives Develop Finite Element methods and tools to predict the behaviour of aircraft structures subjected to high velocity impacts & survivable crash loads Enhance safety through damage tolerant aircraft design and the development of crashworthy aircraft concepts, hence reduce the accident rate in case of survivable crash scenarios Reduce development cost and time to market for the aircraft Develop FE methods for enabling the incorporation of composites into the primary structures to optimise weight saving
Simulation of Aircraft Response to High Velocity Impact Scenarios Objective - to develop FE methods and tools to predict the response of aircraft structure to high velocity impacts in order to improve design methodology for enhanced safety Emphasis on Verification of methods and models through Test
Typical Impactors hailstone Birdstrike Tyre Runway Debris Engine Debris
Typical Impacted Structures Wing Leading Edge htp/vtp Front Spar Wing Access Panels
Building Block Approach characterise impactor characterise target material characterise joints undertake pre-strike simulations conduct impact tests undertake post-strike simulations
Characterisation of Impactors Comparison of x-strain for Flexible Plate Test strain 8 6 4 2 0 0-2 0.001 0.002 0.003 0.004 0.005-4 Time (sec) Test Data Lagrangian Model (AIRBUS UK) Runway Debris Bird Strike
Tyre Impactor 0.016 Strain 0.014 0.012 0.01 0.008 0.006 0.004 SG1 SG2 SG3 SG4 ice/hailstone impactor 0.002 0-0.002-0.004-1.0-0.8-0.6-0.4-0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 Time (msecs)
Joint Testing N
BIRD STRIKE EXAMPLE metallic
Pre-strike Simulations SPH Method
Bird Strike Test Programme
Post Test Simulation (AIRBUS UK) Comparison of Analysis and Test for Low Speed Bird Strike Axial Strain History at Position No. 3 10 5 milli-strain 0 0.000-5 0.005 0.010 0.015-10 Pre-Test Measured -15-20 Time (s)
spread in material properties loading conditions manufacturing defects failure modes (uncertainties) -methods reviewed and new methods proposed -deterministic reference shots identified -stochastic simulations underway
Simulation of Transport Aircraft Crashworthiness Environment Objective - generate a load database for the cabin environment (accelerations, velocities, displacements, forces, etc) by crash simulation of full-scale A/C models Acceleration-time histories at the attachment points of cabin furniture will be used for the prediction of their behaviour under crash loads and pre-normative design criteria will be developed with the aim to improve passenger survivability and to reduce fatality rates in survivable crashes
Background Data Accidents Fatalities 12% 46% 13% 24% 16% 14% 19% Duration Accident occurring during take-off and landing : most frequent... but most survivable (AIRBUS FRANCE)
AIRCRAFT TYPE DATE DESCRIPTION REPORTED DAMAGES ATR 72-500 06/11/00 During landing several bird strikes occurred AIRCRAFT TYPE At first inspection, performed by crew, 3 impacts were found (windshield and engines intakes). Propellers have been inspected, impact damages have been found on five blades, on engines intakes and stabilizer. There were no injuries. DATE DESCRIPTION REPORTED DAMAGES ATR 72 08/08/00 In kish island airport the aircraft hit a deer on its landing run. The impact caused damage to nose landing gear, gear door and skin aft of the landing gear bay. There were no injuries.
TEAM 1: Commuter Aircraft Models Using KRASH CRANFIELD IMPACT CENTRE Commuter type A/C (ATR42) KRASH model Material data Fuselage Section Properties Section Mass Distribution etc ATR-42 KRASH Model
TEAM 2: A321 Crash Models (AIRBUS FRANCE) Full Scale Model of A321 Ditching Simulations Using SPH Inlet/Outlet Module MECALOG
TEAM 3: A321, A340 and A380 Crash Models (AIRBUS GERMANY) A321 Rigid Ditching Model
LOCAL/GLOBAL APPROACH TO CRASH MODELLING
Overview of CRAHVI Project Output from CRAHVI Models for materials, joints, impactors and surfaces for use in FE simulations to enable accurate representation of structure behaviour subjected to high velocity impact Bird models for use in FE simulations and the development of substitute material for the bird FE methods to simulate flying debris (tyre and engine debris, stone, hail) impacts on metallic and composite structures
Overview of CRAHVI Project Stochastic methods in aircraft impact simulation Innovative EA design methods for composite leading edge structures Local/global and FE methods for determining structural loading of a complete aircraft under realistic crash conditions Generate a load database (accel, vel, disp, forces) for cabin environment which can be used for the design of innovative cabin safety features with the aim to improve passenger safety Experimental data generated from tests will be valuable for further research in this area
CRAHVI CRashworthiness of Aircraft for High Velocity Impact