SAE ARP 5765: Administration Federal Aviation Analytical .

SAE ARP 5765:Analytical Methodsfor Aircraft SeatDesign andEvaluationPresented to: IAFCSRCBy: David MoorcroftDate: 26 October 2010Federal AviationAdministration

Background AC 20-146: Methodology for Dynamic SeatCertification by Analysis for Use in Parts 23,25, 27, and 29 Airplanes and Rotorcraft– Signed in May 2003; allows simulation results to beused in support of seat certification– Provides high-level guidance on the validation ofseat models– Defines the conditions under which computermodeling can be used in support of certificationSAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluationFederal AviationAdministration22

SAE SEAT Committee Industry group that defines industry bestpractices (includes FAA & Academia)– Aviation Standard (AS)– Aviation Recommended Practice (ARP)– Aviation Information Reports (AIR) SAE ARP 5765: Analytical Methods forAircraft Seat Design and Evaluation– Being developed by a working group within theSEAT committee– Started in 2007SAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluationFederal AviationAdministration33

ARP 5765: GoalProvide a quantitative method to measure andevaluate the degree of correlation between amodel and a physical test, and to provide bestmodeling practices to improve the accuracyand predictability of seat analysesSAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluationFederal AviationAdministration44

SAE ARP 5765 Outline v-ATD Calibration– Establish v-ATD performance criteria Seat System Verification and Validation– How to evaluate the accuracy of seat models Seat Modeling Best Practice Guide– Testing– Modeling Appendices– Test-Simulation Comparison Methodology– Dataset for Hybrid II– Dataset for FAA-Hybrid IIISAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluationFederal AviationAdministration55

v-ATD Calibration (95% complete) Industry lacked multiple v-ATDs that producedaccurate results in aviation-specific scenarios.Goal: define the process for ensuring that vATDs match the anthropometry and kinematicperformance of a physical ATD for aviationspecific applications– Component Response (head, chest, knee, etc.)– Pelvic Shape Evaluation (cushion interaction)– Dynamic Response Forward Facing (FF) 2pt, FF 3pt, FF 4pt, Download– Appendices B & C: NIAR Test InformationSAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluationFederal AviationAdministration66

Dynamic Response Original component tests specifiedconsidering an automotive interiorNeed to evaluate the ATD performance forconditions likely in aircraft seat tests1.2.3.4.FF 2pt belt: extreme flail envelopeFF 3pt belt: torso twistFF 4pt belt: submariningDownload: vertical crash vectorSAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluationFederal AviationAdministration77

Channel DescriptionForwardFacing2-Point BeltXForwardFacing 60 Deg2-Point BeltXSled AxUpper Neck Fx *Upper Neck Fy *Upper Neck Fz *Upper Neck Mx *Upper Neck My *Chest Ax (CFC 180)Lumbar FzLumbar MyRight Lap Belt LoadXLeft Lap Belt LoadXRight Shoulder Belt LoadLeft Shoulder Belt LoadSeat Pan FxXSeat Pan FzXSeat Pan MyXHead CG X PositionXHead CG Z PositionXH-point X PositionXH-point Z PositionXKnee X PositionXKnee Z PositionXAnkle X PositionXAnkle Z PositionXShoulder X PositionShoulder Z PositionOpposite Shoulder X PositionOpposite Shoulder Z PositionHeadAngleSAEARP5765: Analytical Methods for AircraftXSeat Design andPelvis AngleXEvaluation* FAA-Hybrid III onlyForwardFacing3-Point BeltXXXXXXXForwardFacing4-Point al AviationAdministrationXX88

Comparison of Test-Sim Curves[Appendix A] Input:– Consistent units– Appropriate sampling rates 10 kHz for electronic instrumentation 1 kHz for photometric– Equal time lengths. Duration: onset of the test pulse throughsignificant system response, often dummymotion, as seen in the physical test.SAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluationFederal AviationAdministration99

Comparison of Test-Sim CurvesElectronic Data [Forces, Moments, Accelerations] Error on the PeakError PeakTest Peak SimPeakTest*100% Shape Error - Sprague and GeersComprehensive Error* Sprague MA and Geers TL. A Spectral-Element Method for Modeling Cavitation in TransientFluid-Structure Interaction. International Journal for Numerical Methods in Engineering. 60 (15),2467-2499. 2004.SAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluationFederal AviationAdministration1010

Comparison of Test-Sim CurvesMotion Data [Position, Angle] Coordinate Transformation Error on the Peak*Error PeakTest Peak Sim Shape Error - Sprague and GeersComprehensive Error* Sprague MA and Geers TL. A Spectral-Element Method for Modeling Cavitation in TransientFluid-Structure Interaction. International Journal for Numerical Methods in Engineering. 60 (15),2467-2499. 2004.SAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluationFederal AviationAdministration1111

Comparison of Test-Sim CurvesMotion Data [Position, Angle] Coordinate TransformationSAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluationFederal AviationAdministration1212

Example Data: Lap Belt LoadFF 3-pt Belt, 21g, Right Lap Belt Load3000Load ime (ms)SAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluation07324-807324-9Federal Aviation1307324-29AdministrationSim A13

Example Data: Lap Belt LoadFF 3-pt Belt, 21g, Right Lap Belt LoadError on Peak: 1%3000[Proposed Limit: 10%]Load (lbs)2500Shape Error: 9%2000[Proposed Limit: 10%]150010005000020406080100120140160180Time (ms)SAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluation07324-807324-9Federal Aviation1407324-29AdministrationSim A14

Example Data: Pelvic X MotionFF 2-pt Belt, 16g, Pelvic PositionPelvic Position (in)12.010.08.06.04.02.00.0050100150200Time (ms)SAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluation07324-407324-7Federal Aviation07324-28Sim A15Administration15

Example Data: Pelvic X Motion - OffsetFF 2-pt Belt, 16g, Pelvic PositionPelvic Position (in)8.07.06.05.04.03.02.01.00.0050100150200Time (ms)SAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluation07324-407324-7Federal Aviation07324-28Sim A16Administration16

Example Data: Pelvic X Motion - OffsetPelvic Position (in)FF 2-pt Belt, 16g, Pelvic Position8.0Delta Error: 1.5”7.0[Proposed Limit: 0.25”]6.0Shape Error: 22%5.0[Proposed Limit: 10%]4.03.02.01.00.0050100150200Time (ms)SAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluation07324-407324-7Federal Aviation07324-28Sim A17Administration17

Best Practices: Modeling (60% complete) Information needed to build aircraft specificmodels–––––––Global ParametersPhysical DiscretizationMaterial Definition (metals, foam, plastic)Contact DefinitionLoad ApplicationInitial Conditions (ATD positioning, pitch and roll)Output ControlSAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluationFederal AviationAdministration1818

Challenges in Finite Element Simulation Determining the proper degree of fidelity requiredin the model Fittings/Joints Interface between seats and aircraft attachment Restraints Cushion Models Floor Deformation Permanent Deformation Material Characterization Failure CriteriaSAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluationFederal AviationAdministration1919

Simulated Pitch and RollVideo courtesy of NIARSAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluationFederal AviationAdministration2020

Load Application – Sled Pulse R&D – use Factor of Safety Validation – match physical test Certification – ideal pulse or typical pulsefor your facilitySAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluationFederal AviationAdministration2121

Load Application – Sled PulsePartSeat Orient Vel G’sft/s23 Crew Horz422623 Crew Vert311923 Pass Horz422123 Pass Vert311525AllHorz441625AllVert351427/29 AllHorz42 18.4RTms5050606090807127/2931AllVert3030Calculated V2*RT ½ Vmsft/sft/s100 20.93 41.86100 15.30 30.59120 20.29 40.57120 14.49 28.98180 23.18 46.37160 18.03 36.06142 21.03 42.066214.97FederalAviation* Italic/Red: Calculated Velocity RequiredVelocityAdministrationSAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluation29.942222

Best Practices: Testing (95% complete) Provide guidance for things to considerduring test setup so that the necessaryinformation is collected to support modeling Modifications to typical test protocols tocollect quality data for modeling– Consistent ATD positioning Joint locations, pelvic angle– Belt information (material props, lengths, pre-tension)– Tips for photometric analysis H-pt KneeSAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluationFederal AviationAdministration2323

System Validation (10% complete) Ensure that the system (v-ATD, restraints,seat, etc.) behaves in a predictable manner Verification– Code– Calculation Validation– Materials– Component Test– Sensitivity Analysis DocumentationSAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluationFederal AviationAdministration2424

Future Work v-ATD Calibration: finalize limits, evaluatecurrent v-ATDs System Validation: refine and evaluateprocess Best Practices: develop and refine content ES-2?SAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluationFederal AviationAdministration2525

Contact Information Terence Lim – working group leader– Terence.Lim@airbus.com www.sae.org/servlets/works/committeeHome.do?comtID TEASEATSAE ARP 5765: Analytical Methods for Aircraft Seat Design andEvaluationFederal AviationAdministration2626

modeling practices to improve the accuracy. and predictability of seat analyses. Federal Aviation 5 5 Administration SAE ARP 5765: Analytical Methods for Aircraft Seat Design and Evaluation . International Journal for Numerical Methods in Engineering. 60 (15), 2467-2499. 2004. Federal Aviation. 12. 12