A Component Head Injury Criteria Tester for Aerospace ......A Component Head Injury Criteria Tester...

A Component Head Injury Criteria Tester for Aerospace

Applications

Hamid LankaraniNational Institute for Aviation Research

Wichita State UniversityEmail: [email protected]

Fire & Cabin Safety Research ConferenceAtlantic City, New Jersey

October 22-25, 2001

Fire & Cabin Safety Research Conference October 22 – 25, 2001

Problem Statement

The compliance with the Head Injury Criteria (HIC) poses a significant problem for aerospace industry

Where, a(t) is the head resultant acceleration of the Part 572 Hybrid IIATD in g’s and t1 and t2 are the response times to maximize the function.

Non injurious if: HIC < 1000

( ) ( )max

5.2t

t1212

2

1

)t(att

1ttHIC

∫−

−=

HIC problem encountered in:

Bulkhead Class Dividers Cabin Furnishings Cockpit Glare Shields Cabin Side Walls Row-to-Row Instrument Panel Entry Door Steps Wind Screen Posts/Side Posts


Problems Related To Dynamic Full-scale Sled Tests

Difficult to identify and test the critical conditionsSeveral test articles are destroyed to certify one test conditionRequire large flow timeInherent variations in sled test data may result in excessive HIC scatterAssociated with significant cost


Component Level Testers

Advantages Easier to setupShorter flow timeEffective product development tool Cost effectiveAppropriate for identifying critical impact location(s)

Validation CriteriaHICHIC window, ∆t = t2 – t1Average head C.G. accelerationGeneral form of the head acceleration time history

GoalDevelop an enhanced component test method as an alternate procedure to support HIC compliance for front row bulkhead seating


ATD Kinematics During a 16g Dynamic Test


Component HIC Test Devices


Evaluation of Component HIC Test Devices

The component HIC test devices provide reasonable correlation compared with the 16g dynamic full-scale sled tests only for

Configurations with dominantly normal head impact velocity (short distances to impact surface) Relatively short duration impacts(relatively hard surfaces) Properly utilized system effective masses

Factors affecting these differences may include:articulation of other body segments for the ATD belt compliance & motion (translation) of the pelvisfriction of the pelvic/seat and head/frontal-structure

The HIC window t = t2 – t1 is usually much smaller for all the component HIC testers compared to the results from dynamic sled tests


Methodology


Design of an Inverted Pendulum Device

Production Bulkhead

16.2 in.Length of Pendulum

63.5 lbSum of Upper Torso, Arms, and Hands

Seat Setback Seat Reference Point

Seat

Hybrid II Head-neck Assembly

Hybrid II ATD

Inverted Pendulum model

Revolute Joint

88.2 lbSum of Lower Torso, Upper and Lower Legs, and Feet

Inverted Pendulum ModelFull-scale Model


Qualification Test with Inverted Pendulum Setup


Comparison of Results


Adjustments in Design Based on Madymo Analysis

Hybrid II Head –neck Assembly

28.8 kg (63.5 lb)Sum of spine , Upper

Torso and Hands

40 kg (88.2 lb)Sum of Lower Torso , Upper

Lower Legs, and Feet

Hybrid II Head –neck Assembly

10 kg (22.2 lb)Pendulum Arm

64 kg (141.1 lb)Lower Torso

Initial design based on ATD weight distribution.

Weight distribution based on Madymo analysis.

Design Iteration/ Parametric Study

0.412 m (16.2 in.)

0.508 m (20 in.)


Final Design of the Component HIC Tester

Rear Torso

Support ArmHead Top Actuator

Pendulum Arm Actuator Stand

Linear Bearings

Sliding plateLower Torso

ProEngineer Model of Component HIC Tester


Fabricated Component HIC Tester

Support Arm Extension

Top Actuator

Support Arm

Top Actuator Stand

Pendulum Arm

Lower Torso

Slide Plate

Base Plate


Operation of NIAR’s Component HIC Tester

Mode:1Lower torso constrained in the forward directionLower torso allowed to snap backward at the time of impact and resisted by springs/dampers, or crushable honeycombOperated only by top actuator

Mode:2Fixed lower torso (similar to MGA device)Operated only by top actuator


Operating Methodology of Component HIC Tester


Component HIC Test Methodology – Flow Chart

Conduct a baseline dynamic sled test with Hybrid II ATD for a particular seat setback distance, restraint system and bulkhead

Note all the test setup conditionsCollect the evaluation criteria data from full-scale test like head C.G acceleration profile, head impact angle, head impact velocity, HIC window

Conduct a test with Component HIC tester in Mode-I/II condition with the same test conditions used for the full-scale sled test

Note all the test setup conditionsCollect all the critical data from component tester like head C.G acceleration profile, head impact angle, head impact velocity, HIC window

Compare the obtained data form sled test and component test for the evaluation criteria

Does data correlate?

Yes

No

Component HIC tester calibrated in Mode-I/II by checking for repeatability and for different seat setback distance, restraint system and bulkheads

Vary parameters such as actuator pressure, pendulum

arm length


MODE-I: Calibration Tests with Aluminum Bulkhead


Calibration of MODE-I Tests with Full-Scale Sled Test

Description Full-Scale Test#96288-004

CompHIC Test#01057-24


HIC 694 676 703 Head impact angle (deg) 38 37 37.5

Head impact velocity (fps) 45.1 41.0 44.0 HIC window (ms) 23.7 20.0 22.5

Head CG peak acceleration (g’s) 142.5 145.0 142.9

Head CG average acceleration (g’s) 61.0 64.0 62.5

2.78 2.79 2.8 2.81 2.82 2.83 2.84 2.85 2.86Time (s ec)

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HeadCGResultantAcceleration(g's)

S led Te s t Data (Tes t#96288-004)Component Te s t Data (Tes t#01057-24)S led Contact S tartS led Contact EndComponent Contact S tartComponent Contact Endtc1ts1ts2tc2

MODE-IValidation Tes t 01057-24(35 inch Seat S e tback, Aluminum 2024-O Bulkhead)

ts1=2.7925sec

TSe=2.8565sec

tc1=2.7924sec

TCs=2.8404sec

tc2=2.8124sec

ts2=2.8162sec

TCs=2.7924sec

TSs=2.7925sec

2.79 2.8 2.81 2.82Time (s ec)

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S led Tes t DataComponent Tes t DataTs1Ts2Tc1Tc2

MODE-IValidation Tes t 01057-24(35 inch Seat Setback, Aluminum 2024-O Bulkhead)

Ts1=2.7926sec

Ts2=2.8163sec

Tc1=2.7924sec

Tc2=2.8124sec


MODE-I Repeatability

1.49 1.495 1.5 1.505 1.51Time (s ec)

10

20

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Component Tes t#01057-24Component Tes t#01057-25

MODE-IRepeatability Tes t 01057-24 &Tes t 01057-25(35 inch S eat S e tback, Aluminum 2024-O Bulkhead)

Repeatability Plot

1.471.4751.481.4851.491.4951.51.5051.511.5151.521.5251.531.5351.541.5451.55Time (s ec)

10

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Component Tes t#01057-24Component Tes t#01057-25

MODE-IRepeatability Tes t 01057-24 &Tes t 01057-25(35 inch S eat S e tback, Aluminum 2024-O Bulkhead)


MODE-II: Calibration Tests with Aluminum Bulkhead

Full-Scale Sled Test#96288-004

Calibration Test#01057-28


Calibration of MODE-II Tests with Full-Scale Sled Test




HIC 694 677 700 Head impact angle (deg) 38 38 37

Head impact velocity (fps) 45 46 46 HIC window (ms) 23.7 24.3 29

Head CG peak acceleration (g’s) 142.5 142 139

Head CG average acceleration (g’s) 61 g 65.7 60

2.78 2.79 2.8 2.81 2.82 2.83 2.84 2.85 2.86Time (s ec)

0

10

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S led Tes t DataComponent Te s t DataS led Contact S tartS led Contact EndComponent Contact EndComponent Contact S tartts 1tc1ts 2tc2

MODE-IIValidation Tes t 01057-27(35 inch S eat S e tback, Aluminum 2024-O Bulkhead)

TSs=2.7925sec

TSe=2.8565sec

TCs=2.7925sec

TCe=2.8387sec

tc1=2.7925sec

ts1=2.7925sec

ts2=2.8162sec

tc2=2.8168sec

2.79 2.8 2.81 2.82Time (s ec)

0

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S led Tes t DataComponent Tes t DataTs1Ts2

MODE-IIValidation Tes t 01057-27(35 inch S eat S e tback, Aluminum 2024-O Bulkhead)

Ts1=2.7926sec

Ts2=2.8163sec


MODE-II Repeatability

Repeatability Plot


Comparison Of The Component HIC Test Data With MGA Test

CORRELATION OF MGA TEST 197011 AND NIAR ENHANCED COMPONENT HIC TEST 01057-25 WITH SLED TEST


MODE-I: Calibration Tests with Honeycomb Bulkhead

Full-Scale Sled Test# 01008-008

Calibration Test# 01057-43


MODE-I: Calibration Tests with Honeycomb Bulkhead




HIC 862 834 980 Head impact angle (deg) 38 38 38

Head impact velocity (fps) 44.0 40.3 41.0 HIC window (ms) 28.7 32.9 31.8

Head CG peak acceleration (g’s) 132.3 131.0 134.0

Head CG average acceleration (g’s) 61.0 58.0 62.5

3.18 3.2 3.22 3.24 3.26 3.28 3.3Time (s ec)

0

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HeadC.GresultantAcceleration(g's)

Component Tes t# 01057-43S led Tes t# 01008-008Ts1Ts2Tc1Tc2

Mode - IValidation Tes t 01057-43(35 in. s eat s e tback dis tance , Nomex Honeycomb pane l)

Ts1=3.200sec

Ts2=3.302sc

Tc1=3.2089sec

Tc2=3.2469sec

e c

3.18 3.2 3.22 3.24 3.26 3.28 3.3Time (s ec)

0

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HeadC.GresultantAcceleration(g's)

Component Te s tS led te s tS led Contact S tartS led Contact EndComponent Contact S tartComponent Contact Endts1ts2tc1tc2

Mode - IValidation Tes t 01057-43(35 in. s eat s e tback dis tance , Nomex Honeycomb pane l)

TSs=3.2000se

TSe=3.302sec

TCs=3.2089sec

TCe=3.2469sec

ts1=3.2000sec

ts2=3.2328sec

tc1=3.2089sec

tc2=3.2418sec


Pressure – Velocity Calibration Charts

25 30 35 40 45 50Head Impact Ve locity (ft/s ec)

90100110120130140150160170180190200210220230240250

ActuatorPressure(psi)

P = 0.2917V2 - 15.4996V +296.0768

25 30 35 40 45 50Head Impact Ve locity (ft/s e c)

60708090

100110120130140150160170180190200210220230240250260


P = 0.3471V2 - 18.6858V +322.0912


30405060708090

100110120130140150160170180190200


P = -0.0091V2 + 7.4019V -147.988

35 degrees 40 degrees 45 degrees

20 25 30 35 40 45 50Head Impact Ve locity (ft/s e c)

405060708090

100110120130140150160170180190200210220230240250260


P = 0.2538V2 - 10.5720V + 155.1803

25 30 35 40 45 50Head Impact Ve locity (ft/s ec)

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190


P = 0.0098V2 + 4.4262V - 60.0306


30405060708090

100110120130140150160170180190200210220230240250


P = 0.0871V2 + 1.6739V - 59.3593

50 degrees 55 degrees 60 degrees


Concluding Remarks

A component HIC tester was designed, fabricated and tested for aerospace applications.

Calibration of the device was conducted for aluminum and honeycomb-type bulkheads.

Preliminary tests of the NIAR component HIC tester have shownpromising results.

Pressure-velocity calibration charts have been developed. The charts are independent of the physical characteristics and surface treatment of the bulkhead.

Preliminary tests with aluminum bulkheads at small and large seat setback distances have indicated that the device can be used with reasonably good correlation in Mode-1 for small head impact angles (less than 40 degrees) and in Mode-II for high head impact angles (greater than 40 degrees).

The system will be enhanced to have a representation of the upper torso restraint system or at least calibrated for the presence of the upper torso system.


Concluding Remarks

A range of impact angles and velocities from the dynamic sled tests will be used for calibration of the device.

The system will also be evaluated for the seating configurations utilizingtypical airline seats rather than iron seats.

Other bulkhead types and surface treatments will also be considered and the system will be evaluated for these bulkhead types.

The system will also be calibrated for Part 23 applications.

Project will deliver a tool that can be utilized to easily identify potential solutions for bulkhead HIC problem.

The component HIC tester will offer the capability of evaluating different designs and/or test conditions at relatively low cost and short period of time.

Detailed test methodology and guidelines for the use of the system as an eventual compliance test method is being developed.

A Component Head Injury Criteria Tester for Aerospace ......A Component Head Injury Criteria Tester...

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