wichita state university Mechanical Engineering Department National Institute For Aviation Research College of Engineering
Spacer


Bulkhead Testing
Component HIC   Frontal Crash Analysis Landing Gear Analysis
Soft Soil Impact
Water Impact
Child-Restraint Systems
Side-facing Seats
Seat Cushion
Pedestrian Impact
Research Grants


 Impact Dynamics Lab
Comp Mech Lab


Hamid Lankarani
Researchers
Doctorial Students
Masters' Students
Alumni


 Journals
Conference Proceedings
Technical Reports

 

Spacer

DESIGN GUIDELINES FOR SIDE FACING AIRCRAFT SEATS
 

 

ABSTRACT

            A series of side facing seat impact sled tests were conducted using the SID, EuroSID-1 and BioSID side impact Anthropomorphic Test Dummies  (ATDs) at the FAA Civil Aeromedical Institute (CAMI).  The tests were performed on a side facing sofa fixture with a rigid bulkhead adjacent to the forward end of the seat.  The purpose of the research project was to examine the methods utilized by the automobile industry to assess thoracic injuries due to side impact accidents, and to investigate the potential applicability of these methods for side facing seats and sofas in civil aircraft.  Tests were conducted with single and double occupants.   The test conditions complied with the 16g 44 f/s horizontal impact specified in 14 CFR 25.562.  Various side impact injury criteria were evaluated in the tests, including the Thoracic Trauma Index (TTI), Viscous Criteria (VC), rib deflection and pelvis acceleration.  Analysis of the data acquired from the tests and observations related to injury parameters from the three ATDs are presented.  Seating and restraint system configurations that indicated potential improvements in occupant protection for side facing seats were also identified.

INTRODUCTION

            One of the objectives of FAA’s regulations for dynamic seats is to provide occupant protection from the serious injuries most likely to occur as the result of a survivable accident.  The regulation applies to all seats occupied during takeoff or landing, including side facing seats and sofas.   The injury criteria specified in regulation 14 CFR 25.562 were developed with the primary focus on forward facing seats.  No specific guidelines for the certification of side facing seats are included in the pass/fail criteria published in the regulation. 

            FAA’s Advisory Circular (AC) 25.562 prescribes test procedures and documentation that are considered as acceptable means of compliance with the regulation for dynamic seats in transport category aircraft.  The AC states:   "The injury criteria of 14 CFR 25.562 are not adequate to demonstrate the equivalent safety of side facing seats. To demonstrate equivalent safety fully in the absence of such specified criteria, the applicant must use other injury criteria which may be derived from the automotive industry, which uses side impact anthropomorphic test devices or dummies (ATDs)."   The AC does not specify a method of compliance nor the injury pass-fail criteria for side facing seats.

            Another relevant regulation, 14 CFR 25.785, mandates: "Each seat, berth, ...designated as occupiable during takeoff and landing must be designed so that a person making proper use of these facilities will not suffer serious injury in an emergency landing as a result of the inertia forces specified in §25.561 and §25.562."  In order to provide a level of protection consistent with forward facing seats, it may be necessary to consider potential serious injuries unique to the side facing seat environment.

            It is important to note that, although AC 25.562 suggests the use of criteria from the automotive industry, the situation for aircraft side facing seats is quite different from the automotive side impact protection environment.  Automobile side impact protection is based on an accident scenario involving a stationary vehicle being struck on the door by another vehicle.  The force of the impact on the door results in deformation and intrusion of the door into the passenger compartment.  The side impact ATD seated adjacent to the struck door is exposed to the forces and energy from the encroachment of the door structures. 

            Aircraft seat dynamic performance is evaluated by a test procedure that exposes the seat, ATD, and proximal structures to an impact pulse.  There is no requirement to evaluate the effects of fuselage intrusion.  Thus, contact injuries are assessed by the flail motion of the ATD as it strikes a seat back, instrument panel, wall, or other furnishing included in the dynamic test.

The purpose of the research presented in this report is to evaluate the various injury assessment methods available with automobile side impact ATDs, when tested by the methods prescribed for aircraft seats.  Comparison of the responses and injury criteria measured from the distinctly different ATDs may indicate whether any (or all) of the ATDs provide results that could be used to establish performance standards for side facing seats in airplanes.  

 SIDE IMPACT ATDS AND INJURY CRITERIA

            The side impact ATDs used by the automotive industry in dynamic testing includes Side Impact Dummy (SID), European Side Impact Dummy (EuroSID-1) and Biofidelic Side Impact Dummy (BioSID).  A comparison between these three ATDs outlining their important features is made in Table 1.  Figure 1 shows the instrumentation of the side impact ATDs. 

Table 1.  Comparison of side impact ATDs – (SID, EuroSID-1 and BioSID)

SID

(Side Impact Dummy - Part 572)

EuroSID-1

(European Side Impact Dummy)

BIOSID

(Biofidelic Side Impact Dummy)

·         Developed by University of Michigan Transport Research Institute (UMTRI) for NHTSA in 1979

·         Developed by APR, INRETS, TNO AND TRL in 1989

·         Developed by SAE in 1989

·         Modified Hybrid II

·         Chest Includes

·         A hydraulic shock absorber linked to five interconnected steel ribs to the spine

·         No arms

·         From earlier EuroSID-1 (1986)

·         Chest includes

·         Three Ribs attached to spine by piston-cylinder assembly and spring-damper system

·         Uses Hybrid III components, but is otherwise a new design.

·         Chest design is based on “far side” mounted rib concept.

·         One arm on struck side

·         Major Biofidelic deficiencies are the lack of shoulder load path, no elasticity in the thoracic compliance and a very heavy rib mass

·         The side impact response of EuroSID-1 ATD provides closer approximation of cadaver response but lower plateau force and more compliance needed for human-like response

·         BIOSID can measure required thoracic and pelvis injury potential as well as rib deflection and other compression based injury criteria

·         Used for automotive side impact tests and FMVSS 214 standard test.

·         Used for side impact ATD tests for the draft European side impact Regulation (ECE) 95.

·         Used for evaluating advanced automotive side impact restraint systems

 

                                        

SID                                                            EuroSID-1                                                BioSID

Figure 1.  Side Impact ATDs instrumentation

The automotive industry has developed injury criteria that are used to evaluate the potential for occupant injuries in automobile side impact accidents.  Several of these injury criteria have been adopted as regulatory requirements by the government authorities for automobile regulations of various countries. Others have been used solely for research purposes.  In the US, the SID ATD is specified in 14 CFR 572 subpart F, and the side impact test requirements for automobiles is defined in 14 CFR 214 (which is commonly referred to as Federal Motor Vehicle Safety Standard 214, or FMVSS-214).  These injury criteria warrant careful examination to determine if they may be useful as a means of evaluating potential injuries in side facing aircraft seats.  A comprehensive list of these potential injury criteria are listed in the following:

Pelvis Acceleration

The potential for pelvis fracture is evaluated by measuring the lateral acceleration of the pelvis.  This acceleration must not exceed 130 G's.

Thoracic Trauma Index (TTI)

The TTI is an acceleration-based criterion, which is based on the maximum value of the nearside rib and spinal accelerations, irrespective of differences in time of occurrence, to determine an average acceleration response of the ATD. The Thoracic Trauma Index, TTI, as measured by a side impact ATD should not exceed 85g.  This limit corresponds to AIS (Abbreviated Injury Scale) of 3, which is indicative of serious injury to the thoracic region.  The formula for calculating TTI is:

TTI = ˝ (RIBG + T12G)

Where: 
RIBG is the larger of the peak acceleration of the upper or the lower rib (chest) in G's,
T12G is the peak acceleration of the 12 thoracic or the lower spine in G's.

Viscous Criteria (V*C)

VC is evaluated from the product of the velocity of deformation and the instantaneous compression of the chest region of ATD.

V*C =

Where:
D is deflection of the rib(s) or chest,
 is velocity of deformation of the rib(s) or chest,
To is half of undeformed width of the torso or chest.

(V*C) is a measure of the soft tissue injury induced by excessive deformation of the chest. It is rate sensitive and corresponds to potential injuries that are not addressed by compression criteria. 

Rib Deflection

The lateral compression of rib-to-spine deformation should not exceed 1.6-in. (42 mm).

Pubic symphysis forces

As measured by the EuroSID-1 ATD, not to exceed 2,250 lb. (10 KN).

Lateral abdominal forces

As measured by the EuroSID-1 ATD, not to exceed 560 lb. (2.5 KN).

Lateral neck moments

As measured by BIOSID or Hybrid III, not to exceed 354 in-lb. (40 N-m).

Lateral neck forces

As measured by BIOSID or Hybrid III, not to exceed 250 lb. (1.1 KN).

Head Injury Criteria (HIC)

HIC shall not exceed 1000. It is defined as 

Where:        

a(t) is the instantaneous resultant acceleration of head CG in G's, and
t1 and t2 are times in the pulse which maximize the HIC value.

Lumbar Compressive load

Measured between the pelvis and the lumbar column not to exceed 1,500 lb. (7 KN).

Femur load

The axial compressive load in each femur of the ATD shall not exceed 2,250 lb. (10KN).

Shoulder Strap Load

For a three-point restraint system, the tension in the shoulder strap must not exceed 1,750 lb. (7.8 KN).

SIDE FACING SEAT RESEARCH PROGRAM

            The rational used to develop the test protocol is shown in the Figure 2, and a summary test matrix is presented in Table 2.  A preliminary test series was conducted to study occupant kinematics and establish a baseline for occupant modeling. The results of these tests indicated that the following conditions required further study:

1.       Occupant interaction with a barrier (Test # A96107).
2.       Occupant to occupant interactions (Test # A96108).
3.       The effect of padding on the barrier (Test # A96123).

           A preliminary model was then developed by the National Institute for Aviation Research using the occupant simulation software MADYMO to arrive at the test matrix.  A series of sled tests were conducted based on this at CAMI.  The dynamic side facing seat tests were conducted at CAMI using their horizontal deceleration type impact sled, shown schematically in Figure 3.  A typical deceleration pulse is shown in Figure 4.

 

Figure 2.  Methodology for Side facing aircraft seat research program 


                 


    Figure 3.  Schematic of CAMI sled test facility           Figure 4.  Typical deceleration pulse at CAMI

            The impact tests were conducted in a horizontal orientation with no yaw angle between the seat and the impact vector.  The test severity was in accordance with the 16 Gpk horizontal test condition specified in 14 CFR 25.562. A 3-place rigid couch with no energy absorbing features was used.  A rigid impact barrier made from a 0.5-in. (12.7 mm) thick aluminum plate with multiple I-beam back supports was installed at the forward end of the couch to represent an interior cabin wall.  The three point restraints, with a lap belt and shoulder harness of polyester webbing were used for all the tests. 

            A SID, EuroSID-1 and BioSID ATDs were used during the single occupant tests.  The distance between the ATD and the rigid wall barrier was varied according to the range of couch sizes expected in aircraft.  A Hybrid II ATD was used during the double occupant tests to assess the effects of occupant-to-occupant contact. Figure 5 shows the typical sled test setup configuration.

 

Figure 5.  Typical sled test setup configuration 


SIDE FACING SEAT TESTS WITH SID

            The first series of tests were performed using the SID.  The goals of these tests were to determine the effect of the ATD spacing and belt configuration on pelvic acceleration and TTI.  These tests were broadly classified into three sets:

1.       From A97055-60 with single occupant SID ATD

2.       A97061-64 was two-occupant, with SID sitting beside the barrier, and

3.      A97065-67 was two-occupant, with HII sitting beside the barrier.  A summary of all the test and their results is presented in 
      Table 2, with the test configurations shown in Figure 6.

             Each configuration was repeated three times to allow statistical analysis of the data. The data channels that were collected from this test include: pelvic acceleration, shoulder and right lap belt forces, upper chest, lower chest and lower spine accelerations for evaluating TTI.  Head acceleration responses were acquired for evaluating HIC.  Tests A97055-057 (single occupant with ATD centerline distance to barrier – 15-in. (0.38-m)) and A97058-060 (single occupant with ATD centerline distance to barrier – 12-in. (0.30m)) were conducted to assess scatter in the test results.  Statistical analysis was performed using a standard T test, normal distribution, and a 90% confidence level.  It was found from the calculations that 90% of the tests run with these parameters will have a TTI falling into the interval of 91 < m  < 101.  For the series A97058-60 similar analysis was performed which resulted in a interval of 57 < m  < 70, and predicts that 90% of tests run in this condition fall into this interval.

            The variation of pelvic acceleration and TTI for the tests A97055-60 as a function of the distance of the SID ATD to the barrier is shown in Figure 7.  It is evident that the pelvic acceleration was much lower than the severe injury level (130 g) for both the distances to the barrier. For a 15-in. (0.38-m) barrier distance TTI value exceeded 130 g.  The change of the distance of the barrier to 12-in. (0.30-m) reduced TTI well below the severe injury benchmark.

 

                            

SID                                           SID and Hybrid II                                                Hybrid II and SID

Figure 6.  Single and multi-occupant tests with SID

Table 2. Summary of SFS tests with SID

CAMI  Test #

ATD Type & Order

Distance to Barrier (in.)

Distance Between ATDs (in.)

Lap Belt Spacing (in.)

Max Pelvic Accel. (G's)

TTI  (G's)

HIC

A96107

SID

15.75

n/a

20.5

101

95

--

A96108

SID & HII

15.75

19

20.5,20.5

134

107

--

A96123

SID

15.75

n/a

20.5

--

72

--

A97055

SID

15

n/a

30

92.7

93.5

1872

A97056

SID

15

n/a

30

84.1

96.9

1851

A97057

SID

15

n/a

30

108.5

99.7

2206

A97058

SID

12

n/a

24

87.3

60.6

1825

A97059

SID

12

n/a

24

94.9

62.9

1957

A97060

SID

12

n/a

24

80.8

67.8

2196

A97061

SID & HII

12

24

24,24

89.8

62.2

1433

A97062

SID & HII

12

18

21,21

93.1

64.1

1442

A97063

SID & HII

12

18

21,21

86.8

68.5

1711

A97064

SID & HII

9

18

18,18

35.3

32.9

1451

A97065

HII & SID

9

21

18,24

47.5, 53.3

--, 61.4

--, 1916

A97066

HII & SID

9

24

18,30

48.9, 68.5

--, 79.1

300, 1061

A97067

HII & SID

12

24

24,24

107, 54.9

--, 103.9

1840, 4252

                                 *  All the tests except A96123 utilize a rigid impact barrier  


          

Figure 7. Variation of Pelvic acceleration and TTI for different distance to the barrier

            For the tests from A97061-64, the measured responses were below the injury thresholds.  It may be inferred that as the distance between the ATD and wall, the distance between adjacent ATDs, and lap belt anchor spacing decreases, the acceleration values are lowered.  For the subsequent tests ATD positions were interchanged to evaluate the body-to-body impact TTI as the SID is instrumented for one side impact only.  The TTI value resulting from body to body contact was above the threshold for test A97067 which had the greatest spacing. 

            Note that HIC results were above the injury tolerance threshold for all the cases.  Although the primary focus of this effort was directed to thoracic injury criteria, the HIC results indicate that cabin interior designers must carefully consider the location of structures placed forward of a side facing seat.

SIDE FACING SEAT TESTS WITH EuroSID-1

            Based on the results acquired using SID, the second phase of testing was planned using EuroSID-1. In addition to Thoracic Trauma Index (TTI) and pelvis acceleration, which was acquired with the previous SID tests, the EuroSID-1 provided:

1.      Rib deflection data to compute the Viscous Criteria (V*C) injury assessment for the thorax. The ATD has three rib deflection 
      potentiometers and thus three data channels are used to compute V*C.

2.       Pubic force compression load and the lateral abdominal force. 

            The test setup was replicated from previous tests with the SID.  EuroSID-1 was tested with a rigid barrier, padded with of 1-in. (25.4-mm) thick IV3 foam.  For two-occupant tests, a Hybrid II ATD was seated next to EuroSID-1, with the two ATDs shoulder’s touching each other.  The last two tests utilize a body-centered belt.  The detailed test matrix is shown in Table 3 and the test configurations are shown in Figure 8.

            It may be inferred from the test data that the effect of padding resulted in lower acceleration values of ribs and pelvis, with no significant effect on the rib deflections.  In general, it was observed that the rib deflections are relatively high in the tests with normal belt configurations, with some tendency to plateau.  However, the viscous criteria was below the threshold of 1m/s as shown in Figure 9.  From this data, it seems that the occupant is exposed to a longer duration of rib compression than seen in a typical automotive FMVSS 214-test. 

            To reduce the lateral excursion of the occupant, subsequent tests were conducted with a “body-centered” belt in which the forward lap belt was anchored behind the pelvis.  The shoulder harness anchorage was centered behind the neck as shown in Figure 10.  With the centerline of ATD at a distance of 16-in (0.41-m) from the wall, the “body-centered” restraint reduced the lateral movement of the ATD to the extent that there was no significant torso contact with the wall.  Photometric analysis of the ATDs motion revealed that the pelvis translated laterally approximately 6 inches (0.15m) and did not contact the barrier.  The upper torso motion was limited by the upper torso restraint and interaction of the shoulder with the barrier.  There was no indication of rib contact with the wall.  This configuration demonstrated the potential to minimize the acceleration, compression, and force based criteria.

                                       

                Padded wall                           Unpadded wall                               Multi-occupant                                Body-centered Belt

Figure 8.  Single and multi-occupant testing with EuroSID-1

Table 3.  Summary of EuroSID-1 test results

CAMI

Test #

ATD Type & order

Distance toBarrier

(in.)

Distance

b/wATD 

(in.)

Lap Belt Spacing 

(in.)

Max.Pelvic Accel (G's)

TTI

 (G's)

Rib Deflections (mm)

V*Cmax3

  (m/s)

Upper Rib

Middle Rib

Lower Rib

A980051

EuroSID

15.75

N/A

21

105

64.9

45.0

39.9

36.8

0.74

A980062

EuroSID

15.75

N/A

21

150

81.8

50.2

39.7

36.5

0.93

A98007

EuroSID &  HII

15.75

19.5

21, 20

150

86.6

55.9

44.5

40.0

0.99

A98008

EuroSID &  HII

12.00

19.0

21, 21

77

44.5

59.0

46.2

40.9

0.68

A98009

EuroSID

19.00

N/A

10

33.8

44.7

0

0

0

-

A98010

EuroSID

16.00

N/A

10

45.2

46.7

1.5

0

-

-

    1 Padded  wall of 1-in. (25.4 mm) thick IV3 foam.
    2 Rigid barrier 
     3 Maximum value of upper, middle and lower rib is considered

 


     

Figure 9.  Rib deflections and viscous criteria from EuroSID-1 tests

 

 

                              

Figure 10.  Body-centered Belt configuration

            One interesting observation was evident from comparison of TTI values from similar test conditions. TTI results from the SID and EuroSID-1 were consistent, but a slightly lower for EuroSID-1 tests.  This may be attributed to the arm and shoulder structures that differ between the two ATDs.  The high rib deflections acquired from the Eurosid-1 ATD were a concern, and may be a more relevant injury criteria than V*C or TTI for side facing aircraft seats.  Moreover, it may also be a means of assessing the effects of occupant-to-occupant contact issues.

            The force based criteria such as the pubic and the abdominal forces are well below the threshold value of 2250 lb. (10KN) and 560 lb. (2.5 KN) respectively in all the tests.

SIDE FACING SEAT TESTS WITH BioSID

            Tests with the BioSID were replicas of the earlier tests with SID and EuroSID-1 ATDs.  In addition to TTI, pelvis acceleration, rib deflections and viscous criteria the BioSID also provided:

1.       Iliac force.
2.       Upper neck moment in x-direction and force in y-direction
3.       Larger rib deflection measurements capability (up to 75 mm) compared to EuroSID-1. 

Four single-occupant sled tests were conducted.  Tests were conducted with padded rigid bulkheads and the body-centered belt configuration.  The summary of all tests is tabulated in Table 4 and the test setups are shown in Figure 11.

   

 Padded wall                           Unpadded wall

Figure 11.  Single-occupant testing with BioSID

Table 4.  Summary of BioSID test results.

CAMI Test #

ATD Type & order

Dist. To barrier (in.)

Lap Belt Spacing (in.)

Max.Pelvic Accel (G’s)

TTI  (G’s)

Rib Deflections (mm)

Viscous Criteria3 (m/s)

Upper Rib

Middle Rib

Lower Rib

A98011

BioSID

16.00

10

34.5

74.2

11.9

-

7.5

0.12

A98012

BioSID

16.00

10

35.0

74.5

9.7

-

8.9

0.1

A980141

BioSID

15.75

21

119.0

78.8

48.0

-

50.5

1.1

A980152

BioSID

15.75

21

83.4

67.3

52.7

-

54.5

1.14

1 Rigid barrier 
2 Padded  wall of 1-in. (25.4 mm) thick IV3 foam.
 3 Maximum value of upper, middle and lower rib is considered

When BioSID's rib and spine accelerations are compared to the other ATDs, as shown in Figure 12, the BioSID exhibited similar peak rib accelerations and TTI values to that of EuroSID-1.  The responses presented in Figure 12 show the overall response, however, is quite different, with the BioSID producing high frequency  oscillations and less damping compared to the EuroSID-1.  The test with a 1-in. (25.4 mm) thick IV3 foam on the barrier resulted in lower rib and pelvic accelerations as observed earlier with EuroSID-1 and SID tests.  An increase in rib deflections and V*C were also produced.  These results are consistent with other studies that found that padding decreases acceleration levels, but increases the deformation.  The probable reason is the padding affects an earlier contact with the thorax and a longer duration impact.  In general it was observed that the rib deflections and V*C exhibited by BioSID are higher than EuroSID-1. 

            One reason for higher rib deflection and V*C acquired from the BioSID is that the non-articulating shoulder design causes the arm to transfer load to the ribs, rather than rotating partially out of the way as on the EuroSID-1.  When tested with the body centered belt configuration, lateral translation of the BioSID’s pelvis was similar to that seen with the EuroSID-1.  Rib deflections were larger than those acquired with the EuroSID-1, but were well below the injury threshold.  Also, the upper neck moments and HIC values were well above the injury thresholds for all tests with the BioSID.

Comparison of ATD Responces

            Dynamic tests under similar set of configurations using SID, EuroSID-1 and BioSID ATD were compared in terms of peak values for the critical injury parameters such as pelvic acceleration, TTI, rib deflections and viscous criteria.  The comparisons are shown in Figure 13. The description of each test configuration is presented in the figure.  The following observations have been made from these data.

            

 Figure 12.  Comparison of sled test SID, EuroSID-1 and BioSID rib acceleration profiles

                    

                                    (a) Pelvic Acceleration                                                                                                                (b) TTI 

                                                   

                                            (c) Rib deflection                                                                                                      (d) Viscous Criteria

Figure 13.  Comparison of peak injury parameters for all three ATDs

1.       TTI results from similar test conditions with the SID, EuroSID-1 and BioSID were consistent with the SID being somewhat higher than the other two.

2.       TTI and pelvic acceleration are very much dependent on the distance to the barrier or the relative speed generated to the barrier.  For the cases that contact with the wall or bulkhead occur, a critical ATD centerline distance of 12-in. (0.30-m) or less resulted in TTI and pelvic acceleration below injury criteria limits.

3.       For tests with normal restraints, the rib deflections were in general quite large, while the V*C data was near the pass/fail threshold in most cases.  This suggests that rib deflections may be a more relevant injury criteria than the V*C for aircraft occupant injury evaluation on side facing seats.

4.       Effects of body-to-body contact seem to be the most challenging part of injury evaluation.  Acceleration-based injury criteria did not exhibit conclusive evidence of a cause-effect relationship with body-to-body contact.

5         Some belt configuration designs, such as the body-centered lap belt with a shoulder attachment behind the ATD neck were investigated that demonstrated reasonable potential to minimize the compression, acceleration and force based injury criteria.

6         Although the peak rib acceleration values nominally agree, the BioSID has sharp spikes in its upper and lower rib accelerations when compared to the EuroSID-1 data.  The BioSID exhibited less than desired durability in the tests accomplished.  The shoulder rib used in this series of tests was an older design that permanently deformed on every test with side contact.

             The purpose of the research project was to examine the methods utilized by the automobile industry to assess thoracic injuries due to side impact accidents, and to investigate the potential applicability of these methods for side facing seats and sofas in civil aircraft.  This knowledge may be used to develop crashworthiness standards for side facing seats.  The following conclusions can be made from this study:

1.       Limiting acceleration and compression based injury criteria seem to require different and sometimes conflicting seat designs requirements.  Acceleration based criteria are sensitive to relative velocity of impact and the stiffness of the object impacted.  These tests showed that pelvic accelerations are below the injury threshold if the ATD centerline 15-in. (0.38-m) or less from a rigid barrier. Likewise TTI is below the threshold if the ATD centerline is 12-in. (0.30-m) or less.  Both of these criteria are below the threshold for an ATD seated up to 15.75-in. (0.40-m) from a barrier with 1-in. (25.4 mm) of IV3 padding on it.  These findings indicate that a seat design that places an occupant close to a padded supporting wall would be desirable.

2.       In contrast with conclusion 1 above, limiting rib compression-based criteria to acceptable levels requires an opposite approach.  Compression-based criteria are sensitive to the energy transmitted to the rib cage.  The padding used in this project had little affect on rib compression.  Avoidance of contact with the wall was the only effective means of preventing rib compression demonstrated by the tests in this project.  The “body centered restraint” prevented the ATDs ribs from making significant contact with a barrier that was 16-in. (0.41-m) from the ATD centerline.  This design also limited the acceleration-based criteria to acceptable levels.  Other means of limiting the load on the ribs, such as an energy-absorbing wall, may also be useful in meeting both types of injury criteria.

3.       Attempts to quantify the effects of body-to-body contact were not conclusive.  When the H-II ATD was placed aft of the SID or EuroSID-1, both the acceleration and compression based criteria tended to be somewhat higher.  However, limitations in the design of all current side impact dummies, which are only biofidelic when struck from one side at a time, prevent proper assessment of the potential for injures resulting from body-to-body contact.  Further study using occupant-modeling codes may yield the information sought.

4.       Although not a specific focus of this study, other modes of injury were indicated in some of the tests.  The Head Impact Criteria (HIC) and neck lateral moments measured both significantly exceeded their injury thresholds on most tests. To provide an equivalent level of safety, side facing seating systems may need to address these types of potentially serious injures.

5.       The EuroSID-1 was found capable of reliably measuring the desired injury criteria.  During the conduct of this program, the EuroSID-1 was found to be durable, repeatable, and provide data that correlated well with the other side impact ATDs.  The SID was less suitable, because it lacks the ability to measure rib deflection.  It also did not provide accurate lateral flail response when restrained by only belts.  This is primarily due to lack of a clavicle for the shoulder belt to bear on.  The BioSID was also not suitable, since lack of a second arm and the "farside" spine design prevents its use in evaluating body to body contact.  Durability of the BioSID is also a concern.  Repairs were necessary after each test with the BioSID.  There was also concern about the noisy nature of the acceleration data produced by the BioSID ATD.

The analytical results using MADYMO for SID, EuroSID-1 and BioSID ATD is in progress and will be a subject of future work.

Copyright© 2001. All Rights Reserved.
Last modified on 08/20/01
Site Created by Anupama Keshavan
Send Comments and Suggestions to lankaran@me.twsu.edu