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Anthropomorphic Test Dummy; Side Impact Protection

American Government Special Collections Reference Desk

American Government Topics:  National Highway Traffic Safety Administration

American Government Topics:  National Highway Traffic Safety Administration

Anthropomorphic Test Dummy; Side Impact Protection

Christopher A. Hart
Federal Register
October 14, 1994

[Federal Register: October 14, 1994]


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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Part 572

[Docket No. 94-49, Notice 01]
RIN 2127-AE84

 
Anthropomorphic Test Dummy; Side Impact Protection

AGENCY: National Highway Traffic Safety Administration (NHTSA), DOT.

ACTION: Correcting amendment.

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SUMMARY: This document corrects several of the accelerometer 
specifications (including mounting locations) in NHTSA's regulation for 
the side impact test dummy (SID) and in the drawings and user's manual 
for the SID. This action removes a potential source of concern and 
confusion for SID manufacturers and users. It is intended to ensure 
that there is no question among SID manufacturers and users as to 
whether a particular SID meets the specifications of NHTSA's SID 
regulation, and the drawing and specifications package.

DATES: The changes made in this rule are effective October 14, 1994. 
The incorporation by reference of the publications listed in this 
document is approved by the Director of the Federal Register as of 
October 14, 1994.

FOR FURTHER INFORMATION CONTACT: Mr. Stan Backaitis, Office of Vehicle 
Safety Standards, National Highway Traffic Safety Administration, 400 
Seventh Street SW., Washington, D.C. 20590. Telephone: (202) 366-4912.

SUPPLEMENTARY INFORMATION: On October 30, 1990, NHTSA published a rule 
that established dynamic side impact protection requirements for 
passenger cars. (See, final rule amending Federal Motor Vehicle Safety 
Standard No. 214, Side Door Strength, 49 CFR 571.214; 55 FR 45722.) The 
requirements, which became effective September 1, 1993, improve crash 
protection by limiting the amount of impact force that may be imposed 
on an occupant's thorax and pelvis in a crash.

    The amount of force is determined from measurements of 
accelerometer sensors mounted in a side impact dummy, or ``SID.'' The 
SID is specially designed for measuring forces that would be imposed on 
the thorax and pelvis regions of an adult male 50th percentile size 
occupant. At the time of the amendment to Standard 214, specifications 
for the SID were added to NHTSA's test dummy regulation (see, 49 CFR 
part 572, subpart F).

    The specifications provide that the SID is instrumented with four 
accelerometers to assess imposed impact forces. Three accelerometer 
sensors are mounted in the dummy's thorax, and provide acceleration 
values used in determining the ``Thoracic Trauma Index (TTI(d)).'' 
TTI(d) is an injury criterion that measures the risk of thoracic injury 
of a passenger car occupant in a side impact. The fourth accelerometer, 
mounted in the pelvic cavity, measures the potential risk for pelvic 
injury. To meet Standard 214's side impact protection requirements, the 
TTI(d) and pelvis measurements must be below specified maximum values.
Need for Correction
    This document makes several corrections to the accelerometer 
specifications in part 572 and in the drawings and the user's manual 
for the SID.
    NHTSA was very specific in describing in part 572, subpart F, the 
location of the four accelerometers in the SID. However, location 
descriptions for two sets of accelerometers do not allow sufficient 
space for their mounting. This has engendered confusion among SID 
manufacturers. The regulation specifies that one of the thoracic 
accelerometers (T12 spine) is positioned on an accelerometer mounting 
platform that is attached to the dummy (Sec. 572.44(b)(1)). The 
platform is attached such that the accelerometer's ``seismic mass 
center'' (which was approximately at the center of the device) is up to 
0.4 inches from a specified reference point on a part of the dummy 
called the ``thorax to lumbar adaptor.'' Two dummy manufacturers, FTSS 
and Vector Research, informed NHTSA that the accelerometer's seismic 
mass center cannot be located precisely at the specified position. 
Instead, the accelerometer has to be placed about 0.2 inches from that 
position.
    The regulation also specifies a precise location for the pelvic 
accelerometer (Sec. 572.44(c)). The current regulation specifies that 
the seismic mass center of this accelerometer is mounted at a location 
0.9 inches upward and 0.5 inches to the left of a reference point (the 
centerline of a mounting bolt) and 0.4 to 0.5 inches rearward of the 
rear wall of the instrument cavity. Vector Research and First 
Technology Safety Systems said that, due to lack of available space, 
the seismic mass center cannot be located as specified using the mount 
depicted in dummy drawing SID-087, because the mass center is 0.87 
inches (instead of 0.9 inches) upward and 0.67 inches (instead of 0.5 
inches) to the left of the mounting bolt. Thus, the accelerometer will 
be slightly lower and slightly left of the currently specified 
position.
    This document corrects the specifications for locating the T12 
spinal and pelvic accelerometers. The corrections amount to a few 
fractions of an inch. The dimensional adjustments are needed to account 
for imprecision in the way the agency initially measured the exact 
location of accelerometers for the part 572 subpart F regulation. SID 
manufacturers are concerned that, unless the part 572 subpart F 
specifications are corrected, customers might complain that the problem 
with accelerometer placement is with their particular SID, instead of 
the specifications. NHTSA is adjusting the appropriate specifications 
in part 572 subpart F to avoid this potential source of complaint and 
confusion. NHTSA is also providing tolerances for placement of the 
seismic mass centers of the accelerometers, to avoid the implication 
that insignificant variation from the specified locations renders a 
particular SID unsuitable for the applicable crash test.
    This corrections does not impose any additional responsibilities on 
any manufacturer and has virtually no effect on the performance of the 
accelerometers. Computer generated simulations to determine the effect 
of changing the location of the accelerometers showed that, in a 17.3 
and a 25 mile per hour impact, a change of 0.5 inches from the current 
location results in only about a 0.6 percent difference in the T12 
spine peak g, and only about a 0.2 percent difference in the pelvic 
peak g accelerations. A report of the mathematical simulations has been 
placed in the docket.
    This document also makes other minor corrections to the 
specifications for the T12 spine and pelvic accelerometer. As mentioned 
above, Sec. 572.44(b)(1) of part 572 subpart F specifies the position 
of the T12 spine accelerometer relative to the Thorax to Lumbar Adaptor 
on the SID. However, that section also specifies that the accelerometer 
is to be attached to a particular type of accelerometer mount. This 
specification implies that the mount is a required part of the SID. 
This is a erroneous and contrary to NHTSA's aims to free the dummy 
specifications from unnecessary design restrictions. Accordingly, NHTSA 
is making a correcting amendment to Sec. 572.44(b)(1) to remove 
reference to a specific accelerometer mount in determining the location 
of the T12 spine accelerometer. Instead, that section is changed to 
specify that the accelerometer is positioned relative to a reference 
point on the dummy (the centerline of a mounting hole in the SID thorax 
lumbar adaptor assembly). The new method of locating the accelerometer 
to a reference point places the accelerometer in the same position as 
originally specified, but without reference to the Endevco product.
    This document also adds a specification to Sec. 572.44(c) that 
allows the locating and mounting of the pelvic accelerometer for right 
side impacts. Part 572 subpart F specified a location that was 
appropriate for left side impacts, but none for the right side. The new 
location specification for right side impact assures that the 
accelerometer is located the same distance to the right of the 
midsagittal plane as is the left side accelerometer to the left of the 
midsagittal plane for left side impacts. The symmetrical location of 
the right and left accelerometers relative to the midsagittal plane 
will assure that the dummy will respond the same regardless of whether 
the impact is produced from the left or the right sides.

Housekeeping Amendments

    This document also makes minor corrections to the specifications 
for the SID in the SID drawings and specifications package (including 
the SID user's manual).
    The agency is adding the word ``reference,'' or the abbreviation 
``ref.,'' at various places in the SID drawing and specifications 
package to indicate that a specified item is depicted or listed for 
illustration purposes only, and is not a mandatory part of the dummy. 
For example, the package refers occasionally to a specific type and 
design of accelerometer (i.e., the Endevco 7265) and accelerometer 
mount. E.g., drawing SID M001A depicts a mount designed specifically 
for the Endevco 7264 accelerometer. Those items were originally 
specified simply to illustrate the use of a widely available 
accelerometer and its associated mount for the measurement of impact 
responses with the SID. The Endevco products were selected primarily 
because they were the only ones with which the agency had experience in 
the development of the SID dummy and in the evaluation of the side 
impact protection standard (FMVSS No. 214; 49 CFR 571.214). However, 
NHTSA is concerned that references in the drawings to the Endevco 
accelerometer and its mount might be misunderstood as if implying that 
this particular type and design of accelerometer product must be used. 
To the contrary, NHTSA did not intend to preclude SID users from 
employing other suitable accelerometers and mounts comparable and/or 
equivalent to the Endevco models. Accordingly, the agency is adding the 
word ``reference'' to several items in the drawings (e.g., SID M001A 
and the parts lists) to avoid this possible source of confusion and to 
indicate that those items are not mandatory parts of the dummy. The 
word ``equivalent'' is being used in some drawings to indicate that 
other makes than those shown may be used provided that they meet space, 
mass, mounting and performance requirements in the impact environment 
as the referenced part.
    There are several other items that are depicted or listed in the 
SID drawing and specifications package as though they were mandatory 
parts of the dummy. For each of these, NHTSA is adding ``reference'' to 
indicate that they are not integral parts of the dummy, but may be used 
if the testing facility chooses to make those specific impact response 
measurements. For example, drawing SID-M001 shows the SID as having an 
accelerometer in the head, yet at no time is the head acceleration on 
the SID used for compliance purposes. The illustration was based on the 
SID that was used for research purposes, and which had an accelerometer 
installed in the dummy's head. To correct the possible impression that 
the SID must be instrumented with a head accelerometer, NHTSA is adding 
``reference'' on the drawings that depict the accelerometer, to 
indicate that the device is not a mandatory part of the dummy.
    This notice also corrects several inconsistencies primarily in 
drawing SID-M001A. For example, the drawing does not show an installed 
thoracic accelerometer that is required for the SID under part 572 
subpart F, Sec. 572.41(a). This and several other minor adjustments in 
the drawings and in the users manual are summarized below.

Drawing Revisions

    Dummy assembly drawing SA-SID-M0001A is revised as follows (these 
revisions are reflected in drawing ``SA-SID-M001A revision A,'' which 
replaces drawing SID-M001A):

1. Accelerometers shown in item 21 are identified as ``Endevco 7264 
(Reference) or Equivalent;''
2. Appropriate picture notation is added to indicate the attachment of 
accelerometers (ref. item 21) on the ribs and on the thorax-lumbar 
spine adaptor;
3. The word ``reference'' is added to call-out boxes of accelerometer 
mounts SID-036, SID-037, SID-038, SID-039 and 78051-54;
4. A note on the weight table is added to read: ``The weights of body 
segments shown reflect also the masses of accelerometers and 
accelerometer mounts, where appropriate:''

    Drawing SID-087: Drawing SID-087 sheet 1 is revised to remove all 
references to the ``Endevco 7264 or equivalent'' accelerometer and its 
mounting. (Drawing ``SID-087 sheet 1 revision H, dated May 18, 1994'' 
replaces drawing SID-087 sheet 1.)
    Drawing SID-090: Drawing SID-090 is removed from the drawing 
package.
    Drawing SID-005: Geometric tolerances are added. (Drawing ``SID-005 
revision F,'' replaces drawing SID-005.)
    Parts Lists: SA-SID-M001, SA-SID-M030, SA-SID-M050 and SA-SID-M060 
are revised to reflect the changes described above. (SA-SID-M001 is 
replaced by ``SA-SID-M001 revision B.'' The latter three drawings are 
replaced with revised drawings which are dated May 18, 1994 and denoted 
``revision A.'')

Users Manual Revisions

    The revised users manual is dated May 1994.
    1. The paragraphs that reference accelerometer use are moved from 
sections 1.3.06, 1.3.08, 1.3.10 to Accelerometer section 1.4.9. All 
accelerometers in 1.4.9 will be specified as ``Endevco 7264 or 
equivalent'' without the word ``reference.''
    2. The positioning and locations of all accelerometers are referred 
to the revised language used in Sec. 572.44, including Figures 30 and 
31.
    3. The word ``reference'' is added to all accelerometer mounts.
    4. The parts list is revised as noted in the ``Drawing Revisions'' 
section.
    5. Appropriate Figures are replaced, in line with the changes 
described herein.
    This document does not impose any additional responsibilities on 
any vehicle or SID manufacturer. Instead, this document corrects 
several minor omissions and inconsistencies in the October 1990 rule. 
This document simply removes a potential source of concern and 
confusion for SID manufacturers. It also ensures that there is no 
question among SID manufacturers and purchasers as to whether a 
particular SID meets the specifications of part 572 subpart F and 
associated the drawing and specifications package. Accordingly, NHTSA 
finds for good cause that notice and an opportunity for comment on this 
document are unnecessary, and that this rule should be effective upon 
publication.

List of Subjects in 49 CFR Part 572

    Motor vehicle safety, Incorporation by reference.

    In consideration of the foregoing, NHTSA amends 49 CFR Part 572 as 
follows:

PART 572--[AMENDED]

    1. The authority citation for Part 572 continues to read as 
follows:

    Authority: 49 U.S.C. 322, 30111, 30115, 30117 and 30166; 
delegation of authority at 49 CFR 1.50.

Subpart F--Side Impact Dummy 50th Percentile Male

    2. In section 572.41, paragraphs (a) introductory text, (a)(3) 
through (a)(5), and (c) are revised to read as follows:


Sec. 572.41  General description.

    (a) The dummy consists of component parts and component assemblies 
(SA-SID-M001 revision B and SA-SID-M001A revision A, dated May 18, 
1994) which are described in approximately 250 drawings and 
specifications that are set forth in Sec. 572.5(a) with the following 
changes and additions which are described in approximately 85 drawings 
and specifications (incorporated by reference; see Sec. 572.40):
* * * * *
    (3) The thorax assembly consists of the assembly shown as number 
SID-053 and conforms to each applicable drawing subtended by number SA-
SID-M030 revision A, dated May 18, 1994.
    (4) The lumbar spine consists of the assembly specified in subpart 
B of this part (Sec. 572.9(a)) and conforms to drawing SA 150 M050 and 
drawings subtended by SA-SID-M050 revision A, dated May 18, 1994.
    (5) The abdomen and pelvis consist of the assembly specified in 
subpart B of this part (Sec. 572.9) and conform to the drawings 
subtended by SA 150 M060, the drawings subtended by SA-SID-M060 
revision A, dated May 18, 1994, and the drawings subtended by SA-SID-
087 sheet 1 revision H, dated May 18, 1994, and SA-SID-087 sheet 2 
revision H.
* * * * *
    (c) Disassembly, inspection, and assembly procedures; external 
dimensions and weight; and a dummy drawing list are set forth in the 
Side Impact Dummy (SID) User's Manual, dated May 1994 (incorporated by 
reference; see Sec. 572.40).
    3. In section 572.42, paragraph (a) introductory text is revised to 
read as follows:


Sec. 572.42  Thorax

    (a) When the thorax of a completely assembled dummy (SA-SID-M001A 
revision A, dated May 18, 1994, incorporated by reference; see 
Sec. 572.40), appropriately assembled for right or left side impact, is 
impacted by a test probe conforming to Sec. 572.44(a) at 14 fps in 
accordance with paragraph (b) of this section, the peak accelerations 
at the location of the accelerometers mounted on the thorax in 
accordance with Sec. 572.44(b) shall be:
* * * * *
    4. In section 572.43, paragraph (a) is revised to read as follows:


Sec. 572.43  Lumbar spine and pelvis.

    (a) When the pelvis of a fully assembled dummy (SA-SID-M001A 
revision A, dated May 18, 1994, incorporated by reference; see 
Sec. 572.40) is impacted laterally by a test probe conforming to 
Sec. 572.44(a) at 14 fps in accordance with paragraph (b) of this 
section, the peak acceleration at the location of the accelerometer 
mounted in the pelvis cavity in accordance with Sec. 572.44(c) shall be 
not less than 40g and not more than 60g. The acceleration-time curve 
for the test shall be unimodal and shall lie at or above the +20g level 
for an interval not less than 3 milliseconds and not more than 7 
milliseconds.
* * * * *
    5. In section 572.44, paragraphs (b)(1) and (c) are revised to read 
as follows:


Sec. 572.44  Instrumentation and test conditions.

* * * * *
    (b) * * *
    (1) One accelerometer is mounted on the thorax to lumbar adaptor 
(SID-005 revision F, dated May 18, 1994, incorporated by reference; see 
Sec. 572.40) with seismic mass center located 0.5 inches toward the 
impact side, 0.1 inches upward and 1.86 inches rearward from the 
reference point shown in Figure 30 in appendix A to subpart F of part 
572. Maximum permissible variation of the seismic location must not 
exceed 0.2 inches spherical radius.
* * * * *
    (c) One accelerometer is mounted in the pelvis for measurement of 
the lateral acceleration with its sensitive axis perpendicular to the 
pelvic midsagittal plane. The accelerometer is mounted on the rear wall 
of the instrumentation cavity of the pelvis (SID-087 revision H, dated 
May 18, 1994, incorporated by reference; see Sec. 572.40). The 
accelerometer's seismic mass with respect to the mounting bolt center 
line is 0.9 inches up, 0.7 inches to the left for left side impact and 
0.03 inches to the left for right side impact, and 0.5 inches rearward 
from the rear wall mounting surface as shown in Figure 31 in appendix A 
to subpart F of part 572. Maximum permissible variation of the seismic 
location must not exceed 0.2 inches spherical radius.
* * * * *
    6. An appendix A is added to subpart F to read as follows:

Appendix A to Subpart F of Part 572--Figures

BILLING CODE 4910-59-P






    Issued on September 23, 1994.
Christopher A. Hart,
Deputy Administrator.
[FR Doc. 94-24054 Filed 10-13-94; 8:45 am]
BILLING CODE 4910-59-C

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