Anthropomorphic Test Dummy; Side Impact Protection |
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Topics: National Highway Traffic Safety Administration
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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