[Code of Federal Regulations]
[Title 16, Volume 2]
[Revised as of January 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 16CFR1203.17]
[Page 221-223]
TITLE 16--COMMERCIAL PRACTICES
CHAPTER II--CONSUMER PRODUCT SAFETY COMMISSION
PART 1203--SAFETY STANDARD FOR BICYCLE HELMETS--Table of Contents
Subpart A--The Standard
Sec. 1203.17 Impact attenuation test.
(a) Impact test instruments and equipment.
(1) Measurement of impact attenuation. Impact attenuation is
determined by measuring the acceleration of the test headform during
impact. Acceleration is measured with a uniaxial accelerometer that is
capable of withstanding a shock of at least 1000 g. The helmet is
secured onto the headform and dropped in a guided free fall, using a
monorail or guidewire test apparatus (see Figure 9 of this part), onto
an anvil fixed to a rigid base. The center of the anvil shall be aligned
with the center vertical axis of the accelerometer. The base shall
consist of a solid mass of at least 135 kg (298 lb), the upper surface
of which shall consist of a steel plate at least 12 mm (0.47 in.) thick
and having a surface area of at least 0.10 m\2\ (1.08 ft\2\).
(2) Accelerometer. A uniaxial accelerometer shall be mounted at the
center of gravity of the test headform, with the sensitive axis aligned
within 5 degrees of vertical when the test headform is in the impact
position. The acceleration data channel and filtering shall comply with
SAE Recommended Practice J211 OCT88, Instrumentation for Impact Tests,
Requirements for Channel Class 1000.
(3) Headform and drop assembly--centers of gravity. The center of
gravity of the test headform shall be at the center of the mounting ball
on the support assembly and within an inverted cone having its axis
vertical and a 10-degree included angle with the vertex at the point of
impact. The location of the center of gravity of the drop assembly
(combined test headform and support assembly) must meet the
specifications of Federal Motor Vehicle Safety Standard No. 218,
Motorcycle Helmets, 49 CFR 571.218 (S7.1.8). The center of gravity of
the drop assembly shall lie within the rectangular volume bounded by
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x=-6.4 mm (-0.25 in.), x=21.6 mm (0.85 in.), y=6.4 mm (0.25 in.), and
y=-6.4 mm (-0.25 in.), with the origin located at the center of gravity
of the test headform. The origin of the coordinate axes is at the center
of the mounting ball on the support assembly. The rectangular volume has
no boundary along the z-axis. The positive z-axis is downward. The x-y-z
axes are mutually perpendicular and have positive or negative
designations as shown in Figure 10 of this part. Figure 10 shows an
overhead view of the x-y boundary of the drop assembly center of
gravity.
(4) Drop assembly. The combined mass of the drop assembly, which
consists of instrumented test headform and support assembly (excluding
the test helmet), shall be 5.00.1 kg (11.000.22
lb).
(5) Impact anvils. Impact tests shall be performed against the three
different solid (i.e., without internal cavities) steel anvils described
in this paragraph (a)(5).
(i) Flat anvil. The flat anvil shall have a flat surface with an
impact face having a minimum diameter of 125 mm (4.92 in.). It shall be
at least 24 mm (0.94 in.) thick (see Figure 11 of this part).
(ii) Hemispherical anvil. The hemispherical anvil shall have a
hemispherical impact surface with a radius of 481 mm
(1.890.04 in.) (see Figure 12 of this part).
(iii) Curbstone anvil. The curbstone anvil shall have two flat faces
making an angle of 105 degrees and meeting along a striking edge having
a radius of 15 mm0.5 mm (0.590.02 in.). The
height of the curbstone anvil shall not be less than 50 mm (1.97 in.),
and the length shall not be less than 200 mm (7.87 in.) (see Figure 13
of this part).
(b) Test Procedure.
(1) Instrument system check (precision and accuracy). The impact-
attenuation test instrumentation shall be checked before and after each
series of tests (at least at the beginning and end of each test day) by
dropping a spherical impactor onto an elastomeric test medium (MEP). The
spherical impactor shall be a 146 mm (5.75 in.) diameter aluminum sphere
that is mounted on the ball-arm connector of the drop assembly. The
total mass of the spherical-impactor drop assembly shall be
5.00.1 kg (11.00.22 lb). The MEP shall be 152 mm
(6 in.) in diameter and 25 mm (1 in.) thick, and shall have a durometer
of 602 Shore A. The MEP shall be affixed to the top surface
of a flat 6.35 mm (\1/4\ in.) thick aluminum plate. The geometric center
of the MEP pad shall be aligned with the center vertical axis of the
accelerometer (see paragraph (a)(2) of this section). The impactor shall
be dropped onto the MEP at an impact velocity of 5.44 m/s2%.
(Typically, this requires a minimum drop height of 1.50 meters (4.9 ft)
plus a height adjustment to account for friction losses.) Six impacts,
at intervals of 7515 seconds, shall be performed at the
beginning and end of the test series (at a minimum at the beginning and
end of each test day). The first three of six impacts shall be
considered warm-up drops, and their impact values shall be discarded
from the series. The second three impacts shall be recorded. All
recorded impacts shall fall within the range of 380 g to 425 g. In
addition, the difference between the high and low values of the three
recorded impacts shall not be greater than 20 g.
(2) Impact sites. Each of helmets 1 through 4 (one helmet for each
conditioning environment) shall impact at four different sites, with two
impacts on the flat anvil and two impacts on the hemispherical anvil.
The center of any impact may be anywhere on or above the test line,
provided it is at least 120 mm (4.72 in), measured on the surface of the
helmet, from any prior impact center. Each of helmets 5 through 8 (one
helmet for each conditioning environment) shall impact at one site on
the curbstone anvil. The center of the curbstone impacts may be on or
anywhere above the test line. The curbstone anvil may be placed in any
orientation as long as the center of the anvil is aligned with the axis
of the accelerometer. As noted in Sec. 1203.12(d)(1), impact sites, the
order of anvil use (flat and hemispherical), and curbstone anvil sites
and orientation shall be chosen by the test personnel to provide the
most severe test for the helmet. Rivets and other mechanical fasteners,
vents, and any other helmet feature within the test region are valid
test sites.
[[Page 223]]
(3) Impact velocity. The helmet shall be dropped onto the flat anvil
with an impact velocity of 6.2 m/s3% (20.34 ft/
s3%). (Typically, this requires a minimum drop height of 2
meters (6.56 ft), plus a height adjustment to account for friction
losses.) The helmet shall be dropped onto the hemispherical and
curbstone anvils with an impact velocity of 4.8 m/s3% (15.75
ft/s3%). (Typically, this requires a minimum drop height of
1.2 meters (3.94 ft), plus a height adjustment to account for friction
losses.) The impact velocity shall be measured during the last 40 mm
(1.57 in) of free-fall for each test.
(4) Helmet position. Prior to each test, the helmet shall be
positioned on the test headform in accordance with the HPI. The helmet
shall be secured so that it does not shift position prior to impact. The
helmet retention system shall be secured in a manner that does not
interfere with free-fall or impact.
(5) Data. Record the maximum acceleration in g's during impact. See
Subpart C, Sec. 1203.41(b).