§ 572.133 - Neck assembly and test procedure.

§ 572.133 Neck assembly and test procedure.

(a) The neck assembly (refer to § 572.130(a)(1)(ii)) for the purposes of this test consists of the assembly of components shown in drawing 880105-250.

(b) When the head-neck assembly consisting of the head (drawing 880105-100X), neck (drawing 880105-250), bib simulator (drawing 880105-371), upper neck adjusting bracket (drawing 880105-207), lower neck adjusting bracket (drawing 880105-208), six-axis neck transducer (drawing SA572-S11), and either three accelerometers (drawing SA572-S4) or their mass equivalent installed in the head assembly as specified in drawing 880105-100X, is tested according to the test procedure in subsection (c) of this section, it shall have the following characteristics:

(1) Flexion.

(i) Plane D, referenced in Figure O1, shall rotate in the direction of preimpact flight with respect to the pendulum's longitudinal centerline between 77 degrees and 91 degrees. During the time interval while the rotation is within the specified corridor, the peak moment, measured by the neck transducer (drawing SA5572-311), about the occipital condyles may not be less than 69 N-m (51 ft-lbf) and not more than 83 N-m (61 ft-lbf). The positive moment shall decay for the first time to 10 N-m (7.4 ft-lbf) between 80 ms and 100 ms after time zero.

(ii) The moment shall be calculated by the following formula: Moment (N-m)= M_y−(0.01778m) × (F_x).

(iii) M_y is the moment about the y-axis, F_x is the shear force measured by the neck transducer (drawing SA572-S11), and 0.01778m is the distance from force to occipital condyle.

(2) Extension.

(i) Plane D, referenced in Figure O2, shall rotate in the direction of preimpact flight with respect to the pendulum's longitudinal centerline between 99 degrees and 114 degrees. During the time interval while the rotation is within the specified corridor, the peak moment, measured by the neck transducer (drawing SA5572-S11), about the occipital condyles shall be not more than −53 N-m (−39 ft-lbf) and not less than −65 N-m (−48 ft-lbf). The negative moment shall decay for the first time to −10 N-m (−7.4 ft-lbf) between 94 ms and 114 ms after time zero.

(ii) The moment shall be calculated by the following formula: Moment (N-m) = M_y − (0.01778m) × (F_x).

(iii) M_y is the moment about the y-axis, F_x is the shear force measured by the neck transducer (drawing SA572-S11), and 0.01778 m is the distance from force to occipital condyle.

(3) Time-zero is defined as the time of initial contact between the pendulum striker plate and the honeycomb material. All data channels shall be at the zero level at this time.

(c) Test Procedure. The test procedure for the neck assembly is as follows:

(1) Soak the neck assembly in a controlled environment at any temperature between 20.6 and 22.2 °C (69 and 72 °F) and a relative humidity between 10 and 70 percent for at least four hours prior to a test.

(2) Torque the jam nut (drawing 9000018) on the neck cable (drawing 880105-206) to 1.4 ±0.2 N-m (12.0 ±2.0 in-lb).

(3) Mount the head-neck assembly, defined in subsection (b) of this section, on the pendulum described in Figure 22 of 49 CFR 572 so that the midsagittal plane of the head is vertical and coincides with the plane of motion of the pendulum as shown in Figure O1 for flexion tests and Figure O2 for extension tests.

(4)

(i) Release the pendulum and allow it to fall freely from a height to achieve an impact velocity of 7.01 ±0.12 m/s (23.0 ±0.4 ft/s) for flexion tests and 6.07 ±0.12 m/s (19.9 ±0.40 ft/s) for extension tests, measured by an accelerometer mounted on the pendulum as shown in Figure 22 of 49 CFR 572 at the instant of contact with the honey comb.

(ii) Stop the pendulum from the initial velocity with an acceleration vs. time pulse which meets the velocity change as specified below. Integrate the pendulum acceleration data channel to obtain the velocity vs. time curve:

Table B - Pendulum Pulse

Time ms	Flexion		Extension
	m/s	ft/s	m/s	ft/s
10	2.1-2.5	6.9-8.2	1.5-1.9	4.9-6.2
20	4.0-5.0	13.1-16.4	3.1-3.9	10.2-12.8
30	5.8-7.0	19.5-23.0	4.6-5.6	15.1-18.4

[65 FR 10968, Mar. 1, 2000, as amended at 67 FR 46414, July 15, 2002]