Title 49

SECTION 572.143

572.143 Neck-headform assembly and test procedure.

§ 572.143 Neck-headform assembly and test procedure.

(a) The neck and headform assembly (refer to §§ 572.140(a)(1)(ii) and 572.140(a)(1)(iii)) for the purposes of this test, as shown in Figures P2 and P3 of this subpart, consists of the neck molded assembly (drawing 210-2015), neck cable (drawing 210-2040), nylon shoulder bushing (drawing 9001373), upper mount plate insert (drawing 910420-048), bib simulator (drawing TE-208-050), urethane washer (drawing 210-2050), neck mounting plate (drawing TE-250-021), two jam nuts (drawing 9001336), load-moment transducer (drawing SA 572-S19), and headform (drawing TE-208-000).

(b) When the neck and headform assembly, as defined in § 572.143(a), is tested according to the test procedure in paragraph (c) of this section, it shall have the following characteristics:

(1) Flexion.

(i) Plane D, referenced in Figure P2 of this subpart, shall rotate in the direction of preimpact flight with respect to the pendulum's longitudinal centerline between 70 degrees and 82 degrees. Within this specified rotation corridor, the peak moment about the occipital condyle may not be less than 42 N-m and not more than 53 N-m.

(ii) The positive moment shall decay for the first time to 10 N-m between 60 ms and 80 ms after time zero.

(iii) The moment and rotation data channels are defined to be zero when the longitudinal centerline of the neck and pendulum are parallel.

(2) Extension.

(i) Plane D referenced in Figure P3 of this subpart shall rotate in the direction of preimpact flight with respect to the pendulum's longitudinal centerline between 83 degrees and 93 degrees. Within this specified rotation corridor, the peak moment about the occipital condyle may be not more than −43.7 N-m and not less than −53.3 N-m.

(ii) The negative moment shall decay for the first time to −10 N-m between 60 and 80 ms after time zero.

(iii) The moment and rotation data channels are defined to be zero when the longitudinal centerline of the neck and pendulum are parallel.

(c) Test procedure. (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 9001336) on the neck cable (drawing 210-2040) between 0.2 N-m and 0.3 N-m.

(3) Mount the neck-headform assembly, defined in paragraph (a) of this section, on the pendulum so the midsagittal plane of the headform is vertical and coincides with the plane of motion of the pendulum as shown in Figure P2 of this subpart for flexion and Figure P3 of this subpart for extension tests.

(4) Release the pendulum and allow it to fall freely to achieve an impact velocity of 5.50 ±0.10 m/s (18.05 + 0.40 ft/s) for flexion and 3.65 ±0.1 m/s (11.98 ±0.40 ft/s) for extension tests, measured by an accelerometer mounted on the pendulum as shown in Figure 22 of this part 572 at time zero.

(i) The test shall be conducted without inducing any torsion twisting of the neck.

(ii) Stop the pendulum from the initial velocity with an acceleration vs. time pulse which meets the velocity change as specified in Table B of this section. Integrate the pendulum acceleration data channel to obtain the velocity vs. time curve as indicated in Table B of this section.

(iii) Time-zero is defined as the time of initial contact between the pendulum striker plate and the honeycomb material. The pendulum data channel shall be zero at this time.

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