(a) The test objective is to determine the stiffness of the molded lumbar assembly (drawing 420-4100), abdominal insert (drawing 420-4300), and chest flesh assembly (drawing 420-3560) on resistance to articulation between the upper torso assembly (drawing 420-3000) and lower torso assembly (drawing 420-4000) (all incorporated by reference, see §572.170).

(b) When the upper torso assembly of a seated dummy is subjected to a force continuously applied at the head to neck pivot pin level through a rigidly attached adaptor bracket as shown in Figure T5 according to the test procedure set out in paragraph (c) of this section:

(1) The lumbar spine-abdomen-chest flesh assembly shall flex by an amount that permits the upper torso assembly to translate in angular motion relative to the vertical transverse plane 35 ±0.5 degrees at which time the force applied must be not less than 180 N (40.5 lbf) and not more than 250 N (56.2 lbf).

(2) Upon removal of the force, the torso assembly must return to within 8 degrees of its initial position.

(c) Test Procedure. The test procedure for the upper/lower torso assembly is as follows:

(1) Torque the lumbar cable (drawing 420-4130) (incorporated by reference, see §572.170) to 0.9 ±0.2 N-m (8 ±2 in-lbf) and set the lumbar adjustment angle to 12 degrees. Set the neck angle to 16 degrees.

(2) Soak the dummy 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.

(3) Assemble the complete dummy (with or without the legs below the femurs) and attach to the fixture in a seated posture as shown in Figure T5.

(4) Secure the pelvis to the fixture at the pelvis instrument cavity rear face by threading four 1⁄4 -inch cap screws into the available threaded attachment holes. Tighten the mountings so that the test material is rigidly affixed to the test fixture and the pelvic-lumbar joining surface is 18 degrees from horizontal and the legs are parallel with the test fixture.

(5) Attach the loading adaptor bracket to the spine of the dummy as shown in Figure T5.

(6) Inspect and adjust, if necessary, the seating of the abdominal insert within the pelvis cavity and with respect to the chest flesh, assuring that the chest flesh provides uniform fit and overlap with respect to the outside surface of the pelvis flesh.

(7) Flex the dummy's upper torso three times between the vertical and until the torso reference frame, as shown in Figure T5, reaches 30 degrees from the vertical transverse plane. Bring the torso to vertical orientation and wait for 30 minutes before conducting the test. During the 30-minute waiting period, the dummy's upper torso shall be externally supported at or near its vertical orientation to prevent it from drooping.

(8) Remove all external support and wait two minutes. Measure the initial orientation angle of the torso reference plane of the seated, unsupported dummy as shown in Figure T5. The initial orientation angle may not exceed 20 degrees.

(9) Attach the pull cable and the load cell as shown in Figure T5.

(10) Apply a tension force in the midsagittal plane to the pull cable as shown in Figure T5 at any upper torso deflection rate between 0.5 and 1.5 degrees per second, until the angle reference plane is at 35 ±0.5 degrees of flexion relative to the vertical transverse plane.

(11) Continue to apply a force sufficient to maintain 35 ±0.5 degrees of flexion for 10 seconds, and record the highest applied force during the 10-second period.

(12) Release all force at the attachment bracket as rapidly as possible, and measure the return angle with respect to the initial angle reference plane as defined in paragraph (c)(7) of this section three minutes after the release.