(a) Upper/lower torso assembly. The test objective is to determine the stiffness effects of the lumbar spine (drawing 880105-1096), and abdominal insert (drawing 880105-434), on resistance to articulation between the upper torso assembly (drawing 880105-300) and the lower torso assembly (drawing 880105-450) (refer to §572.130(a)(1)(iv)).

(b)

(1) 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 O4 according to the test procedure set out in subsection (c) of this section, the lumbar spine-abdomen assembly shall flex by an amount that permits the upper torso assembly to translate in angular motion relative to the vertical transverse plane 45 ±0.5 degrees at which time the force applied must be not less than 320 N (71.5 lbf) and not more than 390 N (87.4 lbf), and

(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) Soak the dummy in a controlled environment at any temperature between 18.9 and 25.6 °C (66 and 78 °F) and a relative humidity between 10 and 70 percent for at least four hours prior to a test.

(2) 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 O4.

(3) 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 horizontal.

(4) Attach the loading adapter bracket to the spine of the dummy as shown in Figure O4.

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

(6) Flex the dummy's upper torso three times between the vertical and until the torso reference plane, as shown in Figure O4, 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.

(7) 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 O4. The initial orientation angle may not exceed 20 degrees.

(8) Attach the pull cable and the load cell as shown in Figure O4.

(9) Apply a tension force in the midsagittal plane to the pull cable as shown in Figure O4 at any upper torso deflection rate between 0.5 and 1.5 degrees per second, until the angle reference plane is at 45 ±0.5 degrees of flexion relative to the vertical transverse plane.

(9) Continue to apply a force sufficient to maintain 45 ±0.5 degrees of flexion for 10 seconds, and record the highest applied force during the 10-second period.

(10) 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 (6) 3 minutes after the release.