Title 49

SECTION 572.212

572.212 Head assembly and test procedure.

§ 572.212 Head assembly and test procedure.

All assemblies and drawings referenced in this section are contained in Drawings and Specifications, incorporated by reference, see § 572.210.

(a) The head assembly for this test consists of the complete head (drawing 020-1200) with head accelerometer assembly (drawing 020-1013A), and a half mass simulated upper neck load cell (drawing 020-1050).

(b) When the head assembly is tested according to the test procedure in paragraph (c) of this section, it shall have the following characteristics:

(1) Frontal head qualification test. When the head assembly is dropped from a height of 376.0 ± 1.0 mm in accordance with paragraph (c) of this section, the peak resultant acceleration at the location of the accelerometers at the head CG shall have a value between 255 G and 300 G. The resultant acceleration vs. time history curve shall be unimodal; oscillations occurring after the main pulse must be less than 10 percent of the peak resultant acceleration. The lateral acceleration shall not exceed 15 G (zero to peak).

(2) Lateral head qualification test. When the head assembly is dropped from a height of 200.0 ± 1.0 mm in accordance with paragraph (c) of this section, the peak resultant acceleration at the location of the accelerometers at the head CG shall have a value between 114 G and 140 G. The resultant acceleration vs. time history curve shall be unimodal; oscillations occurring after the main pulse must be less than 10 percent of the peak resultant acceleration. The X-component acceleration shall not exceed 15 G (zero to peak).

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

(2) Prior to the test, clean the impact surface of the skin and the impact plate surface with isopropyl alcohol, trichloroethane, or an equivalent. The skin of the head and the impact plate surface must be clean and dry for testing.

(3)(i) For the frontal head test, suspend and orient the head assembly with the forehead facing the impact surface as shown in figure W1 in appendix A to this subpart. The lowest point on the forehead must be 376.0 ± 1.0 mm from the impact surface. Assure that the head is horizontal laterally. Adjust the head angle so that the upper neck load cell simulator is 28 ± 2 degrees forward from the vertical while assuring that the head remains horizontal laterally.

(ii) For the lateral head test, the head is dropped on the aspect that opposes the primary load vector of the ensuing full scale test for which the dummy is being qualified. A left drop set up that is used to qualify the dummy for an ensuing full scale left side impact is depicted in figure W2 in appendix A to this subpart. A right drop set-up would be the mirror image of that shown in figure W2. Suspend and orient the head assembly as shown in figure W2. The lowest point on the impact side of the head must be 200.0 ± 1.0 mm from the impact surface. Assure that the head is horizontal in the fore-aft direction. Adjust the head angle so that the head base plane measured from the base surface of the upper neck load cell simulator is 35 ± 2 degrees forward from the vertical while assuring that the head remains horizontal in the fore-aft direction.

(4) Drop the head assembly from the specified height by means that ensure a smooth, instant release onto a rigidly supported flat horizontal steel plate which is 50.8 mm thick and 610 mm square. The impact surface shall be clean, dry and have a surface finish of not less than 0.2 microns (RMS) and not more than 2.0 microns (RMS).

(5) Allow at least 2 hours between successive tests on the same head.