Document ID: chunk:federal_register_of_legislation:F2015C00542:reg:254:p1
Version: federal_register_of_legislation:F2015C00542
Segment Type: reg
Provision Reference: reg 254 (pt 1/18)
Character Range: 100848–103678

254             222 ± 12

 The deceleration curves should be based on a unimodel vibration. The deceleration curve of the drop height of 254 mm shall run at least 1.2 ms and at most 1.5 ms over 100 g.
               If the requirements given in paragraph 3.2.2.3. are not met, the elastic properties of the phantom head shall be adjusted by varying the thickness of the intermediate ring (13) in the base plate (24). Corrections can be carried out by adjusting the three self-locking hexagonal nuts (8) on the threaded bolts (16) with which the basin (18) is fixed to the base plate (24). The rubber rings (10) under the hexagon nuts (8) should not be brittle or cracked.

               The cover (19) of the impact surface and the intermediate ring (13) should always be replaced immediately if damaged, especially when the phantom head can no longer be adjusted.

              3.2.3. Supporting fixture for testing flat test pieces is as described in paragraph 3.1.3.

              3.2.4. Test conditions are specified in paragraph 3.1.4.

              3.2.5. Tests on complete glazing (used for a drop height between 1.5 m and 3 m). Place the glazing freely on a support with an interposed strip of rubber of hardness 70 IRHD and thickness of about 3 mm.

               The glazing shall be clamped to the supporting structure by means of appropriate devices. The surface of the glazing shall be substantia11y perpendicular to the incident direction of the headform weight. The headform weight shall strike the glazing at a point within 40 mm of its geometric centre on that face which represents the inward face of the plastic glazing when the latter is mounted on the vehicle, and shall be allowed to make only one impact.

               Starting from a selected initial drop height, the drop heights should be raised by 0.5 m respectively in each further experiment. The deceleration curves occurring on impact on the sample for ax, ay and az should be recorded according to time t.

               After the headform test, it should be checked whether a glazing edge has moved more than 2 mm in the mount and whether the requirement for the point of impact was met. The acceleration components ax and ay should be smaller for vertical impact than 0.1 az.

              3.2.6. Evaluation

               The deceleration curves should be evaluated as follows:

               The resulting deceleration ares(t) in the centre of gravity according to equation (1) from the measured deceleration curves ax(t), ay(t) and az(t) is to be compounded as multiples of the acceleration due to gravity.

              (1)

               The time for which a deceleration of 80 g with ares is continually exceeded and the greatest deceleration of ares should be determined. The HIC-value should be calculated as a measurement of