Document ID: chunk:federal_register_of_legislation:F2024L01742:body:0:p22
Version: federal_register_of_legislation:F2024L01742
Segment Type: other
Provision Reference: 
Character Range: 65597–68871

Apparatus

         1.                               The test apparatus is to consist of a pendulum where the pivot is supported by ball-bearings and with a reduced mass MR of 6.8 kg at its centre of percussion.

             1.                         The relationship of MR of the pendulum to the total mass "m" of the pendulum at a distance "a" between the centre of the percussion and the axis of rotation and a distance "L" between the centre of gravity and the axis of the rotation is given by the formula:

         2.                               The lower extremity of the pendulum is to consist of a rigid headform 165 mm in diameter whose centre is identical with the centre of percussion of the pendulum.

         3.                               The headform must be fitted with two accelerometers and a speed transducer, all capable of measuring values in the direction of impact.

     3.                                     Recording Instruments

         1.                               The recording instruments used must be such that measurements can be made with the degrees of accuracy specified below.

         2.                               In the case of acceleration, requirements are:

             1.                         accuracy + 5% of the real value;

             2.                         frequency response up to 1,000 Hz;

             3.                         cross-axis sensitivity > 5% of the lowest point on the scale.

         3.                               In the case of speed, requirements are:

             1.                         accuracy + 2.5% of real value;

             2.                         sensitivity = 0.14 m/s.

         4.                               In the case of time recording, the instrumentation must enable the action to be recorded throughout its duration and readings to be made to within one thousandth of a second.

         5.                               The beginning of the impact at the moment of first contact between the headform and the test component must be noted on the recordings used for analysing the test.

 4.                                           TEST PROCEDURE AND RESULTS

     1.                                     Test Procedure

         1.                               At every point of impact on the surface to be tested the direction of impact is the tangent to the trajectory of the headform of the measuring apparatus defined in clause 1 of this Appendix.

         2.                               Where the angle between the direction of impact and the perpendicular to the surface at the point of impact is 5o or less, the test must be carried out in such a way that the tangent to the trajectory of the centre of percussion of the pendulum coincides with the direction of impact. The headform must strike the test component at a speed of 6.69 m/s.

         3.                               Where the angle between the direction of impact and the perpendicular to the surface at the point of impact is more than 5o , the test may be carried out in such a way that the tangent to the trajectory of the centre of percussion of the pendulum coincides with the perpendicular to the point of impact. The test speed must then be