Document ID: chunk:federal_register_of_legislation:F2025L00028:front:0:p28
Version: federal_register_of_legislation:F2025L00028
Segment Type: other
Provision Reference: 
Character Range: 79255–82291

2.1.5.14. The maximum impactor deformation from the point of first contact, calculated from integration of the accelerometers according to paragraph 6.6.3. of this annex, shall be equal to 330 ± 20 mm.

              2.1.5.15. The final residual static impactor deformation measured after the dynamic test at level B (Figure 2) shall be equal to 310  ± 20 mm.

              2.2. Front plates

              2.2.1. Geometrical characteristics

              2.2.1.1. The front plates are 1,500 ± 1 mm wide and 250 ± 1 mm high. The thickness is 0.5  ± 0.06 mm.

              2.2.1.2. When assembled the overall dimensions of the impactor (defined in Figure 2) shall be: 1,500  ± 2.5 mm wide and 500  ± 2.5 mm high.

              2.2.1.3. The upper edge of the lower front plate and the lower edge of the upper front plate should be aligned within 4 mm.

              2.2.2. Material characteristics

              2.2.2.1. The front plates are manufactured from aluminium of series AlMg2 to AlMg3 with elongation  12 per cent, and a UTS  175 N/mm2.

              2.3. Back plate

              2.3.1. Geometric characteristics

              2.3.1.1. The geometric characteristics shall be according to Figures 5 and 6.

              2.3.2. Material characteristics

              2.3.2.1. The back plate shall consist of a 3 mm aluminium sheet. The back plate shall be manufactured from aluminium of series AlMg2 to AlMg3 with hardness between 50 and 65 HBS. This plate shall be perforated with holes for ventilation: the location, the diameter and pitch are shown in Figures 5 and 7.

              2.4. Location of the honeycomb blocks

              2.4.1. The honeycomb blocks shall be centred on the perforated zone of the back plate (Figure 5).

              2.5. Bonding

              2.5.1. For both the front and the back plates, a maximum of 0.5 kg/m2 shall be applied evenly directly over the surface of the front plate, giving a maximum film thickness of 0.5 mm. The adhesive to be used throughout should be a two-part polyurethane {such as Ciba Geigy XB5090/1 resin with XB5304 hardener} or equivalent.

              2.5.2. For the back plate the minimum bonding strength shall be 0.6 MPa, (87 psi), tested according to paragraph 2.5.3.

              2.5.3. Bonding strength tests:

              2.5.3.1. Flatwise tensile testing is used to measure bond strength of adhesives according to ASTM C297-61.

              2.5.3.2. The test piece should be 100 mm x 100 mm, and 15 mm deep, bonded to a sample of the ventilated back plate material. The honeycomb used should be representative of that in the impactor, i.e. chemically etched to an equivalent degree as that near to the back plate in the barrier but without pre-crushing.

              2.6. Traceability

              2.6.1. Impactors shall carry consecutive serial numbers which are stamped, etched or otherwise permanently attached, from which the batches for the individual blocks and the date of manufacture can be established

              2.7.