The standard way to estimate the resistance to penetration is to fix the test sample and apply pressure load to the indentor (bullet simulator) in contact with the surface of the sample.

1. According to the new technology, a multi-layer test article made of bulletproof fabric is secured between two flat clamping rings with a permanent grip. After that, a pressure load is applied at an indentor with the shape, size and surface finish of a bullet to force it into the surface of the test sample at a required depth. The force should be directed along the axis of the clamping rings. The penetration resistance of the multi-layer bulletproof fabric is then determined by comparing the penetration work performed by the indentor with the reference penetration value found in previous experiments. The work of penetration through bulletproof fabric done by the indentor is calculated according to the formula:



where A is penetration work, Joule; P – current load on the indentor, N; L – current depth of penetration, m; L_o – required depth of penetration, m;

The following specifications have been made for the options of the method:

2. The multi-layer test sample of bulletproof fabric should be secured in flat clamping rings with the proportion between their outer and inner diameters within 1: (1.8-7.2).
3. The depth of the indentor’s penetration into the test armor sample has to be within 4 to 35 mm.
4. The load applied during the test should be within 500 to 10 000 N.
5. The speed of the indentor’s penetration into the test sample is selected within the range of 1 to 200 mm/min.

Russian Scientific and Research Institute of Aviation Materials, ZAO Bison-95CT, Moscow 107005, Radio street 17, VIAM