Evaluation of the Mechanical Properties of Yarns for Ballistic Applications
FABRIC RESEARCH LABS INC DEDHAM MA
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Described are methods used to screen commercially available yarns for ballistic applications. The techniques used include low and high strain rate tensile tests, determination of longitudinal strain wave speed of propagation as a function of strain level, and measurement of transverse critical velocity, the only ballistic test used. In the tensile tests, the yarn modulus and strength generally increase and the elongation decreases as the strain rate increases. The strain wave speed of propagation is found to increase nearly three-fold in some nylons with increasing strain level, while the speed remains nearly constant in polypropylene.