Research on Energy Absorption by Nonwoven Fabrics
Final technical rept. Oct 1970-Sep 1971
UNIVERSITY OF MANCHESTER INST OF SCIENCE AND TECHNOLOGY (UNITED KINGDOM)
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The object of this work has been to gain a greater understanding of the means by which needled nylon fabric absorbs energy when struck transversely by a projectile. To this end needle punched fabric has been subjected to a slow speed penetration test using a rigid steel probe, and to impact with a free flying projectile. The first method of test helped establish the mechanism by which this material deforms during impact. During high speed tests deformation was studied using high speed cine photography and various phenomena observed these included the initial inward movement of fabric during impact, the presence of broken fibers on projectile emergence, and the nature of projectile emergence. Detailed observation of fabric behavior around the impact point when multilayer samples are in use has been carried out using an embedding and sectioning technique. It seems that projectiles extend fabric until its thickness is reduced to such a level that no further resistance is offered. The structure and mechanical properties of needled fabric has been reviewed and its relevance to the ballistic problem analyzed. An existing theoretical approach to the dynamics of impact has been extended and provided the possibility that fabric protection capability could be roughly calculated from data generated during a simple tensile test.