Dynamic Response of Fiber Bundle under Transverse Impact

摘要

Research and development of soft body armor have been extremely critical to efficiently protect the soldiers and law enforcement personnel from ballistic injury. High strength ballistic fabrics have been developed and utilized in soft body armors. Improvement of the fabrics performance against ballistic impact is still ongoing. It is desirable to understand the dynamic response of the fabrics under high-speed transverse impact. Technically it is a good start to investigate the transverse impact response of the fiber bundles that are primary components in fabrics. When a fiber bundle is subjected to transverse impact, both longitudinal and transverse stress waves are generated and then propagate in the fiber bundle. The longitudinal wave stretches the fiber bundle, which produces stress and strain in the fiber bundle. The transverse wave changes the shape of the fiber bundle [1]. The longitudinal stress wave is a characteristic parameter, which is usually a constant for a certain material regardless of loading condition. However, the transverse stress wave is dependent on the loading condition. For example, the transverse wave speed may depend on the external transverse impact speed. A higher transverse wave speed is favorable to transmit the external impact energy outwards so that the strain localization at the impact contact can be avoided [1, 2]. This consequently improves the ballistic performance of the fiber bundle. Unlike longitudinal wave speed, the transverse wave speed is dominated by many material parameters as well as loading conditions. Models are possibly used to correlate the transverse wave speed with the material constants and loading conditions. However, precise models rely on valid experimental data and in-depth understanding of the mechanism of dynamic response of the fiber bundle under transverse impact. In this study, we used a Kolsky bar as the loading device and high-speed photography to investigate the dynamic transverse response of fiber bundle.