Characterization of ultrahigh-strain-rate compressive behaviors in single 10-μm scale fibers using a micro-scale Hopkinson bar method

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High-performance fiber fabrics and composites experienced transverse compression deformation at ultrahigh strain rates near the impact point when subjected to high-velocity impacts, which significantly affected their ballistic limits. In this paper, a fiber-scale experimental method for characterizing ultrahigh strain-rate transverse compression behavior was proposed. To begin with, in order to measure the extremely low stress and strain in small specimens, the conventional Hopkinson bar was reduced to the hundred-micron scale, thereby achieving wave impedance matching with single fibers. In addition, tangential and normal laser Doppler velocimetry (LDV) methods were employed to realize non-contact, high-precision, and high-speed axial velocity measurements of micron-scale incident and transmission bars, respectively. Meanwhile, a microscopic observation system was used to facilitate the installation of miniature fiber samples. The experimental setup and procedures were introduced, and the system accuracy was verified through sample-free loading tests based on one-dimensional stress wave propagation theory. Dynamic compression experiments on Graphene-UHMWPE fibers were carried out, followed by post-compression microstructural characterization via scanning electron microscopy (SEM). Results demonstrated that successful mechanical characterization was achieved at strain rates exceeding 10 5 , an order of magnitude higher than the previously reported maximum rates. Furthermore, during the loading process, the fibers underwent uniform compression deformation while exhibiting pronounced strain-rate effects. This method offers a novel approach for dynamic mechanical characterization of microscale single fibers, enabling the development of comprehensive strain-rate-dependent material models to guide the design of advanced composites and high-performance fibers.

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