Stress transfer of single yarn drawing in soft fabric studied by micro Raman spectroscopy

The load transfer behavior of the Kevlar 49 soft fabric commonly used for bulletproof clothing in yarn drawing test was investigated by micro-Raman spectroscopy. The linear relationship between Raman shift and axial stress of single yarn was established. The axial stresses of warp yarn in soft fabric with and without preload condition were obtained by Raman measurement under tension, and they conform to the theoretical prediction using a yarn-drawing model with interface debonding. The experimental results show that the drawing load is transferred along the yarn from the beginning to the end. In the process of straightening the yarn, the interfacial friction shear stress caused by the yarn relative sliding remains almost constant, and the length of straightened yarn becomes longer as the external load increases. The preload plays a role in inhibiting the straightening of the yarn, which is helpful for the load transfer in the sliding friction section.