Micromechanics of fiber–crack interaction studied by micro-Raman spectroscopy: Broken fiber

• Extended stress transfer model for ductile broken fiber is proposed to describe stress transfer.
• The model considers that the second forward sliding zone exists at the broken fiber-end.
• Reverse sliding gradually transforms into the first forward sliding during reloading.
• Friction sliding and reloading mechanisms are explained by friction shear stress.

Micromechanics of broken fiber/crack interaction were investigated by micro-Raman spectroscopy. The stress distribution on a broken fiber was measured point-by-point using micro-Raman spectroscopy. The interaction between the crack and broken fiber was discussed and a stress transfer model involving the broken fiber was established. A reverse sliding of the broken fiber within the debonded region was gradually transformed into a forward sliding during reloading and the debonded fiber was re-loaded at last. The extended stress model considers that the second forward sliding zone always exists at the broken fiber-end and keeps the same length, while each length of the first forward sliding zone and reverse sliding zone changes with the load. Experimental results of the extended stress model in this study can be used to explain the stress transfer in the case of ductile fiber fracture.