Experimental simulation of bending damage of silicon nitride yarn during 3D orthogonal fabric forming process

The aim of this study executed on Silicon Nitride (Si ₃ N ₄ ) yarn is to examine some bending damage behaviors and fracture mechanisms that occur during the 3D orthogonal fabric forming process. A three point bending experiment device has been developed in order to simulate the Z-binder yarn bending condition. The effects of weft density, fabric thickness, and yarn tension have been studied. The Weibull analysis of the tensile strength show that the bending damage increases with the increase of weft density, fabric thickness, and yarn tension. The resulting bending damage causes a reduction in yarn strength of between 2.5 and 17.2% depending on the bending parameters of yarn. The growth of the fibrillation area also reflects similar trends with tensile strength loss rate. The fibrillation length produced by the yarns is mostly distributed within the range of 0.3 to 0.9 mm. A comparison of the calculation result to experimental data shows the bending fracture probability of filaments inside yarn are less than that of monofilament. The tensile and bending fracture of Si ₃ N ₄ filaments exhibit typical brittle fracture characteristics.