Interactive effect between warp and weft directions of ramie textile under biaxial load

For the issue of interactive effect between warp and weft of fabric under practical working environment,the mechanical properties of ramie fiber fabric at(0°,15°,30°,45°,60°,75°,90°) seven-plane directions and at warp direction set different load threshold values were investigated by biaxial tensile test,and the strain filed was characterized by using digital speckle correlation.The results showed that interactive effect between warp and weft existed and the influence of load at weft on warp was larger than warp on weft.As the load at weft direction linear increased,force values at warp direction nonlinear increased and load ratio,the absolute value of strain at warp and weft directions decreased,but Poisson ratio kept the same essentially since the average and coefficient of variation respectively were 0.338 and 0.484%.As the angle for X-axis and warp direction increased,loading mean value curve at X and Y axis had sine-curve characteristic.There was an axisymmetric distribution trend for loading box charts at 15°and 75°,30°and 60°with the box chart at 45°.The greatest effect of weft on warp happened when the warp-load is about 62.2%,65.3% of the unaxial and biaxial breaking strength,and the maximum rates of load and strain respectively were 2.593 N/s and 0.092 s-1.