Mechanical properties of natural fiber textiles laminate with hole

The mechanical behavior of natural ramie / isocyanate laminate composite with holes was investigated by the biaxial tensile method. The uniaxial and biaxial load tensile tests for four kinds of 0.5, 1.0, 2.0, 4.0mm aperture were conducted, and the effects of displacement and the pore size on strain were characterized by the digital speckle correlation method. The result shows that the displacement field around the hole is uniform distribution when the load changes linearly, however, while the load is closing to failure, non---linear distribution and high strain points appear, which are broken first quickly. As the radius of the pore increases, average strains in x and y directions are reduced within the same area around the hole under 1000~2000N biaxial load and fluctuation of strain decreases slightly.Mechanical characteristics of materials are different under different tensile ways, strength  under biaxial load is lower than the one under uniaxial tension and the reduction ratio, which increases with the size of pore radius raising, is about 14%～27% of the uniaxial load.