Compressive Behavior Of Biaxial Spacer Weft Knitted Fabric Reinforced Composites At Various Strain Rate

As a novel type of 3-D knitted composites material, the spacer weft knitted reinforced composites is attracting more and more interests and attention due to its outstanding mechanical and competitive production cost. The spacer weft knitted fabric is the 3-D construction, which is made of three layers ,the upper and lower layers of the fabric are interlaced with the chain yarns through the thick direction. The composites made from this fabric have high resistance of delaminate and fracture .The structure of the spacer weft knitted lead to the composites have the outstanding damage tolerance under the impulsive loading . It possesses a great application potential in the field of automotive, marine parts, military. It is important to research and analyze the mechanical properties on the impact loading for the material design and engineering application. However ,there is no references concerned with those up to now .This paper fills the blank.Spacer weft fabric is made in to the composites by the scrimp process and then tested by the SHPB at high strain rate and NEW MTS at quasi-static state respectively, high strain rate varies from 700/s to2400/s .By compared the result of high strain-rate to the ones of the quasi-state, it is found that the spacer weft knitted reinforced composites is sensitivity to the strain rate ,whatever the out-plate or in-plate direction, compressive stiffness and failure stress linearly increased with the increase of the strain rate, while failure strain linearly decreased with the increased of the strain rate .As the strain rate increased, there is a deference between the out-plate and the in-plate compressive , the main failure mode at out-of -plane compression is the interlaminar shear failure and the in-plane direction is the delamination. When the strain rate is low ,the composites is destroyed slightly while it is completely broken at high strain rate .