Experimental Study And Multi-scale FEM Analysis Of 4-Harness Satin Woven Composites

Woven composites have good properties of designability,uniform in-plane properties and structural stability.As an advanced composite material,woven composite is widely used in aerospace,ship,auto and building industry.4-harness satin woven composite is studied in this paper,experiment method and FEM method are performed to investigate mechanical property of the composite.Main content of this paper includes uniaxial tensile strength test,cycle tensile test,in-plane shear test,4-point bending test and FEM analysis of a unit cell which can be representative of the whole structure.Firstly,the uniaxial tensile strength test and cycle tensile test are performed.In case of the woven composite with undulate surface,the ultimate force of yarn and ultimate force per unit width are proposed to be used for characterizing the tensile strength of the woven composite.First loading elasticity modulus and subsequent loading elasticity modulus are studied during cycle tensile test,and the change of hysteresis loop areas is investigated during cycle tensile test.The results of tests are valuable to practical engineering application.Secondly,the in-plane shear property of 4-harness satin composite is studied.The composite is extremely thin,existing test fixture can’t be applied to the single-layer composite.Based on the principle of shear test,an in-plane shear test fixture that can be applied to the extremely thin composite is designed for the first time,and a relevant test program is also proposed.And in-plane shear test is performed using the designed fixture.Subsequently,4-point bending test is carried out to investigate the bending mechanical property.Bending stiffness and the curvature when local buckling appears are gained.The results show that curvatures of warp and weft specimen when local buckling appears are almost the same.Finally,mesostructure image of cross section of the 4-harness satin woven composite is obtained by optical microscopy.By studying the mesostructure image,geometric information is obtained,such as the geometrical dimensions of cross section of warp and weft tows and the distance between tows along warp direction and weft direction.Based on the obtained geometric information,a representative unit cell is modeled by ABAQUS.Domain decomposition method is used to guarantee that global domain and fiber domain are coupled in spatial position and mesh nodes.Periodic boundary conditions are applied to the global domain,which guarantee that deformation is coordinating and the displacement is continuous between the corresponding nodes.A unit strain is applied in each case,thus one column of the ABD matrix is obtained.Finally whole ABD matrix is obtained and the results of experiment are used to verify the principal diagonal elements of ABD matrix.Finally,ABD matrix is used to calculate some structures.