An analytical method for calculating stiffness of two-dimensional tri-axial braided composites

This paper presents a new analytical method for calculation of the stiffness of two-dimensional tri-axial braided composites. A unit cell has been introduced as a representative cell of a braided composite and its components. The braided composite is considered as consisting of three layers. The first two layers represent braided tows and the third layer is the axial tow. Then, using rule of mixtures, mechanical properties of each layer are calculated. Next, using analytical relations, the undulation of representative layers of braided tows is calculated. Finally, using a volume averaging method, the total stiffness of the braided composite is calculated. The results are compared with those obtained from experimental methods and the effect of braided tows crimp on the stiffness of braided composites is examined.