Multi directional & quasi isotropic laminates

The bonding of individual unidirectional lamina or plies together is used to form laminates. The laminae are oriented in a multi-directional manner to give the effective properties required for the application. The order and direction of the lay-up can be determined using lamination theory. There are certain rules that should be adhered to. If the lay-up order is not symmetric about the thickness centre line, then the laminate will bend and/or twist when a load is applied. If the directions of the layup through the thickness has different number of orientations in the plane then modulus and strength of the laminate will be different in the x- and y-directions. A quasi-isotropic laminate is one that approximates isotropy by orientation of plies in several or more directions in-plane.