There is no restriction on the lamination. Any number of layers or materials may be laid up at any angle. In the most general case, each layer is a different material. Nodal temperatures and temperature gradients may be specified and material properties may be temperature dependent.

With the higher-order isoparametric formulation, large geometrical regions may be modeled with a single element, and curved boundaries may be fit with a piecewise quadratic or cubic curve.

The shell elements are doubly curved but the surface is completely described by specifying only the three coordinates of each node. Thus, the input is as simple as for plate elements.

One of the special problems of composite analysis which arises in modeling curved structures is specifying the fiber orientations. Most programs give the user only one option - to measure the angles from a specified side of the element. If a detailed model is used, this requires the user to prepare a new set of angle data for each element.

NISA II/COMPOSITES has this option as well as six others, including the option of defining a rotation angle based on local coordinate system. These options simplify the analysis of singly or doubly curved structures by defining lines on the shell surface, which are projections of the global axes. Rotations are in every case about the shell normal and measured from these well defined reference lines. Fiber orientations can be defined at element or node level in either local or global system. Several local coordinate systems can be defined and referenced for defining the fiber orientations.

The result of all this is that modeling a composite structure turns out to be no more difficult than modeling its metal counterpart. All these unique capabilities of NISA saves tremendous amount of time in modeling a composite structure Tennis racket with optimized fiber orientation--first torsional mode Tennis racket with optimized fiber orientation--combined bending torsional mode