The physical properties of beam cross-sections made of possibly heterogeneous anisotropic material are described by solid properties, which rely the definition of a lay-up as illustrated in fig. 1. It consists of N layers of possibly anisotropic material stacked on top of each other. The first layer, layer 1, is at the bottom of the stacking sequence and the last layer, layer N, is at the top.
The depiction of the lay-up presented in fig. 1 is too simplified. Indeed, the various layers might not extend over the entire length of the mold line. The upper portion of fig. 2 shows the sequence of layers that compose the lay-up: it consists of N layers of possibly anisotropic material stacked on top of each other. The first layer of the lay-up, layer 1, espouses the shape of the mold line and the last layer, layer N, is at the top.
Lay-ups are used to define the structural properties of walls and shapes. The geometry of the mold line of the lay-up, see fig. 2, is defined by the NURBS curve inherited from its parent wall or shape. In fig. 2, layers 1, 2, and N, extend over the entire length of the mold line, i.e., the initial and final stations of those layers are ηI = 0 and ηF = 1. Layers 3 and 4 cover a portion of the mold line only. For layer 3, ηI = η2 and ηF = η3 whereas for layer 4, ηI = η1 and ηF = η4. Note the following requirements: 0 ≤ ηI ≤ 1, 0 ≤ ηF ≤ 1, and ηI ηF.
During the curing process, pressure is applied on the top layer and all layers are pressed against the mold line, as illustrated in the bottom portion of fig. 2. At the locations where layer are added or dropped, upper layers undergo a transition that puts them in contact with lower layers. This transition takes place over a finite zone called the “add-drop zone”, as indicated in the fig. 2. The initial configuration of the draping illustrates the draping sequence, as the layer are draped one at a time on the mold. The configuration of the draping after cure is similar to the final, cured configuration.
In summary, the physical characteristics of a generic Layer i are defined by the following parameters: (1) its thickness ti; (2) its material properties; (3) its orientation angles βi and γi; (4) the location of its initial station ηI(i); (5) the location of its final station ηF(i).
The first example creates a four-ply lay-up. Because the material properties and layer thickness are omitted for the first three layers, the default material properties, MatPropT500-4208, and default thickness, t = 0.0625 will be used. The last layer defines its own material properties and thickness.