If the plate is developable, the expanded shape will be an exact two dimensional development of the three dimensional plate shape. If the plate is not developable, there will be a girth length difference between the original and the developed plate shape. This girth difference is displayed at the top left corner of the Part window and gives some indication of how developable the plate is.

The first four items displayed are the girth lengths and differences of the developed plate along the aft, fwd, top and bottom edges of the plate. The second two rows, the Max girth differences, are the greatest girth errors found along the mesh used to develop the plate and so represent the worst girth errors within the plate between opposite edges. Then the plate area and forming method information are given. The final two rows give the maximum and minimum strain which will be required to stretch the 2D expanded plate into the 3D hull plate, this strain is given in the forming direction.

The girth difference indicates how much in-plane strain will be required to deform the developed shape to match the true plate shape. If the girth error indicates that too much strain will be required to lay up the plates accurately, you may wish to break the plate up into a number of smaller pieces.

The difference values are calculated as follows (a girth positive difference indicates that the 2D plate must be stretched, whilst a negative girth difference indicates that it must be shrunk to fit onto the hull):

When determining whether the plate can be feasibly formed, it is important to look at all six values. With the General forming method it is always possible to create an expanded plate which has no strain in the plate edges. However, you must also check that the internal girth differences and maximum and minimum strains are within acceptable limits.