The equivalent of FEA for the design engineer’s structural analysis is computerized mold filling and solidification analysis for the metalcasting engineer; the basis for both is a solid model.
The “other way” for the foundry engineer is the manual calculation of gating, solidification patterns and riser sizes; these are established, relatively simple mathematical techniques used long before the advent of solid models.

This “other way” for the design engineer is not so simple. To take full advantage of engineering sketching/print marking as a way to brainstorm geometry, we must be able to quickly evaluate stress and deflection at important cross-sections in the sketches. As the design engineer well knows, the classic formulas for bending stress, torsional stress and deflection are relatively simple. Each, however, contains the same parameter, section modulus, which is a function of shape and difficult to compute. Therefore, a quick, simple way to compute or estimate section modulus (more specifically, its foundational parameter, area moment of inertia) is needed so that we can move from sketch to improved sketch in our casting geometry brainstorming.

Interestingly, the difficulty in computing area moment of inertia for casting shapes is one of the hidden reasons for the design and use of fabrications. Fabrications are made from building blocks of wrought shapes, like I-beams, rectangular bars, angles, channels and tubes. These shapes, which are simple and constant over their length, have area moments of inertia that are easy to calculate or are available in handbooks. Consequently, stress and deflection calculations are relatively easy. Fabricated designs, however, are heavy and nonuniform in stress compared to a casting well-designed for the same purpose.