The angles on the radome also deflect incoming radar signals, so the ship will be less visible to the enemy. The Navy gave Marhefka its plans for the shape of the radome, and the computer program calculated the best placement of antennas within the structure to minimize interference. The new method analyzes part designs and locates spots where porosity or holes are likely to form during casting, weakening the material. It does so in seconds, unlike more complicated methods that may take hours or days. Miller explained that when hot liquid metal flows into a die, the material closest to the outside cools first and forms a hard shell.
Liquid metal shrinks as it solidifies, creating holes that weaken the final part.
Most shrinkage holes form in the thickest sections of a part - the sections that take the longest to cool and solidify. In a recent issue of the journal Computer-Aided Design, Miller and his colleagues described how they built their new method into software that simulates die casting. The software produces an image of what a part will look like after die casting, and color-codes bright red the areas that will take longest to solidify. If engineers see too much red, or see red in an area of the part where the strength of the material is critical, they'll know to redesign the part before they cast it. The simulation takes only seconds.