Computer assisted engineering enables engineers to analyze a design through computer programs without having to build a prototype. Given the geometry of a design, the degree of interference or clearance between parts can be observed. If moving parts are present in the design, they can be rotated as a dynamic check. The geometric properties such as volume, weight, center of gravity, moments of inertia, radii of gyration, polar moments, etc of 3-D modes can be readily calculated. An important example is the analysis of stress on a part. The program is called a finite element analysis program. Another example is simulated ( by a computer program) wind tunnel testing on a design to determine the wind resistance or drag. Computer programs can lay out the circuitry of a chip. Electrical designs started as sketches can be analyzed. Building designs can be analyzed for wind and earthquake damage. The computer will also automatically insert the building code requirements.
CAD and CAE have improved the productivity of design by a factor of 2 in the case of mechanical design such as automobiles to as much as 30 in the case of designing integrated circuits using silicon compilers.