Computer Aided Engineering is broadly divided into Finite Element Analysis (FEA), Computational Fluid Dynamics (CFD) and 3D modeling.Finite Element Analysis (FEA) is a computer simulation technique used in engineering analysis. It uses a numerical technique called the finite element method (FEM). FEA is the solution to the task of predicting failure due to unknown stresses. It indicates problem areas in material and allows designers to see all of the theoretical stresses and compare them with allowable stresses. It saves the manufacturing costs that would accrue if each sample was actually built and tested.
Engineering equations for stress and deflection (as defined in the applicable code of design like ASME, PD5500 etc) are derived using a set of assumptions that must be true for the equation to be valid. Finite Element Analysis is also useful when Engineering equations do not apply.