Comparison of fem and sea for vibration computing in periodic structures

Some examples of vibration energy computing in beams structure using Finite Element Method (FEM) and Statistical Energy Analysis (SEA) are presented. Calculations are carried out for periodic structure, that consists of equal beams and of beams whose lengths are random variables with equal mean value and some deviation. The later case is real one, when the dimensions of structure elements are not known exactly but are specified as a mean value and some tolerance. It is shown that the beams energies, calculated by FEM, in structure consisting of equal beams and beams, whose lengths are random variables with equal mean value, are different. Thus FEM computation which uses solely mean characteristics can be inaccurate. Difference between average FEM and SEA results is not significant. It is concluded that SEA - less expensive method - is quite suitable for practical engineering computing.