Frequency analysis allows the calculation of the natural (resonant) frequencies of the design and related forms of vibrations. It is useful in carrying out checks for the resonant frequencies in the working frequency range and optimizing the design in such a way as to prevent the emergence of resonances. So developer can improve the reliability and efficiency of the design. In the parameters of frequency analysis determined the number of natural frequencies to be determined. The system may be not fixed (free in space). Calculation of resonant frequencies takes into account the forces acting on the structure (eg gravity). As a result frequencies and their own forms of vibrations are derived. Natural frequency corresponds to the expected resonance frequency of the structure. Shape fluctuations (modes) shows the relative deformation (displacement) which will be in the case of resonance at the corresponding natural frequency. It should be remembered that the forms of vibrations that are displayed in the Postprocessor window represent the relative amplitude of the oscillations only. Analyzing these forms you can draw conclusions about the nature of the resonant displacement but not about their actual amplitude. Knowing the expected form of vibration at a certain natural frequency can for example to specify additional fastening or support in the field of design corresponding to the peak of this form of vibrations that lead to effective change in the spectral properties of the product.