Principle of the approximation by reduced elements

• The reduction is done to a specified point of an original distributed system
• Distributed elements are replaced by reduced elements
• Reduced elements, at the point to which they are reduced, have the same effect as the original distributed system.
• Reduced system, having only one reduced mass m_r and one reduced compliance c_r, has only one resonant frequency
  corresponding to the first mode of vibration of the given structure
• This approximation is thus useful only for a limited frequency range starting at low frequencies and ending at the vicinity of the first mode of vibrations
• General rule for reduced elements calculation is based on the knowledge of the deformation curve of a structure