u2.06.03 Mechanical damping modeling instructions

Linear and non-linear dynamic analyses, for the study of the vibratory response with an excitation in force or in imposed motion or for complex modal analysis, require the addition of mechanical damping characteristics to the stiffness and mass characteristics.

Several classical models are available, applicable to all types of finite elements available. These models are available directly by operators.

• the viscous damping model,

• the hysteretic damping model (also called « structural damping ») for harmonic analysis and mode calculation.

For finer calculations, it is also possible to model materials with realistic visco-elastic behavior, whose behavior is described by a set of internal variables.

For analyses using a modal basis of real eigenmodes, it is possible to introduce modal damping coefficients. These coefficients may come from tests carried out on site as well as from a modal calculation taking into account any of the types of depreciation proposed.

• 1. Viscous damping model
  • 1.1. Proportional « global » viscous damping, or Rayleigh damping
  • 1.2. Viscous damping proportional to the elements of the model
• 2. Hysteretic damping model
  • 2.1. « Global » hysteretic damping
  • 2.2. Hysteretic damping of model elements
• 3. Viscoelastic damping model with internal variables