What is damping?
Damping is an influence within or upon a dynamic system that has the effect of reducing, restricting or preventing its movements. In physical systems, damping is produced by processes that dissipate energy. Damping forces come from several sources simultaneously, such as energy loss during hysteretic loading, viscoelastic material properties, contact friction and so on. Material damping is a kind of Abaqus damping method; keep going reading this useful article to get more information about material damping.
You can find a great blog about the concept and basic understanding here:
Sources of Damping
Generally, we can have damping resulting from:
1. Material nonlinearity ⇒ inelastic dissipation
2. Internal friction ⇒ material behavior
3. External friction ⇒ joint behavior
Why do we use damping in Abaqus?
We take the profit of damping in Abaqus to accurately models the energy loss in a dynamic system. Damping is also beneficial when modeling very fast phenomena and noisy dynamics. It will play a critical role to have a meaningful solution.
So, there are two main reasons for adding damping to a model: to limit numerical oscillations or to add physical damping to the system.
How we can model damping in Abaqus?
The most widely used damping form called viscous damping, in which the damping force is velocity proportional. In fact, the complex damping may be proportional to the square of velocity, such as the damping force of solid motion in liquid, and sometimes it even has nothing to do with speed, such as the friction at the supports.
Two primary aspects for defining damping are available in Abaqus:
Structural damping (imaginary stiffness), is used in frequency domain dynamics and in mode-based transient dynamics.
How we can enter data for damping in Abaqus?
In general, Abaqus has five categories of damping definition sources:
1. Material damping
You specify damping when defining material. When a structure is subjected to oscillatory deformations, its state is represented by a mix of kinetic and potential energy. Some of this energy is lost per deformation cycles in real structures, which is known as material damping.
2. Element damping
Includes contributions from complex spring elements, dashpot elements and connector elements (using connector damping)
3. Global damping
Assumes the damping coefficient is constant in all materials. It is essentially a crude approximation to improve performance (preliminary design).