Tower Damping

Bladed is able to introduce modal damping by applying a damping ratio for each tower mode. The user can choose how many tower modes to specify damping ratios for using the StructuralModes array. This list defines the exact number of tower uncoupled modes to include in a calculation. The damping ratio is assigned to each uncoupled mode shape. The damping ratio is assigned to the mode shapes in order of ascending frequency.

Note

The user can add any metadata adjacent to the damping values, such as "_Name" or "_Mode". Bladed will ignore it so long as it is preceded by an underscore.

An example input is provided below where the user has specified a damping ratio for the first 7 tower modes and selected the modal reduction option to simulate flexibility. The user in this case has also selected the axial loads only geometric stiffness model. The first damping ratio will be assigned to the tower uncoupled mode with the lowest associated frequency.

      "Modelling": {
        "StructuralModes": [
          {
            "DampingRatio": 0.007
          },
          {
            "DampingRatio": 0.005
          },
          {
            "DampingRatio": 0.005
          },
          {
            "DampingRatio": 0.005
          },
          {
            "DampingRatio": 0.005
          },
          {
            "DampingRatio": 0.005
          }
          {
            "DampingRatio": 0.005
          }
        ],
        "StructuralModellingType": "ModalStructuralModelling",
        "GeometricStiffnessModel": "AxialLoadsOnly"
      }