Tidal Bladed Knowledge Base

Output blade and tower mode shapes
Category: Structural dynamics

Problem

Is it possible to output the exact mode shapes of blades and tower from Bladed? 

Solution

It’s possible to find the blade and tower mode shapes in the .$pj file.

(1) Bladed 4.7 and earlier

They are located in the section MSTART RMODE.

The blade modes are reported first. The line NBLADE gives the number of blade modes used, the line FREQ reports the frequency and so on.  

The mode shapes are given in the lines MD011, MD012… etc. The naming convention is such that the first two numbers is the mode number and the last digit is the direction. For example:

MD011                // mode 1, nodal x deflection
MD012                // mode 1, nodal y deflection
MD013                // mode 1, nodal z deflection
MD014                 // mode 1, nodal x rotation
MD015                 // mode 1, nodal y rotation
MD016                 // mode 1, nodal z rotation
MD021                 // mode 2, nodal x deflection

(2) In Bladed 4.8 and later this information is in the XML section under <TowerMode> for tower, or section <BladeModeContainer> for blades

Each six values represents a node displacement in the six degree of freedom.

The mode shapes are normalised by a constant factor so that the maximum translational or rotational deflection is 1. The linear deflections are in meters and angular deflections in radians.





Keywords blade modes, tower modes