Structural Dynamic Behavior of Wind Turbines - Wind Turbine Technology: Fundamental Concepts of Wind Turbine Engineering - page 628

Figure 11-4. Typical flow chart for a computer model used to calculate HAWT blade
loads. [Thresher et al. 1986]
Computational Procedure
The procedure followed in the FLAP Code for solving Equation (11-31), the
fundamental equation of motion for a HAWT blade, can serve as an illustration of an
approach that has been used successfully by the creators of such computer models. The
general approach is as follows:
1. All coefficient matrices are multiplied by the inverse of the mass matrix. Thus the
mass matrix associated with blade tip accelerations multiplied by its inverse gives the
identity matrix. This results in a set of equations with the blade tip accelerations on
one side of the equality and the computed generalized forces on the other. Multiplica-
tion by the inverse mass matrix is only done once, at the beginning of Module 2.