AN ADAPTATION OF MODAL ANALYSIS TO THE COMPUTATION OF STEADY BENDING LOADS ON A ROTATING BEAM

Modal summation or modal displacement methods are not capable of computing the steady bending moments on a rotating beam. Even if it were possible to use an infinite number of blade modes, it would not be possible to obtain a correct solution. There is a way to circumvent this problem by properly combining a force integration formulation with a modal summation approach. At Bell Helicopter Textron, Inc., modifications have been made in the blade loads methodology which allow for the computation of steady loads. The methodology was recently enhanced further to accomodate all types of rotor hubs.