Free Vibrations of an Articulated Helicopter Rotor Blade,
Abstract
An investigation was made of the natural vibration of a helicopter hinged rotor blade in a field of centrifugal forces produced by rotation. A rotor blade is replaced by an elastic axis with discrete masses and moments of inertia. In the solution procedure, the displacements of the centers of mass of blade sections relative to its elastic axis are taken into consideration as well as the influence of the inertia of air masses surrounding the blade. The analysis proposed makes it possible to obtain the modes and the corresponding frequencies of natural vibration. The fundamental assumptions of the model used and the kinetic problems of a rotor blade are discussed. The acceleration components are obtained and the relations for calculating the aerodynamic inertial forces are considered. The moments of inertial forces are determined, taking into account the rotational inertia of the segments into which the rotor blade is subdivided and the moments of aerodynamic inertial forces. It is assumed that for each point of subdivision of the rotor blade, the state of the latter is determined by a vector which is called the vector state. The equilibrium of a blade segment between two successive sections is discussed. Transformation matrices and section matrices are determined. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 10, 1969
- Accession Number
- AD0866947
Entities
People
- L. Kalinowski
Organizations
- National Air and Space Intelligence Center