CAD-Based 3-D Structural Dynamic Modeling of the Tilt Rotor Aeroacoustic Model (TRAM) Proprotor

This paper describes the development of a three-dimensional structural analysis model of the NASA Tilt Rotor Aeroacoustic Model (TRAM) proprotor. The model includes 3-D CAD geometry of the rotor, finite element meshes of flexible parts, multibody joint definitions, composite material modeling, and assembly into an integrated model suitable for dynamic analysis. Preliminary analysis is carried out on a single processor using a novel, high fidelity, 3-D rotor computational structural dynamics solver. The solver utilizes a multibody formulation and treats flexible components with full 3-D finite element analysis. The process for creating the proprotor model, from CAD geometry through discretization of flexible parts into hexahedral meshes and definition of joints, is discussed. Additionally, the use of an effective modulus method to homogenize the constitutive properties of laminated composites is presented. Static analysis of the rotor flexbeam reveals accurate modeling of its bending stiffness. Mass properties for the rotor are also well captured, suggesting the CAD geometry is well defined. Some rotor frequencies are well matched, but others created problems, likely due to a lack of information on the original properties of the materials used in the rotor. Despite this, the rotor model demonstrates that it is capable of predicting the kinematics of complex root end flexures, bearings, and attachments with multiple load paths from first principles.