Investigation of an Improved Flutter Speed Prediction Technique for Damaged T-38 Horizontal Stabilators Using NASTRAN.
Abstract
This thesis concerns the development of a finite element model of the T-38 horizontal stabilator for use on NASTRAN. The model is to be used to analyse degradations in flutter speed due to repair. Static analysis has shown the model to be lacking in torsional stiffness. The probable cause being the inability of NASTRAN plate bending elements to model torsion cells. An increase of elastic and shear moduli of plate bending elements in the model by 30 percent produced more accurate results but additional investigation is necessary. Modal analysis has pointed to a modeling error in the root, trailing edge area. The affect has caused an additional node to appear on the trailing edge for modes above 100 cps in a free-free condition. Investigation of the steady aerodynamic pressure distribution over the stabilator shows good correlation with experimental results. A flutter analysis procedure was established and the affects of the errors found in the structural model were investigated. With no corrections made to the model, a flutter speed equivalent to that predicted using strip theory was achieved for the sea level condition. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1980
- Accession Number
- ADA094769
Entities
People
- Roger Kent Thomson
Organizations
- Air Force Institute of Technology