Initial Development for a Flutter Analysis of Damaged T-38 Horizontal Stabilators Using NASTRAN.
Abstract
This thesis demonstrates the development and response of a finite element model of the T-38 horizontal stabilator using NASTRAN. The finite element model is to be used in a flutter analysis of damaged or repaired stabilators. The objective of the flutter analysis is to determine absolute values and degradations of the flutter speed due to different types of damages and repairs. Development of a finite element model with two dimensional quadrilateral and bar elements is described. For verification, a static analysis of the finite element model yielded for the most part qualitatively agreeable values in comparison to an influence coefficient study. For showing the dynamic response of the finite element model, a model analysis using both rigid and flexible root boundary conditions is used. The rigid root analysis shows agreement between the first two modes and the flexible root compares favorably up to three and possibly four modes. With these results, it is decided to use the finite element model in an initial flutter analysis. In the flutter analysis a doublet lattice aerodynamic model is combined with the finite element model for an undamaged stabilator. Poor agreement of the NASTRAN flutter speed with other available data indicates possible camber effects and the need for a verification aerodynamic model using steady and unsteady airloads. A brief description of a method of simulating repairs and damages of a horizontal stabilator is included. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1980
- Accession Number
- ADA082168
Entities
People
- John O. Lassiter
Organizations
- Air Force Institute of Technology