Engineering topics

Zeiler, Thomas A.

Publications and source records attributed to Zeiler, Thomas A..

21 records · Page 2

NASA NTRS1988

Dynamic analysis of an unrestrained, rotating structure through nonlinear simulation

An alternate derivation based on Hamilton's principle of equations of motion of a flexible body for use in nonlinear simulation modeling is presented. The equations include terms representing variation in the inertial properties of the body resulting from flexibility as well as terms coupling rigid body and flexible momenta that arise from satisfaction of only the linear part of the mean axis conditions. An approximate method for including the centrifugal stiffening in a way that permits a variable spin vector is given. The equations are exercised in a simulation program on an example structure initially spinning about its unstable principal axis in a gravity-free vacuum.

Zeiler, Thomas A.↗

NASA NTRS1987

A new simulation model building process for use in dynamic systems integration research

A framework to build simulation models for aircraft dynamic systems integration is described. The objective of the framework is increased simulation model fidelity and reduced time required to develop and modify these models. The equations of motion for an elastic aircraft and their impact on the framework are discussed in broad terms. A software tool which automatically generates FORTRAN routines for tabular data lookups, the language used to develop a simulation model, and the structures for passing information into a simulation are discussed. A simulation variable nomenclature is presented. The framework has been applied to build an open-loop F/A-18 simulation model. This example model is used to illustrate model reduction issues. Current deficiencies in the framework are identified as areas for future research.

Arbuckle, P. Douglas↗

NASA NTRS1987

Nonlinear simulation of a flexible aircraft in maneuvering flight

A mathematical model integrating nonlinear rigid-body flight mechanics and linear aeroelastic dynamics is examined; the equations of motion for an elastic aircraft in accelerated flight are developed using Lagrangian mechanics. This approach is used to construct a simulation model of an F/A-18 (configured with tip missiles) which includes angular/elastic inertial coupling (IC). In general, the elastic modes significantly affected by IC were aerodynamically decoupled from the rest of the model. The affected modes were those which induced changes in total aircraft mass distribution. The elastic effect is noticeable if deformation-induced mass distribution changes are significant with respect to modal mass and modal frequencies. A modal parameter is presented which characterizes the level of IC between elastic momentum and rigid-body angular momentum.

Buttrill, Carey S.↗