Derivation of a Tapered p-Version Beam Finite Element
Abstract
Finite-element models are used extensively by the rotorcraft industry for determining the vibratory characteristics of helicopter airframes. These airframe models are typically large, usually containing several thousand finite elements, and their definition involves considerable effort. Results obtained by using these models usually do not correlate well with experimental data, particularly at the higher frequencies that are near the predominant rotor excitation frequencies. Although there are several possible reasons for the lack of correlation, one that has recently attracted attention is the accuracy of the elements themselves. Most finite-element codes in use today employ what are commonly referred to as h-version elements. An h-version element uses fixed- order shape functions to relate the discrete nodal displacements of the element to the continuous displacements within the element. Mesh size normally controls the accuracy of the results obtained using h-version elements. As the number of elements is increased, the mesh size decreases and the results tend to converge. Test for convergence checks are often used in studies which employ small models.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1989
- Accession Number
- ADA213443
Entities
People
- Howard E. Hinnant
Organizations
- National Aeronautics and Space Administration