ISSN: 1945-7553
CODEN: JTEVAB
Page Count: 11

Effects of Fixturing Mass on Dynamic Strain Errors in Structural Fatigue Testing

Hewitt, RL
Senior research officer,, Institute for Aerospace Research, National Research Council of Canada,, Ottawa,, Ontario,

(Received 22 September 1999; accepted 30 June 2000)

Abstract

Improvements in control systems have allowed significant increases in testing frequencies for full-scale aircraft structural fatigue tests. This means that it is possible to be testing at frequencies that result in significant dynamic strains, with consequent over-testing.

This paper presents an analysis of a simple cantilever beam as a representation of a test on an aircraft wing. Using a state space formulation and the MatLab mathematical programming system, comparisons between static and dynamic strains for various locations on the beam are made for a variety of loading arrangements.

It is shown that significant dynamic strain errors will occur at testing frequencies above about 10% of the first natural frequency of the specimen itself. The errors can increase significantly due to the mass of the fixturing, and are further exacerbated by static counterbalancing.

Keywords:
aircraft, strain, dynamic errors, control, fatigue, full-scale testing, modeling, simulation

Paper ID: JTE12137J
DOI: 10.1520/JTE12137J
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