Accession Number : ADC028509

Title :   A Combined Range-Mean-Pairs Rainflow Count of Load Time Histories for Use in the Formulation of Structurally Relevant Cost Functions and Fatigue Analysis.

Descriptive Note : Technical rept.,

Corporate Author : ROYAL AIRCRAFT ESTABLISHMENT FARNBOROUGH (UNITED KINGDOM)

Personal Author(s) : Ellis, Susan D.

Report Date : OCT 1981

Pagination or Media Count : 36

Abstract : Operational aircraft experience a loading environment which varies throughout the mission. Response parameters or strain-gauge signals are measured during flight to monitor the accumulation of fatigue damage in critical areas, to provide comparisons with design criteria and to assess the structural significance of the loading patterns. A statistical count of the loading pattern is used to assess the structural severity and a brief review of various counting methods is given. The Report describes the development of a combined range-mean-pairs rainflow counting method suitable for short, long and interrupted data streams. The range and mean of all complete load cycles are counted into a frequency of occurrence matrix but half cycles are dealt with separately. Options for processing these left over half cycles are described and the re-ordered stack method is recommended. (Author)

Descriptors :   *AIRCRAFT, *AERODYNAMIC LOADING, *FATIGUE(MECHANICS), *COST ANALYSIS, *ALGORITHMS, MATHEMATICAL MODELS, COUNTING METHODS, COMPUTERIZED SIMULATION, FORTRAN, SUBROUTINES, TIME.

Subject Categories : Theoretical Mathematics
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE