ISSN: 1546-962X
CODEN: JAIOAD
Published Online: 4 October 2004
Page Count: 14

Variable Amplitude Fatigue Crack Growth Using Digital Signal Processing Technology

Donald, JK
Research Engineers, Fracture Technology Associates, Bethlehem, PA

George, K
Research Engineers, Fracture Technology Associates, Bethlehem, PA

(Received 29 May 2002; accepted 11 November 2003)

Abstract

An automated variable amplitude fatigue crack growth system has been developed using digital signal processing (DSP) technology to provide waveform generation, command-feedback verification, and crack growth monitoring. The system is designed to interface with existing analog or digital closed-loop servo-hydraulic mechanical test systems. An important parameter in the control of variable amplitude testing is the effect of loading errors on the fatigue crack growth rate response. A damage parameter (Γ) has been incorporated to quantify the magnitude and effect of loading errors. In this paper, a FALSTAFF, Mini-TWIST, and truncated Mini-TWIST aircraft spectrum were applied to an M(T) crack growth sample to demonstrate the correlation between the damage parameter and fatigue life.

Keywords:
fatigue crack growth, variable amplitude, automation, servo-hydraulic closed-loop control, digital signal processing

Paper ID: JAI19043
DOI: 10.1520/JAI19043
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