STP1439: 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

    Pages: 14    Published: Jan 2005


    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 (г) 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: STP11297S

    Committee/Subcommittee: E08.06

    DOI: 10.1520/STP11297S


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