Volume 9, Issue 4 (April 2012)

    Fatigue Crack Growth Rate Behavior of A36 Steel using ASTM Load-Reduction and Compression Precracking Test Methods

    (Received 11 May 2011; accepted 14 December 2011)

    Published Online: 2012

    CODEN: JAIOAD

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    Abstract

    Eccentrically-loaded single-edge crack tension, ESE(T), specimens made of A36 structural steel were tested over a wide range in stress ratios (R=0.1 and 0.7) in laboratory air. Two test methods were used: (1) ASTM Standard E647 load-reduction method and (2) compression precracking. After compression precracking (CP), three different loading sequences were used: (1) constant amplitude (CPCA), (2) load reduction (CPLR), and (3) constant stress-intensity factor (CPCK). The crack-compliance method was used to determine that the specimens had no residual stresses; and that the effects of tensile residual stresses from compression precracking dissipated in about 2 compressive plastic-zone sizes. Agreement was found between the A36 and TC-128B steel ΔK-rate data tested at both low and high stress ratio (R) conditions. At R=0.1 loading, the CPCA and CPLR tests generated lower thresholds and faster rates than using the standard ASTM load-reduction method. All load-reduction tests exhibited an accumulation of debris at the crack front near threshold conditions. A crack-closure analysis was preformed to calculate the effective stress-intensity factor range (ΔKeff) against rate using measured 1 % offset (OP1) values for all R=0.1 tests. The ΔKeff-rate data correlated well with the high-R results.


    Author Information:

    Newman, J. C.
    Dept. of Aerospace Engineering, Mississippi State Univ., Mississippi State, MS

    Ziegler, B. M.
    Dept. of Aerospace Engineering, Mississippi State Univ., Mississippi State, MS

    Shaw, J. W.
    Dept. of Aerospace Engineering, Mississippi State Univ., Mississippi State, MS

    Cordes, T. S.
    HBM n-Code Federal, LLC, Advanced Applications Center, Mississippi State Univ., Mississippi State, MS

    Lingenfelser, D. J.
    HBM n-Code Federal, LLC, Advanced Applications Center, Mississippi State Univ., Mississippi State, MS


    Stock #: JAI103966

    ISSN: 1546-962X

    DOI: 10.1520/JAI103966

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    Author
    Title Fatigue Crack Growth Rate Behavior of A36 Steel using ASTM Load-Reduction and Compression Precracking Test Methods
    Symposium , 0000-00-00
    Committee E08