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Panting Fatigue of Welded Steel Tee Details

Shohel, Muhammad Shah Newaz
http://rave.ohiolink.edu/etdc/view?acc_num=akron1428328220

Abstract Details

2015, Doctor of Philosophy, University of Akron, Civil Engineering.
A total of thirty samples of A36 structural “T” were tested under fatigue loading. Of the thirty, ten samples were tested under panting fatigue conditions. At a constant amplitude of stress ratio 0.01, fatigue tests were conducted under axial, combined axial and bending and pure bending conditions. Test data for a predefined stress range (Sre) and number of cycles to failure from the specimens were used to construct the stress range vs. life (S-N) curves for these structural welded “T”s. Differences were observed and noted in the individual S-N curves as well as in the combined S-N curves. Comparison of the S-N curves provided an indication of a suitable design resistance for these welded details. Fatigue design classification systems need to implement this classification for panting conditions, and design provisions are recommended. After testing, fatigue cracks were exposed and examined in a scanning electron microscope (SEM) to study the crack initiation and crack growth kinetics as well as the characteristics features that governed the observed fatigue behavior. The use of stress range as the primary fatigue strength parameter is a direct consequence of the role of residual stresses in the welded details and affects the S-N curves and is reflected in the use of the stress range and influences the slope as compared to typical design S-N curves. In order to understand the residual stresses and the effect on welded “T” fatigue behavior, two specimens were tested by the hole-drilling technique. Both the Power Series and the Integral Methods were employed for reducing the data. Resulting stress profiles and the general data trends were examined and compared for both cases and its effect on the S-N curves were discussed. Experiments were enriched with a Finite Element (FEA) study for axial, axial plus bending and pure bending specimens to numerically calculate the stress intensity factor (KI) in two dimensions as well as three dimensions. Stress intensity factors found in 2D and 3D finite element analysis were verified by widely accepted analytical solutions available in the literature. Three-dimensional opening mode stress intensity factors (3D-SIF) for structural steel welded “T” details study showed that a two-dimensional shape dependent correction factor can be introduced for a semi-elliptical surface crack for evaluating the three dimensional stress intensity factor. The minor axis (a) to major axis (c) i.e. the aspect ratio (a/c) of a semi-elliptical crack plays a key role in the approximation of 3D-SIF values, and in the present study were estimated for a three-dimensional crack analysis. The estimated three dimensional stress intensity factor (3D-SIF) was determined by a correlation between a/c and the two dimensional stress intensity (2D-SIF) factor for semi-elliptical cracks in the thickness direction of a welded “T”. Resulting equations may be used to estimate the 3D-SIF values from the 2D-SIF without much ambiguity. Recommendations regarding the analytical solutions and the design of S-N curves are provided when secondary bending effects are present
Craig Menzemer, Dr. (Advisor)
Anil Patnaik, Dr. (Committee Member)
David Roke, Dr. (Committee Member)
T.S. Srivatsan, Dr. (Committee Member)
Dmitry Golovaty, Dr. (Committee Member)
259 p.
Aerospace Engineering; Civil Engineering; Engineering; Materials Science; Mathematics; Mechanical Engineering
Panting fatigue; welded steel T details; S-N curves; 2D and 3D stress intensity factor; ANSYS

Recommended Citations

Citations

  • Shohel, M. S. N. (2015). Panting Fatigue of Welded Steel Tee Details [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1428328220

    APA Style (7th edition)

  • Shohel, Muhammad. Panting Fatigue of Welded Steel Tee Details. 2015. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1428328220.

    MLA Style (8th edition)

  • Shohel, Muhammad. "Panting Fatigue of Welded Steel Tee Details." Doctoral dissertation, University of Akron, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1428328220

    Chicago Manual of Style (17th edition)

akron1428328220
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© 2015, all rights reserved.
This open access ETD is published by University of Akron and OhioLINK.