0
Research Papers: Gas Turbines: Structures and Dynamics

Strain Rate and Loading Waveform Effects on an Energy-Based Fatigue Life Prediction for AL6061-T6

[+] Author and Article Information
Todd Letcher

e-mail: etcher.7@osu.edu

M.-H. H. Shen

e-mail: shen.1@osu.edu
Mechanical and Aerospace
Engineering Department,
Building 148, 201 W. 19th Ave.,
The Ohio State University,
Columbus, OH 43210

Charles Cross

Turbine Engine Fatigue Facility,
Air Force Research Laboratory,
Wright-Patterson AFB, OH 45433

Contributed by the Structures and Dynamics Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received May 29, 2013; final manuscript received August 28, 2013; published online November 1, 2013. Editor: David Wisler.

J. Eng. Gas Turbines Power 136(2), 022502 (Nov 01, 2013) (6 pages) Paper No: GTP-13-1150; doi: 10.1115/1.4025497 History: Received May 29, 2013; Revised August 28, 2013

The energy-based lifing method is based on the theory that the cumulative energy in all hysteresis loops of a specimens' lifetime is equal to the energy in a monotonic tension test. Based on this theory, fatigue life can be calculated by dividing monotonic strain energy by a hysteresis energy model, which is a function of stress amplitude. Recent studies have focused on developing this method for a sine wave loading pattern—a variable strain rate. In order to remove the effects of a variable strain rate throughout the fatigue cycle, a constant strain rate triangle wave loading pattern was tested. The testing was conducted at various frequencies to evaluate the effects of multiple constant strain rates. Hysteresis loops created with sine wave loading and triangle loading were compared. The effects of variable and constant strain rate loading patterns on hysteresis loops throughout a specimens' fatigue life are examined.

FIGURES IN THIS ARTICLE
<>
Copyright © 2014 by ASME
Your Session has timed out. Please sign back in to continue.

References

Nicholas, T., 1999, “Critical Issues in High Cycle Fatigue,” Int. J. Fatigue, 21, pp. S221–S231. [CrossRef]
United States Air Force, 2004, “Department of Defense Handbook: Engine Structural Integrity Program (EnSIP),” Paper No. MIL-HDBK-1783B w/Change 2.
Scott-Emuakpor, O., Shen, M.-H. H., George, T., and Cross, C., “An Energy-Based Uniaxial Fatigue Life Prediction Method for Commonly Used Gas Turbine Engines Materials,” ASME J. Eng. Gas Turbines Power, 130(6), p. 062504. [CrossRef]
Scott-Emuakpor, O., Shen, M.-H. H., George, T., and Cross, C., 2010, “Multi-Axial Fatigue-Life Prediction Via a Strain-Energy Method,” AIAA J., 48(1), pp. 63–72. [CrossRef]
Ozaltun, H., Shen, M.-H. H., George, T., and Cross, C., 2011, “An Energy Based Fatigue Life Prediction Framework for In-Service Structural Components,” J. Exp. Mech., 51(5), pp. 707–718. [CrossRef]
Wertz, J., Shen, M.-H. H., Scott-Emuakpor, O., George, T., and Cross, C., 2012, “An Energy-Based Torsional-Shear Fatigue Lifing Method,” Exp. Mech., 52(7), pp. 705–715. [CrossRef]
Scott-Emuakpor, O., George, T., Cross, C., and Shen, M.-H. H., 2010, “Hysteresis Loop Representation for Strain Energy Calculation and Fatigue Assessment,” J. Strain Anal. Eng. Design, 45(4), pp. 275–282. [CrossRef]
Letcher, T., Shen, H., Scott-Emuakpor, O., George, T., and Cross, C., “An Energy Based Critical Fatigue Life Prediction Method for AL6061-T6,” Fatigue Fracture Eng. Mater. Struct., 35(9), pp. 861–870. [CrossRef]
Tarar, W., Scott-Emuakpor, O., and Shen, M.-H. H., 2010, “Development of New Finite Elements for Fatigue Life Prediction in Structural Components,” J. Struct. Eng. Mech., 35(6), pp. 659–676. [CrossRef]
Jasper, T. M., 1923, “The Value of the Energy Relation in the Testing of Ferrous Metals at Varying Ranges of Stress and at Intermediate and High Temperatures,” Philos. Mag. Ser., 46, pp. 609–627. [CrossRef]
Enomoto, N., 1965, “On Fatigue Tests Under Progressive Stress,” Proc. ASTM, 55, pp. 903–917.
Stowell, E., 1966, “A Study of the Energy Criterion for Fatigue,” Nucl. Eng. Design, 3, pp 32–40. [CrossRef]
Tarar, W., Shen, M.-H. H., George, T., and Cross, C., 2010, “A New Finite Element Procedure for Fatigue Life Prediction of Al6061 Plates Under Multiaxial Loadings,” J. Struct. Eng. Mech., 35(5), pp. 571–592. [CrossRef]
Miller, K. J., and Rizk, M. N., 1968, “Effects of Strain Rate on Low-Endurance Torsional Fatigue in Commercially Pure Aluminum,” J. Strain Anal., 3(4), pp. 273–280. [CrossRef]
Miller, K. J., 1967, “Strain Rate Effects on Low Endurance Fatigue,” Nature, 213, pp. 317–318. [CrossRef]
MayerCampbell Laird, H., 1995, “Frequency Effects on Cyclic Plastic Strain of Polycrystalline Copper Under Variable Loading,” Mater. Sci. Eng. A, 194(2), pp. 137–145. [CrossRef]
American Society of Test and Materials, 2007, “ASTM E466: Standard Practice for Conducting Force Controlled Constant Amplitude Axial Fatigue Tests of Metallic Materials,” Annual Book of ASTM Standards, Vol. 03.01, ASTM International, West Conshohocken, PA.
AMS D Nonferrous Alloys Committee, 2008, “SAE AMS 2772-E: Heat Treatment of Aluminum Alloy Raw Materials,” SAE, Warrendale, PA.
American Society for Test and Materials, 2008, “ASTM B211-03-M: Standard Specification for Aluminum and Aluminum-Alloy Bar Rod and Wire,” Annual Book of ASTM Standards, Vol. 02.02, ASTM International, West Conshohocken, PA.
American Society for Test and Materials, 2008, “ASTM E8/E8M-08: Standard Test Methods for Tension Testing of Metallic Materials,” Annual Book of ASTM Standards, Vol. 03.01, ASTM International, West Conshohocken, PA.
MTS TestStar IIs Software, Eden Prairie, MN.

Figures

Grahic Jump Location
Fig. 1

Hysteresis loop in generalized coordinates

Grahic Jump Location
Fig. 2

Specimen dimensions

Grahic Jump Location
Fig. 3

Fatigue test setup using an MTS load frame

Grahic Jump Location
Fig. 4

Sinusoidal and triangular loading waveforms

Grahic Jump Location
Fig. 5

Hysteresis loop—sine wave, 241.3 MPa, 2 Hz

Grahic Jump Location
Fig. 6

Hysteresis loop—triangle wave, 241.3 MPa, 2 Hz

Grahic Jump Location
Fig. 7

Different specimen for stress level and waveform (refer to Table 1)

Grahic Jump Location
Fig. 8

Same specimen for each stress level (refer to Table 2)

Grahic Jump Location
Fig. 9

Cumulative energy over specimen lifetime

Grahic Jump Location
Fig. 10

Fatigue life predictions based on two loading waveforms on a single specimen

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In