Life Prediction for a Structural Material under Cyclic Loads with Hold Times Using a Viscoplastic Constitutive Model.
Final rept. 1 Feb 83-31 Jan 84,
GEORGE WASHINGTON UNIV WASHINGTON DC SCHOOL OF ENGINEERING AND APPLIED SCIENCE
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This investigation demonstrates the ability of the Chaboche viscoplastic constitutive theory to model the behavior of Ti-6Al-4V alloy at non-elevated temperature. The range of material behavior considered includes uniaxial monotonic stress-strain primary creep, stress relaxation, kinematic and isotropic hardening and softening under cyclic loading with and without hold times. The six materials parameters of the viscoplastic theory were evaluated from a series of strain-controlled stabilized cyclic loading tests, and room temperature primary creep tests. The viscoplastic strain calculations were integrated into a fatigue life prediction methodology for low cycle fatigue. Two sets of low cycle fatigue life predictions were carried out and compared with experimental data. One involved strain-controlled cyclic loading without hold times, and the other stress-controlled cyclic loading with hold times. Good agreement was found between predicted and actual results.