Mechanical Behavior Laboratory University of Nevada, Reno

Paper

[J49] Jiang, Y. and Zhang, J., 2008, "Benchmark Experiments and Characteristic Cyclic Plasticity Behavior," International Journal of Plasticity, Vol.24, pp.1481-1515. doi: 10.1016j.ijplas.2007.10.003

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Paper Abstract

Key issues in cyclic plasticity modeling are discussed based upon representative experimental observations on several commonly used engineering materials. Cyclic plasticity is characterized by the Bauschinger effect, cyclic hardening/softening, strain range effect, nonproporitonal hardening, and strain ratcheting. Additional hardening is identified to associate with ratcheting rate decay. Proper modeling requires a clear distinction among different types of cyclic plasticity behavior. Cyclic hardening/softening sustains dependent on the loading amplitude and loading history. Strain range effect is common for most engineering metallic materials. Often, nonproportional hardening is accompanied by cyclic hardening, as being observed on stainless steels and pure copper. A clarification of the two types of material behavior can be made through benchmark experiments and modeling technique. Ratcheting rate decay is a common observation on a number of materials and it often follows a power law relationship with the number of loading cycles under the constant amplitude stress controlled condition. Benchmark experiments can be used to explore the different cyclic plasticity properties of the materials. Discussions about proper modeling are based on the typical cyclic plasticity phenomena obtained from testing several engineering materials under various uniaxial and multiaxial cyclic loading conditions. Sufficient experimental evidence points to the unambiguous conclusion that none of the hardening phenomena (cyclic hardening/softening, strain range effect, nonproportional hardening, and strain hardening associated with ratcheting rate decay) is isotropic in nature. None of the hardening behavior can be properly modeled with a change in the yield stress.

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Paper Figures

Fig. 1

Fig. 1. Schematic illustration of the Bauschinger effect (Download data).

Fig. 2

Fig. 2. 1070 steel under zero-to-tension uniaxial loading: (a) stress-strain hysteresis loops (Download data) and (b) stress-plastic strain hysteresis loop for a selected loading cycle (Download data) (Jiang, 1993).

Fig. 3

Fig. 3. Representative stress-strain hysteresis loops of an OFHC copper under fully reversed strain-controlled uniaxial loading (Δε/2 = 0.3%) (Download data) (Zhang, 2004).

Fig. 4

Fig. 4. Variation of the stress amplitude with the loading cycles for fully reversed strain-controlled uniaxial loading of stainless steel 304 (Download data) (Jiang and Kurath, 1997a).

Fig. 5

Fig. 5. Dependence of cyclic softening on loading history: (a) SS304 (Download data) and (b) OFHC copper (Download data) (Zhang, 2004).

Fig. 6

Fig. 6. Stress amplitude variation with number of loading cycles in each loading step in a three-step fully reversed strain-controlled loading sequence (Download data) (Jiang and Kurath, 1997a).

Fig. 7

Fig. 7. Cyclic hardening of OFHC copper under fully reversed strain-controlled uniaxial loading (Download data).

Fig. 8

Fig. 8. Cyclic hardening/softening of stainless steel 304 under fully reversed uniaxial loading (Download data) (Jiang and Kurath, 1997a).

Fig. 9

Fig. 9. Reversals taken from the three-step sequence loading for stainless steel 304 under fully reversed strain-controlled uniaxial loading (data identical to that in Fig. 6) (Download data).

Fig. 10

Fig. 10. Schematic illustration of Masing behavior (Download data).

Fig. 11

Fig. 11. Stabilized stress-plastic strain hysteresis loops with the lower tips tied together: (a) AL-6XN (Kalnaus and Jiang, 2007) (Download data); (b) 16MnR (Gao et al., submitted for publication) (Download data)and (c) 1070 Steel (Jiang, 1993) (Download data).

Fig. 12

Fig. 12. Reversals from the stabilized stress-plastic strain hysteresis loops: (a) SS304 (Jiang and Kurath, 1997a) (Download data); (b) OFHC copper (Download data) and (c) 7075-T651 (Download data).

Fig. 13

Fig. 13. Reversals of stainless steel 304 under uniaxial loading shown in log-log scale (Download data) (Jiang and Kurath, 1997a).

Fig. 14

Fig. 14. Reversibility of cyclic plasticity in a textured OFHC copper: (a) shear stress amplitude versus number of loading cycles (Download data) and (b) shear stress range versus shear plastic strain range (Download data) (Zhang and Jiang, 2005).

Fig. 15

Fig. 15. Experimentally observed sequence dependent cyclic deformation for stainless steel 304 (Download data) (Jiang and Kurath, 1997a).

Fig. 16

Fig. 16. Definition of equivalent stress magnitude and equivalent plastic strain magnitude: (a) equivalent stress concept (Download data) and (b) equivalent plastic strain concept (Download data).

Fig. 17

Fig. 17. Comparison of proportional loading history and nonproportional loading history of stainless steel 304 using an Armstrong-Frederick model (Jiang and Kurath, 1997b): (a) without considering additional nonproportional hardening (Download data) and (b) considering additional nonproportional hardening (Download data).

Fig. 18

Fig. 18. Variations of stress amplitude with loading cycles for the first three loading steps in a multiple-step loading history of stainless steel 304 (Download data) (Jiang and Kurath, 1997b).

Fig. 19

Fig. 19. Stress response obtained from the step loading experiment on OFHC copper; (a) Step 1 (90° out-of-phase axial-torsion, Δε/2/2 = 0.3% and Δγ/2 = 0.52%) (Download data) and (b) Step 2 (pure torsion, Δγ/2 = 0.15%) (Download data).

Fig. 20

Fig. 20. Cyclic strain ratcheting deformation: (a) stainless steel 304 (Download data); (b) 1070 steel (Jiang and Sehitoglu, 1994a) (Download data) and (c) OFHC copper (Download data).

Fig. 21

Fig. 21. Strain response of 1070 steel subjected to axial-torsion loading (Download data) (Jiang and Sehitoglu, 1994a).

Fig. 22

Fig. 22. Ratcheting rate as a function of the number of loading cycle under constant amplitude loading: (a) stainless steel 304 (Fig. 20a); 1070 steel (Fig. 21); and OFHC copper (Fig. 20c) (Download data) and (b) 1026 steel (32 and 31) (Download data).

Fig. 23

Fig. 23. Cyclic ratcheting of 1070 steel after monotonic tension (Download data) (Jiang and Sehitoglu, 1994b).

Fig. 24

Fig. 24. Cyclic ratcheting deformation of 1070 steel under two-step loading (Download data) (Jiang and Sehitoglu, 1994b).

Fig. 25

Fig. 25. Cyclic strain ratcheting of 1070 steel in two consecutive loading steps under block loading (Download data) (Jiang and Sehitoglu, 1994b).

Fig. 26

Fig. 26. Reversals during ratcheting deformation of 1070 steel (data identical to that in Fig. 20b) (Download data).

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