Ratcheting of Stainless Steel 304 Under Multiaxial Nonproportional Loading

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
Kwang S. Kim ◽  
Rong Jiao ◽  
Xu Chen ◽  
Masao Sakane
Keyword(s):  
Stainless Steel ◽  
Shear Stress ◽  
Kinematic Hardening ◽  
Isotropic Hardening ◽  
Mean Stress ◽  
Nonproportional Loading ◽  
Torsional Strain ◽  
Ratcheting Strain ◽  
Stainless Steel 304 ◽  
Strain Cycling

Multiaxial ratcheting is often simulated by use of nonlinear kinematic hardening models, while in reality materials show cyclic hardening/softening and additional hardening under nonproportional loading. The effect of isotropic hardening on ratcheting needs to be addressed in simulation. In this study, ratcheting tests are conducted on stainless steel 304 under uniaxial, torsional, and combined axial-torsional loading. The ratcheting strain is predicted based on the constitutive theory that incorporates a modified Ohno–Wang kinematic hardening rule and Tanaka’s isotropic hardening model. The results show that the main features of the stress-strain response can be simulated with the constitutive model. Ratcheting strain under axial mean stress depends highly on the loading path and load level, and the degree of cyclic changes in shear stress under torsional strain control is not as influential. The torsional ratcheting strain under mean shear stress with (or without) fully reversed axial strain cycling is found close to the axial ratcheting strain under equivalent mean stress with (or without) torsional strain cycling. In all, the experimental and predicted ratcheting strains for nonproportional paths are found in decent correlation. However, overprediction still prevails for some loading paths, and ratcheting rates deviate considerably from experimental values.

Ratcheting of Stainless Steel 304 Under Multiaxial Nonproportional Loading

2007 ◽  
Author(s):  
Kwang S. Kim ◽  
Rong Jiao ◽  
Xu Chen ◽  
Masao Sakane
Keyword(s):  
Stainless Steel ◽  
Kinematic Hardening ◽  
Axial Strain ◽  
Cyclic Hardening ◽  
Load Level ◽  
Loading Path ◽  
Isotropic Hardening ◽  
Ratcheting Strain ◽  
Stainless Steel 304 ◽  
Strain Cycling

Ratcheting tests are conducted on stainless steel 304 under uniaxial, torsional, and combined axial-torsional loading. The ratcheting strain is predicted based on the constitutive theory that incorporates a modified Ohno-Wang kinematic hardening rule and Tanaka’s isotropic hardening model. The results show that the main features of the stress-strain response can be simulated with the constitutive model. The experimental and predicted ratcheting strains for nonproportional paths are found in decent correlation. Ratcheting strain depends highly on the loading path and load level, and less on cyclic hardening or softening of the material. The torsional ratcheting strain under mean shear stress with (or without) fully reversed axial strain cycling is found close to the axial ratcheting strain under equivalent mean stress with (or without) torsional strain cycling.

Ratcheting Simulation of Z2CN18.10 Austenitic Stainless Steel under Pre-Strain Conditions

2016 ◽  
Vol 853 ◽  
pp. 112-116
Author(s):  
Yong Wang ◽  
You Gang Peng ◽  
Xu Chen
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Kinematic Hardening ◽  
Isotropic Hardening ◽  
Good Prediction ◽  
Strain Accumulation ◽  
Modified Model ◽  
Hardening Model ◽  
Ratcheting Strain ◽  
Independent Model

Uniaxial ratcheting behaviors of Z2CN18.10 austenitic stainless steel under both tensile pre-strain (TP) and compressive pre-strain (CP) were experimentally studied at room temperature. The experimental results show that: TP restrains ratcheting strain accumulation of subsequent cycling with positive mean stress; lower level of CP is found to accelerate ratcheting strain accumulation while higher level of CP retards the accumulation. Based on the Ohno-Wang II kinematic hardening rule, rate-independent model, viscoplastic model, isotropic hardening model and a modified model were constructed to describe the ratcheting behaviors under various pre-strain conditions. All the four models gave fairly good prediction on ratcheting strains for various TP. The isotropic hardening model and modified model predicted acceptable ratcheting strain though still showed slight tendency of over prediction.

A Noncyclic Method for Determination of Accumulated Strain in Stainless Steel 304 Pressure Vessels

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Gongfeng Jiang ◽  
Gang Chen ◽  
Liang Sun ◽  
Yiliang Zhang ◽  
Xiaoliang Jia ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Internal Pressure ◽  
Pressure Vessel ◽  
Peak Stress ◽  
Pressure Vessels ◽  
Experimental Results ◽  
Elastic Domain ◽  
Ratcheting Strain ◽  
Stainless Steel 304 ◽  
Accumulated Strain

Experimental results of uniaxial ratcheting tests for stainless steel 304 (SS304) under stress-controlled condition at room temperature showed that the elastic domain defined in this paper expands with accumulation of plastic strain. Both ratcheting strain and viscoplastic strain rates reduce with the increase of elastic domain, and the total strain will be saturated finally. If the saturated strain and corresponded peak stress of different experimental results under the stress ratio R ≥ 0 are plotted, a curve demonstrating the material shakedown states of SS304 can be constituted. Using this curve, the accumulated strain in a pressure vessel subjected to cyclic internal pressure can be determined by only an elastic-plastic analysis, and without the cycle-by-cycle analysis. Meanwhile, a physical experiment of a thin-walled pressure vessel subjected to cyclic internal pressure has been carried out to verify the feasibility and effectiveness of this noncyclic method. By comparison, the accumulated strains evaluated by the noncyclic method agreed well with those obtained from the experiments. The noncyclic method is simpler and more practical than the cycle-by-cycle method for engineering design.

Strain Hardening of Annealed 304 Stainless Steel by Creep

1993 ◽  
Vol 115 (4) ◽  
pp. 345-350 ◽  
Author(s):  
Han-Chin Wu ◽  
Chin-Cheng Ho
Keyword(s):  
Stainless Steel ◽  
Strain Hardening ◽  
Kinematic Hardening ◽  
Constant Strain Rate ◽  
Transient Creep ◽  
304 Stainless Steel ◽  
Isotropic Hardening ◽  
Loading Surface ◽  
Before And After ◽  
Strain Hardening Behavior

Combined axial-torsional experiments have been conducted at room temperature on thin-walled tubes to investigate the strain hardening behavior of annealed 304 stainless steel due to creep. The constant strain-rate dynamic loading (or SCISR) surfaces representing the state of material before and after creep have benn determined. It has been found that transient creep essentially causes the loading surface to undergo kinematic hardening with insignificant amount of isotropic hardening for this material. A conclusion is drawn that the loading surface hardened by transient creep is the same as that hardened by plastic deformation. This is true both for specimens with pure tension and pure torsion loading paths. The results confirm assumptions of the overstress theory of viscoplasticity.

Prediction of Forming Limit Diagram Based on Damage Coupled Kinematic-Isotropic Hardening Model Under Nonproportional Loading

2002 ◽  
Vol 124 (2) ◽  
pp. 259-265 ◽  
Author(s):  
C. L. Chow ◽  
X. J. Yang ◽  
E. Chu
Keyword(s):  
Damage Mechanics ◽  
Kinematic Hardening ◽  
Forming Limit Diagram ◽  
Forming Limit ◽  
Isotropic Hardening ◽  
Strain History ◽  
Sheet Metals ◽  
Nonproportional Loading ◽  
Localized Necking ◽  
Theory Of Damage

Based on the theory of damage mechanics, an anisotropic damage coupled mixed isotropic-kinematic hardening plastic model for the prediction of forming limit diagram (FLD) is developed. The model includes the formulation of nonlinear anisotropic kinematic hardening. For the prediction of limit strains under nonproportional loading, a damage criterion for localized necking of sheet metals subjected to complex strain history is proposed. The model is employed to predict the FLDs of AL6111-T4 alloy. The predicted results agree well with those determined experimentally.

Constitutive Model Development for Thermo-Mechanical Fatigue Response Simulation of Haynes 230

2012 ◽  
Author(s):  
Raasheduddin Ahmed ◽  
Mamballykalathil Menon ◽  
Tasnim Hassan
Keyword(s):  
Stress Response ◽  
Constitutive Model ◽  
Kinematic Hardening ◽  
Isotropic Hardening ◽  
Large Set ◽  
Mean Stress ◽  
Liner Material ◽  
Mechanical Fatigue ◽  
Combustor Liner ◽  
Mean Strain

Turbine engine combustor components are subject to thermo-mechanical fatigue (TMF) during service. The combustor liner temperatures can sometimes reach as high as 1800°F. An accurate estimate of the strains at critical locations in the combustor liner is required for reliable lifing predictions. This demands the need for a detailed analysis of the TMF responses and a robust constitutive model capable of predicting the same. A large set of experiments have been carried out on the liner material, a nickel based alloy, HA 230, in an effort to understand its thermo-mechanical fatigue constitutive response. The out-of-phase strain-controlled TMF experiments with a negative mean strain show a positive mean stress response, while the in-phase TMF experiments with a positive mean strain show a negative mean stress response. A Chaboche based viscoplastic constitutive model is under development. It will have several essential features such as nonlinear kinematic hardening, isotropic hardening, strain range dependence, rate dependence, temperature dependence and static recovery. The constitutive model being developed for accurately calculating the stress-strain response is being carried out with the final objective of predicting the strains in an actual combustor liner in service through finite element simulation for fatigue lifing.

Creep Experiments Under Nonproportional Loadings With Stress Reversals for 2618 Aluminum

1984 ◽  
Vol 106 (4) ◽  
pp. 397-404 ◽  
Author(s):  
J. L. Ding ◽  
W. N. Findley
Keyword(s):  
Shear Stress ◽  
Strain Hardening ◽  
Synergistic Effects ◽  
Kinematic Hardening ◽  
High Stress ◽  
Creep Recovery ◽  
Flow Rule ◽  
Nonproportional Loading ◽  
Stress Levels ◽  
Stress Reversals

Experiments on creep of 2618-T61 aluminum under nonproportional loading steps combined with shear stress reversals, are reported. Compared to previous work, the stress levels, under which nonproportional loading steps were performed, were relatively low in the current work. In addition to the features of the material responses under nonproportional loadings such as anisotropy induced by creep strain, synergistic effects on creep and creep recovery, more findings related to stress reversals were a cyclic softening effect. The effect of shear stress reversal on tension creep was not significant because of the low stress levels. Isotropic strain hardening, kinematic hardening and independent strain hardening theories were evaluated. An auxiliary rule was developed for the isotropic and independent strain hardening approaches to extend the capabilities of the theories. Creep under stress reversals predicted by the kinematic flow rule was well described at low stresses but was too exagerated at high stress levels.

scholarly journals Shear Stress, Temperature, and Inoculation Concentration Influence the Adhesion of Water-Stressed Helicobacter pylori to Stainless Steel 304 and Polypropylene

2006 ◽  
Vol 72 (4) ◽  
pp. 2936-2941 ◽  
Author(s):  
N. F. Azevedo ◽  
A. R. Pinto ◽  
N. M. Reis ◽  
M. J. Vieira ◽  
C. W. Keevil
Keyword(s):  
Stainless Steel ◽  
Shear Stress ◽  
Helicobacter Pylori ◽  
Drinking Water ◽  
Molecular Techniques ◽  
Epifluorescence Microscopy ◽  
Dimensional Structure ◽  
Shear Stresses ◽  
Stainless Steel 304 ◽  
H Pylori

ABSTRACT Although molecular techniques have identified Helicobacter pylori in drinking water-associated biofilms, there is a lack of studies reporting what factors affect the attachment of the bacterium to plumbing materials. Therefore, the adhesion of H. pylori suspended in distilled water to stainless steel 304 (SS304) coupons placed on tissue culture plates subjected to different environmental conditions was monitored. The extent of adhesion was evaluated for different water exposure times, using epifluorescence microscopy to count total cell numbers. High shear stresses—estimated through computational fluid dynamics—negatively influenced the adhesion of H. pylori to the substrata (P < 0.001), a result that was confirmed in similar experiments with polypropylene (P < 0.05). However, the temperature and inoculation concentration appeared to have no effect on adhesion (P > 0.05). After 2 hours, H. pylori cells appeared to be isolated on the surface of SS304 and were able to form small aggregates with longer exposure times. However, the formation of a three-dimensional structure was only very rarely observed. This study suggests that the detection of the pathogen in well water described by other authors can be related to the increased ability of H. pylori to integrate into biofilms under conditions of low shear stress. It will also allow a more rational selection of locations to perform molecular or plate culture analysis for the detection of H. pylori in drinking water-associated biofilms.

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