Cyclic stress-strain curves generated from random cyclic strain amplitude tests

1999 ◽  
Vol 21 (6) ◽  
pp. 521-530 ◽  
Author(s):  
A Jones
Keyword(s):  
Strain Amplitude ◽  
Cyclic Strain ◽  
Cyclic Stress ◽  
Stress Strain ◽  
Cyclic Strain Amplitude

Cyclic Plasticity and Cyclic Creep in Austenitic-Ferritic Duplex Steel

2011 ◽  
Vol 465 ◽  
pp. 431-434
Author(s):  
Jaroslav Polák ◽  
Martin Petrenec ◽  
Jiří Man ◽  
Tomáš Kruml
Keyword(s):  
Creep Rate ◽  
Plastic Strain ◽  
Strain Amplitude ◽  
Cyclic Creep ◽  
Cyclic Stress ◽  
Plastic Strain Amplitude ◽  
Cyclic Plasticity ◽  
Stress Strain ◽  
Duplex Steel ◽  
Mean Stresses

Smooth specimens made from austenitic-ferritic duplex steel were subjected to constant stress amplitude loading with positive mean stresses. Hysteresis loops were recorded during the fatigue life and plastic strain amplitude and cyclic creep rate were determined. Fatigue hardening/softening curves, cyclic creep curves and cyclic stress-strain curves for different positive mean stresses were evaluated. Typical dislocation structures developed in both phases of the duplex steel were identified using TEM, compared with the saturated plastic strain amplitude and correlated with the decrease of the cyclic creep rate during cycling and the slope of the cyclic stress-strain curve.

scholarly journals Analysis of the Effective and Internal Cyclic Stress Components in the Inconel Superalloy Fatigued at Elevated Temperature

2011 ◽  
Vol 278 ◽  
pp. 393-398 ◽  
Author(s):  
Miroslav Šmíd ◽  
Martin Petrenec ◽  
Jaroslav Polák ◽  
Karel Obrtlík ◽  
Alice Chlupová
Keyword(s):  
Strain Amplitude ◽  
Effective Stress ◽  
Stress Amplitude ◽  
Cyclic Hardening ◽  
Cyclic Stress ◽  
Step Test ◽  
Total Strain Amplitude ◽  
Strain Response ◽  
Stress Strain ◽  
Stress Components

Cyclic multiple step test in strain control have been performed on cylindrical specimens of cast polycrystalline Inconel 738LC and 792-5A superalloys at 800 °C in laboratory atmosphere. Hysteresis loops were analyzed according to the statistical theory of hysteresis loop. The effective and internal stress components were evaluated. The effective stress of γ´ precipitate has significant influence on the stress-strain response both materials. The stress amplitude in IN 792-5A is higher than in IN 738LC at approximately same total strain amplitude due to significantly higher effective stress of γ´ phase. Cyclic hardening/softening curves and cyclic stress-strain curves using short-cut procedure were obtained. Cyclic hardening/softening behavior depends both on temperature and strain amplitude. Low amplitude straining is characterized by the saturation of the stress amplitude. In high amplitude straining slight softening was found. The cyclic stress-strain curves for both materials can be fitted by power law. Cyclic stress-strain response in terms of internal and effective stress components is discussed in relation to microstructural parameters of the materials. The observation of surface relief revealed the presence of persistent slip markings.

Cyclic Plastic Deformation of a Circular Plate With Work Hardening

1984 ◽  
Vol 106 (4) ◽  
pp. 336-341
Author(s):  
R. Winter
Keyword(s):  
Fatigue Life ◽  
Low Cycle Fatigue ◽  
Nonlinear Behavior ◽  
Strain Curve ◽  
Strain Range ◽  
Cyclic Strain ◽  
Cyclic Stress ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Element Analysis

An experimental and theoretical study was performed of the nonlinear behavior of a simply supported flat circular aluminum plate under reversed cyclic central load. The application is for the analysis of cyclic stress and strain of structural components in the plastic range for predicting low-cycle fatigue life. The main purpose was to determine the relative accuracy of an elastic-plastic large deformation finite element analysis when the material properties input data are derived from monotonic (noncyclic) stress-strain curves versus that derived from cyclic stress-strain curves. The results showed that large errors could be induced in the theoretical prediction of cyclic strain range when using the monotonic stress-strain curve, which could lead to large errors in predicting low-cycle fatigue life. The use of cyclic stress-strain curves, according to the model developed by Morrow, et al., proved to be accurate and convenient.

scholarly journals Flat-Cladding Fiber Bragg Grating Sensors for Large Strain Amplitude Fatigue Tests

2021 ◽  
Author(s):  
Aihen Feng ◽  
Daolun Chen ◽  
Cheng Li ◽  
Xijia Gu
Keyword(s):  
Fiber Bragg Grating ◽  
Strain Amplitude ◽  
Large Strain ◽  
Hysteresis Loops ◽  
Cyclic Strain ◽  
Fatigue Tests ◽  
Bragg Grating ◽  
Large Strain Amplitude ◽  
Bragg Grating Sensor ◽  
Cyclic Strain Amplitude

We have successfully developed a flat-cladding fiber Bragg grating sensor for large cyclic strain amplitude tests of up to ±8,000 με. The increased contact area between the flat-cladding fiber and substrate, together with the application of a new bonding process, has significantly increased the bonding strength. In the push-pull fatigue tests of an aluminum alloy, the plastic strain amplitudes measured by three optical fiber sensors differ only by 0.43% at a cyclic strain amplitude of ±7,000 με and 1.9% at a cyclic strain amplitude of ±8,000 με. We also applied the sensor on an extruded magnesium alloy for evaluating the peculiar asymmetric hysteresis loops. The results obtained were in good agreement with those measured from the extensometer, a further validation of the sensor.

Reliability Analysis of LCF Life for a Turbine Disk

2010 ◽  
Vol 146-147 ◽  
pp. 1379-1385
Author(s):  
Yang Gao ◽  
Chang Jun Yang ◽  
Kai Lin ◽  
Qing Gao
Keyword(s):  
Reliability Analysis ◽  
Low Cycle Fatigue ◽  
Three Dimensional ◽  
Strain Curve ◽  
Cyclic Strain ◽  
Cyclic Stress ◽  
Turbine Disk ◽  
Fatigue Reliability ◽  
Three Dimensional Model ◽  
Stress Strain

Cyclic stress-strain curve and cyclic strain-life curve appear distinct scatters, and the scatter of fatigue life increases with reducing of the strain levels. A methodology for reliability simulation of low cycle fatigue (LCF) life for turbine disk structures is developed in this paper. First, probabilistic cyclic stress-strain model and linear heteroscedastic probabilistic cyclic strain-life model are founded based on the fatigue test data. Second, three dimensional model of a turbine disk is built, and the fatigue reliability analysis of this turbine disk is implemented in probabilistic design module (PDS) of ANSYS by the combination of response surface method (RSM) and Monte Carlo simulation (MCS). The predicted life with reliability 0.9987 is well consistent with the technology life obtained from disks LCF tests by scatter factors method.

Note on Stress and Strain Redistribution in a Notched Plate Specimen During Cyclic Loading

1969 ◽  
Vol 91 (3) ◽  
pp. 379-382 ◽  
Author(s):  
D. F. Mowbray ◽  
T. Slot
Keyword(s):  
Strain Softening ◽  
Cyclic Strain ◽  
Cyclic Stress ◽  
Computational Method ◽  
Stress And Strain ◽  
Stress Strain ◽  
Fatigue Specimen ◽  
Plate Specimen ◽  
Measured Strain ◽  
Distribution Of Stress

A finite-element computational method is employed to determine the spatial distribution of stress and strain in a notched-plate fatigue specimen fabricated of mild steel. Because of cyclic strain softening of the material, there is a redistribution of stress and strain in the specimen as a function of the number of load cycles. This phenomenon is considered in the analysis by using cyclic stress-strain diagrams as effective stress-strain curves. The numerical results are found to correlate well with measured strain distributions reported in the literature.

scholarly journals A Novel Notion of Local and Nonlocal Deformation-Gamuts to Model Elastoplastic Deformation

2022 ◽  
Author(s):  
Shivang Desai
Keyword(s):  
Elastoplastic Deformation ◽  
Cyclic Strain ◽  
Cyclic Stress ◽  
Strain Hardening Exponent ◽  
Stress Strain ◽  
Shared Information ◽  
Deformation Dynamics ◽  
Strain Coefficient ◽  
Material Points ◽  
Nonlocal Deformation

AbstractLocalization and nonlocalization are characterized as a measure of degrees of separation between two material points in material’s discrete framework and as a measure of unshared and shared information, respectively, manifested as physical quantities between them, in the material’s continuous domain. A novel equation of motion to model the deformation dynamics of material is proposed. The shared information between two localizations is quantified as nonlocalization via a novel multiscale notion of Local and Nonlocal Deformation-Gamuts or DG Localization and Nonlocalization. Its applicability in continuum mechanics to model elastoplastic deformation is demonstrated. It is shown that the stress–strain curves obtained using local and nonlocal deformation-gamuts are found to be in good agreement with the Ramberg–Osgood equation for the material considered. It is also demonstrated that the cyclic strain hardening exponent and cyclic stress–strain coefficient computed using local and nonlocal deformation-gamuts are comparable with the experimental results as well as the theoretical estimations published in the open literature.

Low-Cycled Fatigue Life of S30408 Stainless Steel at Liquid-Nitrogen Temperature

2018 ◽  
Author(s):  
Yingzhe Wu ◽  
Huaijian Xu ◽  
Qunjie Lu ◽  
Jinyang Zheng ◽  
Ping Xu
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Liquid Nitrogen ◽  
Strain Amplitude ◽  
Hysteresis Loops ◽  
Cyclic Strain ◽  
Liquid Nitrogen Temperature ◽  
Cyclic Stress ◽  
Cyclic Softening ◽  
Fatigue Tests

This paper is concerned with the low-cycled fatigue life of S30408 austenitic stainless steel at 77 K. Strain-controlled low-cycled fatigue tests were performed in a liquid-nitrogen bath covering a strain-amplitude range of 0.4%–1.0%. The role of the reduced temperature is examined during the low-cycled fatigue tests by comparing the fatigue performance to the one at ambient temperature that was obtained in our previous work. It is found that the cryogenic low-cycled fatigue life is significantly improved by a factor of 5–10 in the low strain-amplitude range of 0.4%–0.5%, resulting from the pronounced hardening effect due to the low temperature. However, the cryogenic improvement gradually reduces with the increasing strain-amplitude. At 77 K, the cyclic stress amplitude increases rapidly at the beginning of the fatigue test, and no cyclic softening is found due to the cryogenically constrained movement of the dislocations. The fatigue hysteresis loops and fatigue stress-strain curves shows that the cyclic plastic strain at cryogenic temperature accounts for a limited proportion in the total cyclic strain, and the damage may occurs explosively at the beginning of the cyclic load at 77 K.

Sign in / Sign up

Export Citation Format

Share Document