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Cyclic Plasticity (cyclic + plasticity)

Distribution by Scientific Domains

Polymers and Materials Science	80%

Selected Abstracts

Fatigue Design of Notched Components with Stress Gradients and Cyclic Plasticity

ADVANCED ENGINEERING MATERIALS, Issue 9 2009
Mahaman Habibou Maitournam
This paper shows that the fatigue strength of notched specimens under cyclic loading can be simply and accurately estimated by using elastic-plastic computations and by averaging the stress over a critical volume obtained by an optimisation process, minimizing the dispersion between experiments and simulations. The Dang Van high-cycle fatigue criterion is considered. Fatigue tests (tension-compression, bending and torsion) carried out by CETIM, are used to calibrate the critical volume. [source]

Effect of test frequency on fatigue strength of low carbon steel

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 6 2009
N. TSUTSUMI
ABSTRACT Ultrasonic fatigue tests (test frequency: 20 kHz) and conventional tension,compression fatigue tests (10 Hz) have been conducted on annealed and 10% pre-strained specimens of 0.13% carbon steel. Small holes were introduced on the specimen surface to investigate the effect of test frequency on small crack growth. The dynamic stress concentration factor and the stress intensity factor under ultrasonic fatigue tests were checked to be almost the same as those of conventional tension,compression fatigue tests. However, the fatigue properties were dependent on the test frequency. Ultrasonic fatigue tests showed longer fatigue life and lower fatigue crack growth rate for the annealed and 10% pre-strained specimens. Slip bands were scarce in the neighbourhood of cracks under ultrasonic fatigue tests, while many slip bands were observed in a wide area around the crack under conventional fatigue tests. In order to explain the effect of test frequency on fatigue strength, dynamic compression tests with Split Hopkinson bars were carried out. The stress level increases substantially with the strain rate. Thus, the increase in fatigue strength might be, to a large extent, due to a reduction in crack tip cyclic plasticity during ultrasonic fatigue tests. [source]

The evolution of the stress,strain fields near a fatigue crack tip and plasticity-induced crack closure revisited

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 1 2004
L. G. ZHAO
ABSTRACT The evolution of the stress,strain fields near a stationary crack tip under cyclic loading at selected R -ratios has been studied in a detailed elastic,plastic finite element analysis. The material behaviour was described by a full constitutive model of cyclic plasticity with both kinematic and isotropic hardening variables. Whilst the stress/strain range remains mostly constant during the cyclic loading and scales with the external load range, progressive accumulation of tensile strain occurs, particularly at high R -ratios. These results may be of significance for the characterization of crack growth, particularly near the fatigue threshold. Elastic,plastic finite element simulations of advancing fatigue cracks were carried out under plane-stress, plane-strain and generalized plane-strain conditions in a compact tension specimen. Physical contact of the crack flanks was observed in plane stress but not in the plane-strain and generalized plane-strain conditions. The lack of crack closure in plane strain was found to be independent of the material studied. Significant crack closure was observed under plane-stress conditions, where a displacement method was used to obtain the actual stress intensity variation during a loading cycle in the presence of crack closure. The results reveal no direct correlation between the attenuation in the stress intensity factor range estimated by the conventional compliance method and that determined by the displacement method. This finding seems to cast some doubts on the validity of the current practice in crack-closure measurement, and indeed on the role of plasticity-induced crack closure in the reduction of the applied stress intensity factor range. [source]

A fatigue criterion for general multiaxial loading

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 1 2000
Jiang
An incremental fatigue damage model is proposed. The model incorporates the critical plane concept in multiaxial fatigue, plastic strain energy and material memory in cyclic plasticity. With an incremental form the model does not require a cycle counting method for variable amplitude loading. The model is designed to consider mean stress and loading sequence effects. Features of the new model are discussed and the determination of material constants is detailed. Verification of the model is achieved by comparing the predictions obtained by using the new model and experimental data of four materials under different loading conditions. [source]

Numerical Analysis of a Cyclical Loaded Construction under Corrosion Degradation

PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2005
W. Dudda
A contribution for analytical and numerical tools that permits of a deterministic evaluation of structure behavior in external conditions, under multiparameter and/or cyclic mechanical, thermal and chemical loads, is the aim of this paper. Particular structure elements undergo the plastic and corrosion degradation and they dissipate energy, which consists of irreversible contributions, like a work on the inelastic strains. The construction and its unit lifetime are estimated according to a dissipated energy criterion. The paper emphasizes the modeling and numerical implementation of degradation effects, such as cyclic plasticity, generated by mechanical and thermal loads, stress corrosion, electrochemical corrosion and low-cyclic corrosion. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]