Prestrain and mean stress effects on cyclic plastic deformation responses of iron-based alloys.

by Hai Ni

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Plastic deformation, residual stress, and crystalline texture in metal alloys can be measured from the breadth, position, and intensity of the x-ray diffraction peaks (Figure 1). When metals are stressed, they deform both plastically and elastically [1]. Plastic deformation. Despite the well-known correlation between RS and the mechanical behavior, it is not yet well understood how this stress evolves with plastic deformation and how it can affect service life performance of structural components [5]. Some few studies analyzing the influence of plastic deformation on the RS state in MMCs have been conducted []. Q.: A stress of 75 MPa is applied in the [0 01] direction on an fcc single crystal. Calculate (a) the resolved shear stress acting on the () [] slip system and, (b) (b) the resolved shear stress acting on the () [] slip system. Chapter 6 24 Mechanical Twinning Another important plastic deformation mechanism (low T) from G. Gottstein. The interplay of large strain and large strain-rate during high rate severe plastic deformation (HR-SPD) leads to dynamic temperature rise in situ that engenders a recovered microstructure whose characteristics is not just a function of the strain, but also of the strain-rate and the.

Abstract In this work, the complex relationship between deformation history and residual stresses in a magnesium-to-aluminum self-pierce riveted (SPR) joint is elucidated using numerical and experimental approaches. Non-linear finite element (FE) simulations incorporating strain rate and temperatur. Experimental Study on the Deformation and Strength. tuco 27th, Cyclic Plasticity of Engineering Materials Experiments and. of the report indicates that not much cyclic mean stress relaxation would take place, and it is probably best to use the mean stress correction factor throughout the life. The SWT parameter predicts , cycles and the Morrow parameter indicates no failure. References: Morrow, J., ir, "Cycle-Dependent Stress Relaxation," ASTM Symp. Influences of cell walls and grain boundaries on transient responses of an IF steel to changes in strain path. [Interstitial-free] [Interstitial-free] Full Record.

Plastic Collapse Analysis of Propped Cantilever Beams. xeky [PDF] Plastic Analysis and Design of Steel Structures By M. with the stress response—specifically, the immediate, intermediate, and prolonged effects on the body. These processes will be explained in terms of “pathways,” which set in action the systematic and integrative steps of the stress response. Because physi-ology involves specific nomenclature out-side the realm of your everyday vocabulary. Dowling, N. E., “Crack Growth During Low-Cycle Fatigue of Smooth Axial Specimens,” Cyclic Stress-Strain and Plastic Deformation Aspects of Fatigue Crack Growth. ASTM STP American Society for Testing and Materials, , pp. The objective of this program was to develop the appropriate material properties to characterize the cyclic tensile deformation, cyclic elastic-plastic crack growth, and the ductile tearing resistance of a pipe elbow made from a cast stainless steel equivalent to ASME SACF8M.

Prestrain and mean stress effects on cyclic plastic deformation responses of iron-based alloys. by Hai Ni Download PDF EPUB FB2

After studying systematically the cyclic deformation response of two steels under load control conditions, Pokluda and Stanĕk found that in different stress amplitude regime, i.e. high and low amplitudes, positive mean stress had a totally different effect on net cyclic plastic strain range, at high stress amplitude, increasing positive mean.

Furthermore, back stress and effective stress corresponding to each applied prestrain was measured during the unloading of the tensile tests and the subsequent evolutions of these values along with cyclic deformation provide valuable information about the microstructure's stability.

To determine the nature of damage acting on a fatigue crack-tip, it is mandatory to know the detailed cyclic plastic deformation response. In this work, cyclic plastic deformation response has been studied on a stationary CT specimen crack-tip in an elasto-plastic finite element frame work at selected R-ratios and he kinematic hardening model has been used to describe material.

The effect of tensile plastic strain history (peak stress) on cyclic creep was rationalized under the form of three peak stress phases (R0,RI and RII) in which the cyclic deformation mechanisms. Experimental mean stress relaxation data obtained by Arcari et al. [19] were used to assess the accuracy of the simulated cyclic stress-strain response in the presence of a mean stress or strain.

As cyclic stress amplitude and mean stress of PS sample increase with the decrease of strain amplitude, the detrimental effect of pre-strain on LCF life becomes more significant at lower strain. The instantaneous stress response at the strain rate change points were more pronounced than for Al-1Mg.

Download: Download high-res image (KB) Download: Download full-size image; Fig. Stress-strain behavior of Al-5Mg alloys during strain rate jump tests for different CCDP pass numbers. (a) at °C. (b) at °C. cyclic deformation & strain-life (e -n) approach monotonic tension test and stress-strain behavior strain-controlled test methods cyclic deformation and stress-strain behavior strain-based approach to life estimation, e-n determination of strain-life fatigue properties mean stress effects factors influencing strain-life behavior.

The evolution of microstructure during the hot working of steels microalloyed with Nb is governed by the recrystallization kinetics of austenite and the recrystallization-precipitation interaction.

The present study focuses on the effects of prestrain and deformation temperature on the rectrystallization behavior in these steels. The extent of recrystallization is characterized by a softening. H. Ni, Z. WangEffect of pre-strain and mean stress on cyclic plastic deformation response of iron-based alloys Mater Sci Eng A, (), pp.

Google Scholar. This forms a basis for the unifying discussion of the effect of pre-strain, mean stress and start-up procedure of fatigue tests on the cyclic stress–strain response. View Show abstract. For the user, severe plastic deformation (SPD) increases flexibility in tailoring the microstructures and selecting the properties to be emphasized in wrought Mg alloys.

The effect of SPD by hot multiaxial forging and equal channel angular pressing on the formation of fine grain microstructure and on resultant mechanical properties is discussed. The present study addresses the effect of tensile pre-strain histories on cyclic plastic deformation behaviour of T6 aluminium alloy.

effect of pre-strain, mean stress and start-up. The effects of plastic deformation and cyclic loading on residual stress distribution have been studied at welds in high strength MPa steel. Effects of residual stress levels on fatigue life are also presented.

Tensile loading was used to induce precisely controlled plastic deformation. Fatigue (cyclic stresses) 9Cyclic stresses, the S—N curve Depending on the ability of material to undergo plastic deformation before the fracture two fracture modes can be defined - ductile or brittle and mean stress, the range of stress, the stress amplitude.

Ni and Z. Wang, Effect of Pre-strain and Mean Stress on Cyclic Plastic Deformation Response of Iron-based Alloys, Mater. Sci. Sci. Eng.,A, p 12– Fatigue failure is brittle-like (relatively little plastic deformation) - even in normally ductile materials. Thus sudden and catastrophic.

Fatigue failure proceeds in three distinct stages: crack initiation in the areas of stress concentration (near stress raisers), incremental crack propagation, final catastrophic failure.

Cyclic stresses. This study deals with the effect of the loading history on the cyclic behavior and the fatigue life of a L stainless steel at room temperature. The experiments have been performed using two specimens’ categories.

The first one (virgin) has been submitted to only classical fatigue tests while in the second category, prior to the fatigue test; the specimen was subjected to a pre-hardening. Prestrain has recently been characterized experimentallyex vivo (Amini et al., ) and has been identified as an important mechanism in mitralvalve mechanics (Rausch et al., in press).

However, to date, the effects of prestrain and residual stress in thin biological membranes have never been quantified systematically in vivo. In order to represent the results systematically, a yield surface in the σ X, σ Y, σ Z, 3τ XY, stress space for large plastic strain is used.

The work-hardening characteristics for both isotropic and anisotropic materials are discussed, and the rules for anisotropy induced by prestrain and for work-hardening caused by subsequent strain are. [3] H. Ni, Z. Wang, Effect of pre-strain and mean stress on cyclic plastic deformation response of iron-based alloys, Materials Science and Engineering: A, () DOI: /s(00)   To explore the effect of prestrain, we systematically prescribed different prestrain levels, and studied their impact on the overall mechanical characteristics of the mitral leaflet, see Figure 7, left column.

Our central finding is that prestrain has a drastic effect on strain, stress, and stiffness. Fathallah et al. Plastic deformation and residual stresses after shot peening Normal effect (Hertz) Tangential stress IRS) generating process: after Ref.

6 peening The first calculation step is made with a half space assumption, then iterative calculations of redistri­. Cyclic stress and material failure. When cyclic stresses are applied to a material, even though the stresses do not cause plastic deformation, the material may fail due to fatigue.

Fatigue failure is typically modeled by decomposing cyclic stresses into mean and alternating components. Mean stress is the time average of the principal stress. The Effects of Stress. Previously we have discussed the effects of temperature and time on the long-term behavior of polymers.

Now let's take a look at stress. because we are now well into the non-linear or plastic deformation portion of the curve. And if this stress is maintained for the same hr period, the strain grows to 3%, a much.

Small plastic prestrains are shown to cause considerable life reductions. Larger prestrains appear to have little additional adverse effect. It was found possible adequately to correlate results with and without mean stress by a parametric representation of mean stress and strain amplitude.

(3) Material cyclic stress-strain response and degree of cyclic work hardening/softening (Zhuang and Halford, ) Morrow and Sinclair () conducted strain-controlled fatigue tests to quantify the cyclic residual stress relaxation and proposed a relationship between the mean stress and the load cycle, as follows: (3) Where σ mN.

To investigate the effect of residual stress or plastic deformation history on mechanics responses and fatigue life of an actual dent, three dent models are considered in this paper: (a) a true dent with residual stresses and dent formation history, (b) a purely geometric dent having the true dent profile with all stress/strain history removed.

Hydrostatic Stress Effects in Low Cycle Fatigue. Allen. Classical Metal Plasticity • Bridgman’s experiments • Yield – independent of hydrostatic or mean stress, σ.

m • Internal hydrostatic pressure – notched or cracked geometries σ m. I (= = + + σ σ σ. xx yy zz) 3 1 3 1. 1 1 p. m =− =− I • Determine three. K. Walker, The Effect of Stress Ratio During Crack Propagation and Fatigue for T3 and T6 Aluminum, in Effects of Environment and Complex Load History on Fatigue Life.

ASTM STP, (American Society for Testing and Materials, Philadelphia, ), p. Plastic deformation limits the stress around a stress concentration to some value between the yield and ultimate strength of the material.

A more reasonable method is to apply the stress concentration factor to both mean and alternating stresses and then made a correction to the maximum stress K f (S a + S m) when it exceeds the material's. Main Difference – Elastic vs Plastic Deformation.

Deformation is the action or process of deforming or distorting. When a force is applied to an object, the object will either compress or stretch as a response to the force. In mechanics, the force applied to a unit area is called extent of stretching or compressing (as a response to the stress) is called strain.Cyclic stress-strain and plastic deformation aspects of fatigue crack growth: A symposium sponsored by ASTM Committee E-9 on Fatigue, American Society and Materials, St Louis, Mo., May on *FREE* shipping on qualifying offers.

Cyclic stress-strain and plastic deformation aspects of fatigue crack growth: A symposium sponsored by ASTM Committee E-9 on FatigueManufacturer: American Society for Testing and Materials.