A Screening Method for Prevention of Ratcheting Strain Derived From Movement of Temperature Distribution

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Satoshi Okajima ◽  
Takashi Wakai ◽  
Masanori Ando ◽  
Yasuhiro Inoue ◽  
Sota Watanabe
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Screening Method ◽  
Second Step ◽  
Plastic State ◽  
Membrane Stress ◽  
Primary Stress ◽  
Ratcheting Strain ◽  
Section Yield ◽  
Yield State

In this paper, we simplify the existing method and propose a screening method to prevent thermal ratcheting strain in the design of practical components. The proposed method consists of two steps to prevent the continuous accumulation of ratcheting strain. The first step is to determine whether all points through the wall thickness are in the plastic state. This is based on an equivalent membrane stress, which comprises the primary stress and the secondary membrane stress. When the equivalent stress exceeds the yield strength in some regions of the cylinder, the axial lengths of these regions are measured for the second step. The second step is to determine whether the accumulation of the plastic strain saturates. For this purpose, we define the screening criteria for the length of the area with full section yield state. When this length is sufficiently small, residual stress is generated in the direction opposite to the plastic deformation direction. As a result of residual stress, further accumulation of the plastic deformation is suppressed, and finally shakedown occurs. To validate the proposed method, we performed a set of elastoplastic finite element method (FEM) analyses, with the assumption of elastic perfectly plastic material. Not only did we investigate about the effect of the axial length of the area with full section yield state but also we investigated about effects of spatial distribution of temperature, existence of primary stress, and radius thickness ratio.

Proposal of the Screening Method for Prevention of the Accumulation of the Ratcheting Strain Derived From the Movement of the Temperature Distribution

2014 ◽  
Author(s):  
Satoshi Okajima ◽  
Takashi Wakai ◽  
Masanori Ando ◽  
Yasuhiro Inoue ◽  
Sota Watanabe
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Finite Element ◽  
Evaluation Method ◽  
Equivalent Stress ◽  
Plastic Region ◽  
Screening Method ◽  
Second Step ◽  
Ratcheting Strain ◽  
Thermal Ratcheting

The prevention of excessive deformation by thermal ratcheting is important in the design of high-temperature components of fast breeder reactors (FBR). This includes evaluation methods for a new type of thermal ratcheting caused by a traveling temperature distribution. Igari et al. [1] proposed a mechanism-based evaluation method to evaluate thermal ratcheting caused by temperature distributions traveling long and short distances. In this paper, we simplify the existing method and propose a screening method to prevent thermal ratcheting strain in the design of practical components. The proposed method consists of two steps to prevent the continuous accumulation of ratcheting strain. The first step is to determine whether all points through the wall thickness are in the plastic state. This is based on an equivalent stress, which comprises the primary stress, the thermal membrane stress, and the thermal bending stress. When the equivalent stress is less than the yield strength of the cylinder material, overall plastic deformation through the wall thickness does not occur. When the equivalent stress exceeds the yield strength in some regions of the cylinder, the ranges of these regions are measured for the second step. To prevent the acceleration of the plastic deformation due to creep, we define the upper limit of the equivalent stress based on the relaxation strength, Sr. The second step is to determine whether the accumulation of the plastic strain saturates (i.e. if shakedown occurs). For this purpose, we define the screening criteria for the range of the plastic region. When the range of the plastic region is sufficiently small, residual stress is generated in the direction opposite to the plastic deformation direction. As a result of residual stress, further accumulation of the plastic deformation is suppressed, and finally shakedown occurs. If the range of the plastic region exceeds the defined criteria, a more detailed evaluation method (e.g. inelastic finite element analysis) may be used for the component design. To validate the proposed method, we performed a set of elasto-plastic finite element method (FEM) analyses, with the assumption of elastic perfectly plastic material.

Mechanism-Based Evaluation of Thermal Ratcheting due to Traveling Temperature Distribution

2000 ◽  
Vol 122 (2) ◽  
pp. 130-138 ◽  
Author(s):  
Toshihide Igari ◽  
Hiroshi Wada ◽  
Masahiro Ueta
Keyword(s):  
Temperature Distribution ◽  
Structural Design ◽  
Evaluation Method ◽  
Stress Condition ◽  
Membrane Stress ◽  
Primary Stress ◽  
Ratcheting Strain ◽  
Axial Temperature ◽  
Thermal Ratcheting ◽  
New Type

Recently, structural design against a new type of thermal ratcheting under a null-primary-stress condition has been required. The representative case is the thermal ratcheting of a hollow cylinder caused by a traveling temperature distribution. In this paper, the mechanism of this ratcheting is proposed, and the evaluation method of ratcheting strain is shown based on this mechanism. The proposed evaluation method is basically based on the hoop-membrane stress due to the axial temperature distribution, and considers the influence of axial bending stress and traveling distance of temperature distribution. Predicted results by this method correspond to numerical results by FEM and can conservatively estimate the experimental results with several kinds of traveling distance, stress levels, and two types of temperature hold for types 316 and 316FR stainless steels. [S0094-9930(00)01102-1]

Effect of Residual Stress or Plastic Deformation History on Fatigue Life Simulation of Pipeline Dents

2018 ◽  
Author(s):  
Xian-Kui Zhu ◽  
Rick Wang
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Fatigue Life ◽  
Residual Stresses ◽  
Three Dimensional ◽  
Strain History ◽  
Deformation History ◽  
Stress Strain ◽  
Element Analysis ◽  
Fea Model

Mechanical dents often occur in transmission pipelines, and are recognized as one of major threats to pipeline integrity because of the potential fatigue failure due to cyclic pressures. With matured in-line-inspection (ILI) technology, mechanical dents can be identified from the ILI runs. Based on ILI measured dent profiles, finite element analysis (FEA) is commonly used to simulate stresses and strains in a dent, and to predict fatigue life of the dented pipeline. However, the dent profile defined by ILI data is a purely geometric shape without residual stresses nor plastic deformation history, and is different from its actual dent that contains residual stresses/strains due to dent creation and re-rounding. As a result, the FEA results of an ILI dent may not represent those of the actual dent, and may lead to inaccurate or incorrect results. 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 from it, and (c) a purely geometric dent having an ILI defined dent profile with all stress/strain history removed from it. Using a three-dimensional FEA model, those three dents are simulated in the elastic-plastic conditions. The FEA results showed that the two geometric dents determine significantly different stresses and strains in comparison to those in the true dent, and overpredict the fatigue life or burst pressure of the true dent. On this basis, suggestions are made on how to use the ILI data to predict the dent fatigue life.

scholarly journals Elasto-plastic analysis of the contact region between a rigid ellipsoid and a semi-flat surface

2018 ◽  
Vol 10 (9) ◽  
pp. 168781401879739 ◽  
Author(s):  
Pengyang Li ◽  
Lingxia Zhou ◽  
Fangyuan Cui ◽  
Quandai Wang ◽  
Meiling Guo ◽  
...  
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Plastic Strain ◽  
Contact Pressure ◽  
Contact Region ◽  
Three Dimensional ◽  
Von Mises Stress ◽  
Effective Plastic Strain ◽  
Normal Forces ◽  
Von Mises

When the load acting on a mechanical structure is greater than the yield strength of the material, the contact surface will undergo plastic deformation. Cumulative plastic deformation has an important influence on the lifespan of mechanical parts. This article presents a three-dimensional semi-analytical model based on the conjugate gradient method and fast Fourier transform algorithm, with the aim of studying the characteristic parameters of the contact region between a rigid ellipsoid and elasto-plastic half-space. Moreover, normal forces and tangential traction were considered, as well as the contact pressure resulting from various sliding speeds and friction coefficients. The contact pressure, effective plastic strain, von Mises stress, and residual stress were measured and shown to increase with increasing sliding velocity. Finally, when the friction coefficient, contact pressure, and effective plastic strain are increased, the von Mises stress is also shown to increase, whereas the residual stress decreases.

The Effect of Plastic Deformation on the Thermoelastic Constant and the Potential to Evaluate Residual Stress

2011 ◽  
Vol 70 ◽  
pp. 458-463 ◽  
Author(s):  
A. F. Robinson ◽  
Janice M. Dulieu-Barton ◽  
S. Quinn ◽  
R. L. Burguete
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Plastic Strain ◽  
Strain Hardening ◽  
Thermoelastic Stress ◽  
Paint Coating ◽  
Full Field ◽  
Thermoelastic Constant ◽  
Thermoelastic Response ◽  
Measured Change

In some metals it has been shown that the introduction of plastic deformation or strain modifies the thermoelastic constant, K. If it was possible to define the magnitude of the change in thermoelastic constant over a range of plastic strain, then the plastic strain that a material has experienced could be established based on a measured change in the thermoelastic constant. This variation of the thermoelastic constant and the ability to estimate the plastic strain that has been experienced, has potential to form the basis of a novel non-destructive, non-contact, full-field technique for residual stress assessment using thermoelastic stress analysis (TSA). Recent research has suggested that the change in thermoelastic constant is related to the material dislocation that occurs during strain hardening, and thus the change in K for a material that does not strain harden would be significantly less than for a material that does. In the work described in this paper, the change in thermoelastic constant for three materials (316L stainless steel, AA2024 and AA7085) with different strain hardening characteristics is investigated. As the change in thermoelastic response due to plastic strain is small, and metallic specimens require a paint coating for TSA, the effects of the paint coating and other test factors on the thermoelastic response have been considered.

The Crack Arrest Capability of 9-Percent Ni Steels (ASTM 553, Type 1) LNG Storage Tanks

1991 ◽  
Vol 113 (3) ◽  
pp. 380-384
Author(s):  
P. B. Crosley ◽  
E. J. Ripling
Keyword(s):  
Fracture Toughness ◽  
Residual Stress ◽  
High Stress ◽  
Crack Arrest ◽  
Storage Tanks ◽  
Membrane Stress ◽  
High Stress Region ◽  
Fast Running ◽  
Stress Region

Safety of structures can be assured, even if cracks initiate in localized regions of abnormally low toughness, and/or abnormally high stress (LT/HS), if the materials from which they are fabricated have a high enough crack arrest fracture toughness. When this requirement is met, fast-running cracks that initiate in LT/HS regions arrest when their tip encounters material having normal toughness and stresses. The work described in this paper was carried out to determine the crack arrest capability of LNG storage tanks by determining the longest LT/HS region in which a crack could initiate and still arrest when it leaves this region. The determination consisted of relating a fracture analysis with the measured full-thickness crack arrest fracture toughness of three 9-percent Ni plates which were reported in reference [1]. The calculations used a residual stress pattern, produced by welding, superimposed on a typical membrane stress. The residual stress was selected as an example of a localized high stress region. It was found that tanks built from the poorest of the three tested plates could arrest cracks about 3/4 m long, while tanks built from the two tougher plates could arrest cracks almost 2 m long.

scholarly journals Achievements in Micromagnetic Techniques of Steel Plastic Stage Evaluation

2020 ◽  
Vol 20 (1) ◽  
pp. 16-55 ◽  
Author(s):  
M. F. de Campos
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Elastic Deformation ◽  
Magnetic Measurements ◽  
Soft Magnetic Materials ◽  
Hysteresis Curve ◽  
Hole Drilling ◽  
Hole Drilling Method ◽  
Drilling Method ◽  
The Difference

AbstractThe investigation of plastic deformation and residual stress by non-destructive methods is a subject of large relevance for the industry. In this article, the difference between plastic and elastic deformation is discussed, as well as their effects on magnetic measurements, as hysteresis curve and Magnetic Barkhausen Noise. The residual stress data can be obtained with magnetic measurements and also by the hole drilling method and x-ray diffraction measurements. The residual stress level obtained by these three different methods is different, because these three techniques evaluate the sample in different depths. Effects of crystallographic texture on residual stress are also discussed. The magnetoelastic term should be included in micromagnetic methods for residual stress evaluation. It is discussed how the micromagnetic energy Hamiltonian should be expressed in order to evaluate elastic deformation. Plastic deformation can be accounted in micromagnetic models as a term that increases the coercive field in soft magnetic materials as the steels are.

Analysis of Leveling Strategy for a Plate Mill

2010 ◽  
Vol 145 ◽  
pp. 424-428 ◽  
Author(s):  
Li Cui ◽  
Xian Lei Hu ◽  
Xiang Hua Liu
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Time Delay ◽  
Static Pressure ◽  
High Strength ◽  
Plate Mill ◽  
Elastic Plastic ◽  
Residual Curvature ◽  
Deformation Ratio

In order to analysis the effect of leveling strategy on the quality of plate products, the curvature integration by elastic-plastic differences was adopted to simulate leveling results by different leveling strategy. It had studied plastic deformation ratio, residual stress, residual curvature and leveling force for different leveling strategies to find the effectual strategy and the adaptability conditions were given. Additionally, static pressure leveling with the time delay strategy was analyzed, which was proved to be an effectual strategy to resolve the leveling problem for high strength thicker plate by a certain 3500mm mill plate.

Determination of X-ray Elastic Constants in a Ti-14Al-21Nb Nb Alloy and a Ti-14Al-21Nb/SiC Metal Matrix Composite

1990 ◽  
Vol 34 ◽  
pp. 689-698 ◽  
Author(s):  
J. Jo ◽  
R. W. Hendricks ◽  
W. D. Brewer ◽  
Karen M. Brown
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Elastic Constant ◽  
Theoretical Calculation ◽  
Metal Matrix Composite ◽  
Elastic Constants ◽  
Metal Matrix ◽  
Intrinsic Value ◽  
X Ray

Residual stress values in a material are governed by the measurements of the atomic spacings in a specific crystallographic plane and the elastic constant for that plane. It has been reported that the value of the elastic constant depends on microstructure, preferred orientation, plastic deformation and morphology [1], Thus, the theoretical calculation of the elastic constant may deviate from the intrinsic value for a real alloy.

scholarly journals Plastic Deformation and Residual Stress in High Speed Turning of AD730™ Nickel-based Superalloy with PCBN and WC Tools

Procedia CIRP ◽  
2018 ◽  
Vol 71 ◽  
pp. 440-445 ◽  
Author(s):  
Z Chen ◽  
J.M. Zhou ◽  
R.L. Peng ◽  
R M’Saoubi ◽  
D Gustafsson ◽  
...  
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
High Speed ◽  
High Speed Turning ◽  
Nickel Based Superalloy
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