scholarly journals CREEP-FATIGUE DAMAGE RULE UNDER VARIABLE STRAINING BASED ON STRAIN RANGE PARTITIONING CONCEPT

1997 ◽  
Vol 46 (3Appendix) ◽  
pp. 49-55
Author(s):  
Mitsuo MIYAHARA ◽  
Katsuyuki TOKIMASA
Keyword(s):  
Fatigue Damage ◽  
Strain Range ◽  
Creep Fatigue ◽  
Damage Rule

A Direct Method on the Evaluation of Cyclic Steady State of Structures With Creep Effect

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Haofeng Chen ◽  
Weihang Chen ◽  
James Ure
Keyword(s):  
Fatigue Damage ◽  
Mechanical Load ◽  
Direct Method ◽  
Load Condition ◽  
Hysteresis Loops ◽  
Strain Range ◽  
Cyclic Behavior ◽  
Direct Evaluation ◽  
Plastic Strain Range ◽  
Creep Fatigue

This paper describes a new extension of the linear matching method (LMM) for the direct evaluation of cyclic behavior with creep effects of structures subjected to a general load condition in the steady cyclic state, with the new implementation of the cyclic hardening model and time hardening creep constitutive model. A benchmark example of a Bree cylinder and a more complicated three-dimensional (3D) plate with a center hole subjected to cyclic thermal load and constant mechanical load are analyzed to verify the applicability of the new LMM to deal with the creep fatigue damage. For both examples, the stabilized cyclic responses for different loading conditions and dwell time periods are obtained and validated. The effects of creep behavior on the cyclic responses are investigated. The new LMM procedure provides a general purpose technique, which is able to generate both the closed and nonclosed hysteresis loops depending upon the applied load condition, providing details of creep strain and plastic strain range for creep and fatigue damage assessments with creep fatigue interaction.

A Strain Rate Ratio Approach for Assessing Creep-Fatigue Life of 63Sn-37Pb Solder Under Shear Loading

2004 ◽  
Vol 127 (4) ◽  
pp. 407-414 ◽  
Author(s):  
Yutaka Tsukada ◽  
Hideo Nishimura ◽  
Hiroki Yamamoto ◽  
Masao Sakane
Keyword(s):  
Fatigue Life ◽  
Strain Rate ◽  
Rate Ratio ◽  
Life Prediction ◽  
Strain Range ◽  
Shear Loading ◽  
Strain Waves ◽  
Creep Fatigue ◽  
Ratio Approach ◽  
Damage Rule

This paper studies creep-fatigue life prediction under shear loading by making extensive torsion creep-fatigue experiments using four kinds of strain waves. The linear damage rule, strain range partitioning method, frequency modified fatigue life, and ductility exhaustion model were applied to the experimental data, but no methods accurately predicted the creep-fatigue life. A new method based on the strain rate ratio, which predicted the creep-fatigue life within a factor of 4 scatter band, was developed.

Creep-Fatigue Properties of Mod.9Cr-1Mo Steel Under Variable Straining

1993 ◽  
Vol 115 (3) ◽  
pp. 235-241
Author(s):  
M. Miyahara ◽  
K. Tokimasa
Keyword(s):  
Type Strain ◽  
Life Prediction ◽  
Strain Range ◽  
Fatigue Properties ◽  
Rate Equations ◽  
Creep Fatigue ◽  
Slow Type ◽  
Damage Rule ◽  
High Test ◽  
Life Prediction Model

Two-step variable straining tests, which included CP- (slow-fast) type and PC- (fast-slow) type tests, were conducted at 600°C in air for Mod.9Cr-1Mo steel. In the tests, CP and PC-type strain range level varied from high to low for the high-low test and from low to high for the low-high test. The deviations of the experimental data from the linear damage rule prediction were observed. These experimental results and the effect of the strain waveform on the creep-fatigue properties under variable straining were well explained by the life prediction model previously proposed by the authors in which the strain range partitioned crack growth rate equations were applied.

The Creep-Fatigue Evaluation Method for Intermediate Hold Conditions: Proposal and Validation

2011 ◽  
Author(s):  
Satoshi Okajima ◽  
Nobuchika Kawasaki ◽  
Shoichi Kato ◽  
Naoto Kasahara
Keyword(s):  
Initial Stress ◽  
Fatigue Damage ◽  
Evaluation Method ◽  
Strain Range ◽  
Creep Damage ◽  
Fatigue Tests ◽  
Reactor Vessel ◽  
Liquid Sodium ◽  
Improved Method ◽  
Creep Fatigue

In this paper, for the application to the Japan Sodium-cooled Fast Reactor, JSFR, the creep-fatigue damage evaluation method is improved to consider the intermediate holding condition. The improved method is validated through both of the uni-axial and the structure model creep-fatigue tests. In these validations, the target material is 316FR steel, which is planned to use for the reactor vessel. The reactor vessel portion near the liquid sodium surface is one of the most probable points where the creep-fatigue damage is considerable. Because of the relaxation of the temperature gradient, the steady operation stress on the portion near the liquid sodium surface is less than the maximum stress in the transient. In the conventional method, in order to evaluate the creep damage conservatively, the maximum tensile value in the thermal stress transient cycle is used as the initial stress. The improved method evaluates the creep damage using the lower initial stress than the conventional method, while it has the rational margin. For the validation of the improved method, uni-axial creep-fatigue tests and structure model tests are carried out. A series of uni-axial creep-fatigue tests was carried out in the following conditions: 600 degree C testing temperature, 1% total strain range, 1 hour holding time, vacuum or air environments, and the various holding position. While the test environment affects the fatigue damage, it didn’t have significant effect on the creep damage. In the cases with high holding position, the creep damages were evaluated based on the given initial stress with high precision. In the other cases, by the assumption of the steady-stress existence, the rational margin is given for the evaluation. Furthermore, in the design stage, the evaluated creep-fatigue damage has enough margins derived from the conservative evaluation of the initial stress. The structural tests modeled the movement of the liquid sodium surface in the start-up and the shut-down stages, and the relaxation of the temperature gradient in the operation stage. In these tests, the temperature distribution was given by coolant water and an external high-frequency heating coil for the cylindrical specimen, and moved in the axial direction. In addition, the primary stress, which was caused by the weight of the reactor vessel, was given by the screw jack. As a result, using the strain range evaluated by the elastic analysis, the improved method evaluated the crack initiation life due to the creep-fatigue damage with the sufficient safety margin. In the case when the strain range was evaluated by the elastic-plastic analysis, the method predicted the crack initiation life with the good precision. While the evaluation of the crack penetration life was possible, further examination was desired for the precision improvement.

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