The Low Cycle Fatigue and Plastic Strain Response of Coiled Tubing in a Sour Environment With and Without Corrosion Inhibitor Protection

2003 ◽  
Author(s):  
H.B. Luft
Keyword(s):  
Plastic Strain ◽  
Corrosion Inhibitor ◽  
Low Cycle Fatigue ◽  
Strain Response ◽  
Cycle Fatigue ◽  
Coiled Tubing ◽  
Inhibitor Protection

Low-Cycle Fatigue Life of Continuously Cyclic-Hardening Material

2020 ◽  
Author(s):  
Zhong Zhang ◽  
Xijia Wu
Keyword(s):  
Fatigue Life ◽  
Plastic Strain ◽  
Root Mean Square ◽  
Low Cycle Fatigue ◽  
Cyclic Hardening ◽  
Mean Square ◽  
Cycle Fatigue ◽  
Fatigue Crack Nucleation ◽  
Hardening Material ◽  
Plastic Strain Range

Abstract A general fatigue life equation is derived by modifying the Tanaka-Mura-Wu dislocation pile-up model for variable strain-amplitude fatigue processes, where the fatigue crack nucleation life is expressed in terms of the root mean square of plastic strain range. Low-cycle fatigue tests were conducted on an austenitic stainless steel. at 400°C and 600°C, the material exhibits continuously cyclic-hardening behaviour. The root mean square of plastic strain ranges is evaluated from the experimental data for each test condition at strain rates ranging from 0.0002/s to 0.02/s. The variable-amplitude Tanaka-Mura-Wu model is found to be in good agreement with the LCF data, which effectively proves Miner’s rule on the stored plastic strain energy basis.

Damage in Adhesive Joints During Low Cycle Fatigue

2010 ◽  
Author(s):  
Iva´n C. Ca´bulo-Pe´rez ◽  
Juan P. Casas-Rodri´guez
Keyword(s):  
Plastic Strain ◽  
Low Cycle Fatigue ◽  
Stress Test ◽  
Damage Model ◽  
Fatigue Tests ◽  
Constant Stress ◽  
Cycle Fatigue ◽  
Damage Behavior ◽  
Non Linear ◽  
Compressive Loads

The objective of this research is to study the damage behavior of bulk adhesive and single lap joint (SLJ) specimens during low cycle fatigue (LCF). Fatigue tests under constant stress amplitude were done and strain response was measured through cycles to failure using the bulk adhesive and SLJ data. A non linear damage model was used to fit experimental results. Identification of the damage parameters for bulk adhesive was obtained from the damage against accumulated plastic strain plot. It is shown that the plastic strain can be obtained from the constant stress test if the instantaneous elastic modulus, i.e. modulus affected by damage, is evaluated for each cycle. On the other hand, damage in SLJ was seen mainly in the adhesive for itself — no substrate failure — this fact is used to propose that fatigue response in the joint is due to continuum damage accumulation in the adhesive as the number of cycles increases. Damage behavior under compressive loads was not taken into account but good correlation of numerical and experimental data was obtained. It was found that damage evolution behaves in a non linear manner as the plastic deformation grows for each cycle: on fatigue onset an accelerated damage grow is observed, then a proportional evolution, and finally a rapid failure occurs; this characteristics were seen in both the SLJ and bulk adhesive specimen. So far, this research takes the damage model found in a standard adhesive specimen and assumes it is accurate enough to represent the damage behavior of the SLJ configuration.

Latest Development in Physics-Based Modeling of Coiled Tubing Plasticity and Fatigue

SPE Journal ◽  
2021 ◽  
pp. 1-12
Author(s):  
Zhanke Liu ◽  
Steven Tipton ◽  
Dinesh Sukumar
Keyword(s):  
Damage Accumulation ◽  
Low Cycle Fatigue ◽  
Experimental Investigations ◽  
Cycle Fatigue ◽  
State Variables ◽  
Coiled Tubing ◽  
Wall Thinning ◽  
Fatigue Damage Accumulation ◽  
Wide Range ◽  
Novel Algorithms

Summary Coiled tubing (CT) integrity is critical for well intervention operations in the field. To monitor and manage tubing integrity, the industry has developed a number of computer models over the past decades. Among them, low-cycle fatigue (LCF) modeling plays a paramount role in safeguarding tubing integrity. LCF modeling of CT strings dates back to the 1980s. Recently, novel algorithms have contributed to developments in physics-based modeling of tubing fatigue and plasticity. When CT trips into and out of the well, it goes through bending/straightening cycles under high differential pressure. Such tough conditions lead to low- or ultralow-cycle fatigue, limiting CT useful life. The model proposed in this study is derived from a previous one and is based on rigorously derived material parameters to compute the evolution of state variables from a wide range of loading conditions. Through newly formulated plasticity and strain parameters, a physics-based damage model predicts CT fatigue life, along with diametral growth and wall thinning. The revised modeling approach gives results for CT damage accumulation, diametral growth, and wall thinning under realistic field conditions, with experimental validation. For 20 different CT alloys, it was observed that the model improved in accuracy overall by approximately 18.8% and consistency by 14.0%, for constant pressure data sets of more than 4,500 data points. The modeling results provide insights into the nonlinear nature of fatigue damage accumulation. This study allowed developing recommendations to guide future analytical modeling and experimental investigations, summarize theoretical findings in physics-based LCF modeling, and provide practical guidelines for CT string management in the field. The study provides a fundamental understanding of CT LCF and introduces novel algorithms in plasticity and damage.

Low-Cycle Fatigue Life of Continuously Cyclic-Hardening Material

2021 ◽  
Author(s):  
Zhong Zhang ◽  
Xijia Wu
Keyword(s):  
Fatigue Life ◽  
Plastic Strain ◽  
Root Mean Square ◽  
Low Cycle Fatigue ◽  
Cyclic Hardening ◽  
Mean Square ◽  
Cycle Fatigue ◽  
Fatigue Crack Nucleation ◽  
Hardening Material ◽  
Plastic Strain Range

Abstract A general fatigue life equation is derived by modifying the Tanaka-Mura-Wu dislocation pile-up model for variable strain-amplitude fatigue processes, where the fatigue crack nucleation life is expressed in terms of the root mean square of plastic strain range. Low-cycle fatigue tests were conducted on an austenitic stainless steel. At 400 ? and 600 ?, the material exhibits continuously cyclic-hardening behaviour. The root mean square of plastic strain ranges is evaluated from the experimental data for each test condition at strain rates ranging from 0.0002/s to 0.02/s. The variable-amplitude Tanaka-Mura-Wu model is found to be in good agreement with the LCF data, which effectively proves Miner's rule on the stored plastic strain energy basis.

scholarly journals Stress-strain response in gears tooth root due to low cycle fatigue

2019 ◽  
Vol 287 ◽  
pp. 02002
Author(s):  
Marina Franulovic ◽  
Kristina Markovic ◽  
Zdravko Herceg
Keyword(s):  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Material Model ◽  
Strain Response ◽  
Tooth Root ◽  
Loading Conditions ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Main Research ◽  
Damage Initiation

Gears are mechanical components which experience high dynamic loading during their exploitation period. Therefore, their load carrying capacity together with life expectancy are often the main research interest in various studies. The research presented in this paper is focused on the materials response in spur gears tooth root, with the attention given to the repeated overloads during gears operation. In order to simulate low cycle fatigue by using numerical modeling of stress - strain relationship within material, the material model which takes into account isotropic and kinematic hardening is used here. Material response of specimens produced out of steel 42CrMo4 in different loading conditions is used for the calibration of material model, which is then applied to simulate damage initiation and materials stress - strain response in gears tooth root. The results show that materials response to the given loading conditions non-linearly change through the loading cycles.

High Temperature, Low Cycle Fatigue Characterization of P91 Weld and Heat Affected Zone Material

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
T. P. Farragher ◽  
S. Scully ◽  
N. P. O'Dowd ◽  
C. J. Hyde ◽  
S. B. Leen
Keyword(s):  
High Temperature ◽  
Weld Metal ◽  
Heat Affected Zone ◽  
Low Cycle Fatigue ◽  
Base Material ◽  
Strain Response ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Weld Material ◽  
The Cross

The high temperature low cycle fatigue behavior of P91 weld metal (WM) and weld joints (cross-weld) is presented. Strain-controlled tests have been carried out at 400 °C and 500 °C. The cyclic behavior of the weld material (WM) and cross-weld (CW) specimens are compared with previously published base material (BM) tests. The weld material is shown to give a significantly harder and stiffer stress–strain response than both the base material and the cross-weld material. The cross-weld tests exhibited a cyclic stress–strain response, which was similar to that of the base material. All specimen types exhibited cyclic softening but the degree of softening exhibited by the cross-weld specimens was lower than that of the base material and all-weld tests. Finite element models of the base metal, weld metal and cross-weld test specimens are developed and employed for identification of the cyclic viscoplasticity material parameters. Heat affected zone (HAZ) cracking was observed for the cross-weld tests.

Sign in / Sign up

Export Citation Format

Share Document