Performance Assessment of Steel Components

1987 ◽  
Vol 3 (1) ◽  
pp. 27-41 ◽  
Author(s):  
Helmut Krawinkler
Keyword(s):  
Performance Assessment ◽  
Structural Steel ◽  
Seismic Performance ◽  
Damage Accumulation ◽  
Low Cycle Fatigue ◽  
Cumulative Damage ◽  
Structural Performance ◽  
Cycle Fatigue ◽  
Performance Parameters ◽  
Analytical Procedures

This paper presents a methodology for the assessment of cumulative damage in structural steel components subjected to cyclic inelastic loading histories of the type experienced in earthquakes. The methodology is based on low-cycle fatigue concepts and the hypothesis of linear damage accumulation. It will be shown that seismic performance of a component depends on two structural performance parameters and on the number and amplitudes of all inelastic excursions and not only on the maximum excursion. Experimental and analytical procedures for obtaining the parameters needed for a performance assessment are suggested in the paper.

Damage accumulation near a hole under low cycle fatigue proceeding from measurements of local deformation response

2020 ◽  
Vol 86 (10) ◽  
pp. 46-55
Author(s):  
S. I. Eleonsky ◽  
Yu. G. Matvienko ◽  
V. S. Pisarev ◽  
A. V. Chernov
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Damage Accumulation ◽  
Stress Ratio ◽  
Low Cycle Fatigue ◽  
Accumulation Process ◽  
Stress Range ◽  
Cycle Fatigue ◽  
Deformation Response

A new destructive method for quantitative determination of the damage accumulation in the vicinity of a stress concentrator has been proposed and verified. Increase of damage degree in local area with a high level of the strain gradient was achieved through preliminary low-cycle pull-push loading of plane specimens with central open holes. The above procedure is performed for three programs at the same stress range (333.3 MPa) and different stress ratio values 0.33, – 0.66 and – 1.0, and vice versa for two programs at the same stress ratio – 0.33 and different stress range 333.3 and 233.3 MPa. This process offers a set of the objects to be considered with different degree of accumulated fatigue damages. The key point of the developed approach consists in the fact that plane specimens with open holes are tested under real operation conditions without a preliminary notching of the specimen initiating the fatigue crack growth. The measured parameters necessary for a quantitative description of the damage accumulation process were obtained by removing the local volume of the material in the form of a sequence of narrow notches at a constant level of external tensile stress. External load can be considered an amplifier enhancing a useful signal responsible for revealing the material damage. The notch is intended for assessing the level of fatigue damage, just as probe holes are used to release residual stress energy in the hole drilling method. Measurements of the deformation response caused by local removing of the material are carried out by electronic speckle-pattern interferometry at different stages of low-cycle fatigue. The transition from measured in-plane displacements to the values of the stress intensity factor (SIF) and the T-stress was carried out on the basis of the relations of linear fracture mechanics. It was shown that the normalized dependences of the stress intensity factor on the durability percentage for the first notch (constructed for four programs of cyclic loading with different parameters), reflect the effect of the stress ratio and stress range of the loading cycle on the rate of damage accumulation. The data were used to obtain the explicit form of the damage accumulation function that quantitatively describes damage accumulation process. The functions were constructed for different stress ratios and stress ranges.

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.

Effects of Strain Rate on Low Cycle Fatigue Behaviors of High-Strength Structural Steel

2013 ◽  
Vol 20 (7) ◽  
pp. 50-56 ◽  
Author(s):  
Yun-rong Luo ◽  
Chong-xiang Huang ◽  
Ren-hui Tian ◽  
Qing-yuan Wang
Keyword(s):  
Strain Rate ◽  
Structural Steel ◽  
Low Cycle Fatigue ◽  
High Strength ◽  
Cycle Fatigue

Cyclic Stress, Strain, and Energy Variations under Cumulative Damage Tests in Low-Cycle Fatigue

1973 ◽  
Vol 1 (1) ◽  
pp. 58 ◽  
Author(s):  
SF Etris ◽  
KC Lieb ◽  
VK Sisca ◽  
IC Moore ◽  
AL Batik ◽  
...  
Keyword(s):  
Low Cycle Fatigue ◽  
Cyclic Stress ◽  
Cumulative Damage ◽  
Cycle Fatigue ◽  
Stress Strain
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