scholarly journals The method of magnetic coercimetry and its application to assess the residual life of lifting equipment

2019 ◽  
Vol 97 ◽  
pp. 06016
Author(s):  
Boris Popov ◽  
Sergei Evdokimov ◽  
Olga Leonova ◽  
Yury Sokolov
Keyword(s):  
Coercive Force ◽  
Fatigue Damage ◽  
Residual Life ◽  
Industrial Safety ◽  
Fatigue Damage Accumulation ◽  
Wide Range ◽  
Integrity Management ◽  
Electro Magnetic ◽  
Extent Of Damage ◽  
Lifting Equipment

Material fatigue damage accumulation is recognized as one of the least inspectable and controllable operational damage mechanisms of crane structures. The scope method measures electro-magnetic properties of steels being in service, to assess their relative changes induced by the fatigue damage accompanying microstructural effects. The authors’ theoretical and experimental research suggested that the most relevant magnetic parameter to measure is the coercive force Hc, which is a characteristic of ferritic steels’ magnetization-demagnetization hysteresis loop. The authors proposed and developed a correction factor to normalize changes in Hc for various carbon steel thicknesses in the practical range from 5mm to 20mm, and drawn the coercive force nomograms which quantify the extent of damage for typical structural steels used in cranes. This research provided a scientifically justified basis for structures remnant resource assessments. Application of the Coercimetric method contributes into the risk control and promotes industrial safety in lifting equipment operations. The method itself can be practically useful for resolving integrity management challenges in a wide range of industries.

Metal Coercivity as a Measure of Microdamages for Evaluation of Fatigue and Recovery of Mechanical Properties

NDT World ◽  
2016 ◽  
Vol 19 (3) ◽  
pp. 59-61
Author(s):  
Сорочинский ◽  
Sergey Sorochinskiy ◽  
Казак ◽  
Irina Kazak ◽  
Вакуленко ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Cyclic Loading ◽  
Coercive Force ◽  
Fatigue Damage ◽  
Surface Plastic Deformation ◽  
Surface Plastic ◽  
Partial Recovery ◽  
Fatigue Damage Accumulation ◽  
Intermediate Surface

Introduction. The problem of determining the current state of metal parts mechanical properties is always relevant. For its solution a simple, cheap and sufficiently informative NDT method is needed. Today the method of magnetic coercive force seems to be the most suitable. The purpose of this work was to determine patterns of change in a coercive force after cyclic loading of steel samples in the initial state and after surface plastic deformation (work hardening). Method. Two batches of 40X steel cylindrical samples in the delivery condition were put to cyclic tests. The both batches were tested in the same range of tension amplitudes but for the second batch the tests were carried out in two steps with intermediate surface plastic deformation. The change in the level of accumulated fatigue damage was determined by the coercive force method. Results. The most significant coercive force increase (up to 1.5%) was observed in the initial stages of the specimens’ elongation. For samples subjected to preliminary cyclic loading, surface plastic deformation leads to lower coercive force values (by 9%–17%) and to 2.8–3.4 times longer operating life. This effect can be explained by “healing” the accumulated defects by the surface treatment. Discussion. The results indicate high sensitivity of the coercive force to changes in structural state of the metal as a result of both fatigue damage accumulation and partial recovery of the metal structure due to defect “healing”.

Model of fatigue damage in strain-rate-sensitive composite materials

2003 ◽  
Vol 18 (1) ◽  
pp. 77-80 ◽  
Author(s):  
Sanboh Lee ◽  
Tinh Nguyen ◽  
Tze-jer Chuang
Keyword(s):  
Composite Materials ◽  
Strain Rate ◽  
Fatigue Damage ◽  
Damage Accumulation ◽  
Maximum Stress ◽  
Paris Law ◽  
Damage Rate ◽  
Fatigue Damage Accumulation ◽  
Damage Accumulation Model ◽  
Extent Of Damage

A fatigue damage accumulation model based on the Paris law is proposed for strain-rate-sensitive polymer composite materials. A pre-exponent factor c2/f and strain-rate-sensitive exponent n are introduced. Numerical analysis of the model was performed using experimental data obtained in the literature. Both factors were found to enhance fatigue damage accumulation. The analysis also revealed that the extent of damage increases with decreasing frequency and that the damage rate is more sensitive to the applied maximum stress than to the stiffness of the material.

Fatigue damage accumulation around notches

2004 ◽  
Vol 46 (6) ◽  
pp. 309-313
Author(s):  
Yutaka Iino ◽  
Hideo Yano
Keyword(s):  
Fatigue Damage ◽  
Damage Accumulation ◽  
Fatigue Damage Accumulation

A Study on Estimation of Internal Pressure Creep Life Using Small Punch Creep (SPC) Tests for Boiler Pipes

2009 ◽  
Author(s):  
Toshimi Kobayashi ◽  
Toru Izaki ◽  
Junichi Kusumoto ◽  
Akihiro Kanaya
Keyword(s):  
Internal Pressure ◽  
Residual Life ◽  
Test Results ◽  
Creep Life ◽  
Creep Tests ◽  
Good Correspondence ◽  
Small Punch ◽  
Uniaxial Creep ◽  
Wide Range ◽  
The Relationship

The small punch creep (SPC) test is possible to predict residual creep life at a high accuracy. But, the results of SPC tests cannot be compared with uniaxial creep or internal pressure creep results directly. In this report, the relationship between SPC test results and uniaxial creep test results in ASME A335 P11 (1.25Cr-0.5Mo Steel) was studied. The obtained relationship between SPC load and equivalent uniaxial creep stress formed a simple linear equation under the wide range of test temperature and test period. Then, the SPC results can be compared with uniaxial results by converting SPC loads to the equivalent uniaxial creep stresses. The relationship between SPC test results and internal pressure creep tests results was also studied. The internal creep life of as-received P11 pipe was almost same as SPC result when the hoop stress was converted to the SPC load. The creep lives of internal pressure creep influenced materials also showed good correspondence with SPC results. Therefore SPC can estimate the residual life of internal pressure creep influenced materials.

Management of Complex Loading Histories for Use in Probabilistic Creep-Fatigue Damage Assessments

2018 ◽  
Author(s):  
N. A. Zentuti ◽  
J. D. Booker ◽  
R. A. W. Bradford ◽  
C. E. Truman
Keyword(s):  
Fatigue Damage ◽  
Input Parameter ◽  
Three Dimensional ◽  
Complex Loading ◽  
Fe Model ◽  
Plant Component ◽  
Fatigue Lifetime ◽  
Wide Range ◽  
Stress Components ◽  
Creep Fatigue

An approach is outlined for the treatment of stresses in complex three-dimensional components for the purpose of conducting probabilistic creep-fatigue lifetime assessments. For conventional deterministic assessments, the stress state in a plant component is found using thermal and mechanical (elastic) finite element (FE) models. Key inputs are typically steam temperatures and pressures, with the three principal stress components (PSCs) at the assessment location(s) being the outputs. This paper presents an approach which was developed based on application experience with a tube-plate ligament (TPL) component, for which historical data was available. Though both transient as well as steady-state conditions can have large contributions towards the creep-fatigue damage, this work is mainly concerned with the latter. In a probabilistic assessment, the aim of this approach is to replace time intensive FE runs with a predictive model to approximate stresses at various assessment locations. This is achieved by firstly modelling a wide range of typical loading conditions using FE models to obtain the desire stresses. Based on the results from these FE runs, a probability map is produced and input(s)-output(s) functions are fitted (either using a Response Surface Method or Linear Regression). These models are thereafter used to predict stresses as functions of the input parameter(s) directly. This mitigates running an FE model for every probabilistic trial (of which there typically may be more than 104), an approach which would be computationally prohibitive.

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