Electrical Potential Drop and Notch Opening Displacement Methods for Detecting High Temperature Low Cycle Fatigue Cracks of Circumferential Notched Specimens

1988 ◽  
Vol 110 (3) ◽  
pp. 247-252 ◽  
Author(s):  
Masao Sakane ◽  
Masateru Ohnami
Keyword(s):  
Maximum Stress ◽  
Low Cycle Fatigue ◽  
Potential Drop ◽  
Cycle Fatigue ◽  
Displacement Method ◽  
Opening Displacement ◽  
Stress Criterion ◽  
Drop Method ◽  
Notched Specimens ◽  
Dc Potential

This paper assesses the accuracy of the crack initiation detection methods for type 304 SS circumferential notched specimens subjected to strain and stress controlled low cycle fatigue loads at 873 K in air. The methods examined were DC potential drop method (PDM) and the maximum stress criterion in the strain controlled test while they were DC potential drop method and the minimum notch opening displacement method (NOD) in the stress controlled test. The DC potential method and the minimum notch opening displacement method were proved to have a sufficient accuracy for the detection of crack initiation while the maximum stress criterion has less accuracy. The crack length detection based on DC potential drop method is also discussed.

scholarly journals Crack Detection and Crack Length Measurement with the DC Potential Drop Method–Possibilities, Challenges and New Developments

2020 ◽  
Vol 10 (23) ◽  
pp. 8559
Author(s):  
Jürgen Bär
Keyword(s):  
Crack Length ◽  
Crack Detection ◽  
Potential Drop ◽  
General Information ◽  
Ambient Atmosphere ◽  
New Developments ◽  
Drop Method ◽  
Notched Specimens ◽  
Dc Potential ◽  
Crack Length Measurement

The direct current potential drop method (DCPDM) is widely used to determine the crack length in fatigue experiments. In practice, some special features of this method must be considered. Aside from general information on the experimental setup and calibration, some special features of the method, such as the influence of the ambient atmosphere and the application of the method to ferromagnetic materials, are presented and discussed. In addition, with the multiple potential drop measurement, a method is presented which improves the resolution of the DCPDM for detection of cracks and allows to determine crack initiation sites. The capabilities provided by this method are demonstrated on the basis of measurements undertaken on notched round bars and single edged notched specimens.

scholarly journals Low Cycle Fatigue Life Evaluation of Notched Specimens Considering Strain Gradient

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 1001
Author(s):  
Shenghuan Qin ◽  
Zaiyin Xiong ◽  
Yingsong Ma ◽  
Keshi Zhang
Keyword(s):  
Cyclic Loading ◽  
Constitutive Model ◽  
Strain Gradient ◽  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Plastic Behavior ◽  
Cycle Fatigue ◽  
New Model ◽  
Hysteresis Behavior ◽  
Notched Specimens

An improved model based on the Chaboche constitutive model is proposed for cyclic plastic behavior of metal and low cycle fatigue of notched specimens under cyclic loading, considering the effect of strain gradient on nonlinear kinematic hardening and hysteresis behavior. The new model is imported into the user material subroutine (UMAT) of the finite element computing software ABAQUS, and the strain gradient parameters required for model calculation are obtained by calling the user element subroutine (UEL). The effectiveness of the new model is tested by the torsion test of thin copper wire. Furthermore, the calibration method of strain gradient influence parameters of constitutive model is discussed by taking the notch specimen of Q235 steel as an example. The hysteresis behavior, strain distribution and fatigue failure of notched specimens under cyclic loading were simulated and analyzed with the new model. The results prove the rationality of the new model.

NDT of Cavity Defect in Metallic Plate Using dc Potential Drop Method

2018 ◽  
Vol 46 (2) ◽  
pp. 20170092
Author(s):  
Xiaojuan Wang ◽  
Wenlu Cai ◽  
Zhenmao Chen
Keyword(s):  
Potential Drop ◽  
Metallic Plate ◽  
Drop Method ◽  
Dc Potential

Investigation of Fatigue Behaviour and Notch Sensitivity of Ti-6Al-4V

2011 ◽  
Vol 80-81 ◽  
pp. 7-12 ◽  
Author(s):  
Shabnam Hosseini ◽  
Mohammad Bagher Limooei
Keyword(s):  
Biomedical Application ◽  
Low Cycle Fatigue ◽  
Fatigue Behaviour ◽  
Notch Sensitivity ◽  
Cycle Fatigue ◽  
Bending Fatigue ◽  
Notched Specimens ◽  
Bending Fatigue Test ◽  
Sensitivity Data ◽  
Low Sensitivity

In this research, fatigue behaviour of Ti-6Al-4V alloy was investigated for smooth and notched specimens with stress concentration factor(Kt) 3.6 and 4.1.This investigation was conducted for various diameter bars having different ultimate strength.Rotating bending fatigue test at R= -1 was emploied for this research. Notch sensitivity data was compared with those of steels. The result indicated that the presence of notch in this alloy has a different amount of sensitivity when the notch specimens were subjected to high cycle fatigue (HCF) and low cycle fatigue(LCF) tests.The notch sensitivity of this alloy was shown generally to be much lower than steel alloys with similar ultimate strength values. Therefore,considering the low sensitivity to notch of this alloy, can be recommended for applications with the presence of notch such as biomedical application

DC potential drop method for evaluating material degradation

2004 ◽  
Vol 18 (8) ◽  
pp. 1368-1374 ◽  
Author(s):  
Chang-Sung Seok ◽  
Bong Kook Bae ◽  
Jae-Mean Koo
Keyword(s):  
Potential Drop ◽  
Material Degradation ◽  
Drop Method ◽  
Dc Potential
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