scholarly journals Lifetime Predictions under PVC Pipes subjected to Oscillating Pressures Using by Crack Propagation Law

2020 ◽  
Vol 26 (1) ◽  
pp. 25-32
Author(s):  
Hitone Inagaki ◽  
Kenji Hiyoshi
Keyword(s):  
Crack Propagation ◽  
Propagation Law

Probabilistic Crack Propagation Behavior of Railway B Grade Steel

2010 ◽  
Vol 97-101 ◽  
pp. 484-487
Author(s):  
Wei Li ◽  
Qiang Li ◽  
Ping Wang
Keyword(s):  
Crack Propagation ◽  
Reliability Assessment ◽  
Threshold Value ◽  
Threshold Region ◽  
Propagation Behavior ◽  
Propagation Law ◽  
Confidence Degree ◽  
State Region ◽  
Crack Propagation Behavior ◽  
Grade Steel

Fatigue crack growth rate (FCGR) test of B grade steel was performed to clarify the probabilistic behavior of crack propagation in near-threshold region and steady-state region. As a result, a crack propagation law considering influence of threshold value and average stress can be well proposed to estimate crack propagation behavior of B grade steel. The estimated value of threshold value ΔKth is 293.65MPamm1/2, approaching the experimental value of ΔKth, about 280.39MPamm1/2. Furthermore, the probabilistic FCGR curves of B grade steel are established from the viewpoint of survival probability and confidence degree, which reflects the influence of scatter regularity of data and sample size on reliability assessment.

Description of Small Fatigue Crack Propagation in ODS Steel

2014 ◽  
Vol 891-892 ◽  
pp. 911-916
Author(s):  
Pavel Hutař ◽  
Ivo Kuběna ◽  
Miroslav Šmíd ◽  
Martin Ševčík ◽  
Tomáš Kruml ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
High Stress ◽  
Oxide Dispersion Strengthened ◽  
Ods Steel ◽  
Small Fatigue Crack ◽  
Propagation Law

The oxide dispersion strengthened (ODS) steels are widely studied as possible candidate material for fission and fusion technology. Due to application of the ODS materials, mainly low cycle fatigue is important. Therefore, small crack initiation and propagation for rather high stress amplitude are in focus. The main aim of the presented work is description of the small fatigue crack propagation for ODS-EUROFER steel. Due to limited quantity of ODS steel special miniaturized cylindrical specimens for fatigue testing were designed. Crack propagation law based on plastic part of J-integral is presented and applied for mentioned material. The resulting fatigue crack propagation rates for ODS-EUROFER steel and EUROFER 97 are compared and discussed.

Experimental and theoretical fatigue-crack propagation lives of variously notched plates

1974 ◽  
Vol 9 (2) ◽  
pp. 61-66 ◽  
Author(s):  
R A Smith ◽  
K Jerram ◽  
K J Miller
Keyword(s):  
Fatigue Life ◽  
Crack Propagation ◽  
Finite Element Analyses ◽  
Intensity Factors ◽  
Complex Profile ◽  
Propagation Law ◽  
Theoretical Predictions ◽  
Life Predictions ◽  
Theoretical Results

The fatigue lives of variously notched plates have been determined theoretically and experimentally. Theoretical predictions of fatigue lives involved the determination of stress-intensity factors from finite-element analyses. By invoking a crack propagation law, fatigue-life predictions were made for four specimens. Fatigue experiments were conducted on four notched plates subjected to end load plus bending. Comparison with theoretical results shows that the experimental lives were greater by factors of 1.30 to 1.54. These results are most satisfactory since (1) a safe prediction of fatigue life has been made for a complex profile subjected to non-simple loading conditions, and (2) a theoretical elastic analysis has sufficed for a situation involving plastic strains.

Research on High Temperature Low Cycle Fatigue Crack Propagation of 2.25Cr-lMo Steel under Complex Stress State

2011 ◽  
Vol 361-363 ◽  
pp. 1422-1425
Author(s):  
Wen Xiao Zhang ◽  
Guo Dong Gao ◽  
Guang Yu Mu
Keyword(s):  
Fatigue Crack ◽  
High Temperature ◽  
Stress State ◽  
Crack Propagation ◽  
Low Cycle Fatigue ◽  
Complex Stress ◽  
Complex Stress State ◽  
J Integral ◽  
Cycle Fatigue ◽  
Propagation Law

The crack propagation law of 2.25Cr-1Mo steel with notched cylinder was researched under high temperature low cycle fatigue. The crack propagation life was viewed by fatigue experiment and the equivalent stress-strain on the crack tip was calculated by the ANSYS. The equivalent J-integral range which was computed by equivalent elastic and plastic strain ranges were employed to denote the fatigue crack propagation rate. The results showed that crack propagation law of this material under complex stress state can be characterized by equivalent J-integral ranges and the relation between da/dN and ΔJf is not influenced by the type of notch and the load strain range.

Boundary Conditions Effects on the Crack Growth Mechanism Under Cycling Bending

2019 ◽  
Author(s):  
Giovanni Pio Pucillo ◽  
Luca Esposito ◽  
Davide Leonetti
Keyword(s):  
Aspect Ratio ◽  
Boundary Conditions ◽  
Crack Propagation ◽  
Crack Front ◽  
Crack Depth ◽  
Internal Boundary ◽  
Design Stage ◽  
Crack Shape ◽  
Propagation Law ◽  
Bending Load

The recent increase of train speed and frequency determines a rise of the loads transmitted to the superstructure. Therefore, railway components might experience service loads that have not considered at the design stage. Moreover, wear and backlash modification between components of a mechanical system might be able to modify the internal boundary conditions of the assembly. According to damage tolerance philosophy, an initial flaw is assumed to exist in the fatigue critical location of a structural component, and the analysis of the crack propagation life for such component needs accurate Stress Intensity Factor (SIF) evaluations. In this study, the effects of the boundary conditions on the crack propagation life have been evaluated for a semi-elliptical surface crack having semi-axes a and c and growing from the root of a shoulder fillet notch in a round bar loaded in bending. Two cases have been analyzed: - the shoulder is free from external forces; - the shoulder is in contact with an adjacent generic body. At first, the SIF distribution has been calculated with the Virtual Crack Closure Technique, considering or not the nonlinear effect induced by the contact forces arising from the interaction between the shoulder and the neighboring component. Successively, in both the above cases a two-parameters propagation law has been utilized to predict the evolution of both crack shape and crack depth when a cyclic bending load is applied to the rod. For this purpose, different values of the Stress Concentration Factor at the root of the fillet, and of the initial aspect ratio of the crack front, were considered in the calculations. It is found that the aspect ratio evolves to a unique asymptote, taking or not into account the non-linearity introduced by the contact at the shoulder, and this value depends on the notch severity. The ratio between the dimensionless SIFs obtained with and without the unilateral constraint at the shoulder, βcs / βfs, does not depend on the relative crack depth and crack shape. Also, the effect of the notch severity on the dimensionless SIF appears to be evident only for the portion of the crack front in the vicinity of the free surface.

Effect of Constraint on Fatigue Crack Propagation in Notched Plates

2010 ◽  
Author(s):  
Xin Wang
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Crack Tip ◽  
Crack Propagation Rate ◽  
Propagation Rate ◽  
Fatigue Crack Propagation Rate ◽  
Rate Model ◽  
Propagation Law ◽  
Crack Tip Constraint

It has been observed that the loss of crack tip constraint leads to enhanced resistance to both cleavage and ductile tearing. Recent developments on constraint-based fracture mechanics have enabled the practical assessment of defective components including the constraint effect. In fatigue analyses, it is common practice to use the Paris crack propagation law, which is based on the stress intensity factor alone. Although in recent years several research attempts have been made to investigate the effect of constraint on fatigue, how to quantify the effect of crack tip constraint on the fatigue crack propagation rate is still an open issue. In this paper, the effect of crack tip constraint on the fatigue crack propagation of small cracks at notched plates is investigated. A fatigue crack propagation rate model developed earlier which incorporates both low and high constraint conditions is used. It is shown that the effect of constraint on crack propagation rate is significant when the crack is small (within the stress concentration of the notches). This effect can be accounted for by using the fatigue crack propagation rate model.

A Study of the Law of Crack Propagation

1967 ◽  
Vol 89 (3) ◽  
pp. 487-493 ◽  
Author(s):  
C. T. Yang
Keyword(s):  
Aluminum Alloy ◽  
Crack Propagation ◽  
Power Law ◽  
Alloy Sheet ◽  
Finite Width ◽  
Mathematical Function ◽  
Design Work ◽  
Exact Function ◽  
Propagation Law ◽  
Power Law Equation

A general form of the mathematical function in the crack-propagation law for specimens of both infinite and finite widths was determined by means of dimensional analysis. The exact function of the latter type was then determined by experiments. It was found that the general equation of the power law holds for specimens of finite width for three metals: Cold-rolled types 301 and 310 stainless-steel sheet and 2014-T6 aluminum-alloy sheet tested at 78° F and low cyclic load rates. The indices n of the power-law equation for the two stainless steels were found to be different from that of the aluminum alloy. The valuable application of the power-law equation to design work is mentioned.

Plastic Energy Required for Fatigue Failure of Specimens Containing Cracks

1975 ◽  
Vol 97 (2) ◽  
pp. 172-178 ◽  
Author(s):  
Thang Bui-Quoc ◽  
Andre Biron
Keyword(s):  
Experimental Data ◽  
Crack Propagation ◽  
Hysteresis Loops ◽  
Mean Value ◽  
Repeated Loading ◽  
Plastic Energy ◽  
Propagation Law ◽  
The Mean ◽  
Damage Rule ◽  
Propagation Stage

A study is conducted to determine the plastic energy absorbed by a material subjected to cyclic loading during the crack propagation stage. The analysis is based on Liu’s elastoplastic solution for calculating the plastic energy around the crack tip combined with a modified crack propagation law. The plastic energy per cycle Δw is found to be dependent upon the fatigue crack length and therefore varies with the number of applied cycles. The mean value of this energy corresponds to the plastic energy obtained by measuring the area within the stress-strain hysteresis loops of the material under repeated loading. If fatigue damage is based on plastic energy, the trend of variation of Δw with the applied cycles in the present analysis shows that the application of the linear damage rule (such as Miner’s law) should be more successful in the low-cycle region than in the high-cycle region. This is consistent with experimental data.

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