Fatigue Crack Propagation and Fatigue Life Evaluation of High-Performance Steel using Modified Forman Model

2011 ◽  
Vol 35 (11) ◽  
pp. 1361-1368
Author(s):  
Sung-Won Choi ◽  
Dong-Hwan Kang ◽  
Jong-Kwan Lee ◽  
Tae-Won Kim
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
High Performance ◽  
Life Evaluation ◽  
Fatigue Life Evaluation ◽  
High Performance Steel

Fatigue Damage Accumulation of Welded Bridge Member during Crack Growth Propagation with Initial Crack

2007 ◽  
Vol 353-358 ◽  
pp. 24-27
Author(s):  
Tai Quan Zhou ◽  
Tommy Hung Tin Chan
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Initial Crack ◽  
Experimental Result ◽  
Variable Ratio ◽  
Elliptical Shape ◽  
Fatigue Experiment

The crack growth behavior and the fatigue life of welded members with initial crack in bridges under traffic loading were investigated. Based on existed fatigue experiment results of welded members with initial crack and the fatigue experiment result of welded bridge member under constant stress cycle, the crack keeps semi-elliptical shape with variable ratio of a/c during crack propagation. The calculated method of the stress intensity factor necessary for welded bridge member crack propagation was discussed. The crack remained semi-elliptical shape with variable ratio of a/c during crack propagation. The fatigue crack propagation law suitable for welded steel bridge member fatigue crack propagation analysis was deduced based on the continuum damage mechanics and fracture mechanics. The proposed fatigue crack growth model was then applied to calculate the crack growth and the fatigue life of existed welded member with fatigue experimental result. The calculated and measured fatigue life was generally in good agreement, at suitable initial conditions of cracking, for welded member widely used in steel bridges.

Estimation of Fatigue Crack Propagation of Subsurface Cracks by “SCAN”

2006 ◽  
Author(s):  
Shin Nakanishi ◽  
Fuminori Iwamatsu ◽  
Masaki Shiratori ◽  
Hisao Matsushita
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Surface Crack ◽  
Surface Cracks ◽  
Subsurface Crack ◽  
Subsurface Cracks ◽  
Influence Coefficients ◽  
Asme Code

The authors have proposed an influence function method to calculate stress intensity factor, K, of the surface cracks. This method makes the calculating task easier for arbitrarily distributed surface stresses. They have developed the database of influence coefficients, Kij, for various types of surface cracks through a series of finite element analyses.[1] They also have developed a software system “SCAN” (Surface Crack Analysis), from the database. The K values of surface cracks can be evaluated immediately, and further, fatigue crack propagation can be simulated easily with a personal computer. A fatigue crack often initiates from a defect located at the subsurface of a structural member. In this case, it is important to account for the fatigue life from the initiation of a subsurface crack to its propagation into a surface crack. However, since it is difficult to simulate this process precisely, the authors have proposed a simple model about the transition from a subsurface crack into a surface crack based upon ASME CODE SECTION XI [2] and WES 2805 STANDARD. [3] They have developed a SCAN system – Subsurface Crack Version-. They calculated the fatigue life for some models of subsurface cracks and compared the quantitative differences between two standards.

Adhesion Failure in Bonded Rubber Cylinders Part 2: Fatigue Life Prediction of External Ring-Shaped Cracks Using Tearing Energy Approach

2003 ◽  
Vol 76 (2) ◽  
pp. 365-385 ◽  
Author(s):  
Douglas C. Leicht ◽  
C. Rimnac ◽  
R. Mullen
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Propagation ◽  
Crack Length ◽  
Fatigue Crack Propagation ◽  
Shape Factors ◽  
External Ring ◽  
Adhesion Failure ◽  
Shaped Crack ◽  
Tearing Energy

Abstract Rubber disks bonded between flat parallel metal plates are often used as adhesion test specimens; for example, ASTM D 429 1999, Method A. However, the mechanics of adhesion failure (debonding) for this geometry have not previously been fully analyzed. Therefore, a study was conducted to determine the strain energy release rate (tearing energy) for bonded rubber disks having external ring cracks at the rubber-to-metal bond and to develop a method for predicting the fatigue life. Finite element analysis was used to determine the tearing energy as a function of crack length for disks of various dimensions (shape factors). The crack configurations considered were an external-ring-shaped crack located at the outside circumference of either one or both rubber-to-metal bonds. The fatigue crack propagation (FCP) behavior was characterized for a generic filled natural rubber material. The tearing energy was found to be a non-linear function of crack length. For small cracks, the tearing energy was small and approached zero as the crack length decreased. The tearing energy then increased as the crack grew, indicating accelerating growth, until it passed through a maximum value. The peak tearing energy was found to depend on the height of the disk. Finally at large cracks, the tearing energy decreased or was essentially constant as the crack grew. The fatigue life of the rubber cylinders at different shape factors was determined experimentally. An empirical model coupled with the fatigue crack propagation behavior (FCP) for the material at different tearing energies was used to predict the fatigue life. The experimental and predicted fatigue life showed excellent agreement at low and moderate shape factors. However at high shape factors, fatigue life was not well predicted. From the experimental results, it was found that, at high shape factors, cavitation occurs causing a series of “dimples” to form, which leads to the development of an internal penny-crack, thereby violating the assumed model of an external ring-shaped crack.

Effect of Pre-Deformation on Fatigue Crack Propagation Life of X60 Pipeline Steel

2006 ◽  
Author(s):  
Xinwei Zhao ◽  
Jinheng Luo ◽  
Rong Wang ◽  
Maosheng Zheng ◽  
Baosheng Dong
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Oil And Gas ◽  
Tensile Deformation ◽  
Pipeline Steel ◽  
Fatigue Crack Initiation ◽  
Mechanical Damage ◽  
Fatigue Crack Propagation Life

It is impossible to keep oil and gas pipeline free from defects in fabrication, installation and serving processes. Mechanical damage is one of import causes of pipeline failure accidents. Mechanical damage might endanger the safety of pipelines and even shorten their service life. Pre-tensile deformation of X60 steel is employed to experimentally simulate the influence of dents on the fatigue crack initiation life. The investigation indicates that the fatigue crack propagation life of pre-deformed X60 pipeline steel can be predicted using a previously proposed equation, i.e., da/dN = B(ΔK − ΔKth)2. The threshold ΔKth for fatigue crack propagation decreases with the pre-deformation. The fatigue crack propagation coefficient B increases with the pre-deformation. So pre-deformation accelerates fatigue crack propagation and shortens fatigue life. The result is expected to be beneficial to the understanding of the effect of dents on the safety of pipelines and fatigue life prediction.

scholarly journals Characterization of Microstructures and Fatigue Properties for Dual-Phase Pipeline Steels by Gleeble Simulation of Heat-Affected Zone

Materials ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 1989 ◽  
Author(s):  
Zuopeng Zhao ◽  
Pengfei Xu ◽  
Hongxia Cheng ◽  
Jili Miao ◽  
Furen Xiao
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Propagation ◽  
Grain Boundaries ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Heat Affected Zone ◽  
Peak Temperature ◽  
Coarse Grained ◽  
Dual Phase

To increase transmission efficiency and reduce operation cost, dual-phase (DP) steels have been considered for pipeline applications. Welding has to be involved in such applications, which would cause a localized alteration of materials and cause many potential fatigue issues to arise under cyclic loading. In this work, the fatigue crack propagation and fatigue life of simulated heat-affected zone (HAZ) were examined. Results indicate that when the maximum stress is at the same magnitude, the fatigue life at a peak temperature of 1050 °C is very close to that of a peak temperature of 850 °C, and both of them are higher than that of a peak temperature of 1350 °C. The changes in da/dN with ΔK for HAZ subregions are attributed to the variation of crack path and fracture mode during the crack propagation. The fatigue cracks may propagate along the bainite lath preferentially in coarse-grained HAZ (CGHAZ), and the prior austenite grain boundaries can change the crack growth direction. A considerable amount of highly misoriented grain boundaries in fine-grained HAZ (FGHAZ) and intercritical-grained HAZ (ICHAZ) increase the crack growth resistance. The difference of fatigue crack propagation behavior in HAZ subregions between actual and simulated welded joints was also discussed.

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