Mode II Fatigue Crack Propagation

1971 ◽  
Vol 93 (4) ◽  
pp. 671-680 ◽  
Author(s):  
R. Roberts ◽  
J. J. Kibler
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Transverse Mode ◽  
Mode I ◽  
Mode Ii ◽  
Growth Equation ◽  
Plane Mode

Fatigue crack propagation rates were obtained for 2024-T3 bare aluminum plates subjected to in-plane, mode I, extensional loads and transverse, mode II, bending loads. These results were compared to the results of Iida and Kobayashi for in-plane mode I-mode II extensional loads. The engineering significance of mode I-mode II fatigue crack growth is considered in view of the present results. A fatigue crack growth equation for handling mode I-mode II fatigue crack growth rates from existing mode I data is also discussed.

Pre-Strain Effects on Mixed-Mode Fatigue Crack Propagation Behaviour of the P355NL1 Pressure Vessels Steel

2018 ◽  
Author(s):  
João Ferreira ◽  
José A. F. O. Correia ◽  
Grzegorz Lesiuk ◽  
Sergio Blasón González ◽  
Maria Cristina R. Gonzalez ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Mixed Mode ◽  
Pressure Vessels ◽  
Mode I ◽  
Pure Mode

Pressure vessels and piping are commonly subjected to plastic deformation during manufacturing or installation. This pre-deformation history, usually called pre-strain, may have a significant influence on the resistance against fatigue crack growth of the material. Several studies have been performed to investigate the pre-strain effects on the pure mode I fatigue crack propagation, but less on mixed-mode (I+II) fatigue crack propagation conditions. The present study aims at investigating the effect of tensile plastic pre-strain on fatigue crack growth behavior (da/dN vs. ΔK) of the P355NL1 pressure vessel steel. For that purpose, fatigue crack propagation tests were conducted on specimens with two distinct degrees of pre-strain: 0% and 6%, under mixed mode (I+II) conditions using CTS specimens. Moreover, for comparison purposes, CT specimens were tested under pure mode I conditions for pre-strains of 0% and 3%. Contrary to the majority of previous studies, that applied plastic deformation directly on the machined specimen, in this work the pre-straining operation was carried out prior to the machining of the specimens with the objective to minimize residual stress effects and distortions. Results revealed that, for the P355NL1 steel, the tensile pre-strain increased fatigue crack initiation angle and reduced fatigue crack growth rates in the Paris region for mixed mode conditions. The pre-straining procedure had a clear impact on the Paris law constants, increasing the coefficient and decreasing the exponent. In the low ΔK region, results indicate that pre-strain causes a decrease in ΔKth.

Modeling of Fatigue Crack Propagation

2004 ◽  
Vol 126 (1) ◽  
pp. 77-86 ◽  
Author(s):  
Yanyao Jiang ◽  
Miaolin Feng
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Initiation ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Damage ◽  
Fatigue Crack Propagation ◽  
Fatigue Crack Initiation ◽  
Cyclic Plasticity ◽  
R Ratio

Fatigue crack propagation was modeled by using the cyclic plasticity material properties and fatigue constants for crack initiation. The cyclic elastic-plastic stress-strain field near the crack tip was analyzed using the finite element method with the implementation of a robust cyclic plasticity theory. An incremental multiaxial fatigue criterion was employed to determine the fatigue damage. A straightforward method was developed to determine the fatigue crack growth rate. Crack propagation behavior of a material was obtained without any additional assumptions or fitting. Benchmark Mode I fatigue crack growth experiments were conducted using 1070 steel at room temperature. The approach developed was able to quantitatively capture all the important fatigue crack propagation behaviors including the overload and the R-ratio effects on crack propagation and threshold. The models provide a new perspective for the R-ratio effects. The results support the notion that the fatigue crack initiation and propagation behaviors are governed by the same fatigue damage mechanisms. Crack growth can be treated as a process of continuous crack nucleation.

Fatigue Crack Propagation Limit Curves for S690QL and S960M High Strength Steels and their Welded Joints

2018 ◽  
Vol 1146 ◽  
pp. 44-56 ◽  
Author(s):  
János Lukács ◽  
Ádám Dobosy ◽  
Marcell Gáspár
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Welded Joints ◽  
High Strength Steels ◽  
High Strength ◽  
Base Materials ◽  
Propagation Limit

The objective of the paper is to present the newest results of our complex research work. In order to determination and comparison of the fatigue resistance, fatigue crack growth tests were performed on different grades of S690QL quenched and tempered, and S960TM thermomechanically rolled high strength steels.15 mmand30 mmthick base materials were used for our investigations. Welded joints were made from these base materials, using gas metal arc welding with matching, overmatching, and undermatching filler metals. In the paper, the performance of the welding experiments will be presented, especially with the difficulties of the filler material selection; along with the results of the fatigue crack growth examinations executed on the base materials and its welded joints. Statistical aspects were applied both for the presenting of the possible locations of the cracks in the base materials and the welded joints and for the processing of the measured data. Furthermore, the results will be compared with each other, and the possibility of derivation of fatigue crack propagation limit curves will be referred.

Effect of Environment on Fatigue Crack Propagation Behavior of an Al-Cu-Mg Aluminum Alloy

2014 ◽  
Vol 1004-1005 ◽  
pp. 142-147
Author(s):  
Ming Liu ◽  
Kun Zhang ◽  
Sheng Long Dai ◽  
Guo Ai Li ◽  
Min Hao ◽  
...  
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Fatigue Crack Growth Rate ◽  
Fatigue Crack Propagation Behavior ◽  
Stress Ratios

The fatigue crack propagation behaviors of an Al-Cu-Mg alloy are investigated in different environments and with varying stress ratios. Fatigue experiments are carried out via a fatigue crack growth rate test in laboratory air, a 3.5% (mass fraction) NaCl solution and a tank seeper. The results show that a corrosion environment has an obvious influence on the fatigue crack growth rate, and the degrees of influence of the two different corrosive environments are basically identical. When the stress ratio is R = 0.5 and 0.06 with a decrease of the stress intensity factor, the difference in the crack propagation rates for the corrosion and air environments gradually increases. However, the corrosion acceleration in each stage of crack propagation is obvious while R=−1.

Investigation on Mode I Propagation Behavior of Fatigue Crack in Precipitation-Hardened Aluminum Alloy with Different Mg Content

2017 ◽  
Vol 889 ◽  
pp. 143-147 ◽  
Author(s):  
Samsol Faizal Anis ◽  
Motomichi Koyama ◽  
Hiroshi Noguchi
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Optical Microscope ◽  
Al Alloys ◽  
Dynamic Strain ◽  
Mode I ◽  
Al Alloy ◽  
Excess Mg

The influence of excess Mg on the Mode I propagation of fatigue crack was examined in newly developed precipitation-hardened Al alloy containing Zr and excess Mg. The aim of this study was to evaluate the underlying factor affecting fatigue crack growth rate in the stage II region. For this purpose, the rotating bending fatigue tests were performed in constant amplitude loading, and replication technique with an optical microscope was used to measure the crack growth in the Al alloys. Through analyses of the crack propagation on the specimen surface and striation formation of the fracture surface, the effects of excess Mg in the Al alloys were clarified to promote the occurrence of mode I fatigue crack, and decelerate the fatigue crack propagation. These facts suggest that the dynamic strain aging of Mg induces the formation of fatigue striation and reduce the driving force of the crack propagation. The findings were supported by the fractographic observations in the fatigue crack propagation region.

Fatigue Crack Growth Rates in Friction Stir Welding Joints of 7075-T6 Al Alloy and Fatigue Life Prediction Based on AFGROW

2011 ◽  
Vol 337 ◽  
pp. 507-510 ◽  
Author(s):  
Bin Lian Zou ◽  
Xin Qi Yang ◽  
Jia Hua Chen
Keyword(s):  
Fatigue Crack ◽  
Friction Stir Welding ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Al Alloy ◽  
International Institute ◽  
Welding Seam ◽  
Friction Stir

In this work, a study of fatigue crack propagation (FCP) behavior of friction stir welding (FSW) joints of 7075-T6 aluminum alloy was carried out. Fatigue crack growth rate curves were determined for cracks growing in different locations of the welding lines, including prefabricated crack through welding seam center, advancing side (AS), retreating side (RS), and vertical to welding seam. A computational simulation of fatigue crack propagation was conducted by AFGROW with different stress ratios R, and the effects of R on FCP rate were analyzed. Results showed that the FCP rate in RS of the Heat Affected Zone (HAZ) was the lowest and the highest was in the region vertical to the welding seam. In the low stress intensity factor range (△K) region, the FCP rate in Nugget Zone (NZ) was lower than that in AS of the HAZ, but in the high △K region, the situation was contrary. Reasons of the results were analyzed. Compared with the standard of International Institute of Welding (IIW), FCP rates in all regions were lower and it concluded nice fatigue properties of FSW 7075-T6. The simulation made in terms of crack propagation rate (da/dN) versus △K generally showed a good agreement with the measured values. The study of effects of different R on FCP rates based on AFGROW indicated that FCP rates increased with increasing R.

Control Effect on Fatigue Crack Propagation of TiNi Fiber Reinforced PMMA Composites

2005 ◽  
Vol 297-300 ◽  
pp. 2929-0
Author(s):  
Cheong Cheon Lee ◽  
Akira Shimamoto
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Fiber Reinforced ◽  
Control Effect ◽  
The Matrix

In this paper, the TiNi fiber reinforced/PMMA (Poly methyl methacrylate) composite is developed, and its effectiveness of controlling fatigue crack growth is studied. The TiNi fiber reinforced/PMMA composite’s mechanical property enhancement and deformation resistance are also studied. The fatigue behavior and crack propagation are observed with a SEM servo-pulser (fatigue testing instrument with scanning electron microscope) while increasing temperature. As the results, it is confirmed that the fatigue life and resistance are improved. How the shape memory effect and expansion behavior of the matrix caused by temperature increasing affect the fatigue crack propagation control is examined. It is verified that the control of fatigue crack growth is attributed to the compressive stress field in the matrix due to shrinkage of the TiNi fibers above austenitic finishing temperature (Af).

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