scholarly journals Fatigue Crack Growth under Non-Proportional Mixed Mode Loading in Rail and Wheel Steel Part 2: Sequential Mode I and Mode III Loading

2019 ◽  
Vol 9 (14) ◽  
pp. 2866 ◽  
Author(s):  
Makoto Akama ◽  
Akira Kiuchi
Keyword(s):  
Crack Growth ◽  
Mixed Mode ◽  
Fatigue Cracks ◽  
Rolling Contact ◽  
Material Strength ◽  
Shear Mode ◽  
Mode I ◽  
Mode Iii ◽  
Plane Shear ◽  
Branch Crack

Rolling contact fatigue cracks in rail and wheel undergo non-proportional mixed mode I/II/III loading. Fatigue tests were performed to determine the coplanar and branch crack growth rates on these materials. Sequential and overlapping mode I and III loading cycles were applied to single cracks in round bar specimens. Experiments in which this is done have been rarely performed. The fracture surface observations and the finite element analysis results suggested that the growth of long (does not branch but grown stably and straight) coplanar cracks was driven mainly by mode III loading. The cracks tended to branch when increasing the material strength and/or the degree of overlap between the mode I and III loading cycles. The equivalent stress intensity factor range that can consider the crack face contact and successfully regressed the crack growth rate data is proposed for the branch crack. Based on the results obtained in this study, the mechanism of long coplanar shear-mode crack growth turned out to be the same regardless of whether the main driving force is in-plane shear or out-of-plane shear.

Fatigue Crack Growth Thresholds of Deflected Mixed-Mode Cracks in PWA1484

2005 ◽  
Vol 127 (1) ◽  
pp. 2-7 ◽  
Author(s):  
K. S. Chan ◽  
J. Feiger ◽  
Y.-D. Lee ◽  
R. John ◽  
S. J. Hudak,
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Mixed Mode ◽  
Fatigue Cracks ◽  
Symmetry Plane ◽  
Crystallographic Analysis ◽  
Mode I ◽  
Test Technique ◽  
Crack Paths

The fatigue crack growth (FCG) behavior of PWA1484 single crystals was characterized in air under mixed-mode loading at 593°C as a function of crystallographic orientation using an asymmetric four-point bend test technique. Most mixed-mode fatigue cracks deflected from the symmetry plane and propagated as transprecipitate, noncrystallographic cracks, while self-similar fatigue crack growth occurred on the (111) planes in (111)/[011] and 111/[112]¯ oriented crystals. The local stress intensity factors and the crack paths of the deflected mixed-mode cracks were analyzed using the finite-element fracture mechanics code, FRANC2D/L. The results indicated that the deflected crack path was close to being normal to the maximum tensile stress direction where the Mode II component diminishes. Crystallographic analysis of the deflected crack paths revealed that the Mode I and the deflected mixed-mode cracks were usually of different crystallographic orientations and could exhibit different Mode I FCG thresholds when the crystallography of the crack paths differed substantially. These results were used to identify the driving force and conditions for cracking mode transition.

Evaluation of Static and Dynamic Stress Intensity Factors under Pure Mode I and Mixed Mode I/II Fracture

2015 ◽  
Vol 220-221 ◽  
pp. 667-672 ◽  
Author(s):  
Marius Gintalas ◽  
Kaspars Kalniņš ◽  
Algis Pakalnis ◽  
Petras Šadreika ◽  
Antanas Žiliukas
Keyword(s):  
Mixed Mode ◽  
Test Procedure ◽  
Orientation Angle ◽  
Initial Crack ◽  
Shear Mode ◽  
Mode I ◽  
Pure Mode ◽  
Dynamic Stress Intensity Factors ◽  
Plane Shear ◽  
Fracture Characteristics

The focus of this work is to investigate pre-cracked plate element fracture under mixed mode I/II loading. In order to look into element with inclined initial crack, the test procedure was also performed due to pure opening fracture (I mode) and in-plane shear mode (II mode). For this purpose, static and dynamic tests were performed with original testing device, in which the specimen was fixed in so called “Arcan disc”. The results showed fracture characteristics dependence under initial crack orientation angle, i.e. due opening mode, in-plane shear mode and mixed mode I/II fracture.

Mixed-Mode [I/III] Fracture Simulation of Rubber

2014 ◽  
Vol 931-932 ◽  
pp. 1053-1057
Author(s):  
Kiatisak Permpipat ◽  
Petch Jearanaisilawong
Keyword(s):  
Mixed Mode ◽  
Shear Loading ◽  
Mode I ◽  
Mixed Mode Fracture ◽  
Tearing Mode ◽  
Mode Iii ◽  
Plane Shear ◽  
Finite Element Software ◽  
Fracture Simulation ◽  
Out Of Plane

The objective of this work is to develop fracture simulations of rubber undergoing a combined tensile and out-of-plane shear loading. Rubber sheets are tested under mode-I (opening mode), mode-III (tearing mode) and mixed-mode [I/II of fracture. The experiments are simulated in finite element software to evaluate the J-integral for each mode of deformation. Comparison between simulation and testing results are in good agreement. The simulations serve as test cases and evaluation tools for the development of mixed mode fracture criterion of rubber.

Deviant Crack Path Behaviour of Aluminium-Lithium Alloy AA8090 Plate

1996 ◽  
Vol 210 (2) ◽  
pp. 117-121
Author(s):  
P J Gregson ◽  
I Sinclair
Keyword(s):  
Crack Growth ◽  
Mixed Mode ◽  
Fatigue Testing ◽  
Fatigue Cracks ◽  
Elastic Strain Energy ◽  
Strain Energy Release ◽  
Mode I ◽  
Mixed Mode Crack ◽  
Energy Release Rates ◽  
Strain Energy Release Rates

The unusual susceptibility of the Al-Li alloy AA8090 to sustained macroscopic deviation of fatigue cracks from a nominal mode I path during conventional fatigue testing is discussed. It is demonstrated that the mixed mode crack growth associated with macroscopic deviation may be characterized in terms of elastic strain energy release rates for a range of mixed mode loading conditions. It is specifically shown that this form of mixed mode crack growth may lead to non-conservative crack growth predictions when these materials are subjected to conventional, mode I based structure lifing techniques.

Description of Fatigue Crack Propagation under Mixed-Mode II+III in Terms of J-Integral

2014 ◽  
Vol 627 ◽  
pp. 145-148 ◽  
Author(s):  
Jana Horníková ◽  
Pavel Šandera ◽  
Tomáš Vojtek ◽  
Jaroslav Pokluda
Keyword(s):  
Fatigue Crack ◽  
Crack Growth ◽  
Mixed Mode ◽  
Armco Iron ◽  
Fatigue Cracks ◽  
Mode Ii ◽  
J Integral ◽  
Mode Iii ◽  
Equivalent Factor ◽  
The Difference

The paper is dedicated to experiments on near-threshold fatigue cracks under mixed-mode II+III in the ARMCO iron. The mixed mode crack growth was described using an equivalent factor ΔJeff,eq=(1-α)ΔJeff,eqII+αΔJeff,eqIII. The most appropriate description was found for α = 0.67 indicating that the mode III component should be more efficient than that of the mode II which is in contradiction of a ΔKeq–based analysis. This result shows that, unlike in the austenitic steel, the difference in the efficiency of modes II and III in the ARMCO iron is very small.

scholarly journals Fatigue Crack Growth under Non-Proportional Mixed Mode Loading in Rail and Wheel Steel Part 1: Sequential Mode I and Mode II Loading

2019 ◽  
Vol 9 (10) ◽  
pp. 2006 ◽  
Author(s):  
Makoto Akama
Keyword(s):  
Crack Growth ◽  
Growth Rates ◽  
Mixed Mode ◽  
Crack Tip ◽  
Wheel Steel ◽  
Mode I ◽  
Mode Ii ◽  
Mode Ii Loading ◽  
Crack Growth Rates ◽  
Branch Crack

Fatigue tests were performed to estimate the coplanar and branch crack growth rates on rail and wheel steel under non-proportional mixed mode I/II loading cycles simulating the load on rolling contact fatigue cracks; sequential and overlapping mode I and II loadings were applied to single cracks in the specimens. Long coplanar cracks were produced under certain loading conditions. The fracture surfaces observed by scanning electron microscopy and the finite element analysis results suggested that the growth was driven mainly by in-plane shear mode (i.e., mode II) loading. Crack branching likely occurred when the degree of overlap between these mode cycles increased, indicating that such degree enhancement leads to a relative increase of the maximum tangential stress range, based on an elasto–plastic stress field along the branch direction, compared to the maximum shear stress. Moreover, the crack growth rate decreased when the material strength increased because this made the crack tip displacements smaller. The branch crack growth rates could not be represented by a single crack growth law since the plastic zone size ahead of the crack tip increased with the shear part of the loading due to the T-stress, resulting in higher growth rates.

Rock fracture under anti-plane shear (Mode III) loading

2005 ◽  
Vol 12 (S1) ◽  
pp. 125-128 ◽  
Author(s):  
Qiu-hua Rao ◽  
Zhen-feng Liao
Keyword(s):  
Rock Fracture ◽  
Shear Mode ◽  
Mode Iii ◽  
Plane Shear

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.

Sign in / Sign up

Export Citation Format

Share Document