scholarly journals Effect of grain boundaries on bending fatigue life of aluminum bicrystals with 0.5 schmid factor on primary slip systems

2008 ◽  
Vol 58 (3) ◽  
pp. 93-97
Author(s):  
Ken Atagi ◽  
Yoshihiro Okumoto ◽  
Kouji Nishimoto
Keyword(s):  
Fatigue Life ◽  
Grain Boundaries ◽  
Slip Systems ◽  
Bending Fatigue ◽  
Schmid Factor

Calculation of the Stress Interaction between Dislocation Pile-Ups in Neighbouring Misoriented Grains

2016 ◽  
Vol 879 ◽  
pp. 1731-1736 ◽  
Author(s):  
R. Schouwenaars ◽  
A. Ortiz ◽  
V. H. Jacobo
Keyword(s):  
Plastic Deformation ◽  
Grain Boundaries ◽  
External Stress ◽  
Dislocation Slip ◽  
Shear Stresses ◽  
Slip Systems ◽  
Dislocation Loops ◽  
Stress Concentrations ◽  
Pile Up ◽  
Schmid Factor

During the early stages of the plastic deformation of a polycrystal, dislocations can pile-up against grain boundaries. Experimental results on large-grained materials have provided excellent verification of this phenomenon. Such a pile-up may activate dislocation slip in the neighbouring grain. Whether this occurs depends on the misorientation between the grains and the resolved shear stresses in the affected grain. Several approximate criteria have been proposed to predict the occurrence of this mechanism. Here, the problem will be assessed directly by calculating the Peach-Köhler force produced by a single dislocation pile-up in one grain on all the possible slip systems in the neighbouring grain, in combination with the effect of the applied external stress as obtained through calculation of the Schmid factor. It will be seen that the problem is significantly more complex than what is generally assumed in basic explanations of the Hall-Petch effect: highly localised stress concentrations are generated for certain misorientations, which are capable of punching out small dislocation loops which may then propagate into the neighbouring grain.

Observation of secondary slip systems in tungsten bicrystals

1984 ◽  
Vol 42 ◽  
pp. 478-479
Author(s):  
J. R. Fekete ◽  
R. Gibala
Keyword(s):  
Stress Field ◽  
Grain Boundaries ◽  
Deformation Behavior ◽  
Stress Axis ◽  
Polycrystalline Materials ◽  
Slip Systems ◽  
Metallic Materials ◽  
Twist Boundary ◽  
Secondary Slip ◽  
Plane Normal

The deformation behavior of metallic materials is modified by the presence of grain boundaries. When polycrystalline materials are deformed, additional stresses over and above those externally imposed on the material are induced. These stresses result from the constraint of the grain boundaries on the deformation of incompatible grains. This incompatibility can be elastic or plastic in nature. One of the mechanisms by which these stresses can be relieved is the activation of secondary slip systems. Secondary slip systems have been shown to relieve elastic and plastic compatibility stresses. The deformation of tungsten bicrystals is interesting, due to the elastic isotropy of the material, which implies that the entire compatibility stress field will exist due to plastic incompatibility. The work described here shows TEM observations of the activation of secondary slip in tungsten bicrystals with a [110] twist boundary oriented with the plane normal parallel to the stress axis.

Distinct fatigue cracking modes of grain boundaries with coplanar slip systems

2016 ◽  
Vol 120 ◽  
pp. 120-129 ◽  
Author(s):  
L.L. Li ◽  
Z.J. Zhang ◽  
P. Zhang ◽  
J.B. Yang ◽  
Z.F. Zhang
Keyword(s):  
Grain Boundaries ◽  
Fatigue Cracking ◽  
Slip Systems ◽  
Cracking Modes

Fatigue Life Prediction of Gear Transmission Based on ANSYS

2014 ◽  
Vol 1055 ◽  
pp. 161-164
Author(s):  
Tao Wang ◽  
Wei Zhong Zhang ◽  
Chen Xie ◽  
Deng Xia Zhang ◽  
Yan Ru
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Reliable Data ◽  
Cumulative Damage ◽  
Gear Transmission ◽  
Fatigue Life Prediction ◽  
Nominal Stress ◽  
Bending Fatigue ◽  
Unmanned System ◽  
Damage Theory

With the study subject of the gear transmission in an unmanned system, several common methods of fatigue life prediction are analyzed. According to the actual running state, S-N nominal stress method is used to predict the fatigue life of the gears. Based on the S-N data of the gear material and the linear cumulative damage theory, ANSYS is used to estimate the bending fatigue life of the gears, so as to obtain the fatigue life loss coefficient of the gears. It provides a reliable data reference of the design, use and maintenance of the gear transmission in unmanned system.

scholarly journals Fatigue Performance and Multiscale Mechanisms of Concrete Toughened by Polymers and Waste Rubber

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Bo Chen ◽  
Liping Guo ◽  
Wei Sun
Keyword(s):  
Fatigue Life ◽  
Polyvinyl Alcohol ◽  
Water Soluble ◽  
Fatigue Performance ◽  
Tire Rubber ◽  
Bending Fatigue ◽  
Waste Tire ◽  
Waste Rubber ◽  
Bonding Effect ◽  
Waste Tire Rubber

For improving bending toughness and fatigue performance of brittle cement-based composites, two types of water-soluble polymers (such as dispersible latex powder and polyvinyl alcohol powder) and waste tire-rubber powders are added to concrete as admixtures. Multiscale toughening mechanisms of these additions in concretes were comprehensively investigated. Four-point bending fatigue performance of four series concretes is conducted under a stress level of 0.70. The results show that the effects of dispersible latex powder on bending toughness and fatigue life of concrete are better than those of polyvinyl alcohol powder. Furthermore, the bending fatigue lives of concrete simultaneously containing polymers and waste rubber powders are larger than those of concrete with only one type of admixtures. The multiscale physics-chemical mechanisms show that high bonding effect and high elastic modulus of polymer films as well as good elastic property and crack-resistance of waste tire-rubber powders are beneficial for improving bending toughness and fatigue life of cementitious composites.

Numerical model for bending fatigue life estimation of carburized spur gears with consideration of the adjacent tooth effect

2021 ◽  
Vol 153 ◽  
pp. 106515
Author(s):  
Krešimir Vučković ◽  
Ivan Čular ◽  
Robert Mašović ◽  
Ivica Galić ◽  
Dragan Žeželj
Keyword(s):  
Fatigue Life ◽  
Numerical Model ◽  
Spur Gears ◽  
Bending Fatigue ◽  
Life Estimation ◽  
Adjacent Tooth ◽  
Fatigue Life Estimation

scholarly journals PENGARUH PENGHILANGAN KEKASARAN PERMUKAAN TERHADAP KEKUATAN FATIK = EFFECT OF SURFACE ROUGHNESS REMOVAL TO FATIGUE STRENGTH

2015 ◽  
Vol 9 (3) ◽  
pp. 115-130
Author(s):  
H. Agus Suhartono
Keyword(s):  
Surface Roughness ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Fatigue Loading ◽  
Bending Fatigue ◽  
Aisi 1045 Steel ◽  
Aisi 1045 ◽  
1045 Steel ◽  
Test Result ◽  
Effect Of Surface

The aim of the study is to investigate and to prove that the fatigue failure of steel is initiated from the surface. Hence the preventif action of smoothening the surface that has been loaded by fatigue loading is very important. The specimen of AISI 1045 Steel is loaded by means of rotary bending fatigue. The fatigue loading will be interupted as the fatigue life reaching 50% of fatigue life and 75% of fatigue life. During the interuption the specimen will be grinded and polished, before tested completely until fatigue fracture occured. The fatigue life of each group of scpecimen based on the art of loading will be compared to the specimen tested by fatigue loading without interuption.The Miner rule is used to evaluated the test result. The influence of interuption and surface treatment is evaluated and analyzed. ABSTRAKTujuan penelitian ini adalah untuk menyelidiki dan membuktikan bahwa kegagalan kelelahan baja dimulai dari permukaan. Oleh karena itu tindakan pencegahan dengan memperhalus permukaan sangat penting untuk mencegah beban kelelahan baja. Spesimen dari AISI 1045 Steel dimuat dengan cara uji kelelahan lentur putar. Kelelahan pemuatan akan disela sebagai umur kelelahan mencapai 50% dari umur kelelahan dan 75% dari umur kelelahan. Selama gangguan lainnya yang spesimen akan digiling dan dipoles, sebelum diuji benar-benar sampai patah akibat kelelahan yang terjadi. Umur kelelahan dari setiap kelompok specimen diuji berdasarkan beban akan dibandingkan dengan spesimen oleh kelelahan bongkar tanpa aturan. The Miner rule digunakan untuk mengevaluasi hasil tes. Pengaruh gangguan lainnya dan perlakuan permukaan dievaluasi dan dianalisis. 

Improvement of Fatigue Behaviour of High Strength Aluminium Alloys by Fluidized Bed Peening (FBP)

2007 ◽  
Vol 344 ◽  
pp. 87-96 ◽  
Author(s):  
M. Barletta ◽  
F. Lambiase ◽  
Vincenzo Tagliaferri
Keyword(s):  
Fatigue Life ◽  
Fluidized Bed ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Maximum Amplitude ◽  
High Strength ◽  
Operational Parameters ◽  
Bending Fatigue ◽  
Rotating Bending Fatigue ◽  
Rotating Bending

This paper deals with a definition of a relatively novel technique to improve the fatigue behavior of high strength aluminum alloys, namely, Fluidized Bed Peening (FBP). Fatigue samples made from AA 6082 T6 alloy were chosen according to ASTM regulation about rotating bending fatigue test and, subsequently, treated by varying FBP operational parameters and fatigue testing conditions. First, a full factorial experimental plan was performed to assess the trend of number of cycles to rupture of fatigue samples varying among several experimental levels the factors peening time and maximum amplitude of alternating stress applied to fatigue samples during rotating bending fatigue tests. Second, design of experiment (DOE) technique was used to analyze the influence of FBP operational parameters on fatigue life of AA 6082 T6 alloy. Finally, ruptures of FB treated samples and untreated samples were discussed in order to evaluate the influence of operational parameters on the effectiveness of FBP process and to understand the leading process mechanisms. At any rate, the fatigue behavior of processed components was found to be significantly improved, thereby proving the suitability of FBP process as alternative mechanical technique to enhance fatigue life of components made from high strength aluminum alloy.

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