THE STUDY OF THE PROCESS OF ROLLING PIPES FROM ANISOTROPIC MATERIAL

2017 ◽  
Vol 21 (4) ◽  
pp. 75-87
Author(s):  
G. M. Zhuravlev ◽  
A. E. Gvozdev ◽  
A. A. Kalinin ◽  
O. V. Kuzovleva ◽  
E. V. Ageev ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Stress State ◽  
Stress Distribution ◽  
Plane Deformation ◽  
Yield Condition ◽  
Biaxial Stress ◽  
Resource Saving ◽  
Cylindrical Anisotropy ◽  
Biaxial Stress State ◽  
Deformation State

The process of rolling pipe with simultaneous significant changes in pipe diameter and thickness is carried out at the mandrel stage. In the region of plastic deformation, biaxial stress and plane deformation state of a pipe take place. The area of biaxial stress state is characterized by the presence of two sections: a section of the sptial bending before the contact with the roll and a section which is in contact with the cylindrical surface of the roll. It is assumed that the material of a tube blank is incompressible, has a cylindrical anisotropy of mechanical properties, is anisotropically hardenable, for which the Mises-Hill yield condition and the associated law of plastic flow are valid. The article considers stress distribution in the areas of biaxial stress state. To take into account the anisotropic hardening of the material information concerning distribution of deformations in the region of plastic deformation was taken into account. The problem of stress distribution in the region of plane deformation state of the region of plastic deformation was considered. It is assumed that radial flow of the material occurs in the region and Coulomb's law of friction is realized at the contact boundaries of the workpiece and the tool. The change in the direction of material flow at the inlet and outlet of the region is taken into account by means of radial stress modification with regard to the discontinuity of the tangential component at the boundary of the deformation region by the work balance method. The expressions obtained for determining deformations and stresses makes it possible to analyze the process of rolling pipes at the mandrel stage taking into account material anisotropy. The obtained results can be used to create resource-saving technologies for processing metallic materials using new nanocomposite lubricants and coatings.

Atomistic Simulation Study on the Tensile Deformation Behaviour of Nanocrystalline Ni

2013 ◽  
Vol 745-746 ◽  
pp. 315-320
Author(s):  
Wen Bin Li ◽  
Fu Ping Yuan ◽  
Xiao Lei Wu
Keyword(s):  
Plastic Deformation ◽  
Stress State ◽  
Dislocation Density ◽  
Tensile Stress ◽  
Deformation Behaviour ◽  
Strain Curve ◽  
Biaxial Stress ◽  
Transverse Tensile ◽  
Biaxial Stress State ◽  
Average Grain Size

Using molecular dynamics simulations, the influence of transverse tensile stresses on the plastic deformation behaviour of nanocrystalline (NC) Ni under tension has been investigated. The sample with an average grain size of 20 nm was created using a Voronoi construction, and two different tensile tests of the sample were performed at a constant strain rate. The simulation results revealed that more partials were emitted from the grain boundaries and propagate into the grain interiors after adding the transverse tensile stress, enhancing the dislocation density in the grain interiors. This increased dislocation density can cause additional strain hardening observed in the stress strain curve. Meanwhile, it was observed from microstructures that nanovoids are easier to form and coalesce into cracks under the biaxial stress state, causing strain softening. The two competing effects of the transverse tensile stress on the plastic deformation behaviour of NC Ni resulted in the flow stresses from 4% to 10% strain in the biaxial stress state slightly larger than those in the uniaxial stress state.

Characteristics of Residual Stress by Water-Jet Peening

2013 ◽  
Vol 768-769 ◽  
pp. 564-571 ◽  
Author(s):  
Kenji Suzuki ◽  
Takahisa Shobu ◽  
Ayumi Shiro
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Water Jet ◽  
Biaxial Stress ◽  
X Rays ◽  
Lattice Plane ◽  
Scanning Method ◽  
Depth Direction ◽  
Biaxial Stress State ◽  
Specimen Material

The specimen material was austenitic stainless steel, SUS316L. The residual stress was induced by water-jet peening. The residual stress was measured using the 311 diffraction with conventional X-rays. The measured residual stress showed the equi-biaxial stress state. To investigate thermal stability of the residual stress, the specimen was aged thermally at 773 K in air to 1000 h. The residual stress kept the equi-biaxial stress state against the thermal aging. Lattice plane dependency of the residual stress induced by water-jet peening was evaluated using hard synchrotron X-rays. The residual stress measured by the soft lattice plane showed the equi-biaxial stress state, but the residual stress measured by the hard lattice plane did not. In addition, the distributions of the residual stress in the depth direction were measured using a strain scanning method with hard synchrotron X-rays and neutrons.

Plastic behaviour of perforated sheets under biaxial stress state

1997 ◽  
Vol 39 (7) ◽  
pp. 781-793 ◽  
Author(s):  
Seung Chul Baik ◽  
Heung Nam Han ◽  
Sang Heon Lee ◽  
Kyu Hwan Oh ◽  
Dong Nyung Lee
Keyword(s):  
Stress State ◽  
Biaxial Stress ◽  
Plastic Behaviour ◽  
Biaxial Stress State ◽  
Perforated Sheets

Mastering the biaxial stress state in nanometric thin films on flexible substrates

2014 ◽  
Vol 306 ◽  
pp. 70-74 ◽  
Author(s):  
D. Faurie ◽  
P.-O. Renault ◽  
E. Le Bourhis ◽  
G. Geandier ◽  
P. Goudeau ◽  
...  
Keyword(s):  
Thin Films ◽  
Stress State ◽  
Biaxial Stress ◽  
Flexible Substrates ◽  
Biaxial Stress State

Application of a Multiaxial Fatigue Criterion for the Evaluation of Life of Gears of Complex Geometry

2003 ◽  
Author(s):  
Leonardo Borgianni ◽  
Paola Forte ◽  
Luigi Marchi
Keyword(s):  
Fatigue Life ◽  
Stress State ◽  
Life Prediction ◽  
Complex Geometry ◽  
Biaxial Stress ◽  
Fatigue Life Prediction ◽  
Random Loading ◽  
Complex Load ◽  
Biaxial Stress State ◽  
Principal Axes

Gears can show significant biaxial stress state at tooth root fillet, due to the way they are loaded and their particular geometry. This biaxial stress state can show a significant variability in principal axes during meshing. Moreover loads may have non predictable components that can be evaluated with the aid of recorded data from complex spectra. In these conditions, commonly adopted approaches for fatigue evaluation may be unsuitable for a reliable fatigue life prediction. This work is aimed at discussing a computer implementation of a fatigue life prediction method suitable for multiaxial stress states and constant amplitude or random loading. For random loading a counting procedure to extract cycles from complex load histories is discussed. This method, proposed by Vidal et al., is based on the r.m.s. value of a damage indicator over all the planes through the point where the fatigue life calculation is made. Miner’s rule is used for the evaluation of the overall damage. The whole fatigue life of the component is evaluated in terms of the numbers of repetitions of the loading block. FEM data are used to evaluate stresses under load. The implementation was validated using test data found in the technical literature. Examples of applications to gears are finally discussed.

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