The Influence of Different Stress States on 16MnR Deformation Capacity

2013 ◽  
Vol 716 ◽  
pp. 590-594
Author(s):  
Shi Lei Zhao ◽  
Yi Liang Zhang ◽  
Gong Feng Jiang
Keyword(s):  
Plastic Deformation ◽  
Stress State ◽  
Equivalent Stress ◽  
Great Influence ◽  
Equivalent Strain ◽  
Complex Stress State ◽  
Biaxial Stress ◽  
Deformation Capacity ◽  
Engineering Structures ◽  
Stress States

16MnR is the typical material of pressure equipment which worked under complex stress state in engineering application. In order to be close to the actual combined tension-shearing stress state and explore the relationship of deformation capacity and different stress state, many groups of combined tension-torsion tests on 16MnR specimens were designed and the equivalent stress-strain relation under different stress state was obtained. The concept of stress triaxiaty (TS value) was cited to characterize the different stress state and the result showed different stress states have a great influence on the material plastic deformation capacity, TS value turns larger, the plastic deformation weakened; 16MnR has a strongest plastic deformation capacity in pure torsion; the level of tensile stress had no significant effect on the maximum stress in the biaxial stress state, but has a significant inverse relationship with the maximum equivalent strain .At last, the mathematical relationship between maximum equivalent-strain and stress triaxiaty could be found. If the stress state of one point in the engineering structures is certain, the maximum equivalent-strain can be estimated.

scholarly journals Efficiency of Plasticity Correction in the Hole-Drilling Residual Stress Measurement

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3396
Author(s):  
Tomáš Návrat ◽  
Dávid Halabuk ◽  
Petr Vosynek
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Uniaxial Tension ◽  
Relative Error ◽  
Computational Simulation ◽  
Equivalent Stress ◽  
Biaxial Stress ◽  
Hole Drilling ◽  
Plane Shear ◽  
Plasticity Effect

This paper focuses on the analysis of the plasticity effect in the measurement of the residual stress by the hole-drilling method. Relaxed strains were evaluated by the computational simulation of the hole-drilling experiment using the finite element method. Errors induced by the yielding were estimated for uniaxial tension, plane shear stress state and equi-biaxial stress state at various magnitudes of residual stress uniformly distributed along the depth. The correction of the plasticity effect in the evaluation of residual stress was realized according to the method proposed by authors from the University in Pisa, which was coded in MATLAB. Results obtained from the MATLAB script were compared to the original input data of the hole-drilling simulation and discussed. The analyses suggested that the plasticity effect is negligible at the ratio of applied equivalent stress to yield stress, being 0.6, and that the correction of the plasticity effect is very successful at the previous ratio, being 0.9. Failing to comply with the condition of the strain gauge rosette orientation according to the principal stresses directions causes an increase in the relative error of corrected stresses only for the case of uniaxial tension. It affects the relative error negligibly for the plane shear and equi-biaxial stress states.

The Influence of Stress Ratio on the Fracture Behavior of Brittle Materials

2007 ◽  
Vol 353-358 ◽  
pp. 937-940
Author(s):  
Wei Hong Li ◽  
Xiong Chen ◽  
De Shen Zhao ◽  
Yi Wang Bao
Keyword(s):  
Stress State ◽  
Fracture Behavior ◽  
Stress Ratio ◽  
Process Analysis ◽  
Failure Process ◽  
Brittle Materials ◽  
Simulation Method ◽  
Critical Stress Intensity Factor ◽  
Complex Stress State ◽  
Biaxial Stress

The fracture behavior of brittle materials under different stress ratio has been investigated by means of numerical simulation method with software RFPA2D (Realistic Failure Process Analysis). The fracture dependence of brittle material on biaxial plane stress state was confirmed. The results show that the critical stress intensity factor under biaxial stress increases with the increase of biaxial stress ratio. The simulation tests reveal that the biaxial stresses have strong influence on the fracture properties of glass. The results confirmed that the strain criterion of fracture is feasible while brittle materials under complex stress state.

Analysis on the Temperature Rise Produced by Plastic Deformation Heat for Nanoscale Orthogonal Cutting of Copper Workpiece

2012 ◽  
Author(s):  
Zone-Ching Lin ◽  
Ying-Chih Hsu ◽  
Liang-Kuang Chen
Keyword(s):  
Plastic Deformation ◽  
Temperature Distribution ◽  
Temperature Rise ◽  
Calculation Method ◽  
Orthogonal Cutting ◽  
Equivalent Stress ◽  
Equivalent Strain ◽  
Perfect Crystal ◽  
Molecular Statics ◽  
Cutting Model

The quasi-steady molecular statics nanoscale orthogonal cutting model developed by this paper not only can calculate cutting force, equivalent stress and equivalent strain, but also can calculate the temperature rise of the cut perfect crystal copper workpiece. This paper considers that during nanoscale orthogonal cutting, the temperature rise of the cut perfect crystal copper workpiece is produced by plastic deformation heat only. The calculation method of equivalent stress and equivalent strain uses three-dimensional quasi-steady molecular statics nanocutting model to calculate and simulate the phenomenon. The model for plastic deformation heat developed by this paper can be used to calculate the equivalent stress and equivalent strain of the cut copper workpiece. Furthermore, the calculation method of temperature rise of the cut workpiece produced by plastic deformation heat is developed. Afterwards the analysis of temperature distribution is also conducted. And the obtained temperature distribution of the cut copper workpiece computed by this paper is qualitatively compared with the temperature distribution obtained by molecular dynamics method in the reference.

scholarly journals Mykhailo Dendiuk, Lyubomir Flud, Nazar Semenyshyn Software implementation of the construction of curves short-term strength of wood with biaxial stress state

2020 ◽  
Vol 8 ◽  
pp. 21-26
Author(s):  
Mykhailo Dendiuk ◽  
◽  
Lyubomir Flud ◽  
Nazar Semenyshyn ◽  
◽  
...  
Keyword(s):  
Stress State ◽  
Failure Criteria ◽  
Biaxial Stress ◽  
Term Strength ◽  
Short Term ◽  
Tangential Plane ◽  
Biaxial Stress State ◽  
Short Term Strength ◽  
Cross Platform ◽  
Stress States

This paper is devoted to implementing the algorithm for constructing short-term strength curves of wood with biaxial stress states in the radial-tangential plane of structural symmetry. To implement this algorithm was developed software based on the Qt cross-platform toolkit, which allows to build and analyze short-term strength curves in the cross section of wood. The created program has a possibility to choose one of three failure criteria, a kind of wood, temperature and humidity distribution of lumber. The C++ program code is designed so that you can easily add another type of wood as well as a failure criterion. To display the curves, you can select table or graph mode. Graphs can be fixed on a graphics widget, and new ones can be added to compare to previous ones. Based on the analysis of the constructed curves, the ultimate stress state of the material in partial cases is established. In conclusion about expedient using some criteria to describe the strength characteristics of wood with strong and weak asymmetry of strength limits.

The Influence of Multiaxial Stress Relaxation on Component Creep Damage Accumulation

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Nayden Matev ◽  
Robert A. Ainsworth ◽  
Meini Su ◽  
Mark Stevens ◽  
Alan Jappy
Keyword(s):  
Stress State ◽  
Stress Drop ◽  
Damage Accumulation ◽  
Stress Ratio ◽  
Equivalent Stress ◽  
Creep Damage ◽  
Biaxial Stress ◽  
Multiaxial Stress ◽  
Multiaxial Stress State

Abstract Unless inelastic analysis is used, high temperature codes base creep relaxation on the start-of-dwell equivalent stress, which relaxes according to a uniaxial creep law. Elastic follow-up is also included. This approach only evaluates equivalent stress and creep strain rate and the multiaxial stress state is assumed to remain at its initial value as the stress relaxes. Codes suggest that the stress drop is limited to a fraction (typically 20%) of the initial equivalent stress to ensure this assumption does not introduce significant inaccuracies. This article provides a numerical examination of creep relaxation of a cruciform plate subjected to displacement-controlled biaxial loading, with the aim to provide clarification of any required constraint on stress drop. The initial biaxial stress ratio, the plate geometry and the power in a power–law creep model are varied, leading to variations in the elastic follow-up describing the creep relaxation. The biaxial stress ratio is generally found to change with relaxation and a multiaxial ductility approach is used to evaluate the associated creep damage accumulation. This is compared with the damage estimated assuming relaxation is controlled by the equivalent stress with no change in multiaxial stress state. For biaxial plane stress with one principal stress initially being compressive and one tensile, it is found that significant equivalent stress drops (about 40% of the initial stress) can be allowed without the simplified equivalent stress approach becoming inaccurate. More care is required for tensile–tensile stress biaxiality where multiaxial stress changes depend on the initial stress biaxiality and the degree of elastic follow-up. The results will be used to propose improved guidance for simplified inelastic calculations.

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.

Low Cycle Fatigue Crack Initiation of Rotating Structures Under Biaxial Stress States

2009 ◽  
Author(s):  
Chao Zhang
Keyword(s):  
Stress State ◽  
Crack Initiation ◽  
Low Cycle Fatigue ◽  
Cyclic Stress ◽  
Biaxial Stress ◽  
Test Results ◽  
Primary Stress ◽  
Biaxial Stress State ◽  
Fatigue Characteristics ◽  
Stress States

Rotating structures can experience biaxial stress states with a wide range of biaxiality ratios on structure surfaces. Low cycle fatigue (LCF) crack initiation in such conditions demonstrates different fatigue characteristics in terms of crack orientation, fatigue life, etc. The biaxial stress states can be categorized into two types: in-phase and out-of-phase under which fatigue characteristics can be significantly different according to rig test results. This paper presents an investigation of LCF crack initiation under in-phase and out-of-phase biaxial stress states based on rig test results of a nickel alloy. The crack orientations are reviewed and discussed at different stress states. Relations of biaxial LCF life debit factor vs biaxiality ratio are derived (the debit factor is defined as a ratio of the LCF life at a biaxial stress state to the LCF life at corresponding uniaxial stress state which has same cyclic and mean stresses as the primary cyclic and mean stressees of the biaxial stress state). The rig test results showed that the crack orientation is usually normal to the primary stress vector under in-phase biaxial stress states but is inclined to the primary stress vector under out-of-phase stress states. As per the derived biaxial LCF life debit factors, the LCF life was found to be slightly reduced with increasing biaxiality ratios under in-phase biaxial stress states but significantly reduced under out-of-phase biaxial stress states compared with corresponding uniaxial primary stress states. The equivalent cyclic stress fatigue criterion is also employed to theoretically model the biaxial LCF life debit factor under in-phase biaxial stress states. The hydrostatic cyclic stress is included in the equivalent cyclic stress in order to take into account the hydrostatic cyclic pressure effects. The equivalent cyclic stress in the criterion can physically reflect the materials’ ductility reduction under in-phase multiaxial stress states.

COMBINED EXTRUSION OF GLASSES WITH A CONICAL BOTTOM. KINEMATIC AND STRESS STATES OF THE PLASTIC REGION LOCATED UNDER THE CONICAL SURFACE OF THE PUNCH

2021 ◽  
pp. 2-7 ◽  
Author(s):  
A. L. Vorontsov ◽  
D. A. Lebedeva
Keyword(s):  
Plastic Deformation ◽  
Stress State ◽  
Plastic Flow ◽  
Mathematical Analysis ◽  
Plastic Region ◽  
Conical Surface ◽  
Flat Part ◽  
The Future ◽  
Stress States ◽  
Conical Bottom

For extrusion of glasses with a conical bottom using the method of plastic flow by A. L. Vorontsov, the kinematic and stress states of the extruded metal in the area of the plastic deformation center located under the conical surface of the punch were determined. The resulting formulas will be used to determine the stress state in the region of the hearth located under the central flat part of the punch-son՚s working end. In the future, the results of this mechanical and mathematical analysis will also make it possible to investigate the question of the presence of the taper of the punch, which is optimal in terms of strength.

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