Fatigue Failure Criterion of Laminated Composites Under a Complex Stress-Strain State

2016 ◽  
Vol 52 (3) ◽  
pp. 369-378 ◽  
Author(s):  
V. Strizhius
Keyword(s):  
Fatigue Failure ◽  
Failure Criterion ◽  
Strain State ◽  
Laminated Composites ◽  
Complex Stress ◽  
Stress Strain ◽  
Stress Strain State

Thermal-Fatigue Analysis of Turbine Discs under Complex Thermo-Mechanical Loading with Account of Plasticity and Creep Effects

2015 ◽  
Vol 725-726 ◽  
pp. 955-960 ◽  
Author(s):  
Igor Ignatovich ◽  
Artem S. Semenov ◽  
Sergey Semenov ◽  
Leonid Getsov
Keyword(s):  
Stress Concentration ◽  
Strain State ◽  
Local Strain ◽  
Complex Stress ◽  
Material Behavior ◽  
Stress Concentration Zone ◽  
Concentration Zone ◽  
Stress Strain ◽  
Thermomechanical Cycling ◽  
Stress Strain State

During operation of transport and maneuverable gas-turbine units, there are crack formation in turbine disc rims what exerted by thermomechanical cycling loads. For in-depth study of these problems we have to use theories of plasticity and creep which form the basis for determining the complex stress-strain state in the stress concentration zone for disc rims, and a modern failure criterion which can predict lifetime under conditions of simultaneous plastic and creep strain accumulation. There is a finite-element method (FEM) that allows us to evaluate the stress-strain state in a stress concentration zone for a non-elastic material behavior. With plasticity and creep theories, it is possible to determine local strain quiet reliable by FEM.

scholarly journals INVESTIGATION OF LOCAL UNLOADING OF AN ELEMENT IN A FINITE ELEMENT CONTINUUM

2021 ◽  
pp. 86-96
Author(s):  
A.Yu. Burtsev ◽  
◽  
V.V. Glagolev ◽  
A.A. Markin ◽  
◽  
...  
Keyword(s):  
Finite Element ◽  
Failure Criterion ◽  
Strain State ◽  
Plastic Region ◽  
Elastoplastic Problem ◽  
The Body ◽  
Stress Strain ◽  
Adjacent Element ◽  
Stress Strain State ◽  
Ansys Workbench

The subcritical elastoplastic deformation and the fracturing of an element of a finite element continuum in the Ansys Workbench complex are considered. When solving the elastoplastic problem of the subcritical deformation, a finite element with the failure criterion reached is selected. In a pre-fracture state of the element, the nodal forces provided by the interaction with an adjacent element are determined using the Ansys Workbench internal procedure. The following step is the consideration of the varying stress-strain state of the body during the element destruction. The elastoplastic problem is solved in the conditions of simple unloading of the body surface adjacent to the destructible element while maintaining the external load corresponding to the destruction initiation. When implementing the local unloading, a possibility of the new plastic region formation and the partial unloading are studied. As a result, the stress-strain state of the body at the beginning of local unloading is not the same as that at the end of the process. The proposed approach differs from the “element killing” procedure when the element stiffness after the failure criterion reached is assumed to be close to zero. The paper provides solutions to the problems of deformation of elastic and elastoplastic plates with a side cut taking into account their element destruction.

scholarly journals Modeling and assessment of the stress-strain state of above-ground pipelines at different types of compensation sections

2021 ◽  
Vol 266 ◽  
pp. 01022
Author(s):  
Z.A. Besheryan ◽  
I.F. Kantemirov
Keyword(s):  
Strain State ◽  
Complex Stress ◽  
Operating Conditions ◽  
The Arctic ◽  
Design Parameters ◽  
The Finite Element Method ◽  
Stress Strain ◽  
Stress Strain State ◽  
Actual Operating ◽  
Different Types

The development of Russian fuel and energy complex in the short term is connected with the development of new hydrocarbon field in the permafrost zone and the need to build Arctic pipelines north of the 60th parallel. The ground-based structural scheme of pipeline laying is the most optimal while constructing trunk pipelines in permafrost areas in the Arctic and subarctic latitudes. The actual operating conditions of these systems are insufficiently studied. The above-ground pipeline in permafrost is in an complex stress-strain state. This study presents the results of the assessment of the stress-strain state of linearly extended above-ground pipelines at different compensation sections (triangular compensator; trapezoidal compensator; U-shaped compensator) under actual operating conditions. Using the finite element method on mathematical models, the dependences of the transverse displacements of the pipeline on movable supports and stresses arising in dangerous sections of the typical pipeline section during self-compensation of deformations on the variable design parameters of the system for various load combinations were established (the simulation was carried out in the ANSYS software package).

scholarly journals Influence of stresses on deformation process under the irradiation creep and swelling

2021 ◽  
pp. 23-28
Author(s):  
Dmytro Breslavsky
Keyword(s):  
Numerical Modelling ◽  
Strain State ◽  
Strain Tensor ◽  
Complex Stress ◽  
Complex Stress State ◽  
Structural Elements ◽  
Stress Strain ◽  
Radiation Creep ◽  
Stress Strain State ◽  
Radiation Swelling

Approaches for describing the deformation of structural elements made from the material, in which radiation creep and swelling strains develop simultaneously, are discussed. The technique for description of irradiation swelling strains, which is used for calculational analysis of stress-strain state arising in structural elements under the joint action of irradiation and thermal-stress fields, is regarded. A complete system of equations of the boundary –initial value problem is presented, in which elastic and thermal strains, strains of radiation creep and swelling are taken into account. Numerical modelling was carried out using the specialized software FEM Creep, in which the boundary value problem is solved by the Finite Element Method, and the initial one is integrated in time by the difference predictor-corrector method. Two forms are given for the equation of state describing the radiation swelling strains: first is for the components of the strain tensor as well as second is prepared for their rates. The hypothesis about the linear correspondence of the received radiation dose and the deformation time, during which radiation swelling strains develop, are analyzed. A number of questions that require answers when using equations with a complex stress state in which the radiation swelling strains are directly depend on stresses, are discussed. Based on the processing of experimental data on the swelling of tubes made of steel 316Ti in the temperature range of 450-460 °С, a form of the equation for the radiation swelling strain rate is proposed, and the constants included in it are determined. Using the example of numerical modelling of the deformation of tubes were made of steel 316Ti and loaded by inner pressure, the applicability of the classical approach for the analysis of the stress-strain state in the presence of radiation swelling strains is shown.

Investigation of the stress-strain state of beams with different types of web perforation

2021 ◽  
Vol 103 (3) ◽  
pp. 79-87
Author(s):  
Ivan Pidgurskyi ◽  
Vasyl Slobodian ◽  
Denys Bykiv ◽  
Mykola Pidgurskyi
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Strain State ◽  
Analytical Calculation ◽  
Complex Stress ◽  
The Finite Element Method ◽  
Stress Strain ◽  
Advantages And Disadvantages ◽  
Stress Strain State ◽  
Element Method

This article is devoted to evaluating the effectiveness of I-beams with different web perforations: hexagonal, round, oval and elliptical. The technology of manufacturing of castellated beams is described. For the purpose of verification the analytical calculation of the beam with hexagonal web perforation and for comparison the calculation by the finite element method is given. To correctly assess the stress-strain state, the mesh of finite elements in the area of openings was concentrated. The results of maximum normal stresses and strains obtained by different methods were compared with each other and the efficiency of using the finite element method to determine the stress-strain state of castellated beams was proved. In the castellated beams there is a complex stress-strain state, which was confirmed in this work for the most characteristic shapes of openings. Beams with hexagonal, round, oval (horizontal and vertical), elliptical and elliptical (rotated by 45°) openings are considered in the article, their geometric parameters and characteristics as well as advantages and disadvantages are described. Beams with round openings are currently the most widely used. In addition, the parameters that affect the efficiency of castellated beams with oval (horizontal and vertical) and elliptical rotated by 45° openings were identified. In this work, it was found that the shape of the openings significantly affects the stress-strain state of the castellated beams, especially for hexagonal openings, which are mainly used so far. The stress distribution in the first opening for each of the considered types of perforations and the nature of the change of σmax in other openings is shown. The stress-strain state of castellated beams was studied using the finite element method. The results of this study are of practical value because they can be used when arranging the sections and openings of castellated beams.

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