Creep Rupture of Anisotropic Pipes

1998 ◽  
Vol 120 (3) ◽  
pp. 223-225 ◽  
Author(s):  
S. A. Shesterikov ◽  
A. M. Lokochtchenko ◽  
E. A. Mjakotin
Keyword(s):  
Experimental Data ◽  
Stress State ◽  
Anisotropic Material ◽  
Complex Stress ◽  
Complex Stress State ◽  
Creep Rupture ◽  
Suggested Method ◽  
Strength Anisotropy ◽  
Anisotropy Coefficient ◽  
Thin Walled

The problem of creep rupture of pipes from an anisotropic material is studied. The authors suggest a method describing the results of creep rupture tests on thin-walled pipes under complex stress state by taking the strength anisotropy of material into account. A coefficient of strength anisotropy has been determined from the results of creep rupture testing, and a method is given for calculation under various modes of complex stress state. This procedure is based on evaluating the values of the statistical spread from the experimental data. The anisotropy coefficient corresponding to the minimum spread is adopted. The suggested method of calculating the strength anisotropy coefficient is confirmed experimentally.

Modeling of the High Temperature Creep and Rupture under the Complex Stress State

2016 ◽  
Vol 870 ◽  
pp. 528-534 ◽  
Author(s):  
T.R. Stepanova ◽  
T.V. Prokhorova
Keyword(s):  
Experimental Data ◽  
Stress State ◽  
Damage Mechanics ◽  
Complex Stress ◽  
Complex Stress State ◽  
Creep Rupture ◽  
Creep Failure ◽  
Notched Specimens ◽  
Mechanics Model ◽  
Calculation Results

A damage mechanics model linked to the creep strain and stress three-axiality has been adopted to predict the creep lifetime under the complex stress state. The model accounts for primary-secondary-tertiary creep laws. Constitutive equation parameters were determined using experimental data of smooth specimens. Finite element modeling of creep rupture in notched specimens is presented in this work. The calculated creep failure strain and time to rupture for notched specimens (semicircular with radius 4.0 mm and U-notched with radius 1.2 mm) have been compared with experimental data for the X10CrMoVNb-9-1 steel tested at 625 °C. The calculation results of creep rupture for smooth and notched specimens show notch strengthening or notch weakening depending on the tensile stresses level and notch geometry.

Application of the concept of criterion of a complex stress state to a simple tension for appraisal of resistance of fatigue of structural materials. Part 2. Drawing up criterion and its checking on compliance to experimental data

2021 ◽  
pp. 41-45
Author(s):  
P.N. Kozlov
Keyword(s):  
Experimental Data ◽  
Stress State ◽  
Structural Material ◽  
Complex Stress ◽  
Complex Stress State ◽  
Static Loads ◽  
Regular Change ◽  
Regular Cycle ◽  
Simple Tension ◽  
Dangerous Point

The criterion for appraisal of resistance of fatigue of structural material at action on it of repeatedly variables loads and static loads in the form of a bend or tensioncompression together with torsion, and also at action of loads, which create two-axis regular change of stress state in a dangerous point of material is constructed. The received criterion will acceptable be coordinated with the known experimental data. Keywords: dangerous point of material, regular cycle of loading, equivalent amplitude, equivalent average stress, chart of extreme amplitudes of stresses. [email protected]

scholarly journals Creep of isotropic homogeneous and nonaging of linear-viscoelastic materials under the complex stress state

2019 ◽  
pp. 150-153
Author(s):  
Y. V. Pavlyuk
Keyword(s):  
Stress State ◽  
Stressed State ◽  
Complex Stress ◽  
Complex Stress State ◽  
Complex Stressed State ◽  
Viscoelastic Materials ◽  
Linear Viscoelastic ◽  
Thin Walled ◽  
Hereditary Properties ◽  
Axial Stretching

The relaxation of isotropic homogeneous and non-aging linear-viscoelastic materials under conditions of complex stress state is considered. Thin-walled tubular specimens of High Density Polyethylene (HDPE) for creep under a single-axial stretching, with a pure twist and combined load tension and torsion are considered as base experiments, tests. The solution is obtained by generalizing the initial one-dimensional viscoelasticity model to a complex stressed state, constructed using the hypothesis of the proportionality of deviators. The heredity kernels are given by the Rabotnov’s fractional-exponential function. The dependence between the kernels of intensity and volumetric creep is established, which determine the scalar properties of linear viscoelastic materials in the conditions of a complex stressed state in the defining equations of the type of equations of small elastic-plastic deformations, and the kernels of longitudinal and transverse creep defining the hereditary properties of linear-viscoelastic materials under the conditions of the uniaxial tension. The problems of stress relaxation calculation of thin walled tubes under combined tension with torsion have been solved and experimentally approved.

scholarly journals Method of Predicting Necking True Stress in a Thin-Walled Tube Under a Complex Stress State

2020 ◽  
Vol 70 (2) ◽  
pp. 101-116
Author(s):  
Kozbur Halyna
Keyword(s):  
Stress State ◽  
Maximum Load ◽  
Complex Stress ◽  
Complex Stress State ◽  
Tube Material ◽  
Short Term ◽  
Axial Tension ◽  
Thin Walled Tube ◽  
Thin Walled ◽  
Principle Of Maximum

AbstractMethod of predicting the strength of thin-walled tubes under a complex stress state, taking into account changes in the initial dimensions, is proposed. Uniform plastic deformation of a thin-walled tube under short-term static load by internal pressure and axial tension is considered. The tube material is considered to be homogeneous, isotropic and incompressible. The principle of maximum load is used to derive analytical dependences. The main decisions and conclusions were made using the Considere scheme.

scholarly journals NONLINEAR DEFORMATION-FORCE MODEL OF A CONCRETE BAR WITH NON-METALLIC COMPOSITE REINFORCEMENT IN THE GENERAL CASE OF A STRESSED STATE

2021 ◽  
Vol 3 (1) ◽  
pp. 6-26
Author(s):  
I. Karpiuk ◽  
◽  
Ye. Klymenko ◽  
V. Karpiuk ◽  
M. Karpiuk ◽  
...  
Keyword(s):  
Stress State ◽  
Stressed State ◽  
Bearing Capacity ◽  
Nonlinear Deformation ◽  
Complex Stress ◽  
Complex Stress State ◽  
Force Model ◽  
Metallic Composite ◽  
Aggressive Environment ◽  
Deformation Force

The article discusses a nonlinear deformation-force model of a concrete bar structure with a non-metallic composite reinforcement (NKA-FRP) in the general case of a stressed state, when all four internal force factors from an external load (namely, bending and twisting moments, transverse and longitudinal forces). A sufficiently deep and meaningful analysis of well-known studies on the selected topic is given. It has been established that the proposed nonlinear deformation-force model of a bar structure with FRP in the general case of a stressed state can be practically useful due to the possibility of its application in the design or reinforcement of beams, girders, columns and elements of rosette trusses of rectangular cross-section, which are operated under aggressive environmental conditions. This model can also be used to check the bearing capacity of existing FRP concrete bar structures, which operate not only under the influence of an aggressive environment, but also under conditions of a complex stress-strain state. In the course of the research, an algorithm was developed for determining the bearing capacity of the design section of a concrete rod with FRP under its complex stress state. General physical relations for the design section are given in the form of a stiffness matrix. The algorithm for calculating a concrete bar with FRP consists of a block for inputting the initial data, the main part, auxiliary subroutines for checking the conditions for increasing the load vector and depletion of the bearing capacity, as well as a block for printing the calculation results. At each stage of a simple static stepwise increasing load, the calculation is carried out by performing a certain number of iterations until the accuracy of determining all components of the deformation vector satisfies a certain predetermined value. The features and patterns of changes in normal and tangential stresses, generalized linear and angular deformations, as well as the equations of equilibrium of a concrete bar with FRP, which operates under the influence of an aggressive environment under conditions of a complex stress state, are also considered.

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