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 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.

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.

scholarly journals INFLUENCE OF TEST CONDITIONS ON STRENGTH PROPERTIES OF THIN-WALL RUBBER PRODUCTS

2020 ◽  
pp. 78-84
Author(s):  
D. Kudelin ◽  
T. Nesnolovskaya
Keyword(s):  
Stress State ◽  
Uniaxial Tension ◽  
Stress Concentrator ◽  
Strength Properties ◽  
Complex Stress ◽  
Complex Stress State ◽  
Complex Stressed State ◽  
Shear Stresses ◽  
Thin Wall ◽  
Element Analysis

A computer simulation of the loading of the rubber membrane by a spherical indenter is performed using a finite element analysis package. It is shown that in the complex stress state rubber based on crystallize rubber IR are significantly inferior in strength properties as in the absence and in the presence of stress concentrator to rubber based on amorphous rubber SBR, while in uniaxial tension they are superior. It is revealed that in the complex stress state, rubbers based on IR rubber filled with 40 parts by weight of carbon black N339 have low resistance to shear stresses, inferior to SBR and BR vulcanizates, which results in low strength properties of rubbers based on it in comparison with strength characteristics determined under uniaxial tension. An analysis of the strength properties of rubbers in the presence of a stress concentrator shows that in a complex stress state, rubbers based on amorphous SBR rubber have the maximum tear resistance, exceeding IR and BR vulcanizates by this indicator, respectively by ~ 4 and 2 times. Under uniaxial tension, the most important factor is the ability of the material to orientation hardening, due to the regularity of the rubber structure and the presence of reinforcing filler, and in the complex-stressed state, the most important factor is a density of the nodes of the fluctuation mesh from the point of view of strength properties.

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.

Application of the concept of the criterion of equivalence of complex stress state to simple tension for assessing the fatigue resistance of structural materials. Part 1. Review of some experimental data with the preparation of the necessary information for subsequent use

2021 ◽  
pp. 24-27
Author(s):  
P.N. Kozlov
Keyword(s):  
Stressed State ◽  
Fatigue Resistance ◽  
Numerical Data ◽  
Structural Materials ◽  
Complex Stress ◽  
Complex Stress State ◽  
Static Loads ◽  
Simple Tension ◽  
Long Time ◽  
Equivalence Criterion

A brief overview of the features of the fatigue resistance of some steels is given with the selection of terms, concepts and numerical data necessary for the subsequent compilation and verification of the equivalence criterion in relation to assessing the ability of structural materials to resist fatigue for a long time under the action of certain combinations of alternating and static loads. Keywords: regular loading cycle, extremely stressed state, static stressed state, bending, torsion, biaxial static tension. [email protected]

Micromechanical Analysis of SiC/Ti6Al4V Composite Under Complex Stress State

2022 ◽  
Author(s):  
Pengjian Zou ◽  
Xuming Niu ◽  
Xihui Chen ◽  
Zhigang Sun ◽  
Yan Liu ◽  
...  
Keyword(s):  
Stress State ◽  
Complex Stress ◽  
Complex Stress State ◽  
Micromechanical Analysis

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]

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