scholarly journals Application of the Methods of the Theory Similarity and Dimensional Analysis for Research the Local Stress-strain State in the Neighborhood of an Irregular Point of the Boundary

2016 ◽  
Vol 153 ◽  
pp. 151-156 ◽  
Author(s):  
L.U. Frishter
Keyword(s):  
Dimensional Analysis ◽  
Strain State ◽  
Local Stress ◽  
Stress Strain ◽  
Stress Strain State ◽  
Irregular Point

scholarly journals Experimental study of wind impact on multilevel industrial scaffolding

2020 ◽  
Vol 157 ◽  
pp. 06009
Author(s):  
Lyudmila Frishter ◽  
Maxim Lukin
Keyword(s):  
Strain State ◽  
Experimental Approach ◽  
Domain Boundary ◽  
Local Stress ◽  
Plane Domain ◽  
Stress Strain ◽  
Stress Strain State ◽  
Polymer Models ◽  
The Subject ◽  
Irregular Point

In the article, the local stress-strain state of structures and constructions is investigated, various variants for the design of the boundary are taken into account: special lines, points. The acting forced deformations don’t satisfy the compatibility conditions. They have a finite discontinuity along the contact line (surface) of the domains, including the irregular point of the boundary, causing stresses. The subject of article is stress concentrators the singularity of the stress-strain state of structures and constructions exhibiting “constructive heterogeneity” and discontinuous forced deformations determined on polymer models of photoelasticity and defrosting of deformations. A complex theoretical-numerical-experimental approach, for obtaining and analyzing the stress state in the neighborhood of the irregular point of the plane domain boundary, is proposed to extrapolate reliable experimental data to a domain where the fringe contour is not readable.

Fatigue Life Prediction of Notched Components Based on Multiaxial Local Stress-Strain Approach

2009 ◽  
Author(s):  
Baoxiang Qiu ◽  
Zengliang Gao ◽  
Xiaogui Wang
Keyword(s):  
Strain State ◽  
Notch Root ◽  
Constitutive Relations ◽  
Local Stress ◽  
Cyclic Plasticity ◽  
Multiaxial Stress ◽  
Stress Strain ◽  
Stress Strain State ◽  
Multiaxial Stress State ◽  
Notched Components

A multiaxial local stress-strain approach based on the Armstrong-Frederick type cyclic plasticity theory was proposed to perform the stress analysis and the fatigue analysis on the notched components. A robust cyclic plasticity model was adopted to describe the non-Masing behavior of 16MnR steel. The incremental form of the multiaxial local stress-strain approach was formulated with the incremental constitutive relations and the incremental Neuber’s rule. The multiaxial stress-strain state at the notch root of notched components subjected to proportional and nonproportional loading was predicted by the multiaxial approximate approach. On the basis of the multiaxial local stress-strain state and the Fatemi-Socie criterion, the fatigue lives of the notched components were predicted. The analytical results show that the proposed multiaxial local stress-strain method can describe the multiaxial stress state at the notch root very well, and the predicted fatigue lives correlate well with the experimental data.

scholarly journals Comparison of the stress and strain intensity factors for the corner area of the structure boundary

2018 ◽  
Vol 193 ◽  
pp. 03029
Author(s):  
Lyudmila Frishter
Keyword(s):  
Strain State ◽  
Engineering Practice ◽  
Stress And Strain ◽  
Strain Intensity ◽  
Intensity Factors ◽  
Stress Strain ◽  
Elasticity Theory Problem ◽  
Limit Values ◽  
Stress Strain State ◽  
Irregular Point

The stress-strain state of structures in areas with corner cut-outs and cuts of boundaries features the occurrence of areas of stress concentration and requires assessment of strength and reliability of facilities, which is a relevant task in engineering practice. Theoretical analysis of stress-strain state (SSS) of corner cut-outs zones of the area boundary is reduced to the study of singular solutions of the elasticity theory problem with exponential features. At that, the concept of stress or strain concentration in an irregular point of the area boundary is meaningless. This paper considers the stress-strain state in the vicinity of the top of the corner cut-out of the flat area boundary, which is recorded using the intensity factors as limit values of stresses and strains. We give two approaches for obtaining the limit values for stress and strain in the vicinity of an irregular point of the plane area boundary using the stress intensity factors and the strain intensity factors. The stress-strain state in the corner cut-outs zone of structures and buildings boundary recorded in the form of limit values of stresses and strains may further be used to determine and record the influence of changing the factors of intensity of stresses and strains on SSS of structures, which is a separate task of solid mechanics. The difference in the expressions of stresses and displacements obtained for limit values of stresses and strains determines practical significance of the work when carrying out experiments and at determination of critical values of stresses and strains.

Local Stress–Strain State of Tribocomposites with Spherical Microcapsules Filled with Liquid Lubricant

2018 ◽  
Vol 47 (2) ◽  
pp. 147-154
Author(s):  
V. I. Kolesnikov ◽  
V. V. Bardushkin ◽  
I. V. Kolesnikov ◽  
F. V. Myasnikov ◽  
A. P. Sychev ◽  
...  
Keyword(s):  
Strain State ◽  
Local Stress ◽  
Stress Strain ◽  
Liquid Lubricant ◽  
Stress Strain State

Monitoring of the elements of aviation structures using strain-gauge measurement

2019 ◽  
Vol 85 (1(I)) ◽  
pp. 57-63 ◽  
Author(s):  
A. A. Bautin
Keyword(s):  
Strain State ◽  
Local Stress ◽  
Test Methods ◽  
Aircraft Structure ◽  
Stress Strain ◽  
Term Operation ◽  
Stress Strain State ◽  
Longitudinal Joints ◽  
Using Data ◽  
Periodic Inspections

Analysis of the kinetics of the stress-strain state was carried out using data of tensometry as one of the methods for monitoring the integrity of the aircraft structure and a promising approach to ensure safety of aviation equipment during long-term operation. The advantages of condition monitoring using on-board systems prior to routine procedures aimed at maintaining the airworthiness (which consist mainly in periodic inspections) are presented. The results of using monitoring when studying the fatigue characteristics of the aircraft structure elements at the Central Aerohydrodynamic Institute (Russia) are shown. The study was carried out on samples of longitudinal fuselage joints. Several types of fatigue damages typical for operation of longitudinal joints are considered. The possibility of detecting defects by monitoring of the local stress-strain state with the help of strain gauges under various modes of destruction is assessed. Data on the of fracture surfaces of the damaged elements, fronts and crack propagation rates corresponding to different number of applied cycles were used. The assessment of the controllability of several typical structural and technological variants of longitudinal joints is presented. The results of determining zones of changes in stress-strain state in a bearing sheet with a single main crack are presented, which is the most typical fatigue damage to the longitudinal fuselage joints. The optimal location of the sensors for monitoring the integrity of the joint is proposed. Studies proved that the method of structural health monitoring using tensometry data can be successfully applied to tests for durability and has a prospect of being used in maintaining the integrity of joints and other places of limited access by instrumental non-destructive test methods.

Development of structural health monitoring methods through the analysis of kinetics of local stress-strain state

2019 ◽  
Vol 85 (2) ◽  
pp. 42-47
Author(s):  
A. A. Bautin ◽  
Yu. A. Svirsky ◽  
A. V. Pankov
Keyword(s):  
Cyclic Loading ◽  
Health Monitoring ◽  
Strain State ◽  
Fatigue Cracks ◽  
Local Stress ◽  
State Control ◽  
Monitoring Methods ◽  
Stress Strain ◽  
Stress Strain State ◽  
Kinetics Of

The paper describes one of the most promising ways of structure health monitoring based on analysis of the kinetics of local stress-strain state. Comparison with other methods of damage detection and advantages of the stress-strain state control are considered. To implement this method of monitoring, two types of sensors are considered: strain gauges and fiber Bragg gratings (FBG). The advantages of FBG, due to which their use in operation is most preferable, are presented. The possibility of using stress-strain state control is analyzed for a promising transport aircraft using the results of tensometry under cyclic loading. The relevance of the work is confirmed by various examples of using monitoring methods in on-board systems during operation. The possibility of monitoring the airframe parts is demonstrated for longitudinal fuselage joints as an example. The change in the stress-strain state of the longitudinal joints, caused by structural damage was confirmed by tensometry analysis and by analysis of the stress-strain state of bearing sheet by the finite element method (FEM), taking into account the fatigue cracks originated during cyclic loading. The results of the calculation are compared with the tensometry data. Proceeding from the results of the calculation of the stress-strain state of the damaged and undamaged structure, the zones of the greatest deformation change are determined to optimize potential locations for the sensors. The optimal placing of the sensors for monitoring the integrity of the joints is proposed. The study confirms that the method of damage monitoring of the structure, developed on the basis of changes in the kinetics of the stress-strain state, can be successfully used in tests for maintaining the integrity of joints and other places with multi-site damages, where the methods of visual and non-destructive testing are not effective.

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