The Analysis of Different Stochastic Patterns during Loading in Plastic Area Using DIC Method

2014 ◽  
Vol 611 ◽  
pp. 490-495
Author(s):  
Martin Schrötter ◽  
Martin Hagara ◽  
Matúš Kalina
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Correlation Method ◽  
Mean Value ◽  
Image Correlation ◽  
Black And White ◽  
Unloaded State ◽  
Measured Deformation ◽  
The Mean ◽  
Estimated Error

The aim of this article is to present the influence of stochastic pattern on results accuracy of digital image correlation method in plastic areas. The various types of stochastic patterns were applied on testing specimens which were then tensioned. There was correlated the intensity of black and white color (denoted as grey value) dispersed on a specimen, then the mean value of estimated error for unloaded state as well as state of highest measured deformation and finally the amount of non-correlated facets. Also the maximal deformation of specimens was compared by which the damage of stochastic pattern emerged.

scholarly journals Spring Deformation Gauge for Measuring Local Deformations in Triaxial Apparatus

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Mostafa A. Ismail ◽  
Yasser E. Ibrahim
Keyword(s):  
Accurate Determination ◽  
Cost Effective ◽  
Local Deformation ◽  
Spring Steel ◽  
Metal Strip ◽  
Triaxial Tests ◽  
Strain Gauges ◽  
Soil Stiffness ◽  
Triaxial Apparatus ◽  
Measured Deformation

Local measurement of deformations of a soil specimen has become inevitable for accurate determination of soil stiffness in triaxial tests. Although there are now many devices that can be used to perform this task, each has its own advantages and limitations that render development of new devices with better desirable features. This paper presents an innovative device called spring deformation gauge (SDG) that has many advantages over many of the existing devices and can be readily manufactured in both research and commercial laboratories. The device is based on using a highly flexible, yet very strong metal strip of spring steel secured between two stiff, stainless steel L-shaped legs; the spring strip is provided with four strain gauges. With this arrangement, local deformation of a specimen is transferred into significant bending in the metal strip and elongation or shortening of the strain gauges. In addition to being very cost effective, the SDG is characterized by the ability to control both range and resolution of measured deformation, its linear output, and a clever pinning mechanism that protects it from being damaged when it goes out of range. Success of the SDG was demonstrated in a true K0 test on carbonate sand.

scholarly journals Tilt offset associated with local seismicity: the Mt. Etna January 9, 2001 seismic swarm.

2016 ◽  
Vol 8 (1) ◽  
pp. 514-522 ◽  
Author(s):  
Salvatore Gambino
Keyword(s):  
Local Stress ◽  
Tectonic Structure ◽  
Local Seismicity ◽  
Seismic Swarm ◽  
Long Baseline ◽  
Volcanic Source ◽  
Active Tectonic ◽  
Mt Etna ◽  
Measured Deformation ◽  
2001 Eruption

AbstractOn the 9th of January 2001 a seismic swarm on the southeastern flank of Mt. Etna at 3.5 km beside sea level (b.s.l.), caused co-seismic variations on short and long baseline tiltmeters of the Mt. Etna permanent tilt network.Taking account of the geometry and mechanism of the active tectonic structure obtained by seismological studies, the theoretical tilt linked to the faulting source was calculated at multiple different recording stations. It was found that the amount of measured deformation exceeded that which was generated seismically, indicating that much of the deformation along the fault was aseismic.The 9 January 2001 episode represents a shear response to a local stress caused by a volcanic source that acted in the period preceding the 2001 eruption. Tilt data also suggest a marked slip of 70-140 cm along the fault, probably due to the presence of fluids.

scholarly journals Calculation of Constrained Stress in Expansive Mortar with a Composite Creep Model

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Hyeonggil Choi ◽  
Bongsuk Cho
Keyword(s):  
Tensile Stress ◽  
Creep Deformation ◽  
Maximum Tensile Stress ◽  
Composite Model ◽  
Creep Model ◽  
Hydration Products ◽  
Step Method ◽  
Creep Analysis ◽  
Measured Deformation ◽  
Expansive Additive

The creep phenomenon of hardening cement paste mixed with an expansive additive was modeled by considering the creep performance of hydration products of cement and expansive additive. A new composite model that is appropriate for particle conditions is proposed by considering the balance of the hydration products of cement and expansive additive and the stress redistribution phenomenon of hydration products newly generated by the progress of hydration. The creep of mortar and concrete mixed with the expansive additive was evaluated using a composite model of the paste and aggregate. Under the assumption that the modeled creep deformation is proportional to the stress and the gel volume of the hydration products, which allows the law of superposition to be applied, the distribution stress was predicted by applying the step-by-step method at each time increment. By predicting the maximum tensile stress applied to an inner steel ring through a creep analysis based on the measured deformation of the inner steel ring, it is possible to predict the stress progression with age to some degree.

The Effect of Specimen Size on the Determination of Residual Stress in Polymer Pipe Wall

2014 ◽  
Vol 627 ◽  
pp. 141-144 ◽  
Author(s):  
Jan Poduška ◽  
Jaroslav Kučera ◽  
Pavel Hutař ◽  
Martin Ševčík ◽  
J. Křivánek ◽  
...  
Keyword(s):  
Residual Stress ◽  
Axial Stress ◽  
Three Dimensional ◽  
Axial Direction ◽  
Polymer Materials ◽  
Axial Residual Stress ◽  
Axial Dimension ◽  
Measured Deformation ◽  
Different Dimensions

As a result of the production process, there are axial and tangential residual stresses present in pressure pipes made of polymer materials such as polyethylene or polypropylene. The residual stress magnitude and distribution have a significant influence on the pipe lifetime. In this contribution the results from experiments focused on determining the tangential residual stress distribution in the walls of polypropylene pipes of different dimensions are compared. The experimental method used involves measuring the deformation of ring shaped specimens that were slit in the axial direction. Measured deformation of the ring specimen is a result of the tangential and axial stress superposition. However, the effect of the axial residual stress depends on the specimen axial dimension and tangential residual stress estimated basing on experimental data should be corrected according to axial dimension of the specimen used. The correction suggested in this article is determined based on three-dimensional FEM simulations of the experiment.

scholarly journals Different Deformation Patterns in High Core Wall Rockfill Dams: A Case Study of the Maoergai and Qiaoqi Dams

2019 ◽  
Vol 2019 ◽  
pp. 1-17
Author(s):  
Rui Feng ◽  
Yun-Long He ◽  
Xue-Xing Cao
Keyword(s):  
Deformation Behaviour ◽  
Horizontal Displacement ◽  
Wide Range ◽  
Deformation Law ◽  
Mechanical Behaviours ◽  
Measured Deformation ◽  
Dam Deformation ◽  
Deformation Patterns ◽  
Reservoir Filling ◽  
Displacement Patterns

The time-dependent behaviour of high rockfill dams is complex and not easy to accurately predict. Many discrepancies were revealed by the comparison of the observed deformation histories of different dams, and the deformation of some high rockfill dams did not correspond to the general deformation law. Field monitoring is therefore an effective method for understanding complex dam deformation behaviour. In this paper, actual measured deformation data resulting from continuous monitoring of the Maoergai and Qiaoqi dams are analysed. These two dams have similar heights, crest lengths, and alluvium overburden thicknesses. Our aim is to explain the actual deformation histories on the basis of the mechanical behaviours of these dams in order to warn engineers about potential problems that cannot be predicted. The results indicate that the deformation patterns of the two dams are completely different. The dam construction and water impoundment schedule is the major reason for the different horizontal displacement patterns. The reservoir filling rates and rainfall are the main reasons for the different settlement patterns. The case histories are useful for understanding the wide range of possible postconstruction deformation in a dam.

scholarly journals Comparison of Experimentally Measured Deformation of the Plate on the Subsoil and the Results of 3D Numerical Model

2014 ◽  
Vol 14 (1) ◽  
pp. 57-66 ◽  
Author(s):  
Jana Labudková ◽  
Radim Čajka
Keyword(s):  
Finite Element ◽  
Numerical Model ◽  
Boundary Conditions ◽  
Parametric Study ◽  
3D Model ◽  
3D Elements ◽  
Final Deformation ◽  
Measured Deformation ◽  
3D Numerical Model

Abstract The purpose of this paper is to compare the measured subsidence of the foundation in experiments and subsidence obtained from FEM calculations. When using 3D elements for creation of a 3D model, it is, in particular, essential to choose correctly the size of the modelled area which represents the subsoil, the boundary conditions and the size of the finite element network. The parametric study evaluates impacts of those parameters on final deformation. The parametric study is conducted of 168 variant models.

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