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Experiment E7/0,3-displacement processes in non cohesive sand mass during active translative motion of retaining wall
Koudelka, Petr
2016 - English
The first part of information on the new experiment denominated as E7/0,3 with active pressure of non-cohesive quartz sand on time behaviour of the mass was presented at the last Conference (P. Koudelka, 2015). The second part is object of this Paper. The experiment was performed at the Institute of Theoretical and Applied Mechanics in 2014. The moved rigid front wall of the experimental equipment was translatively moved towards active direction (out of the mass) at a position of supposed acting of active pressure value, then the wall motion was stopped and time pressure stability was monitored. After more than three months the wall was moved at the last position of 100 mm from original position before the experiment. The experiment ran four and a half months. The paper presents firstly results on the deforming mass through the course of the wall movement at a supposed position for active pressure mobilization of 1.357 mm and after the further movement. The experiment was repeated to be the results proved (Experiment E8/0,3). New results are analysed.
Keywords:
retaining wall; active lateral earth pressure; non-cohesive material; sandy mass behaviour; wall movement modus; displacements
Available on request at various institutes of the ASCR
Experiment E7/0,3-displacement processes in non cohesive sand mass during active translative motion of retaining wall
The first part of information on the new experiment denominated as E7/0,3 with active pressure of non-cohesive quartz sand on time behaviour of the mass was presented at the last Conference (P. ...
Determination of thermal response of Carrara and Sneznikovsky marble used as building material
Petráňová, Veronika; Valach, Jaroslav; Viani, Alberto; Pérez-Estébanez, Marta
2016 - English
Physical weathering of marble, widely used as a cladding material on buildings, is one of the most common damaging mechanism caused by anisotropic thermal expansion of calcite grains. The extent of marble deterioration depends mainly on stone fabric and texture. Dry cuboids of Carrara marble and marble from Dolni Morava quarry were subjected to microscopic analysis and thermal cycling, to determine the thermal expansion related to stone fabric and predominant lattice orientation of grains (i.e. texture).
Keywords:
marble; anisotropic thermal expansion; thermal dilatation
Available at various institutes of the ASCR
Determination of thermal response of Carrara and Sneznikovsky marble used as building material
Physical weathering of marble, widely used as a cladding material on buildings, is one of the most common damaging mechanism caused by anisotropic thermal expansion of calcite grains. The extent of ...
Investigation of aeroelastic bridge instabilities using the multidimensional Fokker-Planck equation and wind-tunnel experiment
Král, Radomil
2016 - English
Stability of bridges and other line-like engineering structures is an important part of their overall design. It is also still of great interest nowadays due to a higher demand on increasing the span while maintaining an economical cost and service. During the previous decades sophisticated methods for the aeroelastic instability prediction have evolved and successfully applied to the real structures and many questions have been adequately answered.
Keywords:
aeroelastic instability; Fokker-Planck equation; wind-tunnel; bridges
Available at various institutes of the ASCR
Investigation of aeroelastic bridge instabilities using the multidimensional Fokker-Planck equation and wind-tunnel experiment
Stability of bridges and other line-like engineering structures is an important part of their overall design. It is also still of great interest nowadays due to a higher demand on increasing the span ...
Identification of damaged zones in C/PPS specimens subjected to fatigue loading based on high-resolution thermography
Koudelka_ml., P.; Kytýř, Daniel; Fenclová, Nela; Šperl, Martin
2016 - English
In this study high resolution thermography is used for identification of damaged zones in Carbon fiber/polyphenylene sulfide (C/PPS) long fiber composite specimens with induced impact damage subjected to tensile fatigue loading. Image processing techniques were applied on thermographs from all loading cases to obtain segmented images of the damaged location that were then used for\ncalculation of the heated area. Results show that the considered method can be used to identify heated area in the vicinity of damage with high confidence at low number of cycles where no significant fatigue effect is present in the material.
Keywords:
fatigue; damage; long fiber composite; C/PPS; thermography
Available at various institutes of the ASCR
Identification of damaged zones in C/PPS specimens subjected to fatigue loading based on high-resolution thermography
In this study high resolution thermography is used for identification of damaged zones in Carbon fiber/polyphenylene sulfide (C/PPS) long fiber composite specimens with induced impact damage subjected ...
Comparison of optical methods for characterization of glass mosaic weathering
Kocour, Vladimír; Petráňová, Veronika; Valach, Jaroslav
2016 - English
The work presented in this paper is a part of research project supported by Ministry of Culture and devoted to conservation of precious mosaic of 'Last Judgement' on St. Vitus Cathedral in Prague. The aim of the project is to enhance external protective polymeric coating on glass tesserae of mosaic and also to develop optical method for assessment of coating’s surface conditions. The paper concentrates on comparison of various methods for surface evaluation assesses their advantages and disadvantages and also discusses their suitability for long term monitoring of coating state, namely reflectometry, scanning probe microscopy, nanoindentation, white-light interferometry, and scanning electron microscopy. It is found that white-light interferometry and reflectometry methods are the most suitable ones for monitoring purposes.
Keywords:
surface; reflectance; photometry; roughness; glass mosaic
Available at various institutes of the ASCR
Comparison of optical methods for characterization of glass mosaic weathering
The work presented in this paper is a part of research project supported by Ministry of Culture and devoted to conservation of precious mosaic of 'Last Judgement' on St. Vitus Cathedral in Prague. The ...
Health monitoring of building structures: preliminary considerations on a case study
Bayer, Jan; Urushadze, Shota; Zíma, Pavel
2016 - English
Ageing, erosion, local damage or increase of the operating loads can decrease the reliability and load bearing capacity of building structures. Vibration monitoring may provide a promising solution of this problem, however robust health monitoring techniques are needed before wider practical applications. The presented analytical and experimental case study on a simple supported steel beam is an introductory practical investigation into this topic. It shows the sensitivity of chosen parameters to artificially induced damage and outlines possible directions or further research in conclusions. Special attention is paid to simultaneous monitoring of deformations and strains which can provide us with a useful information about the stress redistribution in monitored or tested structures.
Keywords:
damage detection; modal parameters; dynamic loading tests; relative strain vibration; comparison of analysis and experiments
Available on request at various institutes of the ASCR
Health monitoring of building structures: preliminary considerations on a case study
Ageing, erosion, local damage or increase of the operating loads can decrease the reliability and load bearing capacity of building structures. Vibration monitoring may provide a promising solution of ...
Deformation characteristics of chopped fibre composites subjected to quasi-static tensile loading
Šleichrt, J.; Adorna, M.; Neühauserová, M.; Fenclová, N.; Petráňová, Veronika
2016 - English
This work presents deformation behaviour of cost effective chopped fiber composites. Use of chopped fibre is advantageous for manufacturing however complex shape parts production technology could be challenging. Batches of samples with different fibres composition were subjected to uni-axial tensile loading to obtain overall materials properties and inspection of proper manufacturing based on local deformation inhomogeneities. Both crossbeam displacement and optical strain measurement were used for elastic characteristics evaluation. Deformation response was derived from full-field optical strain measurements based on digital image correlation method. Relatively large variation of mechanical properties testing of samples was found.
Keywords:
chopped fibre composites; full-field measurement; digital image correlation
Available at various institutes of the ASCR
Deformation characteristics of chopped fibre composites subjected to quasi-static tensile loading
This work presents deformation behaviour of cost effective chopped fiber composites. Use of chopped fibre is advantageous for manufacturing however complex shape parts production technology could be ...
Approximation of the movement of the spherical pendulum
Fischer, Cyril; Náprstek, Jiří
2016 - English
The horizontally driven two-degrees of freedom spherical pendulum is an auto-parametric system which exhibits a wide variety of response types. Depending on the amplitude and frequency of the excitation the response can vary from stationary to chaotic regime. It has been already shown that the response can be described using time variable parameters of an inscribed ellipse. Such a description has a potential to close the gap between description of stationary, quasi-periodic and chaotic types of response. This study presents methodology and results of an analysis of the experimentally measured data providing the time dependent parameters of a twisting ellipse. The obtained results are discussed and some open problems are indicated.
Keywords:
spherical pendulum; quasi-periodic response; data analysis
Available on request at various institutes of the ASCR
Approximation of the movement of the spherical pendulum
The horizontally driven two-degrees of freedom spherical pendulum is an auto-parametric system which exhibits a wide variety of response types. Depending on the amplitude and frequency of the ...
The influence of deformation of the frame of testing device on the accuracy of Brazilian test and indirect assessment of Young modulus
Major, Štěpán; Vavřík, Daniel; Kocour, Vladimír; Bryscejn, Jan
2015 - English
This article deals with determination of mechanical properties based on indirect measurements of brittle building materials like stones using portable device. Due to the fact, that the material samples may change their properties during transportation, it is preferred to test samples on site. For these reasons, portable testing device was developed. The testing machine operates on the split test principle. The device also shall to serve for estimation of other mechanical characteristics of the tested material, such as Young's modulus, compressive strength or flexural strength, etc. This paper concentrates on the effect of deformation of frame on the accuracy of indirect determination of mechanical properties.
Keywords:
split test; Brazilian disc; tensile strength; portable testing device; finite element analysis
Available at various institutes of the ASCR
The influence of deformation of the frame of testing device on the accuracy of Brazilian test and indirect assessment of Young modulus
This article deals with determination of mechanical properties based on indirect measurements of brittle building materials like stones using portable device. Due to the fact, that the material ...
Solution of the multi-dimensional Fokker-Planck by means of finite element method
Náprstek, Jiří; Král, Radomil
2015 - English
As a demonstrative example, the two-degree-of-freedom system is investigated. A combination of Rayleigh\nor Van der Pol with Duffing types of differential equations are assumed characterized by the\nnonlinear behavior both in the stiffness and damping. This system is subjected to the additive and\nthe multiplicative Gaussian white noise which represents a part of non-linear aero-elastic effects in\nthe system.
Keywords:
Fokker-Planck equation (FPE); finite element method (FEM); nonlinear behaviour
Available at various institutes of the ASCR
Solution of the multi-dimensional Fokker-Planck by means of finite element method
As a demonstrative example, the two-degree-of-freedom system is investigated. A combination of Rayleigh\nor Van der Pol with Duffing types of differential equations are assumed characterized by ...
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