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Marble epistyles under shear: an experimental study of the role of “Relieving Space”

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Frontiers of Structural and Civil Engineering 2019年第4期13卷 767-786页

作者： E. D. PASIOU I. STAVRAKAS D. triantis S. K. KOURKOULIS Department of Mechanics Laboratory of Testing and Materials National Technical University of Athens Athens 15773 Greece Department of Electronics Laboratory of Electrical Characterization of Materials and Electronic Devices Technological Edu-cational Institution of Athens Athens 12210 Greece

The mechanical response of mutually interconnected epistyles is studied experimentally. The specimens are made of two marble blocks connected to each other with an “I”-shaped titanium connector placed in grooves sculptured on the blocks and covered with cementitious material. The specific way of connecting epistyles simulates the one used by scientists restoring the ancient “connections” of the epistyles of the Parthenon Temple. This “connection”, although designed to sustain mainly tensile loading, undertakes, also, shear load, in case of excitations imposing to the epistyles displacements normal to the connector’s axis. Attention is focused to enlighten the role of a novel design technique aiming to relieve the stress field around the connector. According to this technique, part of the connector’s web is left uncovered, forming the so-called “Relieving Space”, assisting the unconstrained deformation of the connector. Both traditional and innovative sensing techniques were employed in an effort to obtain data from the interior of the three-material-complex (marble-cementitious material-titanium). Analysis of the data indicated that the “Relieving Space” reduces the overall stiffness of the system, protecting marble in case of over-loading. Moreover, it was concluded that the innovative techniques employed provide pre-failure indicators well in advance of the catastrophic failure of the specimens.

关键词： monuments of cultural heritage marble epistyles pressure stimulated currents acoustic emission digital image correlation

On the cell biology of pit cells,the liver-specific NK cells

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World Journal of Gastroenterology 2000年第1期6卷 1-11页

作者： Luo DZ Vermijlen D Ahishali B triantis V Plakoutsi G Braet F Vanderkerken K Wisse E Laboratory for Cell Biology and Histology Free University of Brussels(VUB)Brussels-JetteBelgium Department of Pathology Guangxi Medical University NanningChina Laboratory for Cell Biology and Histology Free University of Brussels(VUB)Brussels-JetteBelgium Department of Hematology and Immunology Free University of Brussels(VUB)Brussels-JetteBelgium

INTRODUCTION Natural killer (NK) cells are functionally defined by their ability to kill certain tumor cells and virus-infected cells without prior

关键词： Subject headings pit cells hepatic natural killer cells large granular lymphocytes

Nondestructive Testing Electrical Methods for Sensing Damages in Cement Mortar Beams

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Open Journal of Applied Sciences 2013年第1期3卷 50-55页

作者： Charalampos Stergiopoulos Ilias Stavrakas George Hloupis Antonios Kyriazopoulos Dimos triantis Cimon Anastasiadis John Stonham Department of Electronics Technological Educational Institute of Athens Athens Greece School of Engineering and Design Brunel University Brunel United Kingdom

This paper discusses the experimental results of concurrently measured Electrical and Acoustic Emissions in order to evaluate the mechanical health status of cement mortar beams subjected to three-point bending mechanical tests. In particular, the Electrical Resistance and the Electrical Current emissions are recorded concurrent with Acoustic Emissions and the experimental results are discussed under the concept of crack initiation and propagation processes. For the first time, the electrodes that are used for conducting the measurements are placed in the bulk of the specimen, near the tensile zone, during its preparation. The damage evolution is examined by monitoring the fractional change of the Electrical Resistance and the variation of the Electrical Current in combination with the Acoustic Emission recordings.

关键词： Non-Destructive Testing Electrical Resistance Acoustic and Electrical Current Emissions Cement

Using AC Conductivity Measurements to Study the Influence of Mechanical Stress on the Strength of Geomaterials

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Open Journal of Applied Sciences 2012年第2期2卷 61-65页

作者： Ilias Stavrakas Kostantinos Moutzouris Kostantinos Ninos Nikos Mitritsakis Zacharias Agioutantis Dimos triantis Department of Electronics Technological Educational Institute of Athens Athens Greece Department of Mineral Resources Engineering Technical University of Crete Chania Greece

The Dielectric Spectroscopy technique is a tool that can be used to provide information regarding the physical and chemical properties of materials. In this work Dielectric Spectroscopy (DS) measurements were conducted on marble specimens that were previously subjected to uniaxial compressive stress up to fracture in order to investigate the influence of the mechanical stress on the dielectric properties of the specimens. Specifically, the ac conductivity (σac) was measured when an ac electric field in the frequency range 1 kHz - 1 MHz was applied upon dry and saturated specimens which were subjected successively to higher levels of mechanical stress. The experimental results indicate that there are systematic variations in the values of the ac conductivity after each stress application at a higher stress level. Such variations become more intense at higher stress values and can be used to indicate the upcoming fracture since significant increase of conductivity is recorded when microcracks formations appear and propagate in the sample bulk.

关键词： AC Conductivity Measurements Marble Mechanical Load