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Time lapse tomography of fracture progress in silicate-based composite subjected to the loading a combination with acoustic emission scanning
Kumpová, Ivana ; Kytýř, Daniel ; Fíla, Tomáš ; Veselý, V. ; Trčka, T. ; Vopálenský, Michal ; Vavřík, Daniel
The initiation and propagation of a fracture in quasi-brittle materials (such as silicatebased composite) is an increasingly discussed topic for which various methods of research have been developed/applied. As the quasi-brittle silicate-based composite compounds are very non-homogenous, the mechanism of the crack initiation and propagation can be very different even for samples with the\nidentical geometry. One possible approach to study the fracture mechanism in quasi-brittle materials is to use several different experimental techniques in a single experiment and perform detail analysis to identify generally valid fracture process phenomena. In this work, a simultaneous monitoring of fracture\nprocess zone formation and propagation by three different methods is presented and discussed. A three point bending test was performed on a notched silicate composite specimen. During the loading process, a highly accurate force displacement dependence was recorded accompanied with X-ray radiography,\nX-ray computed tomogra-phy and acoustic emission scanning.
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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
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.
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X-ray Observation of the Loaded Silicate Composite
Vavřík, Daniel ; Fíla, Tomáš ; Jandejsek, Ivan ; Veselý, V.
An intensive internal material damage evolution precedes a failure in quasi-brittle materials. Not only the existence of damage but also its quantification and the geometry of the Fracture Process Zone have to be identified in order to validate approaches on both numerical modelling of quasi-brittle behaviour and experimental determination of fracture properties. Radiographic techniques and Digital Image Correlation method are very appropriate for analysing of the Fracture Process Zone evolution during specimen loading.
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