National Repository of Grey Literature 21 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Concrete with steel reinforcement
Kumpová, Ivana ; Jandejsek, Ivan ; Vavřík, Daniel
The work was focused on X-Ray tomography and creating of 3D computer models of ten concrete samples with various steel reinforcement contents and different production technology. From these models, the volume ratios of individual components (concrete: reinforcement: pores) and directional layout of individual fibers were calculated.
Comprehensive research report to experimental work on fatigue crack initiation in the sandstone and research of influences of the consolidation for fracture behavior in cases of cracks
Šperl, Martin ; Drdácký, Miloš ; Jandejsek, Ivan
Fatigue crack initiation in the sandstone specimens (location – Božanov) was made using a resonant testing machine in three point bending mode. It produced the geometrically similar damage. Subsequent fracture tests made it possible to assess the effect of the consolidation solutions on fracture properties of the material investigated.
Portable device for indirect assessment of strength in tension of building materials and problem of boundary condition
Major, Štěpán ; Jandejsek, Ivan ; Valach, Jaroslav ; Vavřík, Daniel
A sensitive determination of mechanical properties of brittle building materials of existing buildings, requires gathering of samples by core drilling. Due to the fact, that the material samples may change their properties during transportion, it is preferred to test samples on site. Development of portable machine for Split test was therefore the first choice.
Experimental evaluation of strain fields in the vicinity of V-notch in ductile metal
Jandejsek, Ivan ; Jiroušek, Ondřej ; Vavřík, Daniel
This work deals with the experimental measurement of full-field displacements and strains evaluation on the surface of flat high-ductile aluminum specimens in the vicinity of the V-notch during loading. Two different specimen geometry configurations, boundary and middle notch, are tested and compared in terms of deformation constraint. The enhanced Digital Image Correlation method in conjunction with strain gage measurement is employed for the precise full-field strain evaluation.
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.
Experimental measurement of full-field strains in the vicinity of U-notch in ductile material
Jandejsek, Ivan ; Jiroušek, Ondřej ; Vavřík, Daniel
The paper deals with the measurement of full-field displacements and strains evolution in the vicinity of the U-notch in the flat high-ductile aluminum specimen during its loading. The full-field displacements are measured using Digital Image Correlation method in a set of vertices of a triangular mesh reflecting the presence of the stress concentrator. From the known displacements strain distribution is computed. The resulting strain field is compared with simultaneous strain gauge measurement. These strain gauges are located just in a few well-defined positions and serve for correction of a systematical error caused by rigid-body motion of the specimen during loading. The experimental results are used as referential for Finite Element simulation using the same triangular mesh.
Portable Testing Device for In-situ Testing of Building Material
Vavřík, Daniel ; Jandejsek, Ivan
Examination of brittle buildings materials using mechanical tests requires sampling of studied elements and materials (stones, bricks or concrete). In case of existing integral structures the best suitable sampling method is core drilling. It is preferred to test samples in situ in all cases where it is possible to avoid changes of the material properties during transportation and storing. Moreover it is possible to prepare other samples operationally wen some uncertainty occurred if in situ testing is possible. For such a purpose, a portable testing device has been designed and manufactured. This device is primary devoted for so called split test technique which is based on well know testing of Brazilian disk. Analytical equation used for evaluation of the split test is based on several assumptions which have to be verified. For such verification Digital Image Correlation technique was used in our work.
Experimental Methods for Evaluation of the Energy Balance in Vicinity of the Crack Tip
Jandejsek, Ivan ; Vavřík, Daniel
This work deals with experimental methodology for comprehensive observation in vicinity of stress concentrator in the high ductile material for the purpose of evaluation of the overall energy balance. The strain and stress fields, level of plasticity and thermal dissipation at the vicinity of the stress concentrator are determined employing combination of simultaneous optical, strain gauge and thermal measurement.
Identification of material parameters of an orthotropic metal sheet
Vavřík, Daniel ; Fiala, Zdeněk ; Grediac, M. ; Jandejsek, Ivan ; Micka, Michal ; Minster, Jiří ; Pierron, F.
Identification of constitutive equation parameters of orthotropic specimens is a highly demanding task requiring a full field measurement of the strain fields. This measurement is done using a Digital Image Correlation technique. The material parameters are identified by employing the Finite Element Method Updating and the Virtual Field Method alternatively.
Optimization and Calibration of Digital Image Correlation Method
Jandejsek, Ivan ; Valach, Jaroslav ; Vavřík, Daniel
An example of instrumentation and optimization of Digital Image Correlation measurement system for given class of experiments is described in this paper.

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