• Non-destructive methods in concrete blast resistance assessment

    Security & Future, Vol. 2 (2018), Issue 2, pg(s) 91-93

    The paper deals with the assessment of material used for the construction of protective structures and elements of military and civilian infrastructure. Since the main reason of protective structures is to protect personnel, equipment and equipment from attack by hostiles, it is necessary to conduct tests of material ballistic resistance and resistance against contact or distant explosion when choosing suitable materials for building protective structures.
    In order to achieve the aim of this work, from several basic groups of NDT methods was selected. Based on the evaluation of their advantages and technical possibilities, representatives from 4 principally and physically different groups of NDT methods were selected, i.e. visual method, ultrasonic method, hardness method and resonance method.
    The practical part of the paper is focused on the design of the material evaluation by means of NDT methods. In the first stage, the setting of the measuring devices was performed. Laboratory measurement was then carried out, on the basis of which calibration relations were established to determine the basic mechanical properties of the material. The material evaluation is described fort both, newly designed elements and for material in already built structures. Laboratory and field tests were performed during the assessment of the material of the newly constructed elements. In laboratory tests, the test specimens were evaluated by NDT methods. In the field tests, the test specimen was subjected to an explosion, the effect of which was subsequently evaluated by NDT methods and compared with the results of the same method prior to loading.


    Machines. Technologies. Materials., Vol. 8 (2014), Issue 11, pg(s) 46-48

    Thermography measurements allow to detect the defects that may appear on a joint at welding of components. Energy pulse generated by a xenon lamp with adequate power in a short period of time is sufficient for thermal excitation and enables to register the temperature distribution using the thermography high resolution camera FLIR SC7000. The impulse with 6kJ energy and 6ms time generate sufficient power to measure the temperature distribution on the surface of the weld tested. During cooling the temperature of the area with defect changes more slowly than in the areas without defects, because of to the less intense heat dissipation. This allows the registration of defects in welds "on-line" at the production process. Material used for analysis detection of defects in the welded joints is Inconel 718, stainless steel 410 and stainless steel 321. The peak energy which flow throw the samples with defects in the welded joints its completely or partially blocked. It cause different temperature distribution on the surface in the places where the connection discontinuity take place.