Národní úložiště šedé literatury Nalezeno 7 záznamů.  Hledání trvalo 0.01 vteřin. 
Comparison of calibration functions for short edge cracks under selected loads
Seitl, Stanislav ; Miarka, Petr ; Malíková, Lucie ; Krejsa, M.
Attention to the fatigue cracks in steel structures and bridges has been paid for long time. In spite to efforts to eliminate the creation and propagation of fatigue cracks throughout the designed service life, cracks are still revealed during inspections. Note, that depending on location of initial crack, the crack may propagate from the edge or from the surface. The theoretical model of fatigue crack progression is based on linear fracture mechanics. Steel specimens are subjected to various load (tension, three- and four-point bending, pure bending etc.). The calibration functions for short edge cracks are compared for various load and the discrepancies are discussed.
Fatigue damage prediction of short edge crack under various load: Direct Optimized Probabilistic Calculation
Krejsa, M. ; Seitl, Stanislav ; Brožovský, J. ; Lehnert, P.
Fatigue crack propagation depends on a number and value of stress range cycles. This is a time factor in the course of reliability for the entire designed service life. Three sizes are important for the characteristics of the propagation of fatigue cracks - initial size, detectable size and acceptable size. The theoretical model of a fatigue crack progression can be based on a linear elastic fracture mechanics (uses Paris-Erdogan law). Depending on location of an initial crack, the crack may propagate in structural element (e.g. from the edge or from the surface under various load) that could be described by calibration functions. When determining the required degree of reliability, it is possible to specify the time of the first inspection of the construction which will focus on the fatigue damage. Using a conditional probability and Bayesian approach, times for subsequent inspections can be determined based on the results of the previous inspection. For probabilistic modelling of a fatigue crack progression was used the original and a new probabilistic method - the Direct Optimized Probabilistic Calculation ('DOProC'), which uses a purely numerical approach without any simulation techniques or approximation approach based on optimized numerical integration. Compared to conventional simulation techniques is characterized by greater accuracy and efficiency of the computation.
Probabilistic designing of bolted support
Janas, P. ; Krejsa, M. ; Šňupárek, Richard ; Krejsa, V.
The paper briefly reviews one of the proposed methods of probabilistic reliability assessment of anchoring reinforcement usable in mine excavations and undergroundworkings. Application of this koncept – software „Kotvení“ (Anchoring) was especiallydeveloped for this purpose usingDirect Determined Fully Probabilistic Method (DDFPMB).
Pravděpodobnostní posudek spolehlivosti kotevní výztuže dlouhých důlních a podzemních děl
Janas, P. ; Šňupárek, Richard ; Krejsa, V. ; Krejsa, M.
The paper briefly reviews one of the proposed methods of probabilistic reliability assessment of anchoring reinforcement, usable in mine excavations and underground workings. Application of this concept – software „Kotvení“ was especially developed for this purpose using DDFPM (Direct Determined Fully Probabilistic Method).

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2 Krejsa, M.
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