Papers by Keyword: Loss of Stability

Abstract: The European standard EN1992-1-1 shows a significant lack of an overall reliability in cases when loss of stability of concrete columns precedes reaching of resistance in a critical cross-section. The columns, subjected to axial force and bending moment, experimentally tested in the laboratory of Faculty of Civil Engineering SUT in Bratislava, were designed so that the loss of stability occurs at the concrete strain about 1.5 ‰ on the compressed edge of a critical cross-section.

Abstract: We discuss the dynamic behavior of stepped columns subjected to follower forces. In particular, limit cases which correspond to columns with hinges or cracks and concentrated lateral supports are studied for the stability limit. Typically, solutions suffer jumps in certain derivatives, which have to satisfy compatibility conditions. The influence of these interface conditions on the critical force is investigated. The aim is to optimize the location of such singularities and thus to obtain maximum critical loads, respectively worst case estimates for the loss of stability.

Abstract: Most of researchers at research of "self evicted vibrations" in machining state that they are resulted by passing of force stability boundaries of the mechanical system at which oscillations increase hardly. Explanations of process development from the point of view of grinding dependencies are absent. The article is allotted to analyze the process in time, it is shown how in result of action of forced vibrations with frequencies different from any natural frequency of the system new vibrations with some natural frequency of the system are propagated. New properties of the system are formed. Equations are deduced and calculation results are presented in the article.