After approximately 60 years of service the original shafts of the hydropower plant in Kaprun were dismantled and replaced by a modern single shaft. The original shaft which was watergas welded is characterized by metallography, tensile test, Charpy test and fracture mechanic tests. The observed behavior revealed that this kind of joints shows – in areas without flaws – a satisfying behavior similar to the base material. In areas where oxides, stemming from the heating process during welding, exists the strength and deformability is limited.
COBISS.SI-ID: 12537366
The paper addresses a new approach to optimization of statically loaded shell structures by considering stability constraints. A special technique for structural response computation is introduced, which removes practically all difficulties met during analysis and optimization of a statically unstable structure. The formulation of the optimization problem is adjusted correspondingly. The optimization procedure also automatically determines the ‘worst-case’ imperfection of the structure. A gradient-based algorithm is used for solving the optimization problem.
COBISS.SI-ID: 11905814
The paper treats almost periodic vibrations of the rotor system with an electromagnetic damping and nonlinear characteristics of bearings as well as bifurcations during the transition from periodic to aperiodic vibrations by using the Incremental harmonic balance (IHB) method with multiple time scales. The paper is important in the design of various rotor systems with the emphasis on the stable operation. The original scientific paper is published in the Int. J. for Numer. Meth. in Engineering.
COBISS.SI-ID: 8442134
The paper treats nonstationary oscillations of clamped-hinged beam in the passage through nonstationary fundamental resonance with slowly varying excitation frequency or excitation amplitude. In the study, the influence of internal resonance and excitation of superharmonic resonances in dependence on excitation amplitude level are considered. The work is important for design of various structures because responses are computed on the real assumptions and are fundamentally different from the responses in the stationary case.
COBISS.SI-ID: 12081430
The presented paper shows how the temperature field in beams has impact on vibrations of beams. Due to the relatively high possible temperature variations in beams we have developed the mathematical model where fundamental thermomechanical properties of state are functions of temperature. The detailed analysis shows, that also small changes of temperature cause significant changes of natural frequencies for beams. The comparison between our analytical model and experimental data shows good agreement.
COBISS.SI-ID: 11624470