Srđan Bošnjak

Appropriate Modeling of Dynamic Behavior of Quayside Container Cranes Boom Under a Moving Trolley

The paper deals with the analysis of moving trolley effects on the dynamic behavior of flexible structure of a mega high-performance quayside container crane (QCC) boom. The boom is modeled as a system with distributed parameters, comprising reduced stiffnesses and lumped masses from other parts of the upper structure. This paper looks both at the “moving force” and “moving mass” trolley modeling approaches to achieve the required performance of the QCC boom structure. Deterministic simulation for both considered approaches gives dynamic structural response of the boom for container transfer from quay-to-ship. The obtained results for “moving force” and “moving mass” models are compared in the scope of real values of parameters and future expectations in design of QCC. The conclusions lead to an appropriate way of model selection that can be used by engineers in practice.

External Load Variability of Multibucket Machines for Mechanization

This paper discusses the problems of identifying external loads of multibucket machines for mechanization. External loads are dominantly dynamic with distinguished stochasticity in certain cases. The paper presents the procedures for determining external loads caused by resistance-to-excavation (for bucket wheel excavators) or grabbing soil (for bridge-type coal stacker-reclaimers), as well as a short description of the model upon which is based and defined the response of the stacker-reclaimer to the external changeable load. It points to the significance of the problem of identifying the external load, as well as to the potentially very detrimental and dangerous consequences of eventual shortcomings during solving the mentioned problem.

Dynamic Responses of Mobile Elevating Work Platform and Mega Container Crane Structures

The modern design methods lead to the objectivisation of the process of thinking, which is important for the new system development. The aim of objectivisation and decomposition of the design is obvious: it should enable a new approach in the problem solving and thinking of the designer, enriches the large quantity of new information, facts and ideas, which are important for the system designing. The first part of this paper gives a brief presentation of mobile elevating work platform structure response to the wind excitation in possible resonant states. The second part is dedicated to the dynamic analysis of the mega container crane structure subjected to the moving load.

Integrity and life estimation of turbine runner cover in a hydro power plant

This paper presents integrity and life estimation of turbine runner cover in a vertical pipe turbines, Kaplan 200 MW nominal output power, produced in Russia, and built in six hydro-generation units of hydroelectric power plant „Đerdap 1” in Serbia. Fatigue and corrosion-fatigue interaction have been taken into account using experimentally obtained material properties, as well as analytical and numerical calculations of stress state, to estimate appropriate safety factors. Fatigue crack growth rate, da/dN, was also calculated, indicated that internal defects of circular or elliptical shape, found out by ultrasonic testing, do not affect reliable operation of runner cover.