Dinamičko ponašanje određenih klasa transportnih mašina sa aspekta incidentnih događaja

Abstract

The doctoral dissertation deals with incidents of heavy lifting and construction machinery. The research studies the stability and the risk of mechanical systems at the dynamic impulse influences which determine the safety of supporting structures. Typical incident events, at work of machinery, which influence in unique way on placed modelling and dynamical simulation, here are selected. The surveys on a group of five types of machines were carried out whereby the models of numerical simulations were developed, with the help of five experimental investigations of the structures for supporting model verification. The results of the disertation are: Exact identification of dangerous forced vibration frequencies; Mathematical formulation of incidental excitation forces; Mathematical forms of wind excitation forces with medium strength in multiple gusts; Geometry of frame structures with low dynamic stability; Mathematical forms of malicious excitations with large vibration amplitudes. Elements of risk are separated and defined: high accelerations, large deflections, shaking (tremor), extreme dynamic coefficients, loss of contact of structural parts. The finite element method (FEM) is applied in transient dynamic analysis of mechanical system. The experiments on tower crane, bridge crane, shipbuilding (levelluffing) crane, mining stacker and mobile elevating platform were performed. The obtained technical models are an incidental design template which checks sensitivity on extreme and unexpected influences.