Facta Universitatis, Series: Mechanical Engineering

107 - 121

Authors: Gil Rama

Heavy lift jack-up vessels (HLJV) are used for the installation of components of large offshore wind farms. A systematic FE-analysis is presented for the HLJV THOR (owned by Hochtief Infrastructure GmbH) under extreme weather conditions. A parametric finite element (FE) model and analysis are developed by using ANSYS®1-APDL2 programming environment. The analysis contains static and dynamic nonlinear FE-calculations, which are carried out according to the relevant standards (ISO 19905) for in-place analyses of jack-up vessels. Besides strategies of model abstraction, a guide for the determination of the relevant loads is given. In order to calculate the dynamic loads, single degree of freedom (SDOF) analogy and dynamic nonlinear FE-calculations are used. As a result of detailed determination of dynamic loads and consideration of soil properties by spring elements, the used capacities are able to be reduced by 28 %. This provides for significant improvement of the environmental restrictions of the HLJV THOR for the considered load scenario.

137 - 148

Authors: Christopher Heine, Markus Plagemann

A detailed description of the rubber parts’ properties is gaining in importance in the current simulation models of multi-body simulation. One application example is a multi-body simulation of the washing machine movement. Inside the washing machine, there are different force transmission elements, which consist completely or partly of rubber. Rubber parts or, generally, elastomers usually have amplitude-dependant and frequency-dependent force transmission properties. Rheological models are used to describe these properties. A method for characterization of the amplitude and frequency dependence of such a rheological model is presented within this paper. Within this method, the used rheological model can be reduced or expanded in order to illustrate various non-linear effects. An original result is given with the automated parameter identification. It is fully implemented in Matlab. Such identified rheological models are intended for subsequent implementation in a multi-body model. This allows a significant enhancement of the overall model quality.

157 - 169

Authors: Vesna Jovanović, Dragoslav Janošević, Nikola Petrović

The paper presents a procedure for experimental determination of slewing bearing loads in the rotating platform drive mechanisms of hydraulic excavators with an excavating manipulator. A mathematical model is defined which enables the determination of the vectors of force and moment of bearing loads, on the basis of the measured quantities of the state of an excavator in operation under exploitation conditions. The measured quantities of the state of an excavator relate to the position of the kinematic chain and pressures of the hydrostatic system in the actuator ducts of the excavator drive mechanisms. As an example, the paper provides the research results obtained in the experimental determination of slewing bearing loads in the rotating platform drive mechanism of a hydraulic excavator with the mass of 16t.

183 - 193

Authors: Abdulrahim Haroun Ali, Shahaboddin Shamsirband, Nor Badrul Anuar1, Dalibor Petković

Intrusions are a problem with the deployment of Networks which give misuse and abnormal behavior in running reliable network operations and services. In this work, a Dynamic Fuzzy Logic Controller (DFLC) is proposed for an anomaly detection problem, with the aim of solving the problem of attack detection rate and faster response process. Data is collected by PingER project. PingER project actively measures the worldwide Internet’s end-to-end performance. It covers over 168 countries around the world. PingER uses simple ubiquitous Internet Ping facility to calculate number of useful performance parameters. From each set of 10 pings between a monitoring host and a remote host, the features being calculated include Minimum Round Trip Time (RTT), Jitter, Packet loss, Mean Opinion Score (MOS), Directness of Connection (Alpha), Throughput, ping unpredictability and ping reachability. A set of 10 pings is being sent from the monitoring node to the remote node every 30 minutes. The received data shows the current characteristic and behavior of the networks. Any changes in the received data signify the existence of potential threat or abnormal behavior. D-FLC uses the combination of parameters as an input to detect the existence of any abnormal behavior of the network. The proposed system is simulated in Matlab Simulink environment. Simulations results show that the system managed to catch 95% of the anomalies with the ability to distinguish normal and abnormal behavior of the network.