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  • Article
    Citation - WoS: 38
    Citation - Scopus: 43
    Experimental and Numerical Analysis of a Bolted Connection in Steel Transmission Towers
    (Elsevier Sci Ltd, 2016) Baran, Eray; Akis, Toga; Sen, Gokmen; Draisawi, Ammar
    This paper presents an integrated numerical and experimental study on a bolted splice connection used in main legs of steel lattice transmission towers. At specific locations, where the number of angle sections in built-up cross section of main leg members changes, the complex geometry around the connection region results in eccentricities in the load path and indirect load transfer. Such complex configurations and uncertainties in the load path have led to overdesigned connections with increased number of bolts and redundant connection reinforcing members. The current study was conducted in an attempt to gain a better understanding of the load-flow mechanism at this specific location where the cross section of main leg members changes. The experimental part included tensile load testing of six specimens with different connection details. The main parameters used in the testing program were the number of bolts used in the connection as well as the presence of connection reinforcement angles and tie plate. For all connection configurations studied, the failure occurred due to net section fracture of upper main member angle near leading bolt holes. The calculated load capacity based on the measured material strength closely predicted the measured load capacity of specimens. The experimentally determined response of each connection configuration was better predicted by the FE model that incorporates bolt slip as compared to the model that assumes no slip. The experimental and numerical results also indicate that major differences among the investigated connection details do not cause any appreciable difference in behavior under tensile loading. (C) 2016 Elsevier Ltd. All rights reserved.
  • Article
    Citation - WoS: 14
    Citation - Scopus: 15
    A New Axial Flux Permanent Magnet Synchronous Alternator Autonomously Adapted To Wind Speeds
    (Elsevier Sci Ltd, 2015) Kalender, Osman; Ege, Yavuz; Eskidere, Omer; Karen, Idris; Gurdal, Osman; Unal, Cevat; Kabadayi, Murat
    In this study, a new axial flux permanent magnet synchronous generator (PMSA) design and prototyping procedures are presented. It is composed of a stack of rotor-stator blocks on the same shaft. In other words, it is made up of four alternators based on axial flux permanent magnets that can generate electrical energy within the limits of rotor rotational speed with varying wind speeds. A control system is also introduced to the generator. The control system connects or disconnects the stator blocks to the load according to the changing speeds of the wind. It produces electrical energy with stable voltage, frequency and variable power at the output. The efficiency of the generator is tested with different load and speed conditions. It is observed that the efficiency is high when the speed is low in case the load is connected only one stator. The efficiency is high when the speed is above 200 rpm for the case where several stators are connected to the load. It can be seen that the incremental structure of the generator is suitable for changing speeds of the wind. It can have high efficiency for both low and high speeds with changing the number of stator blocks connected to the load. (C) 2015 Elsevier Ltd. All rights reserved.