A parametric FEM model of multi-layer drums

A parametric FEM model of multi-layer drums

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Drums with mul~-Iayer rope windings are popular in crane, maribme, offshore and mining industry to accommodate the increasing rope lengths. In this paper a parametric FEM model of the complete rope package is presented which can be incorporated in any axi-symmetric dNm model. Like the model presented by the same author at the OIPEEC Conference of 2013 all windings can be individually pre-stressed and can be in contact with each other and the drum (nange and barrel). The type of rope, the number of windings in a layer and the number of layers are all parameterized. The rope model used for the behaviour of a single winding in the winch package represents both the axial and lateral stiffness of the rope. The rope characteristic can be determined with estimations proposed in the work of Prof. Dietz Of by direct measurements on the rope itself. The here presented FEM-model can be seen as an extension to the original simplified FEM model used by Dietz. The pressure pattern on the drum can be calculated and the stNctural integrity of the winch can be checked. With this FEM-model the rope tension can be changed for every layer and even every winding. Not only the constant rope tension over the full working range, such as for example for a hoisting winch can be simulated but also the situation with only a couple of fully stressed layers which is common for a mooring winchFor different winch sizes and also these different load pattems the results of the parametric model are in good agreement with various strain gauge measurements on the different winches. The results of the model are in closer agreement with the measured data than if the design Nles of DNV or even the guidelines of the Australian Standard are used, which is based on the findings of Dietz and his simplified FEM model. The presented axi-symmetric FEM model can be very useful to prove the real compression values for a specific winch and rope type. The model confirms that the C-value can be over 3 for hoisting applications but remains below 1.75 for mooring-type winches.

Author:W. van den Bos