Rigid Finite Element Method in Analysis of Dynamics of Offshore Structures

Author(s):  
Edmund Wittbrodt ◽  
Marek Szczotka ◽  
Andrzej Maczyński ◽  
Stanisław Wojciech
2018 ◽  
Vol 18 (02) ◽  
pp. 1850017 ◽  
Author(s):  
Iwona Adamiec-Wójcik ◽  
Łukasz Drąg ◽  
Stanisław Wojciech

The static and dynamic analysis of slender systems, which in this paper comprise lines and flexible links of manipulators, requires large deformations to be taken into consideration. This paper presents a modification of the rigid finite element method which enables modeling of such systems to include bending, torsional and longitudinal flexibility. In the formulation used, the elements into which the link is divided have seven DOFs. These describe the position of a chosen point, the extension of the element, and its orientation by means of the Euler angles Z[Formula: see text]Y[Formula: see text]X[Formula: see text]. Elements are connected by means of geometrical constraint equations. A compact algorithm for formulating and integrating the equations of motion is given. Models and programs are verified by comparing the results to those obtained by analytical solution and those from the finite element method. Finally, they are used to solve a benchmark problem encountered in nonlinear dynamic analysis of multibody systems.


2010 ◽  
Vol 54 (01) ◽  
pp. 34-40
Author(s):  
Zhou Bo ◽  
Liu Yujun ◽  
Ji Zhuoshang

Lifting padeyes are widely used in the construction of offshore structures and ships. It has been shown that the traditional check method cannot reflect the realistic value and distribution of actual stress on the padeyes. A more accurate method for the padeye stress calculation is essential and important for promoting the safety of the padeyes. In this paper, a new check formula is proposed based on the analysis of deformation and external loads distribution on lifting padeyes. The results of finite element method and the solutions of traditional check formula and new check formula are compared. It is shown that, by applying the stress check formula derived in the paper, the value and the location of the dangerous stresses occurred can be evaluated easily and exactly. The safe reliability of structure design can be improved significantly.


2015 ◽  
Vol 62 (1) ◽  
pp. 101-114 ◽  
Author(s):  
Iwona Adamiec-Wójcik ◽  
Andrzej Nowak ◽  
Stanisław Wojciech

Abstract The rigid finite element method (RFEM) has been used mainly for modelling systems with beam-like links. This paper deals with modelling of a single set of electrodes consisting of an upper beam with electrodes, which are shells with complicated shapes, and an anvil beam. Discretisation of the whole system, both the beams and the electrodes, is carried out by means of the rigid finite element method. The results of calculations concerned with free vibrations of the plates are compared with those obtained from a commercial package of the finite element method (FEM), while forced vibrations of the set of electrodes are compared with those obtained by means of the hybrid finite element method (HFEM) and experimental measurements obtained on a special test stand.


2013 ◽  
Vol 60 (3) ◽  
pp. 313-318 ◽  
Author(s):  
Edmund Wittbrodt ◽  
Stanisław Wojciech

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