Multibody Techniques in Offshore Dynamics With an Application to a Crane Ship

2004 ◽  
Author(s):  
Joost den Haan ◽  
Hermione van Zutphen
Keyword(s):  
Efficient Method ◽  
Time Domain ◽  
Equations Of Motion ◽  
Response Prediction ◽  
Transformation Method ◽  
Computationally Efficient ◽  
Velocity Transformation ◽  
Offshore Engineering ◽  
Initial Results ◽  
Equations Of Motions

In this paper multibody dynamics techniques are reviewed for their applicability to offshore engineering, for example to cases like installation, decommissioning, salvage, offloading, pipe laying and dredging. The basis of every simulation is formed by the equations of motion. Multibody techniques have the advantage over analytical methods that they are generic: the equations of motions are derived by a computer algorithm rather than by hand. This allows for a large variety of systems to be analyzed with a single program. The review shows that the topology dependent semi-recursive velocity transformation method (VTM) provides a computationally efficient method for spatial time domain simulations. As an application a crane vessel payload-pendulation problem is studied. The initial results of this study suggest that multibody techniques in offshore dynamics provide better insight and possibly higher accuracy in response prediction than other methods.

Systematic Construction of the Equations of Motion for Multibody Systems Containing Closed Kinematic Loops

1989 ◽  
Author(s):  
P. E. Nikravesh ◽  
G. Gim
Keyword(s):  
Equations Of Motion ◽  
Transformation Matrix ◽  
Velocity Transformation ◽  
Constraint Equations ◽  
Advantages And Disadvantages ◽  
Lagrange Multiplier Technique ◽  
Joint Coordinates ◽  
Minimum Number ◽  
Kinematic Loops ◽  
Equations Of Motions

Abstract This paper presents a systematic method for deriving the minimum number of equations of motion for multibody system containing closed kinematic loops. A set of joint or natural coordinates is used to describe the configuration of the system. The constraint equations associated with the closed kinematic loops are found systematically in terms of the joint coordinates. These constraints and their corresponding elements are constructed from known block matrices representing different kinematic joints. The Jacobian matrix associated with these constraints is further used to find a velocity transformation matrix. The equations of motions are initially written in terms of the dependent joint coordinates using the Lagrange multiplier technique. Then the velocity transformation matrix is used to derive a minimum number of equations of motion in terms of a set of independent joint coordinates. An illustrative example and numerical results are presented, and the advantages and disadvantages of the method are discussed.

Parametric Rolling Simulations of Container Ships

2013 ◽  
Author(s):  
Anton Turk ◽  
Jasna Prpić-Oršić ◽  
Carlos Guedes Soares
Keyword(s):  
Time Domain ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Full Range ◽  
Ship Motions ◽  
Computationally Efficient ◽  
Parametric Roll ◽  
Parametric Rolling ◽  
Strip Theory ◽  
The Time Domain

A hybrid nonlinear time domain seakeeping analysis is applied to the study of a container ship advancing at different headings and encounter frequencies. A time-domain nonlinear strip theory in six degrees-of-freedom has been extended to predict ship motions by solving the unsteady hydrodynamic problem in the frequency domain and the equations of motion in the time domain which allows introducing nonlinearities in the linear model. The code is used to make parametric roll predictions for various speeds and headings and the results are summarized in a very intuitive 2D and 3D polar plots showing the full range of the parametric rolling realizations. The method developed is fairly accurate, robust, very computationally efficient, and can predict nonlinear ship motions. It is well suited to be used as a tool in ship design or as part of a path optimization model.

Systematic Construction of the Equations of Motion for Multibody Systems Containing Closed Kinematic Loops

1993 ◽  
Vol 115 (1) ◽  
pp. 143-149 ◽  
Author(s):  
P. E. Nikravesh ◽  
Gwanghun Gim
Keyword(s):  
Equations Of Motion ◽  
Transformation Matrix ◽  
Velocity Transformation ◽  
Constraint Equations ◽  
Advantages And Disadvantages ◽  
Lagrange Multiplier Technique ◽  
Joint Coordinates ◽  
Minimum Number ◽  
Kinematic Loops ◽  
Equations Of Motions

This papers presents a systematic method for deriving the minimum number of equations of motion for multibody system containing closed kinematic loops. A set of joint or natural coordinates is used to describe the configuration of the system. The constraint equations associated with the closed kinematic loops are found systematically in terms of the joint coordinates. These constraints and their corresponding elements are constructed from known block matrices representing different kinematic joints. The Jacobian matrix associated with these constraints is further used to find a velocity transformation matrix. The equations of motions are initially written in terms of the dependent joint coordinates using the Lagrange multiplier technique. Then the velocity transformation matrix is used to derive a minimum number of equations of motion in terms of a set of independent joint coordinates. An illustrative example and numerical results are presented, and the advantages and disadvantages of the method are discussed.

scholarly journals Differential Quadrature and Differential Transformation Methods in Buckling Analysis of Nanobeams

2019 ◽  
Vol 6 (1) ◽  
pp. 68-76 ◽  
Author(s):  
Subrat Kumar Jena ◽  
S. Chakraverty
Keyword(s):  
Boundary Conditions ◽  
Differential Quadrature Method ◽  
Nonlocal Parameter ◽  
Transformation Method ◽  
Nonlocal Theory ◽  
Buckling Analysis ◽  
Differential Quadrature ◽  
Load Parameter ◽  
Computationally Efficient ◽  
Differential Transformation

AbstractIn this paper, two computationally efficient techniques viz. Differential Quadrature Method (DQM) and Differential Transformation Method (DTM) have been used for buckling analysis of Euler-Bernoulli nanobeam incorporation with the nonlocal theory of Eringen. Complete procedures of both the methods along with their mathematical formulations are discussed, and MATLAB codes have been developed for both the methods to handle the boundary conditions. Various classical boundary conditions such as SS, CS, and CC have been considered for investigation. A comparative study for the convergence of DQM and DTM approaches are carried out, and the obtained results are also illustrated to demonstrate the effects of the nonlocal parameter, aspect ratio (L/h) and the boundary condition on the critical buckling load parameter.

scholarly journals An Effective Potential for Frenkel Excitons

2020 ◽  
Author(s):  
Bartosz Błasiak ◽  
Wojciech Bartkowiak ◽  
Robert Władysław Góra
Keyword(s):  
Energy Transfer ◽  
Excitation Energy ◽  
Efficient Method ◽  
Effective Potential ◽  
Excitation Energy Transfer ◽  
Computationally Efficient ◽  
Frenkel Excitons

Excitation energy transfer (EET) is a ubiquitous process in life and materials sciences. Here, a new and computationally efficient method of evaluating the electronic EET couplings between interacting chromophores is...

Modal Control by Modal Force Technique

1991 ◽  
Author(s):  
C. D. Tsai ◽  
M. S. Ju ◽  
Y. G. Tsuei
Keyword(s):  
Feedback Control ◽  
Control Problem ◽  
Efficient Method ◽  
Time Domain ◽  
Modal Control ◽  
Global Dynamic ◽  
Recent Developments ◽  
Modal Force ◽  
Frequency Domain Approach ◽  
Direct Feedback

Abstract Modal control of structure requires the estimation of the modal states variables for feedback. One approach that does not require modal states variables estimation is the direct feedback control. Recent developments in modal control for direct feedback are mainly time domain methods. In this paper, an efficient method based on frequency domain approach named Modal Force Technique is developed. The method not only allows one to modify the global dynamic behavior of the synthesized structure but also can be utilized for modal control problem if the acceleration, velocity and displacement feedbacks are used.

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