scholarly journals Analysis of the Coupled Dynamics of an Offshore Floating Multi-Purpose Platform: Part A — Rigid Body Analysis

2019 ◽  
Author(s):  
L. Li ◽  
M. Collu ◽  
C. Ruzzo ◽  
G. Failla ◽  
K. A. Abhinav ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Rigid Body ◽  
Coupled Model ◽  
Rigid Body Dynamic ◽  
The Past ◽  
Wave Energy Converters ◽  
Operational Load ◽  
Hydroelastic Analysis ◽  
Offshore Industry ◽  
Body Dynamic

Abstract A multi-purpose platform (MPP) is an offshore system designed to serve the purposes of more than one offshore industry. Indeed, over the past decades, a number of industries have expanded, or are expanding, from onshore to offshore locations (renewables, aquaculture, tourism, mineral extractions, etc.), and the research on these type of platform is increasing. In the present work, a MPP able to accommodate wind turbines, wave energy converters, and aquaculture systems are considered. This work presents the first part (Part A) of the analyses of the dynamics of the floating support structure for this MPP, focusing on the rigid body dynamic response, while its complementary hydroelastic analysis is presented in Part B (OMAE2019-96282). The aim here is to assess the dynamic response of the platform with respect to the preliminary requirements imposed by the wind turbine, the aquaculture system, and the other ancillary systems. After describing the platform analyzed, and explaining the aero-hydro coupled model of dynamics approach adopted, two independent analyses are conducted, one using the SESAM package by DNV-GL, and another using ANSYS AQWA, in order to verify the results, in absence of experimental data. Considering a severe, but still operational, load case, the preliminary results seem to demonstrate that the chosen platform can satisfy the dynamics constraints imposed by the payload systems.

Steady-State Rigid-Body Dynamic Response of Cam-Follower Mechanisms

1994 ◽  
Author(s):  
Andi I. Mahyuddin ◽  
Ashok Midha
Keyword(s):  
Steady State ◽  
Dynamic Response ◽  
Rigid Body ◽  
Angular Speed ◽  
Integration Scheme ◽  
Rigid Body Dynamic ◽  
Speed Variation ◽  
Cam Follower ◽  
Speed Fluctuation ◽  
Body Dynamic

Abstract The camshaft of a cam-follower mechanism experiences a position-dependent moment due to the force exerted on the cam by the follower, causing the angular speed of the camshaft to fluctuate. In this work, a method to expediently predict the camshaft speed fluctuation is developed. The governing equation of motion is derived assuming that the cam-follower system is an ideal one wherein all members are treated as rigid. An existing closed-form numerical algorithm is used to obtain the steady-state rigid-body dynamic response of a machine system. The solution considers a velocity-dependent moment; specifically, a resisting moment is modeled as a velocity-squared damping. The effects of flywheel size and resisting moment on camshaft speed fluctuation are studied. The results compare favorably with those obtained from transient response using a direct integration scheme. The analytical result also shows excellent agreement with the camshaft speed variation of an experimental cam-follower mechanism. The steady-state rigid-body dynamic response obtained herein also serves as a first approximation to the input camshaft speed variation in the dynamic analysis of flexible cam-follower mechanisms in a subsequent research.

scholarly journals Analysis of the Coupled Dynamics of an Offshore Floating Multi-Purpose Platform: Part B — Hydro-Elastic Analysis With Flexible Support Platform

2019 ◽  
Author(s):  
C. Ruzzo ◽  
G. Failla ◽  
F. Arena ◽  
M. Collu ◽  
L. Li ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Rigid Body ◽  
Beam Model ◽  
Elastic Analysis ◽  
Wave Loads ◽  
Support Structure ◽  
Substantial Impact ◽  
Wave Energy Converters ◽  
Restoring Forces ◽  
Offshore Industry

Abstract A multi-purpose platform (MPP) is an offshore system designed to serve the purposes of more than one offshore industry. Indeed, over the past decades, a number of industries have expanded, or are expanding, from onshore to offshore locations (renewables, aquaculture, tourism, mineral extractions, etc), and the research on these type of platform is increasing. In the present work, a MPP able to accommodate wind turbines, wave energy converters, and aquaculture systems is considered. For an overview of the MPP platform considered and its research context, please refer to the EU H2020 project overview (OMAE 2019-96104). This work presents the second part (Part B) of the analyses of the dynamics of the floating support structure for this MPP, focusing on the hydro-elastic analysis, while its complementary rigid-body hydrodynamic analysis is presented in Part A (OMAE2019-96212). The aim here is to assess if the support platform structural elasticity has a substantial impact on the dynamic response of the platform. A beam model and a 3D solid model of the support structure have been developed, and the inertial forces, hydrodynamic added mass forces, hydrostatic and mooring restoring forces have been considered in the hydro-elastic analyses performed. The results show that the dynamic response to the wave loads is not substantially influenced by the elasticity of the support structure, and that, at first approximation, a rigid-body approach is acceptable.

On Steady-State Response of Multi-Cylinder Engine System

1996 ◽  
Author(s):  
Yassir Shanshal ◽  
Kambiz Farhang
Keyword(s):  
Steady State ◽  
Dynamic Response ◽  
Rigid Body ◽  
Combustion Engine ◽  
Rigid Body Dynamic ◽  
State Response ◽  
Combustion Duration ◽  
Crank Angle ◽  
Engine Systems ◽  
Body Dynamic

Abstract This paper deals with the rigid-body dynamic response of an internal combustion engine. An earlier work (Farhang and Midha, 1989) has presented an efficient algorithm for computing the steady-state rigid-body dynamic response of single degree of freedom engine systems. The method is utilized in the present work to examine the effects of spark time and combustion duration on the performance of a four-stroke, four-cylinder engine. In contrast with the earlier work in which combustion is viewed as an instantaneous process, in this work the combustion is accounted for and is related to the reference crank angle.

A Closed-Form Numerical Method for Calculating the Steady-State Dynamic Response of Rigid-Body Machine Systems

1989 ◽  
Vol 111 (1) ◽  
pp. 66-72 ◽  
Author(s):  
K. Farhang ◽  
A. Midha
Keyword(s):  
Steady State ◽  
Dynamic Response ◽  
Rigid Body ◽  
Closed Form ◽  
Computation Time ◽  
Variable Coefficients ◽  
Average Speed ◽  
Rigid Body Dynamic ◽  
Machine Systems ◽  
Body Dynamic

The rigid-body dynamic response of most single-degree-of-freedom machine systems are known to be governed by second-order, nonlinear, inhomogeneous, ordinary differential equations with variable coefficients. An earlier effort produced a solution algorithm, by linearizing such an equation and expressing it in the first-order form, to obtain the steady-state rigid-body dynamic response. This paper formulates a “closed-form numerical” algorithm for obtaining this steady-state response. It is demonstrated as leading to significant reductions in computation time. Efficient iterative methods, based on the criterion of balance of energy over the fundamental cycle, are formulated to treat the more practical problems involving known forcing and unknown average speed, and those involving unknown forcing and known average speed. In addition, two numerical procedures are proposed to treat problems involving systems with large coefficients of fluctuations. All methods are shown to be efficient and stable through examples involving a four-stroke reciprocating engine.

scholarly journals Implicit Constraint Enforcement for Rigid Body Dynamic Simulation

2006 ◽  
pp. 490-497 ◽  
Author(s):  
Min Hong ◽  
Samuel Welch ◽  
John Trapp ◽  
Min-Hyung Choi
Keyword(s):  
Rigid Body ◽  
Dynamic Simulation ◽  
Rigid Body Dynamic ◽  
Constraint Enforcement ◽  
Body Dynamic

Pseudo-rigid-body dynamic modeling and analysis of compliant mechanisms

2017 ◽  
Vol 232 (9) ◽  
pp. 1665-1678 ◽  
Author(s):  
Yue-Qing Yu ◽  
Qian Li ◽  
Qi-Ping Xu
Keyword(s):  
Rigid Body ◽  
Dynamic Model ◽  
Dynamic Modeling ◽  
Dynamic Models ◽  
Compliant Mechanisms ◽  
Lagrange Equation ◽  
Dynamic Responses ◽  
Modeling And Analysis ◽  
Rigid Body Dynamic ◽  
Body Dynamic

An intensive study on the dynamic modeling and analysis of compliant mechanisms is presented in this paper based on the pseudo-rigid-body model. The pseudo-rigid-body dynamic model with single degree-of-freedom is proposed at first and the dynamic equation of the 1R pseudo-rigid-body dynamic model for a flexural beam is presented briefly. The pseudo-rigid-body dynamic models with multi-degrees-of-freedom are then derived in detail. The dynamic equations of the 2R pseudo-rigid-body dynamic model and 3R pseudo-rigid-body dynamic model for the flexural beams are obtained using Lagrange equation. Numerical investigations on the natural frequencies and dynamic responses of the three pseudo-rigid-body dynamic models are made. The effectiveness and superiority of the pseudo-rigid-body dynamic model has been shown by comparing with the finite element analysis method. An example of a compliant parallel-guiding mechanism is presented to investigate the dynamic behavior of the mechanism using the 2R pseudo-rigid-body dynamic model.

SPHERE ENCAPSULATED ORIENTED-DISCRETE ORIENTATION POLYTOPES (S-DOP) COLLISION CULLING FOR MULTI-, RIGID BODY DYNAMIC

2015 ◽  
Vol 75 (2) ◽  
Author(s):  
Norhaida Mohd Suaib ◽  
Abdullah Bade ◽  
Dzulkifli Mohamad
Keyword(s):  
Rigid Body ◽  
Collision Detection ◽  
Simulation System ◽  
Improve Performance ◽  
Excellent Performance ◽  
Approximation Techniques ◽  
Rigid Body Dynamic ◽  
Rigid Body Simulation ◽  
Body Dynamic

This paper discusses on sphere encapsulated oriented-discrete orientation polytopes (therefore will be referred to as S-Dop) collision culling for multiple rigid body simulation. In order to improve performance of the whole simulation system, there are available options in sacrificing the accuracy over speed by using certain approximation techniques. The aim of this research is to achieve excellent performance through implementation of suitable culling technique, without jeopardizing the resulting behavior so that the simulation will still be physically plausible. The basic idea is to identify the highly probable pairs to collide and test the pair with a more accurate collision test in broad-phase collision detection, before the pair is passed to a more costly stage. Results from the experiments showed that there are a number of ways to implement the sphere encapsulated or-Dops (S-Dop) collision culling on a multiple rigid body simulation depending on the level of performance needed.  

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