A NUMERICAL SIMULATION INVESTIGATION OF THE HYDRODYNAMIC MOTIONS OF A SHIP ADVANCING IN WAVES

2021 ◽  
Vol 156 (A4) ◽  
Author(s):  
D C Lo ◽  
D T Su ◽  
J T Lin
Keyword(s):  
Computer Aided Design ◽  
Degrees Of Freedom ◽  
Fluid Dynamic ◽  
Wave Interaction ◽  
Six Degrees Of Freedom ◽  
Ship Model ◽  
Computer Aided ◽  
Cad Tool ◽  
Aided Design ◽  
Wave Incidence

This study establishes a relationship diagram of the ship-wave interaction under a ship advancing in waves. A finite difference method based on volume of fluid (VOF) principles was used to simulate the hydrodynamic motions of a ship advancing in waves. A ship model was constructed using a computer aided design (CAD) tool. The computational fluid dynamic (CFD) technique was used to calculate the hydrodynamic motions effect of a ship sailing in waves at varying angles of incidence. This study investigates a number of significant related parameters, such as the speed of the ship model, the various wave incidence angles, the wave height, and the navigation time. A chart is also used to show the flow field, and changes in the six degrees of freedom motion and continually compare changes in the drag force.

Solving reachable workspace of some parallel manipulators by computer-aided design variation geometry

2008 ◽  
Vol 222 (9) ◽  
pp. 1773-1781 ◽  
Author(s):  
Y Lu ◽  
Y Shi ◽  
B Hu
Keyword(s):  
Computer Aided Design ◽  
Degrees Of Freedom ◽  
Parallel Manipulators ◽  
Six Degrees Of Freedom ◽  
Reachable Workspace ◽  
Spline Curves ◽  
Computer Aided ◽  
Design Variation ◽  
Aided Design ◽  
The Given

To shape the workspace of some novel parallel manipulators (PMs) is significant. A novel computer-aided design (CAD) variation geometry approach is proposed to shape and solve the reachable workspace of some PMs with three to six degrees of freedom (DOFs). Some basic techniques are described for designing the simulation mechanism and solving the reachable workspace. The simulation mechanisms of some PMs with three to six DOFs are created. When varying the driving dimensions of the active legs in the given extent, the simulation mechanisms vary correspondingly, and the position components of the moving platform are solved automatically. By transferring the position solutions into spatial spline curves in the simulation mechanism, all the boundary surfaces of the workspace can be created and visualized dynamically. Comparing with analytic approaches for solving workspace, the CAD variation geometry approach is simple, straightforward, accurate, and repeatable.

Determination of the Workspace of a Three-Degrees-of-Freedom Parallel Manipulator Using a Three-Dimensional Computer-Aided-Design Software Package and the Concept of Virtual Chains1

2015 ◽  
Vol 8 (2) ◽  
Author(s):  
Andrew Johnson ◽  
Xianwen Kong ◽  
James Ritchie
Keyword(s):  
Computer Aided Design ◽  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Graphical Representation ◽  
Three Dimensional ◽  
Parallel Manipulators ◽  
Workspace Analysis ◽  
Computer Aided ◽  
Aided Design

The determination of workspace is an essential step in the development of parallel manipulators. By extending the virtual-chain (VC) approach to the type synthesis of parallel manipulators, this technical brief proposes a VC approach to the workspace analysis of parallel manipulators. This method is first outlined before being illustrated by the production of a three-dimensional (3D) computer-aided-design (CAD) model of a 3-RPS parallel manipulator and evaluating it for the workspace of the manipulator. Here, R, P and S denote revolute, prismatic and spherical joints respectively. The VC represents the motion capability of moving platform of a manipulator and is shown to be very useful in the production of a graphical representation of the workspace. Using this approach, the link interferences and certain transmission indices can be easily taken into consideration in determining the workspace of a parallel manipulator.

A Reduced‐Fluid Dynamic Discharge Model for Applications in Technology‐Oriented Computer‐Aided Design

1996 ◽  
Vol 143 (6) ◽  
pp. 1940-1944
Author(s):  
R. P. Brinkmann ◽  
R. Fürst ◽  
Chr. Werner ◽  
Matthias Hierlemann
Keyword(s):  
Computer Aided Design ◽  
Fluid Dynamic ◽  
Computer Aided ◽  
Discharge Model ◽  
Aided Design ◽  
Dynamic Discharge

Mechanical/Naval Design of an Underwater Remotely Operated Vehicle (ROV) for Surveillance and Inspection of Port Facilities

2007 ◽  
Author(s):  
Juan A. Rami´rez ◽  
Rafael E. Va´squez ◽  
Luis B. Gutie´rrez ◽  
Diego A. Flo´rez
Keyword(s):  
Visual Information ◽  
Computer Aided Design ◽  
Degrees Of Freedom ◽  
Remotely Operated Vehicle ◽  
Port Facilities ◽  
Computer Aided ◽  
Computational Fluid Dynamics Cfd ◽  
High Level ◽  
Aided Design ◽  
And Control

This paper presents the mechanical/naval design process of an underwater remotely operated vehicle (ROV), required to obtain reliable visual information, used for surveillance and maintenance of ship shells and underwater structures of Colombian port facilities. The design was divided into four main subsystems: mechanical/naval, hardware, software and guidance, navigation and control. The most relevant design constraints were evaluated considering environmental conditions, dimensional restrictions, hydrostatics, hydrodynamics, degrees of freedom and the availability of instrumentation and control hardware. The mechanical/naval design was performed through an iterative process by using computational tools, including Computer Aided Design CAD, Computer Aided Engineering CAE, Computational Fluid Dynamics CFD and a high level programming environment. The obtained design ensures that the reliable operation of the robot will be achieved by using a consistent construction process. The new ROV constitutes an innovative product in Colombia, and it will be used for surveillance and oceanographic research tasks.

SPICE MODEL FOR COMPUTER-AIDED DESIGN OF BIOPOTENTIAL AMPLIFIER

2004 ◽  
Vol 16 (03) ◽  
pp. 151-156 ◽  
Author(s):  
YUN-LI LIU ◽  
DONG-LONG LIN ◽  
YUE-DER LIN
Keyword(s):  
Computer Aided Design ◽  
Electrode Impedance ◽  
External Interference ◽  
Proposed Model ◽  
Computer Aided ◽  
Biopotential Amplifier ◽  
Cad Tool ◽  
Power Line Interference ◽  
Aided Design ◽  
Distinct Features

There are many different kinds of biopotential signal. These signals are tiny in amplitude and the measurement is easily corrupted by external interference. For these reasons, the design of high-quality biopotential amplifier is usually an empirical task. To make the design of biopotential amplifier more efficient, this study proposes a simulation model for bioelectric signal measurement such that the design task can be achieved thoroughly by powerful computer-aided design (CAD) tool. The proposed model has two distinct features, one is the simulated biopotential signal is used for the genesis of biosignal, and the other one is the skin-electrode impedance is replaced by its corresponding equivalent circuit, which is a complex RC network. To verify the feasibility of the proposed model, an ECG amplifier is designed in Spice-related CAD tool and is implemented for ECG recording. From the results, the amplifier characteristics agree well between the simulated and the implemented circuit. Besides, the effect due to the commonly encountered power-line interference during biopotential measurement can be reasonably evaluated in the proposed model.

Computer-Aided Design of a Cleanroom Ceiling Plenum System with a Limited Space for HVAC Equipment

1999 ◽  
Vol 42 (6) ◽  
pp. 34-39 ◽  
Author(s):  
Ting-Kwo Lei ◽  
Andrew Manning ◽  
Felix Kersting
Keyword(s):  
Flow Field ◽  
Computational Fluid Dynamic ◽  
Computer Aided Design ◽  
Fluid Dynamic ◽  
Flow Distribution ◽  
Velocity Fields ◽  
Computer Aided ◽  
Distribution Uniformity ◽  
Aided Design ◽  
Number Of Cells

Acommercial Computational Fluid Dynamic (CFD) software program was used to analyze the flow field inside a cleanroom ceiling plenum. The design required restricted space for the HVAC equipment. The effect of the number of cells used in the computational model on the simulation output was investigated. Pressure and velocity fields were examined. A comparison of flow distribution uniformity between a reference ceiling plenum system and a ceiling plenum system containing more ducted air supplies was made. An analysis of the effect of diffusion plates was conducted.

A Computer-Aided Design Tool in Java for Planar Gripper Design

2004 ◽  
Vol 4 (1) ◽  
pp. 43-48 ◽  
Author(s):  
Mike Tao Zhang ◽  
Ken Goldberg
Keyword(s):  
Computational Efficiency ◽  
Computer Aided Design ◽  
Design Tool ◽  
Java Applet ◽  
Physical Experiments ◽  
Computer Aided ◽  
Cad Tool ◽  
Aluminum Part ◽  
Aided Design ◽  
Final Orientation

We describe an Internet-based CAD tool that automatically designs gripper jaws that will rotate a given rigid convex polygonal part from a selected stable resting orientation to a desired final orientation to facilitate insertion or assembly. In this paper we describe the CAD algorithm, its Java implementation, and improvements that relax input specifications and improve computational efficiency. We illustrate with physical experiments using a machined aluminum part and the resulting gripper as designed by the CAD tool. We also consider cases where a solution may not exist and derive a class of triangular parts that cannot be rotated with the planar grippers. The CAD tool, implemented as a Java applet, is available online at www.ieor.berkeley.edu/∼goldberg/sa-gripper/.

Dynamic rolling analysis of triangular-bipyramid robot

Robotica ◽  
2014 ◽  
Vol 33 (4) ◽  
pp. 884-897 ◽  
Author(s):  
Yaobin Tian ◽  
Yan-An Yao
Keyword(s):  
Kinematic Analysis ◽  
Computer Aided Design ◽  
Degrees Of Freedom ◽  
Step Length ◽  
Computer Aided ◽  
Zero Moment ◽  
Aided Design ◽  
Four Bar Linkage ◽  
Three Degrees Of Freedom ◽  
Rolling Robot

SUMMARYIn this paper a rolling robot resembling the shape of a triangular-bipyramid is proposed. The robot has three degrees of freedom and is formed by connecting two tripod mechanisms with three spherical joints. By kinematic analysis, the robot can be viewed as a planar four-bar linkage. Further, its dynamic rolling ability is discussed by Zero Moment Point (ZMP) analysis. We show that the robot has the capability to roll, adjust its step length, and switch rolling directions. These functions are verified by a series of simulations with a CAD (computer-aided design) model and experiments with a prototype.

scholarly journals Computer Aided Design and Analysis of Tapping Tool with Diametrical flexibility

2017 ◽  
Vol 7 (2 (S)) ◽  
pp. 226
Author(s):  
Satish Bahale ◽  
Amit Shende
Keyword(s):  
Computer Aided Design ◽  
Metal Cutting ◽  
Longitudinal Axis ◽  
Rotational Energy ◽  
Machined Surface ◽  
Machine Shop ◽  
Computer Aided ◽  
Cutting Operation ◽  
Cad Tool ◽  
Aided Design

Tapping operation which refers to production of internal threads forms an integral part of any machine shop and it is intended to provide semi permanent fastening to the components of product so as to lend themselves for repairs and replacements. Though various methods of internal threading are available such as internal threading by milling, grinding or forming but internal threading by metal cutting which employs a tapping tool is indeed the mostly used for products where accuracy forms the base of evaluation. Last few decades have seen the growth of automobile industries and has resulted in development of its allied operations of which tapping is one of the crucial operation performed. The conventional tapping operation which surely involves rotating the tool and feeding past the pre drilled hole to create the contours called as internal threads and this is followed by withdrawal of tapping tool by reversing it with aid of rotational energy. The present paper attempts to design and analyze a tapping tool which will have no requirement of reversing of tool at the end of cutting operation which is essentially done by changing the design of conventional solid tap. The solid tapping tool is divided into two parts along the longitudinal axis and a mechanism is prompted to give the two parts actuation which would shrink at the end of cutting operation to be dragged out of hole without damaging the machined surface and providing the diametrical flexibility to engulf other diameters to be machined. This tapping tool with diametrical flexibility is designed in CAD tool named as CATIA V5 and efficiently analyzed by using FEA technique which is the working phenomenon for ANSYS.

scholarly journals Development of robotic polishing/fettling system on ceramic pots

2021 ◽  
Vol 18 (3) ◽  
pp. 172988142110128
Author(s):  
Zhangguo Yu ◽  
Hsien-I Lin
Keyword(s):  
Computer Aided Design ◽  
Degrees Of Freedom ◽  
Force Sensor ◽  
Ball Screw ◽  
Force Response ◽  
Geometric Models ◽  
Six Degrees Of Freedom ◽  
Robot Trajectory ◽  
Polishing Force ◽  
Aided Design

Current robot polishing techniques are available for objects with computer-aided design geometric models but not for objects without geometric models such as ceramic or clay pots. In this study, we developed a robotic polishing/fettling system to polish the molding defects of ceramic objects. The polishing force on the object surfaces is required to be constant to obtain better results. Thus, the proposed robotic polishing system was designed with a stepper motor, ball screw, and force sensor. The proposed system acquired a rough robot polishing/fettling trajectory and adopted a fuzzy proportional–integral–derivative controller to regulate the trajectory to maintain the desired contact force response from a ceramic object. We developed the temporary desired value technique to make the polishing force response close to the desired one. We validated the system on a six-degrees-of-freedom Staubli TX 40L robotic arm. Experiments were performed to test the effectiveness of the system. The robot trajectory responses showed that the proposed system performed well in tracking the desired force in the polishing/fettling process. We used a 3D microscope to verify that the molding defect of the ceramic pot was significantly removed to evaluate the polishing/fettling quality.

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