Detailed Analyses of the Tow Line Behaviour in Single, Double and Triple Towages in Case of Emergency Stop and Catenary

2011 ◽  
Author(s):  
A. J. Bos ◽  
R. Heemskerk
Keyword(s):  
Element Model ◽  
Numerical Approach ◽  
Stopping Distance ◽  
Contingency Plans ◽  
Safe Side ◽  
Emergency Stop ◽  
The Wire ◽  
Engine Failure ◽  
The Moment ◽  
Model Approach

Two phenomena have been studied in order to enhance the contingency plans and improve the safety of towages. 1. For multi tug towages it is important to prepare proper contingency plans for the case that a tug fails and overrun by the tow is a probability, especially the towages of FPSO’s and huge rigs performed by more tugs. A model has been developed to assess the time between the failure and the moment the tow will collide. After thorough research not the stopping distance proved important, but the time it takes for both objects to collide. In case the tug is allowed to be pulled towards the FPSO, the time from engine failure to collision is 380 [s] or 6 minutes 20 seconds. Both objects will collide with a speed difference of 2.28 [m/s]. In case the towline is cut, the time until collision is 1479 [s], or 24 minutes and 40 seconds. In this case it is very important to cut the towline instantly after the engine failure. Otherwise the tug will gain a negative speed of 1 m/s within 2 minutes, and the distance between the FPSO and the tug will be reduced to 683 [m] already. 2. Grounding of tow lines must be avoided the standard of the catenary approach to assume a hyperbolic shape is investigated and a detailed finite element model approach shows that the standard assumptions are not accurate enough. A numerical approach has been used to calculate the effect of current and loss of tension in the wire. The influence of current along the towing-wire depends on the speed, diameter, length and the angle of the towing-wire in the water. The maximum depth increases when the speed increases or the tension in the wire decreases. In the example the depths are on the safe side for depths below 35[m], but above 35[m] the values are too optimistic when current is involved.

Calculating Mechanics Characteristics of Single-Walled Carbon Nanotube Materials by Finite Element Method

2017 ◽  
Vol 730 ◽  
pp. 548-553
Author(s):  
Jing Ge ◽  
Hao Jiang ◽  
Zhen Yu Sun ◽  
Guo Jun Yu ◽  
Bo Su ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Radial Direction ◽  
Element Model ◽  
Beam Element ◽  
Beam Position ◽  
Single Walled Carbon ◽  
Finite Element Software ◽  
Calculation Results ◽  
The Moment

In this paper, we establish the mechanical property analysis of Single-walled Carbon Nanotubes (SWCNTs) modified beam element model based on the molecular structural mechanics method. Then we study the mechanical properties of their radial direction characteristics using the finite element software Abaqus. The model simulated the different bending stiffness with rectangular section beam elements C-C chemical force field. When the graphene curled into arbitrary chirality of SWCNTs spatial structure, the adjacent beam position will change the moment of inertia of the section of the beam. Compared with the original beam element model and the calculation results, we found that the established model largely reduced the overestimate of the original model of mechanical properties on the radial direction of the SWCNTs. At the same time, compared with other methods available in the literature results and the experimental data, the results can be in good agreement.

A Simplified Approach to Estimate Flow-Induced Vibrations on an Elbowed Piping System

2018 ◽  
Author(s):  
André Baramili ◽  
Ludovic Chatellier ◽  
Laurent David ◽  
Loïc Ancian
Keyword(s):  
Element Model ◽  
Numerical Approach ◽  
Piping System ◽  
Least Squares Regression ◽  
Flow Induced Vibration ◽  
Simplified Approach ◽  
Eddy Simulation ◽  
Spatially Distributed ◽  
Closed Water ◽  
Modeling Strategy

A mixed experimental and numerical approach was undertaken in order to develop a data-based model of the flow-induced vibration levels attained in a piping system containing a 90° elbow. A closed water loop was used to provide unsteady flow data as well as wall pressure and vibration measurements. In parallel, the unsteady water flow through the elbow was computed using an incompressible Large-Eddy Simulation (LES). Proper Orthogonal Decomposition (POD) and Partial Least Squares Regression (PLSR) were used in order to build a relationship between the flow properties and the resulting excitation. This relationship was then used to estimate the evolution of the spatially distributed loadings, which were finally applied to a finite element model of the piping structure. The results consisted of an estimation of the vibration levels. The estimated vibrations were then compared to measurements in order to validate the proposed modeling strategy.

scholarly journals Predicting Fusing Current for Encapsulated Wire Bonds under Transient Loads

2010 ◽  
Vol 2010 (1) ◽  
pp. 000486-000493 ◽  
Author(s):  
Aditi Mallik ◽  
Roger Stout
Keyword(s):  
Single Pulse ◽  
Element Model ◽  
Current Response ◽  
Temperature Dependent ◽  
Wire Bonds ◽  
Potential Failure ◽  
Different Dimensions ◽  
Transient Loads ◽  
The Wire ◽  
Set Up

For high power IC chips, as device size inevitably decreases, the wire diameter unfortunately must decrease due to the need of finer pitch wires. Fusing or melting of wirebonds thus increasingly becomes one of the potential failure issues for such IC's. Experiments were performed under transient loads on dummy packages having aluminum, gold, or copper wires of different dimensions. A finite element model was constructed that correlates very well with the observed maximum operating currents for such wirebonds under actual experimental test conditions. A qualitative observation of typical current profiles, as fusing conditions were approached, was that current would reach a maximum value very early in the pulse, and then fall gradually. One goal achieved through the modeling was to show that the current in the wire falls with time due to the heating of the wire material. Correspondingly, the wire reaches the melting temperature not at the peak current but rather at the end of pulse. Further, modeling shows that knowledge of external resistance and inductance of the experimental set up are highly significant in determining the details of a fusing event, but if known along with the temperature-dependent wire properties, the simulation can predict the correct voltage and current response of the part with 2% error. On the other hand, lack of external circuit characteristics may lead to completely incorrect results. For instance, the assumption that current is constant until the wire heats to fusing temperature, or that current and temperature both rise monotonically to maximum values until the wire fuses, are almost certain to be wrong. The work has been carried out for single pulse events as well as pulse trains.

Simulation Research on Cross-Sectional Stability of Expanded Diameter Conductors Based on ANSYS

2012 ◽  
Vol 256-259 ◽  
pp. 2838-2843
Author(s):  
Jia Jun Si ◽  
Jian Cheng Wan ◽  
Bin Liu ◽  
Yao Ding
Keyword(s):  
Power Transmission ◽  
Element Model ◽  
Aluminum Wire ◽  
Key Factors ◽  
Cross Sectional ◽  
Simulation Research ◽  
Contact Points ◽  
Electricity Power ◽  
The Wire ◽  
Significant Factors

The expanded diameter conductors are widely used for high voltage electricity power transmission due to its superior ability to prevent electronic corona phenomenon. However an undesired stability problem of wire distribution configuration within the cross-section of the conductor often occurs during the power line stringing processes, especially for the not-well-designed conductor structures. This phenomenon is typically characterized by the appearance of outer wire/wires jumping out of the layer; therefore it is also referred as wire jump-out problem. Finite element model which can predict the wire jump-out phenomenon has been successfully developed in this research project. Series of stimulations have been carried out to investigate the key factors to cause the wire jump-out problem. The reduction of radial distances between the adjacent aluminum wire layers due to the obvious indentation deformation at the trellis contact points were identified to be one of the most significant factors to lead to the wire jump-out problem. Numerical results show that keeping sufficient initial gap between the adjacent outer layer wires in the initial design can be a simple effective way to relieve/avoid the wire jump-out problem.

A Numerical Approach for the Prediction and Reduction of Structure-Borne Noise During the Design Stage of Ground Vehicles

1993 ◽  
Author(s):  
Nickolas Viahopoulos ◽  
Edward V. Shalis ◽  
Michael A. Latcha
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Numerical Approach ◽  
Design Stage ◽  
Structural Components ◽  
Ground Vehicles ◽  
Radiated Noise ◽  
Forcing Function ◽  
Military Applications ◽  
Commercial Applications

Abstract During the design stage of ground vehicles it is important to reduce the noise emitted from structural components. In commercial applications the reduction of the interior noise for passenger comfort is a concern with increased significance. In military applications noise radiated from the exterior of the vehicle is of primary importance for the survivability of the vehicle. Numerical acoustic prediction software can be used during the design stage to predict and reduce the radiated noise. Two formulations, the Rayleigh integral equation1 and the direct boundary element method2,3 were implemented into software for acoustic prediction. The developed code can accept information from a finite element model with a known input forcing function. Specifically, the predicted velocities on the structural surfaces can be used as input to the acoustic code for predicting the noise emitted from a vibrating structure. Computation of acoustic sensitivities4 was also implemented in the code. This information can identify the portions of the boundary that effect the radiated noise most, and it can be used in an optimization process to reduce the noise radiated from a vibrating structure.

Rigid-Plastic Collapse of Cylindrical Shells

1973 ◽  
Vol 95 (1) ◽  
pp. 215-218 ◽  
Author(s):  
H. M. Haydl ◽  
A. N. Sherbourne
Keyword(s):  
Limit Analysis ◽  
Cylindrical Shells ◽  
Numerical Approach ◽  
External Pressure ◽  
Plastic Collapse ◽  
Rigid Plastic ◽  
Limit Loads ◽  
Complex Problems ◽  
Safe Side ◽  
Von Mises

This paper suggests a simple numerical approach to the limit analysis of cantilever cylindrical shells. The loads considered are external pressure and external pressure combined with a moment at the free shell end. It is shown that the collapse loads are within 4.5 percent on the safe side of the exact von Mises limit loads. The extension of the method of analysis to more complex problems is suggested.

Dynamic Behavior of String Subjected to Travelling Mass

2019 ◽  
Author(s):  
Shakti P. Jena ◽  
S. Naresh Kumar ◽  
Hemanth Cheedella
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Green’S Function ◽  
Dynamic Behavior ◽  
Green's Function ◽  
Transverse Vibration ◽  
Element Model ◽  
Numerical Approach ◽  
Complete Analysis ◽  
Numerical Example

Abstract The present study is based on the transverse vibration analogy of a string subjected to a travelling mass. The string is considered to be fixed at their both ends. The responses of the string due to the dynamic behavior of the travelling mass are determined using a numerical approach i.e. Green’s function. A Finite Element Model (FEM) has been developed to authenticate the numerical approach. For the responses analysis of the string, numerical example has been illustrated to study the behavior of the string due to the travelling mass and to check the convergence of the two proposed analogies (Green’s function and FEM). The complete analysis has been performed at constant travelling speed and different masses. The two approaches converge well and the Green’s function methodology found to be suitable one.

scholarly journals A Numerical Approach to Solve Volume-Based Batch Crystallization Model with Fines Dissolution Unit

Processes ◽  
2019 ◽  
Vol 7 (7) ◽  
pp. 453 ◽  
Author(s):  
Mukhtar ◽  
Sohaib ◽  
Ahmad
Keyword(s):  
Numerical Approximation ◽  
Chemical Engineering ◽  
Numerical Study ◽  
Moment Generating Function ◽  
Numerical Approach ◽  
Test Problems ◽  
Batch Crystallization ◽  
One Dimensional ◽  
Engineering Sciences ◽  
The Moment

In this article, a numerical study of a one-dimensional, volume-based batch crystallization model (PBM) is presented that is used in numerous industries and chemical engineering sciences. A numerical approximation of the underlying model is discussed by using an alternative Quadrature Method of Moments (QMOM). Fines dissolution term is also incorporated in the governing equation for improvement of product quality and removal of undesirable particles. The moment-generating function is introduced in order to apply the QMOM. To find the quadrature abscissas, an orthogonal polynomial of degree three is derived. To verify the efficiency and accuracy of the proposed technique, two test problems are discussed. The numerical results obtained by the proposed scheme are plotted versus the analytical solutions. Thus, these findings line up well with the analytical findings.

scholarly journals A new elastic slot system and V-wire mechanics

2017 ◽  
Vol 87 (5) ◽  
pp. 774-781 ◽  
Author(s):  
Andrea Wichelhaus
Keyword(s):  
Permanent Deformation ◽  
Biomechanical Testing ◽  
Three Dimensional ◽  
Nickel Titanium ◽  
Dental Arch ◽  
Rectangular Slot ◽  
Torque Measurements ◽  
Conventional Brackets ◽  
The Wire ◽  
The Moment

ABSTRACT Objective: To biomechanically test a new elastic slot system and V-wire mechanics. Materials and Methods: Conventional twin and self-ligating brackets and the new elastodynamic bracket were biomechanically tested. The conventional brackets had a rectangular 0.022′′ slot and the new elastodynamic bracket had a V-slot, a new slot geometry. Torque measurements were performed with 0.018′′ × 0.025′′ and 0.019′′ × 0.025′′ stainless steel (ss) archwires. A nickel-titanium V wire was used for the biomechanical measurements on the elastodynamic bracket. The measurements were done with the aid of a six-component measuring sensor. Results: The results of the biomechanical testing revealed play in the brackets with rectangular slot geometry. The V slot in the elastodynamic bracket assured that the wire fit perfectly in the slot. Dynamic moments of 5 to 10 Nmm were transmitted without any play. No permanent deformation of the slot occurred in the new elastodynamic bracket because of the elastic slot. Conclusion: Control of torque for three-dimensional positioning of the teeth in the dental arch with rectangular slot geometry as used in straight-wire therapy is difficult. If torque is bent into the wire, because of the play there is a high risk that either too much, too little, or no moment is transmitted to the teeth. The V-slot archwire/bracket geometry in conjunction with nickel titanium composition has no play and allows a reduction of forces and moments with direct and continuous transmission of torque in the bracket. Because of the elasticity of the bracket, there is an upper limit to the moment possible.

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