Verification of a simplified analytical method for predictions of ship groundings over large contact surfaces by numerical simulations

2011 ◽  
Vol 24 (4) ◽  
pp. 436-458 ◽  
Author(s):  
Hu Zhiqiang ◽  
Amdahl Jørgen ◽  
Hong Lin
Keyword(s):  
Numerical Simulations ◽  
Analytical Method ◽  
Contact Surfaces

DYNAMICS OF A PREY-DEPENDENT DIGESTIVE MODEL WITH STATE-DEPENDENT IMPULSIVE CONTROL

2012 ◽  
Vol 22 (04) ◽  
pp. 1250092 ◽  
Author(s):  
LINNING QIAN ◽  
QISHAO LU ◽  
JIARU BAI ◽  
ZHAOSHENG FENG
Keyword(s):  
Numerical Simulations ◽  
Analytical Method ◽  
Impulsive Control ◽  
Dynamical Behavior ◽  
Sufficient Conditions ◽  
Period Doubling ◽  
Lambert W Function ◽  
Impulsive Effect ◽  
State Dependent ◽  
Theoretical Results

In this paper, we study the dynamical behavior of a prey-dependent digestive model with a state-dependent impulsive effect. Using the Poincaré map and the Lambert W-function, we find the analytical expression of discrete mapping. Sufficient conditions are established for transcritical bifurcation and period-doubling bifurcation through an analytical method. Exact locations of these bifurcations are explored. Numerical simulations of an example are illustrated which agree well with our theoretical results.

scholarly journals Determining both radial pressure distribution and torsional stiffness of involute spline couplings

2006 ◽  
Vol 220 (12) ◽  
pp. 1727-1738 ◽  
Author(s):  
A Barrot ◽  
M Paredes ◽  
M Sartor
Keyword(s):  
Analytical Method ◽  
Radial Pressure ◽  
Pressure Profile ◽  
Torsional Stiffness ◽  
Torque Distribution ◽  
Gear Teeth ◽  
Tilted Angle ◽  
Spline Coupling ◽  
Contact Surfaces ◽  
Involute Spline

In this paper, an analytical method is used to investigate the distortions of involute spline teeth. The following hypotheses are adopted: teeth geometry is in conformity with standardization, dimensions are nominal (no defect), there is no friction and the load is a pure torsional torque. Teeth distortions due to bending, shear, compression, and foundation rotation are analysed. As the load is distributed along the tooth height, the displacement calculation differs from the conventional approach used for gear teeth. Sliding over the contact surfaces is also considered as it emerged during the study that this phenomenon, that has not hitherto been taken into account, plays a significant role. A punch model is used to describe the radial distribution of the contact pressure. Ascribing an arbitrary value to the tilted angle between the two contacting flanks enables the pressure profile to be evaluated, from which calculation of teeth distortions can be arrived at so as finally to obtain a new estimation of the tilted angle. Thus, displacements and the contact load can be determined together by iterating the calculation procedure until convergence. Torsional stiffness, which is one of the main parameters required to predict the torque distribution along the spline coupling, is evaluated from the various displacement components. The results derived from the proposed analytical method are compared with finite-element results and show good correlation.

Regenerative Cutting Dynamics for a Periodically Forced Machine-Tool System

2019 ◽  
Author(s):  
Siyuan Xing ◽  
Albert C. J. Luo
Keyword(s):  
Machine Tool ◽  
Numerical Simulations ◽  
Analytical Method ◽  
Orthogonal Cutting ◽  
Periodic Oscillation ◽  
Eigenvalue Analysis ◽  
Stable Period ◽  
Machine Tool Chatter ◽  
Stability And Bifurcations ◽  
Cutting System

Abstract In this paper, a nonlinear, regenerative, orthogonal cutting system with a weak periodic oscillation of workpiece is considered. Period-1 motions in such a system are studied through a semi-analytical method, and the corresponding stability and bifurcations of the period-1 motions are analyzed via the eigenvalue analysis. The vibration of machine-tool varying with excitation is studied, and excitation effects on machine-tool chatters are discussed. Numerical simulations of unstable and stable period-1 motions are completed from analytical predictions. The machine-tool chatter can emerge from the saddle-node or Neimark bifurcation of period-1 motions.

Period-1 Motions in a Periodically Forced, Nonlinear, Machine-Tool System

2019 ◽  
Author(s):  
Siyuan Xing ◽  
Albert C. J. Luo
Keyword(s):  
Machine Tool ◽  
Numerical Simulations ◽  
Analytical Method ◽  
Degree Of Freedom ◽  
Eigenvalue Analysis ◽  
Tool Vibrations ◽  
Stability And Bifurcations ◽  
The Stability ◽  
Two Degree Of Freedom

Abstract In this paper, period-1 motions in a two-degree-of-freedom, nonlinear, machine-tool system are investigated by a semi-analytical method. The stability and bifurcations of the period-1 motions are discussed from the eigenvalue analysis. A condition is presented for the tool-and-workpiece separation in period-1 motions. Machine-tool vibrations varying with displacement disturbance from a workpiece are discussed. Numerical simulations of period-1 motions are completed from analytical predictions.

Towards Numerical Simulation and Model Test Verifications for an Analytical Model of Tubular Member Under Lateral Impact Scenario

2016 ◽  
Author(s):  
Zhiqiang Hu ◽  
Chao Jiang ◽  
Kun Liu
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Model Test ◽  
Analytical Method ◽  
High Speed ◽  
Impact Force ◽  
Structural Deformation ◽  
Resistance Force ◽  
Lateral Impact ◽  
Jacket Platform

Tubular member of jacket platform has the possibility of being struck by the service ship under a lateral impact scenario. An analytical theoretical method has been proposed to predict the structural deformation and the resistance force. This paper addresses a study on the verifications for this analytical method, through numerical simulation and model test methods. The analytical method was proposed based on a new structural sectional deformation mode, which considers both of the local denting and global bending deformation. The analytical method is briefly introduced. The verification work includes three steps. Firstly, a model test was conducted, on purpose of obtaining the structural deformation and the resistance force under the lateral impact scenario when a model tubular member was struck by a wedge hammer. In the test, the tubular member was fixed at both ends and the wedge hammer hit at its middle position. A high speed camera was used to record the instantaneous motion track of the hammer, and with the motion track data, the striking force and the indentation can be obtained. Then, a curve of impact force vs. indentation in time series was got. Secondly, the numerical simulations were conducted to simulate the corresponding impact scenario. The code LS_DYNA was used. The curve of impact force vs. indentation was also obtained. Finally, a comparison study was made, to verify the accuracy of the analytical theoretical model, and it is proved that the curves match well. Furthermore, four more cases were conducted by numerical simulations, to assess the feasibility of the analytical method on prototype scantling using for the tubular member of jacket platform.

Effect of Fractional Damping in Double-Well Duffing–Vander Pol Oscillator Driven by Different Sinusoidal Forces

2019 ◽  
Vol 20 (2) ◽  
pp. 115-124 ◽  
Author(s):  
M. V. Sethu Meenakshi ◽  
S. Athisayanathan ◽  
V. Chinnathambi ◽  
S. Rajasekar
Keyword(s):  
Numerical Simulations ◽  
Analytical Method ◽  
Threshold Value ◽  
Nonlinear Damping ◽  
Sine Wave ◽  
Direct Numerical Simulations ◽  
Periodic Perturbation ◽  
Threshold Condition ◽  
Fractional Damping

AbstractThe effect of nonlinear damping including fractional damping on the onset of horseshoe chaos is studied both analytically and numerically in the double-well Duffing–Vander Pol (DVP) oscillator driven by various sinusoidal forces. The sinusoidal type periodic forces of our interest are sine wave, rectified sine wave, and modulus of sine wave. Using the Melnikov analytical method, the threshold condition for the onset of horseshoe chaos is obtained for each sinusoidal force. Melnikov threshold curves are drawn in (f,\;ω) parameters space for each force. When the damping component (p) increases from a small value, the Melnikov threshold value $(f_{M})$ is decreased for each force. Suppression of horseshoe chaos is predicted due to the effect of weak periodic perturbation and nonlinear fractional damping. Analytical predictions are demonstrated through direct numerical simulations.

Reduced model of linear systems via Laguerre filters

2017 ◽  
Vol 40 (5) ◽  
pp. 1510-1520 ◽  
Author(s):  
Ameni El Anes ◽  
Kais Bouzrara ◽  
José Ragot
Keyword(s):  
Parameter Identification ◽  
Numerical Simulations ◽  
Linear Systems ◽  
Analytical Method ◽  
Fourier Coefficients ◽  
Iterative Technique ◽  
Initial Model ◽  
Discrete Transformation ◽  
Identification Technique ◽  
Laguerre Filters

In this paper, we propose a technique to reduce the complexity of an existing (initial) model via the Laguerre filters. We present an analytical method for the parameter identification of the Fourier coefficients of the Laguerre model. This technique is based on the bilinear discrete transformation and in which the Fourier coefficients are expressed in recurrent form in terms of the Laguerre pole. This latter is estimated by an iterative technique, based on the Newton algorithm. This identification technique is after extended to the case of the ARX-Laguerre model and the MISO-ARX-Laguerre model and its performances are illustrated by numerical simulations.

Periodic Motions in a 2-DOF Self-Excited Duffing Oscillator

2017 ◽  
Author(s):  
Yeyin Xu ◽  
Albert C. J. Luo
Keyword(s):  
Numerical Simulations ◽  
Analytical Solutions ◽  
Analytical Method ◽  
Periodic Motion ◽  
Initial Conditions ◽  
Duffing Oscillator ◽  
Excitation Frequency ◽  
The Self ◽  
Periodic Motions ◽  
Implicit Mapping

In this paper, analytical solutions of periodic motions in a 2-DOF self-excited Duffing oscillator are investigated through a semi-analytical method. The semi-analytical method discretizes the self-excited Duffing oscillator for the discrete implicit mappings. Through the implicit mapping, period-1 motion varying with excitation frequency are presented, and the corresponding stability and bifurcation are discussed via the eigenvalues analysis. The Neimark and saddle-node bifurcations of the periodic motion are obtained. Initial conditions for numerical simulations are from analytical solutions. Numerical and analytical solutions of periodic motions are illustrated for comparison.

Thermal Behavior and Growth of Submerged Ice Blocks: Experimental and Numerical Results

2015 ◽  
Author(s):  
M. Ghobadi ◽  
E. Bailey ◽  
R. Taylor
Keyword(s):  
Thermal Behavior ◽  
Numerical Simulations ◽  
Temperature Profile ◽  
Analytical Method ◽  
Surrounding Water ◽  
Radial Temperature ◽  
Data Loggers ◽  
Before And After ◽  
Broken Ice ◽  
Ice Floes

Ice rubble forms when flexural, shear or compressive forces cause broken ice to pile up at the interface between ice floes or during contact with a structure. The accumulation of rubble into linear features results in the formation of ridges, which are comprised of many individual blocks that are bonded with varying degrees of strength. Essential to the overall consolidation of a ridge is the bonding process that takes place at the interface between individual blocks. In this paper initial experimental and numerical simulations are presented that show the amount of new ice that will grow when an initially cold piece of freshwater ice is submerged in freshwater at 0° C. Understanding the thermal behavior of an ice block is important as the results can be used to understand the freeze-bonding processes that occur between two ice blocks, and further extended to understand the processes that occur between multiple ice blocks (i.e., pressure ridges and ice rubble). In the experiments presented herein, a cylindrical ice sample with an initial temperature of −20° C was submerged in a tank of water at 0° C. As the ice cylinder is initially colder than the surrounding water, heat is diffused from the water into the ice cylinder causing a new layer of ice to form around the samples. Wireless temperature sensors with onboard data loggers were placed inside the ice cylinder to measure temperature. The radius, length and weight of the sample were measured before and after the submersion to calculate the thickness of the new ice layer. COMSOL Multiphysics was employed to analyze the freezing rate and the radial temperature profile of the sample. An analytical method is also used to calculate the maximum thickness of the new ice layer formed around the sample once the temperature has equilibrated to the surrounding water temperature. Results obtained using the analytical method are then compared with experimental results. Temperature profile data collected at specified locations within the ice have also been compared with the numerical simulations. Good agreement between measured and simulated results was observed.

scholarly journals An analytical method to assess the structural responses of ship side structures by raked bow under oblique collision scenarios

2020 ◽  
pp. 147509022098027
Author(s):  
Zeping Wang ◽  
Kun Liu ◽  
Gang Chen ◽  
Zhiqiang Hu
Keyword(s):  
Numerical Simulations ◽  
Analytical Method ◽  
Structural Damage ◽  
Structural Response ◽  
Design Stage ◽  
Shipping Industry ◽  
Oblique Collision ◽  
Finite Element Software ◽  
Hull Structure ◽  
Structural Responses

With the development of the shipping industry, the number of ships at sea has increased significantly. According to the statistical data, oblique ship collisions are much more frequently happened than that of head-on ship collisions. However, there are less researches on oblique ship collisions than those of head-on ship collisions. The responses of hull structure during oblique collision scenarios are different from those in head-on collision scenarios, and might have wider structural damages, which demonstrate the significance of research on oblique collision scenarios and structural damage. In this paper, the oblique collision scenarios are firstly investigated through numerical simulations. Finite element software LS_DYNA is used for the numerical simulations. Six typical oblique collision scenarios are defined, on purpose of finding the main deformation characteristics of the struck ship. Two basic assumptions were made accordingly. Then, a simplified analytical method is proposed to predict the structural response of ship side structures by raked bow under oblique collision scenarios. The new analytical method includes the deformation mechanism of the side plating, the web girder and the transverse frame. The resistance and energy dissipation of these components are used in an integrated way to evaluate the overall crashworthiness of the side structure of the struck ship. The numerical simulation results match well with the results of analytical calculations, which validates the accuracy of the proposed analytical method. The proposed analytical method can provide an effective way to evaluate the structural crashworthiness of ship side structures in oblique collision scenarios during the structural design stage.

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