Stability and Chaos Analysis of Nonlinear Roll Motion of Trimaran Ship With Variable Lay-Out Under Wind and Waves

2020 ◽  
Author(s):  
Yihan Zhang
Keyword(s):  
Dynamic Stability ◽  
Great Influence ◽  
Wave Force ◽  
Heteroclinic Orbits ◽  
Phase Portraits ◽  
Roll Motion ◽  
Asymmetric System ◽  
Stability Performance ◽  
Combined Action ◽  
Nonlinear Roll Motion

Abstract The combined action of wind and waves has a great influence on the dynamic stability of roll motion of a trimaran ship, which may get into chaotic situation even capsizing. The lay-out of the trimaran is the main factor influencing the roll performance and its dynamic stability. In order to study the stability performance of the roll motion, firstly, the nonlinear roll motion equations under transverse wind and beam waves are established, in which the main coefficients are obtained by CFD method combined with model test. Then, the Hamilton system is used to analyze the phase portraits of the homoclinic and heteroclinic orbits under different transverse spacing. Finally, the Melnikov function is used to calculate the critical wave threshold of the asymmetric system under the combined action of wind load and wave force, and the Lyapunov exponent based on RHR algorithm was used to verify it. A series of significant conclusions are obtained by comparing the calculation models of different transverse spacing, which can provide references for the design of the trimaran ship.

scholarly journals NONLINEAR ROLLING STABILITY AND CHAOS RESEARCH OF TRIMARAN VESSEL WITH VARIABLE LAY-OUTS IN REGULAR AND IRREGULAR WAVES UNDER WIND LOAD

Brodogradnja ◽  
2021 ◽  
Vol 72 (3) ◽  
pp. 97-123
Author(s):  
Yihan Zhang ◽  
◽  
Ping Wang ◽  
Yachong Liu ◽  
Jingfeng Hu
Keyword(s):  
Heteroclinic Orbit ◽  
Melnikov Method ◽  
Wave Force ◽  
Nonlinear Damping ◽  
Wind Load ◽  
Irregular Waves ◽  
Roll Motion ◽  
Maximum Lyapunov Exponent ◽  
Moment Coefficient ◽  
Nonlinear Roll Motion

The trimaran vessel rolls strongly at low forward speed and may capsize in high sea conditions due to chaos and loss of stability, which is not usually considered in conventional limit-based criteria. In order to perfect the method of measuring roll performance of trimaran, a set of nonlinear roll motion stability analysis method based on Lyapunov and Melnikov theory was established. The nonlinear roll motion equation was constructed by CFD and high-order polynomial fitting method. The wave force threshold of rolling chaos in regular waves is calculated by Gauss-Legendre numerical integration method. The limited significant wave height of rolling chaos in random sea conditions is deduced by the phase space transfer rate, and the complex effect of wind load is superposed in the calculation. The influence of trimaran configuration on the roll system is analyzed through the state differentiation of homoclinic and heteroclinic orbit in phase portrait. The calculation of the maximum Lyapunov exponent further verified the applicability of Melnikov method, and the topological structure change of gradual failure of the rolling system is analyzed by the erosion of safe basin. The complex changes of the nonlinear damping coefficient and the nonlinear restoring moment coefficient caused by the change of the transverse lay-outs between the main hull and side hull have a significant influence on chaos and stability, and the existence of wind load has a certain weakening effect on the stability and symmetry of the system. The conclusion also further indicates the importance of the lay-outs to the dynamic stability of the trimaran vessel, which is significant for its seakeeping design.

Dynamic Stability Analysis of Size-Dependent Viscoelastic/Piezoelectric Nano-beam

2022 ◽  
Author(s):  
Zahra Tadi Beni ◽  
Yaghoub Tadi Beni
Keyword(s):  
Stability Analysis ◽  
Dynamic Stability ◽  
Piezoelectric Materials ◽  
Equilibrium Points ◽  
Geometrical Nonlinearity ◽  
Saddle Points ◽  
Heteroclinic Orbits ◽  
Phase Portraits ◽  
Bifurcation Points ◽  
Size Dependent

This paper analyzes the dynamic stability of an isotropic viscoelastic Euler–Bernoulli nano-beam using piezoelectric materials. For this purpose, the size-dependent theory was used in the framework of the modified couple stress theory (MCST) for piezoelectric materials. In order to capture the geometrical nonlinearity, the von Karman strain displacement relation was applied. Hamilton’s principle was also employed to obtain the governing equations. Furthermore, the Galerkin method was used in order to convert the governing partial differential equations (PDEs) to a nonlinear second-order ordinary differential one. Dynamic stability analysis was performed and the effects of such parameters as viscoelastic coefficients, size effect, and piezoelectric coefficient were investigated. The results showed that in this system, saddle points, central points, Hopf bifurcation points, and fork bifurcation points could be created, and the phase portraits connecting these equilibrium points exhibit periodic orbits, heteroclinic orbits, and homoclinic orbits.

Coupled effects of surface interaction and damping on electromechanical stability of functionally graded nanotubes reinforced torsional micromirror actuator

2021 ◽  
pp. 030932472110368
Author(s):  
Weidong Yang ◽  
Menglong Liu ◽  
Linwei Ying ◽  
Xi Wang
Keyword(s):  
Casimir Force ◽  
Volume Fraction ◽  
Nonlocal Parameter ◽  
Saddle Points ◽  
Functionally Graded ◽  
Heteroclinic Orbits ◽  
Phase Portraits ◽  
Squeeze Film ◽  
Squeeze Film Damping ◽  
Tilting Angle

This paper demonstrated the coupled surface effects of thermal Casimir force and squeeze film damping (SFD) on size-dependent electromechanical stability and bifurcation of torsion micromirror actuator. The governing equations of micromirror system are derived, and the pull-in voltage and critical tilting angle are obtained. Also, the twisting deformation of torsion nanobeam can be tuned by functionally graded carbon nanotubes reinforced composites (FG-CNTRC). A finite element analysis (FEA) model is established on the COMSOL Multiphysics platform, and the simulation of the effect of thermal Casimir force on pull-in instability is utilized to verify the present analytical model. The results indicate that the numerical results well agree with the theoretical results in this work and experimental data in the literature. Further, the influences of volume fraction and geometrical distribution of CNTs, thermal Casimir force, nonlocal parameter, and squeeze film damping on electrically actuated instability and free-standing behavior are detailedly discussed. Besides, the evolution of equilibrium states of micromirror system is investigated, and bifurcation diagrams and phase portraits including the periodic, homoclinic, and heteroclinic orbits are described as well. The results demonstrated that the amplitude of the tilting angle for FGX-CNTRC type micromirror attenuates slower than for FGO-CNTRC type, and the increment of CNTs volume ratio slows down the attenuation due to the stiffening effect. When considering squeeze film damping, the stable center point evolves into one focus point with homoclinic orbits, and the dynamic system maintains two unstable saddle points with the heteroclinic orbits due to the effect of thermal Casimir force.

scholarly journals Dynamic Stability Performance of Autonomous Microgrid Involving High Penetration Level of Constant Power Loads

Mathematics ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 922
Author(s):  
Mohamed Hassan ◽  
Muhammed Worku ◽  
Abdelfattah Eladl ◽  
Mohammed Abido
Keyword(s):  
Dynamic Stability ◽  
Power Sharing ◽  
Constant Power ◽  
Similar Frequency ◽  
Stability Performance ◽  
High Penetration ◽  
Constant Power Loads ◽  
The Time Domain ◽  
And Control ◽  
The Impact

Nowadays, behaving as constant power loads (CPLs), rectifiers and voltage regulators are extensively used in microgrids (MGs). The MG dynamic behavior challenges both stability and control effectiveness in the presence of CPLs. CPLs characteristics such as negative incremental resistance, synchronization, and control loop dynamic with similar frequency range of the inverter disturb severely the MG stability. Additionally, the MG stability problem will be more sophisticated with a high penetration level of CPLs in MGs. The stability analysis becomes more essential especially with high-penetrated CPLs. In this paper, the dynamic stability performance of an MG involving a high penetration level of CPLs is analyzed and investigated. An autonomous MG engaging a number of CPLs and inverter distributed generations (DGs) is modeled and designed using MATLAB. Voltage, current, and power controllers are optimally designed, controlling the inverter DGs output. A power droop controller is implemented to share the output DGs powers. Meanwhile, the current and voltage controllers are employed to control the output voltage and current of all DGs. A phase-locked loop (PLL) is essentially utilized to synchronize the CPLs with the MG. The controller gains of the inverters, CPLs, power sharing control, and PLL are optimally devised using particle swarm optimization (PSO). As a weighted objective function, the error in the DC voltage of the CPL and active power of the DG is minimized in the optimal problem based on the time-domain simulation. Under the presence of high penetrated CPLs, all controllers are coordinately tuned to ensure an enhanced dynamic stability of the MG. The impact of the highly penetrated CPLs on the MG dynamic stability is investigated. To confirm the effectiveness of the proposed technique, different disturbances are applied. The analysis shows that the MG system experiences the instability challenges due to the high penetrated CPLs. The simulation results confirm the effectiveness of the proposed method to improve the MG dynamic stability performance.

scholarly journals Temporal variation in fish assemblage composition on a tidal flat

2004 ◽  
Vol 52 (1) ◽  
pp. 47-58 ◽  
Author(s):  
Henry L. Spach ◽  
Rodrigo S. Godefroid ◽  
César Santos ◽  
Roberto Schwarz Jr. ◽  
Guilherme M. L. de Queiroz
Keyword(s):  
Tidal Flat ◽  
Fish Assemblage ◽  
Annual Variation ◽  
Full Moon ◽  
Temporal Change ◽  
High Tide ◽  
Great Influence ◽  
Assemblage Composition ◽  
Combined Action ◽  
Wind Intensity

Annual variation in the fish assemblage characteristics on a tidal flat was studied in coastal Paraná, in southern Brazil. Fish were collected between August 1998 and July 1999, during the diurnal high tide and diurnal and nocturnal low tide of the syzygial (full moon) and quadrature (waning moon) tides, to characterize temporal change in assemblage composition. A total of 64,265 fish in 133 species were collected. The average number of species and individuals, biomass, species richness, diversity (mass) and equitability varied significantly over time . The dissimilarity of the assemblage was greatest in August, September and October in contrast with the period from November to January, with the lowest dissimilarity. The combined action of water temperature, salinity and wind intensity had a great influence over the structure of the fish assemblage.

Bifurcation Analysis in a Class of Piecewise Nonlinear Systems with a Nonsmooth Heteroclinic Loop

2018 ◽  
Vol 28 (02) ◽  
pp. 1850026
Author(s):  
Yuanyuan Liu ◽  
Feng Li ◽  
Pei Dang
Keyword(s):  
Limit Cycles ◽  
Polynomial Systems ◽  
Melnikov Function ◽  
Heteroclinic Orbits ◽  
Phase Portraits ◽  
Unperturbed System ◽  
Piecewise Polynomial ◽  
Heteroclinic Loop ◽  
First Order ◽  
Nilpotent Critical Point

We consider the bifurcation in a class of piecewise polynomial systems with piecewise polynomial perturbations. The corresponding unperturbed system is supposed to possess an elementary or nilpotent critical point. First, we present 17 cases of possible phase portraits and conditions with at least one nonsmooth periodic orbit for the unperturbed system. Then we focus on the two specific cases with two heteroclinic orbits and investigate the number of limit cycles near the loop by means of the first-order Melnikov function, respectively. Finally, we take a quartic piecewise system with quintic piecewise polynomial perturbation as an example and obtain that there can exist ten limit cycles near the heteroclinic loop.

scholarly journals Effect of Slip Surface’s Continuity on Slope Dynamic Stability Based on Infinite Slope Model

Mathematics ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 58
Author(s):  
Chuanzheng Liu ◽  
Gang Wang ◽  
Wei Han
Keyword(s):  
Dynamic Stability ◽  
Stress Wave ◽  
Safety Factor ◽  
Slip Surface ◽  
Great Influence ◽  
Stress Wave Propagation ◽  
Surface Model ◽  
Infinite Slope ◽  
Research Results ◽  
The Stability

The slip surface is an important control structure surface existing in the landslide. It not only directly affects the stability of the slope through the strength, but also affects the stress field by affecting the propagation of the stress wave. Many research results have been made on the influence of non-continuous stress wave propagation in rock and soil mass and the dynamic response to seismic slopes. However, the effect of the continuity of the slip surface on the slope dynamic stability needs further researches. Therefore, in this paper, the effect of slip surface on the slope’s instantaneous safety factor is analyzed by the theoretical method with the infinite slope model. Firstly, three types of slip surface model were established, to realize the change of sliding surface continuity in the infinite slope. Then, based on wave field analysis, the instantaneous safety factor was used to analyze the effect of continuity of slip surface. The results show that with the decreasing of slip surface continuity, the safety factor does not simply increase or decrease, and is related to slope features, incident wave and continuity of slip surface. The safety factor does not decrease monotonically with the increasing of slope angle and thickness of slope body. Moreover, the reflection of slope surface has a great influence on the instantaneous safety factor of the slope. Research results in this paper can provide some references to evaluate the stability of seismic slope, and have an initial understanding of the influence of structural surface continuity on seismic slope engineering.

Nonlinear Roll Damping and Roll Motion Study of Asymmetric Catamaran With Variable Layouts

2020 ◽  
Author(s):  
Yihan Zhang ◽  
Jingfeng Hu
Keyword(s):  
Numerical Methods ◽  
Great Influence ◽  
Prediction Method ◽  
Potential Method ◽  
Roll Motion ◽  
Roll Damping ◽  
Overlapping Grids ◽  
Motion Study ◽  
Seakeeping Performance ◽  
Ship Speed

Abstract Because of the interference between the main hull and side hull, the layout of asymmetric catamaran has a great influence on the seakeeping performance. In order to assess the characteristics of roll damping and roll motion of this kind of ship, firstly, a numerical prediction method of roll damping is established by CFD with overlapping grids to simulate the roll decay curves at different transverse and longitudinal spacing and ship speed. The roll damping property is analyzed by energy method and flow field monitoring. Then, based on the correction of nonlinear roll damping, the roll motion response in waves is calculated by 3D potential method. Finally, model tests are carried out to verify the numerical methods. The change of transverse layout has a great influence on the roll damping and roll motion of the asymmetric catamaran, while the longitudinal layout has a little influence on the roll performance. The research results of this paper can provide some useful reference for the design of asymmetric catamaran.

Influence of braking on dynamic stability of car-trailer combinations

2020 ◽  
pp. 095440702095989
Author(s):  
Ning Zhang ◽  
Jian-hua Wu ◽  
Tian Li ◽  
Zi-qian Zhao ◽  
Guo-dong Yin
Keyword(s):  
Dynamic Stability ◽  
Load Transfer ◽  
Great Influence ◽  
Stability Control ◽  
System Dynamic ◽  
Force Distribution ◽  
Single Track ◽  
Two Factors ◽  
Braking Force ◽  
The Ideal

The influence of braking on dynamic stability of a car-trailer combination (CTC) is studied in this paper. The braking is simply modeled and integrated into a single-track model (STM) with a single-axle trailer. On this basis, some fundamentals and analysis results related to system dynamic stability are given through simulation. Furthermore, it is found that the axle load transfer and braking force distribution have a great influence on system dynamic stability. In order to further analyze the influence of these two factors, both of the braking force distribution and the pitch motion are considered in the modeling. Finally, the ideal braking force distribution domain is proposed. Results can be adopted to explain the experimental phenomenon and serve as a guideline for the differential braking strategy in stability control of the CTC.

Sign in / Sign up

Export Citation Format

Share Document