Full Dynamic Model for Liquid Sloshing Simulation in Cylindrical Tank Shape

This study presents a comprehensive full dynamic model designed for simulating liquid sloshing behavior within cylindrical tank structures. The model employs a discretization approach, representing the liquid as a network of interconnected spring-damper-mass systems. Key aspects include the adaptation of liquid discretization techniques to cylindrical lateral cross-sections and the calculation of stiffness and damping coefficients. External forces, simulating various vehicle maneuvers, are also integrated into the model. The resulting system of equations is solved using Maple Software with the Runge-Kutta-Fehlberg method. This model enables accurate prediction of liquid displacement and pressure forces, offering valuable insights for tank design and fluid dynamics applications. Ongoing refinement aims to broaden its applicability across different liquid types and tank geometries.

Mass‑Spring‑Damping Theory Based Equivalent Mechanical Model for Cylindrical Lithium‑ion Batteries under Mechanical Abuse

An equivalent mechanical model with the equivalent physical meaning of mass-spring-damping is proposed for cylindrical lithium-ion batteries through experiments and theory.The equivalent mechanical model of a cylindrical lithium-ion battery consists of a spring-damping parallel unit.Therefore,a spring-damping parallel unit connecting a damping unit in series is selected to construct the constitutive characteristics of the battery under mechanical abuse.Comparison results show that the equivalent mechanical model can more effectively describe the mechanical properties of the batteries than most cubic fitting models,of which the average relative error of the equivalent mechanical model under different states-of-charge is less than 6.75%.Combined with the proposed equivalent mechanical model,the failure process of the batteries was simulated and analyzed using LS-Dyna and HyperWorks.Under rigid rod tests,failure occurred at the core and bottom of the batteries;under hemispherical punch tests,failure occurred at the core and top,consistent with the experimental results.The average prediction error for the failure displacement under different abuse conditions is less than 4%in the simulations.The equivalent mechanical model requires only a few parameters and can be recognized easily.In the future,the model can be used in safety warning devices based on mechanical penetration.

HYBRID APPROACH FOR ESTIMATING COUPLING EFFECT BETWEEN PROPELLANT SLOSHING DYNAMIC AND SPACECRAFT GNC

An approach based on equivalent mechanics theory and computational fluid dynamics （CFD） technology is proposed to estimate dynamical influence of propellant sloshing on the spacecraft. A mechanical model is estab- lished by using CFD technique and packed as a ＂sloshing＂ block used in spacecraft guidance navigation and control （GNC） simulation loop. The block takes motion characteristics of the spacecraft as inputs and outputs of pertur- bative force and torques induced by propellant sloshing, thus it is more convenient for analyzing coupling effect between propellant sloshing dynamic and spacecraft GNC than using CFD packages. An example demonstrates the accuracy and the superiority of the approach. Then, the deducing process is applied to practical cases, and simulation results validate that the proposed approach is efficient for identifying the problems induced by sloshing and evaluating effectiveness of several typical designs of sloshing suppression.

Coupling dynamic analysis of a liquid-filled spherical container subject to arbitrary excitation

Using spherical coordinates, the coupling nonlinear dynamic system of a liquid-filled spherical tank, which can be excited discretionarily, is deduced by the H-O varia- tional principle, and the viscous damping is introduced via the liquid dissipation function. The kinetic equations of the coupling system are deduced by the relationship between the velocity of liquid particles and the disturbed liquid surface equation. Normal differential equations are obtained through the Galerkin method. An equivalent mechanical model is developed for liquid sloshing in a spherical tank subject to arbitrary excitation. The fixed and slosh masses, as well as the spring and damping constants, are determined in such a way as to satisfy the principle of equivalence. Numerical simulations illustrate the theoretical results in this paper as well.

Similarity theory based method for MEMS dynamics analysis

A new method for MEMS dynamics analysis is presented,ased on the similarity theory. With this method, two systems' similarities can be captured in terms of physics quantities/governed-equations amongst different energy fields, and then the unknown dynamic characteristics of one of the systems can be analyzed according to the similar ones of the other system. The probability to establish a pair of similar systems among MEMS and other energy systems is also discussed based on the equivalent between mechanics and electrics, and then the feasibility of applying this method is proven by an example, in which the squeezed damping force in MEMS and the current of its equivalent circuit established by this method are compared.

Distributed Energy Saving Mechanism Based on CoMP in LTE-A System

To reduce the energy consumption of the LTE-A system,a distributed energy-saving mechanism based on Co MP(Co MPDESM) is proposed to solve the inadequate coverage problem under the dormant cells.First,the network is divided into clusters based on the equivalent cell principle.Then,we transfer global optimization into a group of subproblems.Second,a joint processing-based cooperative cell selection model is constructed to determine cooperative cells and dormant cells.Third,the compensative cells with a determined threshold are selected to control users' access.Finally,a simulation is implemented in Matlab.Results show that the energy-saving rate can reach 36.4% and that the mechanism meets the network coverage requirement.Thus,joint processing can be effectively applied in an energy saving mechanism and used to improve the network performance of edge users without increasing transmission power.

Some Ideas of James Watt in Contemporary Energy Conversion Thermodynamics

James Watt contributed significantly to the development of the thermodynamics of energy conversion as a science. Several of his ideas are now integral part of thermodynamics, but Watt as their creator is not mentioned. This paper presents some of Watt’s concepts of energy conversion, including his thermodynamic analysis of the Newcomen steam engine that marks the beginning of thermal engineering. The analysis illuminated the causes of the enormously high heat losses in the installation and showed the ways for their reduction. This led him to a new conception of the steam engine with a separate condenser. Not less important was Watt’s determination of some physical properties of water and steam used as the working substance. In the experiments he observed the decrease of the latent heat of steam with increasing temperature and its disappearance at very high temperature led him to postulate the existence of a thermodynamic critical state of water. He introduced the work associated with volume change into thermodynamics and illustrated it graphically. Several of Watt’s numerous ideas deserve to be included into the history of the thermodynamics of energy conversion but they are rarely mentioned in the scientific literature. Arguably the most important is the First Law of Thermodynamics, which he introduced in his 1769 patent and related works in 1774 and 1778.

Motion stability dynamics for spacecraft coupled with partially filled liquid container

This paper presents a canonical Hamiltonian model of liquid sloshing for the container coupled with spacecraft. Elliptical shape of rigid body is considered as spacecraft structure. Hamiltonian system is an important form of mechanical system. It mostly used to stabilize the potential shaping of dynamical system. Free surface movement of liquid inside the container is called sloshing. If there is uncontrolled resonance between the motion of tank and liquid-frequency inside the tank then such sloshing can be a reason of attitude disturbance or structural damage of spacecraft. Equivalent mechanical model of simple pendulum or mass attached with spring for sloshing is used by many researchers. Mass attached with spring is used as an equivalent model of sloshing to derive the mathematical equations in terms of Hamiltonian model. Analytical method of Lyapunov function with Casimir energy function is used to find the stability for spacecraft dynamics. Vertical axial rotation is taken as the major axial steady rotation for the moving rigid body.

STUDY ON GAP DISTRIBUTION IN MOVABLE SLEEVE-TOOTH DRIVE

A new method for calculating the gap distribution in the movable sleeve tooth transmission is presented. The non linear equations on analyzing the gap distribution are established with the method of equivalent mechanism and are solved successfully.

THE EQUIVALENT MECHANICAL MODELS OF LIQUID SLOSHING IN A SPHERICAL TANK WITH SPACER UNDER LOW GRAVITY

The dynamics of liquid sloshing in a spherical tank with spacer under low gravity was investigated. By extending the characteristic functions, the frequencies of liquid free sloshing, reaction force and moments on the wall of tank were obtained. By mechanical equivalent principle, the equivalent models of spring vibrator damper of liquid sloshing were given. The numerical results obtained show when a spacer is inserted in the tank, the sloshing frequency of liquid and the sloshing mass of liquid will decrease.

Nonlinear Dynamic Modeling for Joint Interfaces by Combining Equivalent Linear Mechanics with Multi-objective Optimization

The nonlinear dynamic modeling by combining the equivalent linear mechanics with the multi-objective optimization algorithm is proposed to describe the nonlinear behaviors of the joint interfaces.The joint interfaces are simplified as the equivalent virtual material or linear spring damper element.The genetic algorithm for multi-objective optimization is then used to identify the mechanical properties of the equivalent joint by minimizing the error between the simulated dynamic characteristics and the experimental results,including the modal frequencies of the bolted joint beam and the frequency response functions(FRFs)of the rubber isolation system.The FRFs are divided into several subsections with frequency-varied dynamic properties of the joint to consider the nonlinear dynamic behaviors,and the effects of subsection number and excitation amplitudes on the FRFs are also investigated.The results show that the simulated dynamic characteristics of modal frequencies and FRFs agree well with the experimental results.With the increase in the subsection number,the simulated FRFs agree better with the experimental results,indicating a good performance of modeling the nonlinear dynamic behaviors of the joint interfaces forced by different excitation amplitudes.Larger excitation amplitudes will decrease the joint stiffness.

DYNAMIC CHARACTERISTICS OF LIQUID SLOSHING IN A RECTANGULAR TANK UNDER LOW GRAVITY

In this paper, the dynamics of liquid sloshing in a rectangular tank under low gravity was investigated. The basic frequencies and the velocity potentials of sloshing of liquid were obtained by expansion of the Fourier series. The characteristics of force and moment of the liquid acting on a rectangular tank were analyzed. The equivalent mechanical models of spring-vibrator-damper of sloshing of liquid were established with mechanical equivalent principle and numerical results were given. The numerical results show that the equivalent sloshing mass increases with the increase of gravity, and that the basic frequency and the equivalent sloshing mass increase with the increase of the liquid depth.

A novel bioinspired mechanism to elucidate the movement flexibility of the honeybee abdomen driven by muscles

The abdomen of a honeybee is a blueprint for bioinspired mechanical design because of its movement flexibility and compactness.However,the abdominal muscles closely related to the movement flexibility mechanism have not been fully identified,limiting the potential biological advantage of their use in bionic mechanism design.In this study,we reveal the muscle distribution of the complete muscular driving unit in a honeybee abdomen using stereoscopy and scanning electron microscopy,and the muscle distribution was effectively verified using X-ray tomography.A novel equivalent unit mechanism(EUM)was then proposed and the kinematic analysis indicated that the extension ratio,bending angle,and swing angle of the EUM reached 9.36%,1.22°,and 4.43°,respectively.The deformation ability of the EUM was consistent with the movement of the abdomen,confirming the movement flexibility.This work may provide a new perspective for distributed bionic mechanism design.