Simulation Of Mechanical Systems Research Articles

A new Timoshenko beam model for simulation of mechanical system with large deformation

Beam model has been used widely in computer aided engineering for mechanical systems and the simulation results largely depend on the beam model, there are great demand for beam model with high accuracy and efficiency in simulating the mechanical system with large deformation. In this work, a new model of Timoshenko beam for large deformations is proposed to improve the accuracy and efficiency. Absolute nodal coordinate formulation and Geometrically-exact beam formulation, which make the model very suitable to simulate large deformation mechanical system, are first combined in the new beam model, the governing equations are then discrete by finite element methods and numerical difficulties are well solved by applying the shape function strategy. The new beam model is then applied to simulate the mechanical systems with large deformation and the simulations based on the traditional beam model and hexahedron element were also carried out to verify the results. The results show that good precision and efficiency in simulating the mechanical systems with large deformation can be obtained by the new Timoshenko beam model at the same time. The presented new method also serves as a good foundation for other simulation of mechanical systems.

Explicit high-order symplectic integrators for charged particles in general electromagnetic fields

This article considers non-relativistic charged particle dynamics in both static and non-static electromagnetic fields, which are governed by nonseparable, possibly time-dependent Hamiltonians. For the first time, explicit symplectic integrators of arbitrary high-orders are constructed for accurate and efficient simulations of such mechanical systems. Performances superior to the standard non-symplectic method of Runge–Kutta are demonstrated on two examples: the first is on the confined motion of a particle in a static toroidal magnetic field used in tokamak; the second is on how time-periodic perturbations to a magnetic field inject energy into a particle via parametric resonance at a specific frequency.

Application of a special class of smooth models of the resultant friction force and moment occurring on a circular contact area

Some special cases of a larger class of smooth models of the resultant friction force occurring on a planar contact area are developed and presented. These models are constructed under assumptions of classical Coulomb’s law of friction on each element of contact and instantaneous transition between two modes: fully developed sliding and rigid stick state without local slips and deformations of the contact area. They are able to model cases of different values of static and kinetic friction factors. The considered models are very effective tools for fast and reliable numerical simulations of mechanical systems with frictional contacts. They are applied in modelling and numerical analysis of a special kind of mechanical system, i.e. a kind of a pendulum with special frictional driving. The rotational joint of the pendulum is elastically suspended in the motion plane. The pendulum is driven by circular frictional contact with a rotating disk. Examples of self-excited bifurcation and chaotic dynamics as well as stick–slip behaviour of the pendulum are presented.

Dynamic response multiobjective optimization of road vehicle ride quality—A computational multibody system approach

Computational multibody system (MBS) method is a practical technique utilized for modeling, simulation, and optimization of mechanical systems. In the methodology of computational multibody system, equations of motion are derived, formulated, and solved through a systematic, generalized, and well-structured computational-mathematical approach. In this paper, the computational multibody system formulation, based on the appended Lagrangian method, is implemented to establish the governing equations of ride dynamics for a nonlinear ride model that represents a versatile half-car two-track model of a road vehicle. The input to the system is a simulated road surface model based on the ISO road surface classification. The solution of the equation of motion is obtained using the direct integration approach along with constraint violation elimination and control techniques. Following the simulation, a time-domain multiobjective design optimization procedure is performed to improve the ride quality of the model. The ride quality comprises both ride comfort and ride safety. The optimization considers relevant objective functions including vibration isolation, suspension travel, road holding, and force index. The results of work show that the proposed method could acceptably estimate the optimal values of design variables for specific road classes and vehicle driving speeds. The simulation-based ride quality optimization performed here could facilitate improvement of suspension and tyre.

Research on Digital Simulation of mechanical and Control System Based on MATLAB

With the rapid development of power electronic technology, microelectronics technology, modern control theory and material science, AC speed control system and electromechanical integration technology presents a broad development and application prospect. Therefore, it is has become a challenging new topic to set up models, make simulation and analysis for such system.In this paper, it takes the simulation of mechanical control system as the breakthrough point, combined with the brief introduction of Matlab/Simulink simulation software and the general method for simulation of mechanical and control system, discussing the realization of the general simulation model of the mechanical and control system based on MATLAB/Simulink.

Behaviour of augmented Lagrangian and Hamiltonian methods for multibody dynamics in the proximity of singular configurations

Augmented Lagrangian methods represent an efficient way to carry out the forward-dynamics simulation of mechanical systems. These algorithms introduce the constraint forces in the dynamic equations of the system through a set of multipliers. While most of these formalisms were obtained using Lagrange’s equations as starting point, a number of them have been derived from Hamilton’s canonical equations. Besides being efficient, they are generally considered to be robust, which makes them especially suitable for the simulation of systems with discontinuities and impacts. In this work, we have focused on the simulation of mechanical assemblies that undergo singular configurations. First, some sources of numerical difficulties in the proximity of singular configurations were identified and discussed. Afterwards, several augmented Lagrangian and Hamiltonian formulations were compared in terms of their robustness during the forward-dynamics simulation of two benchmark problems. Newton–Raphson iterative schemes were developed for these formulations with the Newmark formula as numerical integrator. These outperformed fixed point iteration approaches in terms of robustness and efficiency. The effect of the formulation parameters on simulation performance was also assessed.

Modeling and Simulation of Closed-Loop Mechanical Systems for Underwater Applications

Modeling and Simulation of Closed-Loop Mechanical Systems for Underwater Applications

Dynamics Modeling and Simulation of Mechanical and Servo Systems in Hard Disk Drives

Dynamics Modeling and Simulation of Mechanical and Servo Systems in Hard Disk Drives

Review and comparison of dry friction force models

Friction force models play a fundamental role for simulation of mechanical systems. Their choice affects the matching of numerical results with physically observed behavior. Friction is a complex phenomenon depending on many physical parameters and working conditions, and none of the available models can claim general validity. This paper focuses the attention on well-known friction models and offers a review and comparison based on numerical efficiency. However, it should be acknowledged that each model has its own distinctive pros and cons. Suitability of the model depends on physical and operating conditions. Features such as the capability to replicate stiction, Stribeck effect, and pre-sliding displacement are taken into account when selecting a friction formulation. For mechanical systems, the computational efficiency of the algorithm is a critical issue when a fast and responsive dynamic computation is required. This paper reports and compares eight widespread engineering friction force models. These are divided into two main categories: those based on the Coulomb approach and those established on the bristle analogy. The numerical performances and differences of each model have been monitored and compared. Three test cases are discussed: the Rabinowicz test and other two test problems casted for this occurrence.

The Next Generation of Ultra‐short Pulsed Laser Micro Processing

AbstractUltra‐short pulsed (USP) laser processes for industrial applications put high demands on the machine concept: The need for high flexibility in the machine configuration, constant machining results over long process cycles and efficient laser processes to reduce processing costs require a holistic approach in the design of a laser micro machine. For the development of a new laser machine for USP laser micromachining, the joint venture Micar combines expert competences in the fields of laser system technology, sheet metal system design and manufacturing and simulation of mechanical and fluid systems. The result is a new machine concept based on a mineral casted machine base for high flexibility in the machine structure and application.

A numerical method for the servo constraint problem of underactuated mechanical systems

AbstractServo constraints are used in inverse dynamics simulations of discrete mechanical systems, especially for trajectory tracking control problems [1], whose desired outputs are represented by state variables and treated as servo constraints [2]. Servo constraint problems can be classified into fully actuated and underactuated multibody systems, and the equations of motion take the form of differential algebraic equations (DAEs) including holonomic and servo constraints. For fully actuated systems, control inputs can be solved from the equations by model inversion, as the input distribution matrix is nonsingular and invertible. However, underactuated systems have more degrees of freedom than control inputs. The input distribution matrix is not invertible, and in contrast to passive constraints, the realization of servo constraints with the use of control forces can range from orthogonal to tangential [3]. Therefore, it is challenging for the determination of control inputs which force the underactuated system to realize the partly specified motion. For differentially flat underactuated systems, the differentiation index of DAEs may exceed three. Hence we need to apply specific index reduction techniques, such as the projection approach applied in [3], [4], and [6]. The present work applies index reduction by minimal extension [5] to differentially flat underactuated crane systems and shows that the index can be reduced from five to three and even to one. (© 2015 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Virtual design software for mechanical system dynamics using transfer matrix method of multibody system and its application

The complex mechanical systems such as high-speed trains, multiple launch rocket system, self-propelled artillery, and industrial robots are becoming increasingly larger in scale and more complicated in structure. Designing these products often requires complex model design, multibody system dynamics calculation, and analysis of large amounts of data repeatedly. In recent 20 years, the transfer matrix method of multibody system has been widely applied in engineering fields and welcomed at home and in abroad for the following features: without global dynamic equations of the system, low orders of involved system matrices, high computational efficiency, and high programming. In order to realize the rapid and visual simulation for complex mechanical system virtual design using transfer matrix method of multibody system, a virtual design software named MSTMMSim is designed and implemented. In the MSTMMSim, the transfer matrix method of multibody system is used as the solver for dynamic modeling and calculation; the Open CASCADE is used for solid geometry modeling. Various auxiliary analytical tools such as curve plot and animation display are provided in the post-processor to analyze and process the simulation results. Two numerical examples are given to verify the validity and accuracy of the software, and a multiple launch rocket system engineering example is given at the end of this article to show that the software provides a powerful platform for complex mechanical systems simulation and virtual design.

Index reduction by minimal extension for the inverse dynamics simulation of cranes

The present work deals with the inverse dynamics simulation of underactuated mechanical systems relying on servo constraints. The servo-constraint problem of discrete mechanical systems is governed by differential–algebraic equations (DAEs) with high index. We propose a new index reduction approach, which makes possible the stable numerical integration of the DAEs. The new method is developed in the framework of a specific crane formulation and facilitates a reduction from index five to index three and even to index one. Particular attention is placed on the special case in which the reduced index-1 formulation is purely algebraic. In this case the system at hand can be classified as differentially flat system. Both redundant coordinates and minimal coordinates can be employed within the newly developed approach. The success of the proposed method is demonstrated with two representative numerical examples.

Separated Representations of Incremental Elastoplastic Simulations

Forming processes usually involve irreversible plastic transformations. The calculation in that case becomes cumbersome when large parts and processes are considered. Recently Model Order Reduction techniques opened new perspectives for an accurate and fast simulation of mechanical systems, however nonlinear history-dependent behaviors remain still today challenging scenarios for the application of these techniques. In this work we are proposing a quite simple non intrusive strategy able to address such behaviors by coupling a separated representation with a POD-based reduced basis within an incremental elastoplastic formulation.

Advances in numerical computation based mechanical system design and simulation

This paper highlights the available numerical computation techniques in mechanical engineering field with focus on application of modeling and simulation within renewable energy conversion machines as a particular research case. The study makes special focus on simulation approaches based on finite elements and multibody dynamics that are currently focused within the research community. Developing the simulation model in a computer-aided design (CAD) tool is a precondition for a successful simulation-based mechanical system research. The article discusses and elaborates the methods implemented to integrate design data with other computer-aided engineering functions. The motivation is the fact that simulation-based research is useful for design optimization of mechanical systems that operate in harsh and unfriendly environment where conducting physical testing of prototypes is difficult. In addition, the manufacturing environment is benefiting from the developments in numerical computation techniques through machining simulation that significantly reduce the time-to-market and thus increase competitiveness. The study is also intended to explore the existing gaps of capabilities in current approaches in application of computational techniques in order to draw attention to future challenges and trends.

Nonlinear Behavior Analysis of a Flapping-Wing Mechanism with Clearance Joint

The nonlinear behavior of a flapping-wing mechanism affected by revolute joint clearance is studied in this work. Considering the axial dimension of bearing, energy dissipation and the nonlinear power exponent from material, the nonlinear stiffness coefficient and an improved contact dynamic model in the joint clearance is established. A flapping-wing mechanism dynamic model with joint clearance is also established. Then embed the contact dynamic model and system dynamic model into the mechanical system simulation software package. From large numbers simulations performed, and the analysis of journal trajectories and Poincare maps under the different clearance sizes, it can be concluded that flapping-wing mechanism with joint clearance exhibit a chaotic response, and the more clearance size, the more obvious chaotic behavior.

Variational and linearly implicit integrators, with applications

We show that symplectic and linearly-implicit integrators proposed by [Zhang and Skeel, 1997] are variational linearizations of Newmark methods. When used in conjunction with penalty methods (i.e., methods that replace constraints by stiff potentials), these integrators permit coarse time-stepping of holonomically constrained mechanical systems and bypass the resolution of nonlinear systems. Although penalty methods are widely employed, an explicit link to Lagrange multiplier approaches appears to be lacking; such a link is now provided (in the context of two-scale flow convergence [Tao, Owhadi and Marsden, 2010]). The variational formulation also allows efficient simulations of mechanical systems on Lie groups.

Formal Method to Design a Macro-model of a Transport Vehicle Mechanical System Translational Motion

The article is devoted to the formalization [1] of the design of mathematical model for the computer simulation of complex mechanical systems. The simulation object is the mechanical system of the transport vehicle (railway or automotive). The complete system is split into subsystems (macro-elements), each of macro-element has one degree of freedom. The whole system of macro-elements can be considered as a translational moving system. A two-stage algorithm to construct a mathematical macro-model of the transport vehicle mechanical system - is presented. The results of the computer simulation are presented. This modeling method is beneficial to be used in the educational process to establish interdisciplinary connections, as well as to create e-learning resources for students of applied mathematics, information technology and engineering profiles.

Object-oriented Approach to Design of the Complex Mechanical System Dynamics Mathematical Models

The article presents the results of an object-oriented approach applied to modeling the dynamics of complex mechanical systems when it is used in the educational process. The results of formalization the mathematical model design in the form of the second kind (conventional) Lagrange equations and the resulting Cauchy problem are considered. The article contains the authors’ presentation of the corresponding information flows diagram. The ways to use of object-oriented approach discussed in this article are proposed to be used in the educational process to establish interdisciplinary connections, as well as to create e-learning resources for students of applied mathematics, information technology and engineering profiles. The examples of the display forms for designed software used in the simulation of a transport vehicle mechanical system are presented.

High order variational integrators in the optimal control of mechanical systems

In recent years, much effort in designing numerical methods for the simulation and optimization of mechanical systems has been put into schemes which are structure preserving. One particular class are variational integrators which are momentum preserving and symplectic. In this article, we develop two high order variational integrators which distinguish themselves in the dimension of the underling space of approximation and we investigate their application to finite-dimensional optimal control problems posed with mechanical systems. The convergence of state and control variables of the approximated problem is shown. Furthermore, by analyzing the adjoint systems of the optimal control problem and its discretized counterpart, we prove that, for these particular integrators, dualization and discretization commute.