Continuous System Simulation Language Research Articles

1107 連続系シミュレーション用言語をベースにした粒子法解析用言語「悟空(粒子法)」とその応用例

1107 連続系シミュレーション用言語をベースにした粒子法解析用言語「悟空(粒子法)」とその応用例

A Study on a Elastoplastic Damper Utilizing Continuous Plastic Bending of Thin Metal Rods.

In this paper, a new type of elastoplastic damper utilizing continuous plastic bending of thin metal rods is proposed in order to obtain an elastoplastic damper which yields damping even for a small displacement. The seismic responses of a piping system supported by the elastoplastic damper were calculated using a continuous system simulation language and the effects of the damper on the deflection of the piping system are discussed. The trial damper was made using a thin copper rod, and the resisting force characteristics and fatigue strength of the damper were measured. The seismic responses of an L-shaped pipe supported by the trial elastoplastic damper were measured using an electrohydraulic shaking table. The experimental results were compared with the calculated results.

Automated formula manipulation supports object-oriented continuous-system modeling

Digital continuous-system simulation languages are discussed. It is demonstrated how sophisticated automated formula manipulation can be used to automatically generate state-space models from an object-oriented description of a physical system. The two major complications, algebraic loops and structural singularities, occur frequently as a consequence of couplings between submodels (objects), and these difficulties can often be dealt with by automated formula manipulation. A software tool, Dymola, in which the various formula manipulation techniques have been implemented, is presented. Dymola is an object-oriented continuous-system modeling language and a model manipulator that can be used to generate models in several simulation languages. >

Semiactive Damper Using a Piezoelectric Actuator and a Ball Screw for a Seismic Isolation Device for Machines.

In this paper, a new type of semiactive seismic isolation device for machines is proposed. This isolation device is composed of rubber bearings and semiactive dampers consisting of a ball screw, a brake disk, a brake shoe, a flexure hinge and a piezoelectric actuator. The seismic responses of a machine supported with the isolation device, which is installed on the 5th floor in a 7-story building, are calculated using a continuous system simulation language (FACOM SLCS4), and the effective control condition of the semiactive damper is discussed. An experimental semiactive damper and a model of a machine-isolation device system are made, and the resisting force characteristics of the damper and the seismic response of the machine are measured using an electrohydraulic-type shaking table. The experimental results are compared with the calculated ones, and the effect of vibration isolation of the isolation device is confirmed.

圧電アクチュエータを用いた半能動制御形防振器による配管の地震応答抑制

The authors propose a new type of semiactive damper to control a seismic response of a piping system. The damper is composed of a ball screw and a disk brake with piezoelectric actuators. The brake force is controlled corresponding to the seismic response of the piping or an input acceleration. The damper does not restrict the thermal expansion of the piping because its brake force does not work during a gradual movement. The seismic responses of an L-shaped piping supported with the semiactive damper are calculated using a continuous system simulation language. The restraint effects of the damper are also confirmed experimentally. The results may be summarized as follows : (1) The relative displacement response of the piping can be reduced successfully by the semiactive damper. (2) The semiactive damper has the effect of vibration suppression even by simple control methods such as on-off control and proportional control. (3) The resistance force of the semiactive damper is small compared to that of a mechanical snubber.

Development of an Earthquakeproof Device Using Magnetostrictive Actuators for Piping Systems.

The mechanical snubber is an earthquakeproof device for a piping system under high temperature. It follows a slow displacement of the piping due to thermal expansion, but restrains the piping by a strong resistance force during an earthquake. This strong force can cause elastic failure of grooves on a brake disk, where steel balls are placed. In this report, a new semiactive snubber using giant magnetostrictive actuators and a ball screw is proposed in order to obtain an earthquakeproof device which has less resistance force in comparison with the mechanical snubber. Earthquake responses of a simple beam supported by the semiactive snubber are simulated using a continuous system simulation language, and the restraint effect and the effective controlling condition of the snubber are discussed. The semiactive snubber is built using Terfenol-D (Tb0.3 Dy0.7 Fe1.92-1.95) rods, and its resistance force characteristic is investigated by means of a vibration table.

KBSIM: a system for interactive knowledge-based simulation

The kbsim system integrates quantitative simulation with symbolic reasoning techniques, under the control of a user interface management system, using a relational database management system for data storage and interprocess communication. The system stores and processes knowledge from three distinct knowledge domains, viz. (i) knowledge about the processes of the system under investigation, expressed in terms of a Continuous System Simulation Language (CSSL); (ii) heuristic knowledge on how to reach the goals of the simulation experiment, expressed in terms of a Rule Description Language (RDL); and (iii) knowledge about the requirements of the intended users, expressed in terms of a User Interface Description Language (UIDL). The user works in an interactive environment controlling the simulation course with use of a mouse and a large screen containing a set of ‘live’ charts and forms. The user is assisted by an embedded ‘expert system’ module continuously watching both the system's behavior and the user's action, and producing alerts, alarms, comments and advice. The system was developed on a Hewlett-Packard 9000/350 workstation under the HP-Unix and HP-Windows operating systems, using the Mimer database management system, and Fortran, Prolog/Lisp and C as implementation languages. The kbsim system has great potentials for supporting problem solving, design of working procedures and teaching related to management of highly dynamic systems.

Elastoplastic Damper Using V-Shaped Plates. 1st Report. Seismic Response Analysis of a Base Isolated Building Using the Elastoplastic Damper.

This paper describes the static and dynamic characteristics of a new type of elastoplastic damper and seismic responses of a base isolated building using the elastoplastic dampers. The damper uses two pairs of V-shaped plates and its force-displacement curve is nonlinear with a hardening characteristic in the plastic range. The static force-displacement curve is obtained theoretically, and the dynamically equivalent model which takes into account elasticity, viscosity, plasticity, strain-rate sensitivity and geometry change of the damper is proposed. A seismic isolator consisting of rubber bearings and the elastopladtic dampers is also proposed, and the seismic responses of a 7-story building isolated by this isolator are calculated using a continuous system simulation language (CSSL).

Matrix environments for continuous system modeling and simulation

In any future standard for continuous system simulation lan guages, it is of primary importance that the data and program structures are made sufficiently general and flexible. In this paper, the use of matrix structures in modeling and simulation, and the impact of matrix environments on the design of simulation languages and their experimental frames will be discussed.

Resisting force characteristics of a mechanial snubber and its restraint effect on beam deformation.

A mechanical snubber is used to restrain piping systems in nuclear power plants during an earthquake. It has nonlinearities in both load (or exciting amplitude) and frequency response, so it will be very difficult to analyze the resisting force characteristics of the mechanical snubber theoretically. In this report, the equation of motion of the mechanical snubber is derived and digital simulations of snubber dynamic characteristics over a frequency range are carried out using the Continuous System Simulation Language (CSSL). Also, the restraint effect of the mechanical snubber applied to a simple beam is discussed both numerically and experimentally. The beam is replaced by a lumped mass system and CSSL is used to perform the digital simulations

Vibration Control of Beams by Ball Screw Type Dampers with a Governor

The forced nonlinear vibrations of simple beams supported with two kinds of ball screw type dampers are discussed both numerically and experimentally. The dampers are composed of a ball screw, a flywheel and flyball or perpendicular type governor, and they possess nonlinear characteristics. The beam is replaced by a lumped mass system and the Continuous System Simulation Language is used to simulate the motion of the masses and the damper on a digital computer. The results may be summarized as follows: (1) Two types of dampers are effective for suppressing the amplitude of the beam at the point of attachment of the damper at the first resonance. (2) The linear solution which is obtained by regarding the governor as a flywheel differs from the nonlinear solution in the vicinity of the first resonance frequency of the beam. (3) Each damper approaches the snubber for larger values of moment of inertia J of the flywheel, and acts like a dynamic vibration absorber for smaller values of J.

Vibration control of beams by ball screw type dampers with a governor.

The forced nonlinear vibrations of simple beams supported with two kinds of ball screw type dampers are discussed both numerically and experimentally. The dampers are composed of a ball screw, a flywheel and a flyball or perpendicular type governor, and possess nonlinear characteristics. The beam is replaced by a lumped mass system and the Continuous System Simulation Language is used to simulate the motion of the masses and the damper on a digital computer. The results may be summarized as follows : (1) Two types of dampers are effective for suppressing the amplitude of the beam at the point of attachment of the damper at the first resonance. (2) The linear solution which is solved by regarding the governor as a flywheel differs from the nonlinear solution in the vicinity of the first resonance frequency of the beam. (3) Each damper approaches the snubber for larger values of moment of inertia J of the flywheel, and acts like the dynamic vibration absorber for smaller values of J.

Studies on ball screw type damper with centrifugal brakes.

The effects of vibration isolation of the new type of mechanical damper applied to a single-degree-of-freedom system and a simple beam are discussed numerically and experimentally. The damper is composed of a ball screw, a flywheel and centrifugal brakes, and possesses nonlinear characteristics. The Continuous System Simulation Language is used for the digital simulations of the nonlinear vibration systems. The results may be summarized as follows : (1) The damper is effective for suppressing the amplitude of the single-degree·of-freedom system as well as of the beam at the point of attachment of the damper, at the resonances. (2) The damper approaches a snubber for smaller values of lead L of the ball screw (or larger values of moment of inertia J of the flywheel), and acts like a damper whose damping force is proportional to the square of the velocity for larger values of L (or smaller values of J) .

Some novel applications of a continuous system simulation language

The primary application of a continuous system simulation language involves simulation of dynamic systems described by a set of coupled nonlinear differential (or difference) equations. The built in integration capability in addition to a predefined library of macro operators makes them particularly attractive for a wide range of computationally intensive applications independent of dynamic systems analysis. The purpose of this study is to demonstrate the use of a block oriented continuous simulation language to implement solutions of problems in the field of applied math.

Random process simulation using a continuous system simulation language

Computer simulations of physical systems often include effects of random disturbances. A method is derived for including those disturbances in continuous system simulation language (CSSL) computations. This note shows that the effects of white (or colored) noise are easily implemented by using a random number generator of proper variance. The numerical example of an exponentially correlated random variable illustrates the simulation technique.

ESL - A new Continuous System Simulation Language

ESL is a new Continuous System Simulation Language (CSSL) which is being developed under contract from the European Space Agency. It is based on the concepts outlined in Refer ence 6. The main features of the new language are: (1) Models can be built from submodels (2) Separation of model and experiment (3) Advanced discontinuity-handling (4) A parallel segment feature. The implementation of ESL requires both an interpreter and a translator version of the language. The interpreter translates the user's program into an intermediate code (H-code) which is then interpreted at run-time. The translator may be used to convert the H-code to FORTRAN-77 to produce a more efficient ex ecutable program of production runs. The entire system (with the exception of a few low-level routines) is being written in FORTRAN-77. A prototype version of the language was installed in August 1983 and is currently undergoing evaluations. Details of this version are given with examples of its use.

Computer generation of physical system differential equations using bond graphs

A Computer Aided Modeling Program (CAMP) is developed to process a bond graph representation of a physical engineering system into suitable source input used by Digital Simulation Languages such as IBM DSL (Digital Simulation Language), CSMP (Continuous System Modeling Program), ACSL (Advanced Continuous Simulation Language) or CSSL (Continuous System Simulation Language). The basic philosophy and fundamental principles behind the design of CAMP are presented here. The preprocessed information includes the state variable representation of the system differential equations in first-order form. The appropriate input and interface software that simulation programs require is included in CAMP. The design and simulation of nonlinear systems and control systems has been investigated using this approach. The combination of a bond graph oriented program with a block diagram and FORTRAN oriented program is unique, and offers the best of both worlds, namely, the unified approach to modeling, automatic equation derivation from bond graphs and the extensive and flexible block modules of a continuous system simulator. A variety of cases are considered for mechanical, electromechanical, hydraulic and electrical systems.

DPS — A digital simulation language for the process industries

A digital simulation language program, DPS, developed for the unsteady state simulation of multicomponent process systems, is described. Although a continuous system simulation language, the program allows for the specification of a variety of discrete events of the type encountered in process applications. Typical of these events are the opening/closing of valves, starting/stop ping pumps, etc. DPS uses powerful graphical techniques for sorting and sieving the model equations. The use of DPS is demonstrated by simulating the dynamic behaviour of two dif ferent types of systems: a simple multicomponent mixing pro cess and a control system described by transfer functions.

Some remarks on a continuous-system simulation language (CSSL) for LSI economics

Some remarks on a continuous-system simulation language (CSSL) for LSI economics

Numerical methods for simulation of large systems

The numerical solution of large initial value problems, including those that are derived as approximations to systems of partial differential equations, may encounter difficulties using conventional numerical methods because of stiffness (large range of eigenvalues of the associated linear system). In a nonlinear system, the eigenvalues may change greatly during the solution and a system that is initially well behaved may become stiff, yielding increased computer cost or inaccuracies. This paper contains a discussion of various definitions of stiffness, and several methods for overcoming it, including a new method for identifying and partitioning a two-time-scale system into fast and slow sub-systems. Also included are some experiences using the DARE continuous system simulation language for systems as large as 200 coupled nonlinear ordinary differential equations.