An Annular Plate Model in Arbitrary-Lagrangian-Eulerian Description for the DLR FlexibleBodies Library

The bending deformation of rotating annular plates and the associated vibration behaviour is important in engineering applications which range from automotive or railway brake systems to discs that form essential components in turbomachinery. In order to extend the capabilities of the DLR FlexibleBodies library for such use cases, a new Modelica class has been implemented which is based on the analytical description of an annular Kirchhoff plate. In addition the so-called Arbitray Langrangian-Eulerian (ALE) representation has been adopted so that rotating and non-rotating external loads may be applied conventiently to rotating plates. Besides these particularities the new class AnnularPlate completely corresponds to the concept of FlexibleBodies library with the two already available model classes Beam and ModalBody. This paper gives an overview on the theoretical background of the new class AnnularPlate, explains the usage and presents application examples

Modeling of Flexible Multibody Systems Excited by Moving Loads with Application to a Robotic Portal System

In this paper, an approach to solve mechanical problems with moving loads and flexible bodies is presented. Therefore, the multi-disciplinary modeling language Modelica together with the DLR FlexibleBodies Library is utilized. Rather than solving the equations of motion analytically, this approach solves them numerically. While large overall motions of the flexible parts are described using the Floating Frame of Reference (FFR) method, the deformation is represented by appropriate shape functions. It is shown how a subsystem with masses and spring-damper elements can be connected to the flexible body and how the occurring forces of this moving load affect it. The equations of motion are derived in a general way, yielding a formulation compatible to e. g. a finite element models which are reduced to global shape functions. The usage of this formulation is shown for the simulation of a robotic portal system

PySimulator – A Simulation and Analysis Environment in Python with Plugin Infrastructure

A new simulation and analysis environment in Python is introduced. The environment provides a graphical user interface for simulating different model types (currently Functional Mockup Units and Modelica Models), plotting result variables and applying simulation result analysis tools like Fast Fourier Transform. Additionally advanced tools for linear system analysis are provided that can be applied to the automatically linearized models. The modular concept of the software enables easy development of further plugins for both simulation and analysis

Moving loads on flexible structures presented in the floating frame of reference formulation

The introduction of moving loads in the Floating Frame of Reference Formulation is presented. We derive the kinematics and governing equations of motion of a general flexible multibody system and their extension to moving loads. The equivalence of convective effects with Coriolis and centripetal forces is shown. These effects are measured numerically and their significance in moving loads traveling at high speed is confirmed. A method is presented to handle discontinuities when moving loads separate from the flexible structure. The method is extended from beam models to general flexible structures obtained by means of the Finite Element Method. An interpolation method for the deformation field of the modal representation of these bodies is introduced. The work is concluded by application of the method to modern mechanical problems in numerical simulations

An Annular Plate Model in Arbitrary LagrangianEulerian-Description for the DLR FlexibleBodies Library

The bending deformation of rotating annular plates and the associated vibration behaviour is important in engineering applications which range from automotive or railway brake systems to discs that form essential components in turbomachinery. In order to extend the capabilities of the DLR FlexibleBodies library for such use cases, a new Modelica class has been implemented which is based on the analytical description of an annular Kirchhoff plate. In addition the so-called Arbitray Langrangian-Eulerian (ALE) representation has been adopted so that rotating and non-rotating external loads may be applied conventiently to rotating plates. Besides these particularities the new class AnnularPlate completely corresponds to the concept of FlexibleBodies library with the two already available model classes Beam and ModalBody. This paper gives an overview on the theoretical background of the new class AnnularPlate, explains the usage and presents application examples

The Modeling of Flexible Bodies in the object-oriented multi-domain Framework Modelica

The object-oriented language Modelica presents a modeling framework to interconnect components from different engineering disciplines such as mechanics, electrics, thermodynamics, control etc. and to set-up multi-domain simulations tasks in one consistent environment. Due to the underlying modeling ideas of Modelica the implementation of flexible body components in this framework relies on specific considerations, which are the main focus of the paper. Therefore the conceptual ideas of Modelica are shortly introduced first. Then, the handling of multibody particularies in Modelica are addressed. The theory and the user interface of the DLR FlexibleBodies Library, which is based on the Standard Input Data (SID) format, are presented. A survey on a modular electric vehicle and its suspension system demonstrates, how a multi-domain model with flexible components may be set-up and simulated