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Institut für Technische und Numerische Mechanik



NEWEUL - Software package for the dynamic analysis of mechanical systems


NEWEUL is a software package for the dynamic analysis of mechanical systems with the multibody system method. It comprises the computation of the symbolic equations of motion and the simulation of the dynamic behavior.

This site describes the version of NEWEUL written in FORTRAN. Since 2008, the successor is running in Matlab and can be found here.


The manual may be downloaded as Postscript file, gzipped Postscript file or PDF file.

Multibody Systems

The dynamical analysis of a mechanical system starts with the modeling process. The real physical system is approximated by an idealized model. Multibody systems are mechanical models consisting of:
  • rigid and elasticbodies,
  • arbitrary constraining elements (joints, position control elements),
  • passive coupling elements (springs, dampers), and
  • active coupling elements (servo motors).
The topological structure of the models is arbitrary, thus possible configurations are:
  • systems with tree structure, and
  • systems with closed kinematical loops.
The scleronomic or rheonomic constraints can be either holonomic or nonholonomic.

Fields of Application

The software package NEWEUL has been successfully applied in industrial and academic research institutions since 1979. The major fields of application are
  • vehicle dynamics,
  • satellite dynamics,
  • dynamics of machinery,
  • biomechanics,
  • dynamics of mechanisms.


The software package NEWEUL offers two approaches for multibody system modeling. These are
  • the successive assembly approach using the kinematics of relative motions, and
  • the modular assembly approach based on subsystems.
The input data for NEWEUL have to be entered in input files prepared with prompts and comments. The user has to provide only simple expressions for the description of kinematics and mass distribution with respect to arbitrary reference frames. Observation points allow the determination of position, velocity and acceleration of arbitrary points of the multibody system.

Equations of Motion

NEWEUL generates the equation of motion of multibody systems in symbolic form. The computation is based on a Newton-Euler formalism with application of the principles of d'Alembert and Jourdain. The resulting equations of motion can be
  • linear,
  • partially linearized, or
  • nonlinear
The input data for NEWEUL have to be entered in input files prepared with prompts and comments. The symbolic differential equations. Constant parameters can be included in numerical form. Nonlinear coupling elements in kinematically linear models are also permitted. For the output format of the equations of motion several options are possible. FORTRAN compatible output allows the equations to be included in commercial software packages for dynamic analysis and simulation such as, for instance, ACSL. Another output format allows the processing of the equations with the symbol manipulation program MAPLE. Control parameters for compression and factorization enable the user to change the structure of the output equations. For example, the user may want to obtain fully symbolic equations of motion in order to check the results for modeling and input errors. Later, computationally efficient compressed equations can be generated for the verified model.


The software module NEWSIM allows the simulation of the symbolic equations of motion provided by NEWEUL. NEWEUL automatically generates a problem specific simulation program. The user simply has to add the specification of
  • force laws,
  • system parameter values, and
  • initial conditions.
The simulation results are stored in ASCII data files that can be visualized with arbitrary graphics packages. The simulation results may contain
  • the time history of the state variables,
  • the kinematical data of observation points,
  • data for animation,
  • the time history of the reaction forces, and
  • user-defined output data.
Apart from time simulations additional analyses can be performed with the module NEWSIM. These additional features include
  • the quasi static analysis,
  • the computation of the state of equilibrium, and
  • the treatment of the inverse dynamics problem.


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- Schiehlen, W.: Symbolic Computations in Multibody Systems. In: Computer-Aided Analysis of Rigid und Flexible Mechanical Systems, M. F. O. S. Pereira and J. A. C. Ambrosio (eds.). Dordrecht: Kluwer Academic Publishers 1994, S. 101-136.
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Hardware Requirements

The software package NEWEUL is written in FORTRAN77 and can be implemented on any workstation or mainframe with a FORTRAN77 compiler. NEWEUL uses its own symbol manipulator.

Scope of Delivery

The software package NEWEUL is delivered as executable along with user's manuals.

Recent developments

A follow-up project was started, called NewEul-M², which is running in the Matlab environment.

More Information

For more information please contact Prof. Dr.-Ing. Prof. E.h. Peter Eberhard.