MODRUMEF

(Robust modeling of joints in flexible multibody systems)

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Project Summary

A flexible mechanism is a set of rigid or deformable bodies connected by means of different types of links. It is the case, for example, of robotic arms, deployable structures, control systems for machinery, etc.

This project focuses on the study of two types of links:

Imperfect permanent links. These are the links that connect, at every moment, the moving parts of the mechanism but possess geometrical imperfections that modify their ideal performance (e.g. Gaps, friction, stops (limitations of the movement), etc).
These imperfections can be due to manufacturing tolerances or to actual functional requirements (maximum displacements, estimated tolerances for high temperature processes, etc).
Intermittent links. There are the links that are activated only during a time interval. Examples of this type are: failure models of permanent links due to the breakage of components, contact and impact phenomena. All these can be thought of transient links.

In the context introduced, the basic goals of the current project are:

Develop computational models which should be capable of represent the nonlinear dynamics of flexible mechanisms including permanent links with gaps, friction and stops. Special emphasis should be put on the robustness of the models.
Develop computational models able to represent the dynamical behavior associated with the failure of links and its effects in the performance of the mechanism after failure.
Develop contact and impact models that allow to include the interaction of the mechanism with its environment. This is important in mechanisms responsible of machinery control and in the handling mechanisms which are able to capture and manipulate objects of their surroundings.
Apply the models presented above to specific examples of industrial interest using a computational program developed for this purpose, versatile and robust, which overcomes the current limitations of commercial codes in respect to these type of links.

Duration and funding

December 2003 - December 2006.
Spanish Ministry of Science and Technology, National Plan of Research and Development 2000-2003. Ref. DPI2003-07201
Total funding: 56000 euros

Research staff

Juan C. García Orden (principal researcher)
José M. Goicolea
Felipe Gabaldón
Juan J. Arribas
Ignacio Romero
Luis Lacoma

Related publications

J.C. García Orden, D. Dopico On the stabilizing properties of energy-momentum integrators and coordinate projections for constrained mechanical systems. Accepted in Advances in theory and applications of multibody dynamics (preliminary title) Serie: Computational Methods in Applied Sciences. Springer, (2006).
J.M Goicolea, J. Cuadrado, J.C. García Orden (Editores) Advances in theory and applications of multibody dynamics (preliminary title) Serie: Computational Methods in Applied Sciences. Springer, (2006).
I. Romero y L.M. Lacoma. Analysis of error estimators for the semidiscrete equations of linear solid and structural dynamics Computer Methods in Applied Mechanics and Engineering. 195, 2674--2696 (2006)
I. Romero y L.M. Lacoma. A methodology for the formulation of error estimators for time integration in solid and structural dynamics International Journal for Numerical Methods in Engineering, 66 (4), 635--660, (2006)
L.M. Lacoma e I. Romero. Error estimation for the HHT method non-linear solid dynamics. Submitted to Computers and Structures.
L.M. Lacoma e I. Romero. Estimación de error en dinámica de sólidos deformables Accepted in Revista Internacional de Métodos Numéricos para el Cálculo y Diseño en Ingeniería.
J.C. García Orden, J.M. Goicolea. Robust analysis of flexible multibody systems and joint clearances in an energy conserving framework. Advances in Computational Multibody Systems. pp. 205--237, Springer,ISBN 1-4020-3392-3, (2005)
J.C. García Orden Analysis of joint clearances in multibody systems. Multibody System Dynamics (Kluwer). 13; 401--420, (2005)
I. Romero. Stability analysis of linear multistep methods for classical elastodynamics Computer Methods in Applied Mechanics and Engineering, Elsevier, 193; 2169-2189, (2004)
I. Romero. The interpolation of rotations and its application to finite element models of geometrically exact rods Computational Mechanics, Springer, (2004)

Gallery

All movies show actual calculations performed with the in-house program EPI.

Slider-crank mechanism with an spherical clearance at the slider joint. Movie MPEG 2.55MB
Double pendulum with spherical joints. Spherical clearance. Movie MPEG 1.17 MB
Double pendulum. Blob clearance and spherical clearance. Movie MPEG 1.64 MB
Double pendulum with cilindrical joints. Angular clearance. Movie MPEG 2.55 MB

Grupo de Mecánica Computacional

Universidad Politécnica de Madrid

Last update: 22/06/2006