Development of a Flexible Multibody Model to Simulate Nonlinear Effects in Printing Process

Martin Eckl,Berend Denkena,Thomas Lepper

doi:10.4236/mme.2016.61002

Abstract

Modern high speed printing machines are able to print up to 700 m/min. At this rate, little excita-tions lead to vibrations, which may lead to loss of contact between the rollers (bouncing). This bouncing results in white stripes, being visible on the printed image. To enable the simulation of the whole printing process, including effects like bouncing, a discrete multibody model is developed. The rollers are modeled by several rigid bodies. These bodies are connected to each other by rotational springs, which allow simulation of the first bending eigenmodes of each roller. The contact area between the rollers is modeled by several nonlinear translational springs and damping elements. These elements change their stiffness and damping values depending on the distance between the rollers. If a defined distance is exceeded, the values become zero, which represents the loss of contact (bouncing). The unknown spring and damping elements of this model are parametrized with help of an experimental modal analysis. This paper presents the development of a flexible multibody model to simulate nonlinear effects in printing process.

Highlights

Numerical methods are common tools for the machine design process and can be used for verification during the development phase
If the simulation of the deformation of the bodies and large axis movement is necessary at the same time, the coupling of Finite Element Method (FEM) and multibody simulation (MBS) models is required
This is remarkable, because if the other stiffness values of the machine remain constant, the eigenfrequency of the rollers in contact is expected to be between the eigenfrequencies of the press cylinder (103 Hz) and anilox roll (133 Hz) without contact

Summary

Introduction

Numerical methods are common tools for the machine design process and can be used for verification during the development phase. If the simulation of the deformation of the bodies and large axis movement is necessary at the same time, the coupling of FEM and MBS models is required. By coupling FEM and MBS models the interactions between the machine structure, drive system and control can be investigated and an optimal design and control can be derived to reduce vibrations [6]. Modern high speed printing machines are able to print up to 700 m/min At this rate, little excitations lead to vibrations which may lead to loss of contact between the rollers (bouncing). The most common approach to couple FEM and MBS models is the Craig Bampton method [8]. Unlike Tores, Hackelöer connected the rigid bodies to each other by rotational springs and dampers which allow the simulation of the first bending and torsion eigenmodes. The color unit of a printing machine has not been modeled by DMBS, yet

Multibody Model

Findings

Conclusion