25.1. Overview
What are target applications for MTT3D?
The user can easily carry out a media path simulation for the 3D movement of sheet through a machine such as printer, copier, fax, and other sheet-feeding machines.
MTT3D provides the basic modeling of the sheet as paper, film, other plat sheets, Idealized rollers, and guides.
It is also:
Automate a generation of the contact elements between the sheets and the rollers and guides along the path they follows.
Give the user who is designing and analyzing the media transport system, the particular and epochal solution of modeling the discrete and flexible sheets or the continuous strips that undergo large deformations with linear material properties.
Provide a good solution when the user checks the potential for:
Jamming given different sheet size, weight and stiffness
Different sheet properties due to temperature and humidity extremes
Different sheet velocity due to misalignment of drive-driven roller sets
Differences of roller velocities due to gap, wear or etc.
Group for MTT3D
To make it possible to an easy and convenience GUI, a concept of Group is introduced. Group has predefined sub-entities as bodies, joints, forces, and contacts.
For MTT3D, there are four group entities such as sheet, fixed roller and movable roller, and they make it possible to create and modify all sub-entities dependent on each group through only one time operation. Each group is made of several sub-entities as the following table.
Group |
Sub Entities |
Sheet |
Bodies, Forces, Contact geometry |
Guides |
Contact to Sheet, Contact geometry |
FixedRoller |
Body, Joint, Contact to Sheet, Contact geometry |
MovableRoller |
Bodies, Joints, Contact to Roller and Sheet, Nip Force, Contact geometry |
Customized Contact
To handle a contact problem among a sheet and other rollers or guides in MTT3D, RecurDyn has developed a new contact element. The sheet is meshed many nodal masses. To check a contact condition between the sheet and roller:
The sheet is discretized by triangular patches made of three nodal masses
The roller is parameterized as a cylinder with a radius and a length.
Also, the cylinder to patch contact is used in checking a contact condition between the sheet and a circular guide. And the sheet is discretized by many spheres at the nodal positions in checking the contact condition between a sheet and a linear guide or an arc guide. They use a global detecting method for checking a body pair in the contact condition. The method has an advantage that the number of contact searching can be smaller than other methods for the system in which the position of most of rollers and guides are fixed on a point of the base body such as the ground or one carrier body. Most of sheet feeding machines such as a printer, copier or fax are in that case. A cylinder to cylinder contact is introduced for the roller to roller contact and a soft nip. Also, a maximum gap of a movable roller is defined as cylinder to plane contact. And all new contact elements are formulated in the 3D. The below table summarizes the new contact elements that are developed for MTT3D.
Group |
Contacts |
Fixed Roller |
Roller to Sheet Contact |
Movable Roller |
Roller to Sheet Contact |
Roller to Roller Contact |
|
Roller to Roller Contact for Soft Nip |
|
Roller to Plane Contact for Maximum Gap |
|
Guides |
Sheet to Arc Guide Contact |
Sheet to Linear Guide Contact |
|
Roller to Sheet Contact for a circular guide |
|
Contact |
Sheet to Surface Contact |
Defining units
For MTT3D, it is very important to choose the unit system. In general, the sheet such as paper or film has a small mass. As the user divides the sheet into more segments, so each mass of segment bodies is smaller. So the mass may be smaller than numerical error(about 1.0e-8) in the unit system. The user should check this point in the choosing unit system. RecurDyn recommends the user to use the following unit system.
Step to create media transport system
Build a feeding system
Create a sheet
Modify the contact parameter
Check the assembly information
Run the simulation