Jin Hwan Choi

Simulation and Experimental Methods for Media Transport System: Part II, Effect of Normal Force on Slippage of Paper

Many daily appliances for examples copiers, printers and ATMs contain the media transport system (MTS) and the slippage between the medium in the MTS deteriorates the performance quality of the whole system The slippage of the medium in the MTS is affected by many parameters including the friction coefficient between the feeding rollers and the medium, the velocity of the feeding rollers, and the normal force exerted on the medium by feeding rollers This paper focuses on the effect of the normal force on the slippage while the medium is being fed For this purpose, we developed a two-dimensional simulation model for a paper feeding system. Using the simulation model, we calculated the slippage of the paper for different normal forces We have also constructed a testbed of the paper feeding system to verify the simulation results Experimental results are compared with the simulation resultsKey Words: Media Transport System, Slippage, Normal Force, Friction Coefficients, Paper Modeling

Simulation and Experimental Methods for Media Transport System: Part I, Three-Dimensional Sheet Modeling Using Relative Coordinate

This research presents a three-dimensional modeling technique for a flexible sheet A relative cooidinate formulation is used to represent the kinematics of the sheet The three-dimensional flexible sheet is modeled by multi-rigid bodies interconnected by out-of-plane joints and plate force elements A parent node is designated as a master body and is connected to the ground by a floating joint to cover the rigid motion of the flexible sheet in space Since the in-plane deformation of a sheet such as a paper and a film is relatively small, compared to out-of-plane deformation, only the out-of-plane deformation is accounted for in this research The recursive formulation has been adopted to solve the equations of motion efficiently An example is presented to show the validity of the proposed method

Effective Numerical Analysis Method for Roll-to-Roll System Having the Large Nonlinearity Property

In the Roll-to-Roll (R2R) system, the design and development for a roller path and control system are mainly performed by the expert’s experience. There are some important issues in the numerical analysis method of R2R system. This study proposes an efficient R2R system analysis method. The first one is the Approximated Winding Length Estimation (AWLE) algorithm which can calculate the analytic winded length of the workpiece. The core winder is approximated with line and arc segments in this algorithm. As a result, in the numerical model of R2R system, we can replace the winder characteristics with the approximated winding length estimation (AWLE) algorithm. The second one is the contact algorithm between workpiece and rollers. This contact algorithm must be stable and fast for precise analysis. The third one is the flexible workpiece model. The workpiece can be modeled by the finite elements. By implementing these some important issues, this paper proposes an efficient R2R system analysis method.

Systematic Integration of Finite Element Methods Into Multibody Dynamics Considering Hyperelasticity and Plasticity

This study proposes a systematic extension of a multiflexible-body dynamics (MFBD) formulation that is based on a recursive formulation for rigid body dynamics. It is extended to include nonlinear plastic and hyperelastic material models for the flexible bodies. The flexible bodies in the existing MFBD formulation use a finite element formulation based on corotational elements. The rigid bodies and flexible bodies are coupled using the method of Lagrange multipliers. The extensions to add plasticity and hyperelasticity are outlined. A solid, brick-type element and a shell element are adapted from the literature for use with the plastic material, and a constant volume constraint is introduced to enforce the approximation of incompressibility with the hyperelastic materials. A brief overview of the MFBD formulation and the details required to extend the formulation to incorporate these nonlinear material models are presented. Numerical examples are presented to demonstrate the feasibility of the model.

Numerical Model of Journal Bearing Lubrication Considering a Bending Stiffness Effect

An analysis for operating characteristics of journal bearing lubrication system is performed based on the numerical model. Dynamic bearing lubrication characteristics such as oil film pressure and thickness distribution can be analyzed through a numerical model with an integration of elastohydrodynamics and multi-flexible-body dynamics (MFBD). In particular, the oil film thickness variation by elastic deformation is considered in the elastohydrodynamic analysis by applying the bending stiffness effect of journal. And the oil film thickness variation by the bending stiffness effect is applied to the fluid governing equations to calculate the oil film pressure in the elastohydrodynamic lubrication region. A series of process proposed in this study is available for the analysis of realistic elastohydrodynamic lubrication phenomenon. Also, a numerical example for the journal bearing lubrication system is demonstrated and compared with the experimental results. The numerical results considering the bending stiffness effect show a good agreement with the experimental results.