James St Julien

(Advisor: Prof. Donggang Yao]  

or will defend a master’s thesis entitled,

Simulation of Polymer Imprinting and Embossing using Smoothed Dissipative Particle Dynamics

On

Thursday, May 9 at 2:00 p.m. 

MRDC Room 4404

 Committee

• Prof. Donggang Yao – School of Materials Science and Engineering (advisor)  
• Prof. Chuck Zhang – School of Industrial and Systems Engineering
• Prof. Seung soon Jang – School of Materials Science and Engineering

Abstract

A simulation of an imprinting process using Smoothed Dissipative Particle Dynamics is presented. Finite Element Methods (FEM) are commonplace in industry for the simulation of materials processing; however, FEM has a limited capacity to simulate more complex material behaviors. Finite Difference Methods (FDM) are alternative methods that can overcome many of the limitations that FEM faces, though they face their own unique challenges. Smoothed Dissipative Particle Dynamics (SDPD) is a FDM method incorporating a discretized Navier-Stokes Equations to describe the motions of fluids, which allows for the utilization of known fluid properties to simulate flow behavior. Couette Startup flow was simulated first using SDPD to establish the validity of the simulation method, showing good agreement with analytical results.  Embossing simulations under different settings were then conducted using SDPD. Cavity filling modes and their dependence on die parameters is demonstrated for single and multi-cavity dies. Within a single cavity die, we see a transition of flow peak deformation from single peak to dual peak flow at a cavity half width to film thickness ratio (whi=1), showing results consistent with FEM simulations.  As a particle-based simulation method, SDPD can allow for modeling of more complex fluid behaviors; this is demonstrated by simulations exhibiting elastic-viscoplastic relaxation and droplet formation/material separation. These results demonstrate the potential of SDPD in simulating materials processing scenarios which would prove difficult using FEM methods such as materials separation, common in spraying or jetting processes.