Extension of the natural element method to surface tension and wettability for the simulation of polymer flows at the micro and nano scales

Abstract:The control of metal wettability is a key-factor in the field of brazing or welding-brazing. The present paper deals with the numerical simulation of the whole phenomena occurring during the assembly of dissimilar alloys. The study is realized in the frame of potential applications for the aircraft industry, considering the case of the welding-brazing of aluminum Al5754 and quasi-pure titanium Ti40. The assembly configuration, presented here, is a simplification of the real experiment. We have reduced the three-dimensional overlap configuration to a bi-dimensional case. In the present case, an aluminum cylinder is fused onto a titanium substrate. The main physical phenomena which are considered here are: the heat transfers, the fluid flows with free boundaries and the mass transfer in terms of chemical species diffusion. The numerical problem is implemented with the commercial software Comsol Multiphysics™, by coupling heat equation, Navier-Stokes and continuity equations and the free boundary motion. The latter is treated with the Arbitrary Lagrangian Eulerian method, with a particular focus on the contact angle implementation. The comparison between numerical and experimental results shows a very satisfactory agreement in terms of droplet shape, thermal field and intermetallic layer thickness. The model validates our numerical approach.

show abstract

“…The wetting angle was considered with a "driving" [11] or "wetting" [20] force located at the D point and written as follows:…”

Section: Fluid Flow Problemmentioning

confidence: 99%

Multiphysics Simulation and Experimental Investigation of Aluminum Wettability on a Titanium Substrate for Laser Welding-Brazing Process

Dal

Peyre

2017

Metals

View full text Add to dashboard Cite

show abstract

“…The code includes surface tension and wetting defined by the static contact angle [32]. Newtonian and shear-thinning behaviors can be taken into account.…”

Section: Numerical Simulations Of Leveling With Thermal Diffusion In mentioning

confidence: 99%

“…Newtonian and shear-thinning behaviors can be taken into account. The variational formulation is detailed in [32] and allows to compute the velocity field v and pressure field p in the polymer. The substrate is modelled as a rigid body and is supposed to be fixed.…”

Section: Numerical Simulations Of Leveling With Thermal Diffusion In mentioning

confidence: 99%

See 1 more Smart Citation

Influence of thermal diffusion and shear thinning during the leveling of nanoimprinted patterns in a polystyrene thin film

et al. 2015

Self Cite

View full text Add to dashboard Cite

Science Arts & Métiers (SAM)is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. Abstract. When capillary forces prevail, the leveling of the free surface of a fluid film is a natural phenomenon that has already found applicative interest either with brushmarks for paint coatings or for rheology on polymeric thin films. Among many parameters, the material behavior influences notably this phenomenon and its characterization still arouses curiosity at the nanoscale. In this article the nanoscale properties of a polystyrene film are derived from the leveling rate of nanoimprinted patterns and are compared to bulk values obtained with a parallel plate rheometer. In particular the focus is made on the isothermal assumption during the process and the consequences of an anisothermal state on the material behavior. Both points are investigated by using numerical simulations based on the natural element method. First we demonstrate experimentally that the leveling rate is influenced by the heat exchange at the air-polymer interface and that thermal diffusion should be taken into account within the film and its underlying substrate. Then we numerically investigate the influence of thermal diffusion and shear-thinning on the leveling rate. Finally we show that the bulk properties can represent particularly closely the behavior of the polymer at the nanoscale if adequate thermal boundary conditions are used and if shear-thinning is taken into account. This agreement postulates a decrease by 7• C of the mean temperature of the polystyrene film coated on silicon when experiments are carried out on a hotplate at 100• C in a cleanroom environment.

show abstract

“…To determineγ max eq /γ ref , an in-house developed software [14] has been used. The code uses the natural element method (NEM) to simulate viscous flows.…”

Section: C-nem Simulationsmentioning

confidence: 99%

Legitimate domain of a Newtonian behavior for thermal nanoimprint lithography

Teyssèdre

Pierre

Landis

et al. 2013

Microelectronic Engineering

View full text Add to dashboard Cite

Nanoimprint lithography is an efficient way to reproduce nanostructures down to 20 nanometers in sub-micrometer polymeric films. To optimize this process, simulation using a Newtonian behavior is a cheap and efficient way to predict the polymer flow in micro and nano size cavities. This behavior is nevertheless limited to flows with shear rates below a critical value that can be determined with standard rheology measurements. We have investigated the validity domain of this behavior to simulate thermal NIL. This domain of validity is composed of two uncoupled functions, one for the material properties and the mean pressure applied to the pattern, and one for the geometry considered. The latter function has been determined with numerical simulations using the natural element method. It is demonstrated that knowing the mean applied pressure, the critical shear rate, and the viscosity of the material we are able to determine, depending on stamp geometry, if shear-thinning may or may not occur during an imprinting process.

show abstract

Extension of the natural element method to surface tension and wettability for the simulation of polymer flows at the micro and nano scales

Cited by 13 publications

References 33 publications

Multiphysics Simulation and Experimental Investigation of Aluminum Wettability on a Titanium Substrate for Laser Welding-Brazing Process

Multiphysics Simulation and Experimental Investigation of Aluminum Wettability on a Titanium Substrate for Laser Welding-Brazing Process

Influence of thermal diffusion and shear thinning during the leveling of nanoimprinted patterns in a polystyrene thin film

Legitimate domain of a Newtonian behavior for thermal nanoimprint lithography

Contact Info

Product

Resources

About