Direct numerical simulations of three-dimensional surface instability patterns in thin film-compliant substrate structures

AbstractA comprehensive numerical study of three-dimensional surface instability patterns is presented. The formation of wrinkles is a consequence of deformation instability when a thin film, bonded to a compliant substrate, is subject to in-plane compressive loading. We apply a recently developed computational approach to directly simulate complex surface wrinkling from pre-instability to post-instability in a straightforward manner, covering the entire biaxial loading spectrum from pure uniaxial to pure equi-biaxial compression. The simulations use embedded imperfections with perturbed material properties at the film-substrate interface. This approach not only triggers the first bifurcation mode but also activates subsequent post-buckling states, thus capable of predicting the temporal evolution of wrinkle patterns in one simulation run. The state of biaxiality is found to influence the surface pattern significantly, and each bifurcation mode can be traced back to certain abrupt changes in the overall load–displacement response. Our systematic study reveals how the loading condition dictates the formation of various instability modes including one-dimensional (1D) sinusoidal wrinkles, herringbone, labyrinth, and checkerboard.

Download Full-text

Experimental and Numerical Study of Evaporative Heat Transfer From Ten- Micro Microchannels

Heat Transfer, Volume 2 ◽

10.1115/imece2006-15587 ◽

2006 ◽

Author(s):

Hoki Lee ◽

T. A. Quy ◽

C. D. Richards ◽

D. F. Bahr ◽

R. F. Richards

Keyword(s):

Thin Film ◽

Heat Transfer ◽

Latent Heat ◽

Numerical Study ◽

Electrical Power ◽

Three Dimensional ◽

Working Fluid ◽

Silicon Membrane ◽

Transfer Rates ◽

Evaporative Heat Transfer

Experimental and numerical results are presented for evaporative heat transfer from ten-micron square open-top channels. The radial channels are fabricated in epoxy photoresist on a two micron thick silicon membrane. The working fluid is pumped by capillary forces from a reservoir at the edge of the silicon membrane into the channels where it evaporates. The electrical power dissipated in a thin-film heater in the center of the membrane, the conduction heat transfer rate radially out of the membrane, and the rate of evaporation of the working fluid are measured. A three-dimensional finite difference, time-domain integration is used to predict sensible and latent heat transfer rates. Only 5-10% of the energy dissipated as heat in the thin film heater is carried away as latent heat by the evaporating working fluid. Computed temperatures and heat transfer rates are shown to match the experimental results.

Download Full-text

Three-Dimensional Surface Pattern and Chemical Composition of Mucosal Titanium Implant Compartments

MATERIALS TRANSACTIONS ◽

10.2320/matertrans.43.3036 ◽

2002 ◽

Vol 43 (12) ◽

pp. 3036-3042

Author(s):

Wolf-D. Grimm ◽

Wolfgang H. Arnold ◽

Michael Dietrich ◽

Harald Morgner

Keyword(s):

Chemical Composition ◽

Three Dimensional ◽

Titanium Implant ◽

Surface Pattern ◽

Dimensional Surface

Download Full-text

Thin Film Herringbone Buckling Patterns

MRS Proceedings ◽

10.1557/proc-795-u3.4 ◽

2003 ◽

Vol 795 ◽

Author(s):

Xi Chen ◽

John W. Hutchinson

Keyword(s):

Thin Film ◽

Strain Energy ◽

Metal Film ◽

Thin Metal Film ◽

Thin Metal ◽

Biaxial Compression ◽

Compliant Substrate

ABSTRACTThin metal film deposited on compliant substrate undergoes equi-biaxial compression and buckles into a highly ordered herringbone pattern [1,2]. In this study, it is shown that compare with the bifurcation competing modes, the herringbone mode has the lowest strain energy and therefore it is the preferred buckling pattern in the thin film.

Download Full-text

Heat Transfer Correlations for Condensation in Three-Dimensional Surface Enhanced Heat Transfer Tubes

Volume 2: Heat Transfer Equipment; Heat Transfer in Multiphase Systems; Heat Transfer Under Extreme Conditions; Nanoscale Transport Phenomena; Theory and Fundamental Research in Heat Transfer; Thermophysical Properties; Transport Phenomena in Materials Processing and Manufacturing ◽

10.1115/ht2017-4927 ◽

2017 ◽

Author(s):

Weiyu Tang ◽

Wei Li ◽

Jingxiang Chen ◽

Hua Zhu ◽

Zhichun Liu ◽

...

Keyword(s):

Heat Transfer ◽

Three Dimensional ◽

Complex Surface ◽

Enhanced Heat Transfer ◽

Error Band ◽

Enhanced Tubes ◽

Surface Enhanced ◽

Almost All ◽

The Impact ◽

Dimensional Surface

Experimental condensation heat transfer data from our previous studies were collected to find a suitable heat transfer correlation for three-dimensional surface enhanced heat transfer tubes. Dimples/protrusions and petal arrays make up the enhanced surface of the 1EHT tube, while longitudinal grooves and dimples constitute that of the other two 2EHT tubes. Working fluids investigated includes three refrigerants R22, R32, R410A and three enhanced tubes have a same nominal inner diameter of 12.7mm. Due to the unique and complex surface structure of three EHT tubes, a constant is proposed and utilized for each EHT tube to estimate the impact of enhanced surfaces on interfacial turbulence, boundary layer disruption, flow separation and secondary flow generation. In addition, the Cavallini correlation modified with the constant can predict almost all the data points within a ±5% error band, which can be a good example for how to predetermine the heat transfer coefficient of three-dimensional enhanced tubes with a unique surface.

Download Full-text

Ordered Morphologies of Confined Diblock Copolymers

MRS Proceedings ◽

10.1557/proc-651-t8.1.1 ◽

2000 ◽

Vol 651 ◽

Author(s):

Yoav Tsori ◽

David Andelman

Keyword(s):

Linear Response ◽

Diblock Copolymers ◽

Three Dimensional ◽

Surface Pattern ◽

Two Dimensional ◽

Ginzburg Landau ◽

Disorder Transition ◽

Lamellar Phases ◽

Surface Fields ◽

Dimensional Surface

AbstractWe investigate the ordered morphologies occurring in thin-films diblock copolymer. For temperatures above the order-disorder transition and for an arbitrary two-dimensional surface pattern, we use a Ginzburg-Landau expansion of the free energy to obtain a linear response description of the copolymer melt. The ordering in the directions perpendicular and parallel to the surface are coupled. Three dimensional structures existing when a melt is confined between two surfaces are examined. Below the order-disorder transition we find tilted lamellar phases in the presence of striped surface fields.

Download Full-text

Imaging of platinum-shadowed macromolecular complexes in dark field

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100110891 ◽

1984 ◽

Vol 42 ◽

pp. 146-147

Author(s):

D.W. Andrews ◽

F.P. Ottensmeyer

Keyword(s):

Thin Film ◽

Three Dimensional ◽

Average Diameter ◽

Dark Field ◽

Bright Field ◽

Field Mode ◽

Macromolecular Complexes ◽

Average Mass ◽

Topological Features ◽

Projection Images

Shadowing with heavy metals has been used for many years to enhance the topological features of biological macromolecular complexes. The three dimensional features present in directionaly shadowed specimens often simplifies interpretation of projection images provided by other techniques. One difficulty with the method is the relatively large amount of metal used to achieve sufficient contrast in bright field images. Thick shadow films are undesirable because they decrease resolution due to an increased tendency for microcrystalline aggregates to form, because decoration artefacts become more severe and increased cap thickness makes estimation of dimensions more uncertain.The large increase in contrast provided by the dark field mode of imaging allows the use of shadow replicas with a much lower average mass thickness. To form the images in Fig. 1, latex spheres of 0.087 μ average diameter were unidirectionally shadowed with platinum carbon (Pt-C) and a thin film of carbon was indirectly evaporated on the specimen as a support.

Download Full-text