Two dimensional long‐flexible fiber orientation simulation in squeeze flow

2017 ◽  
Vol 39 (12) ◽  
pp. 4656-4665 ◽  
Author(s):  
Gleb Meirson ◽  
Andrew N. Hrymak
Keyword(s):  
Fiber Orientation ◽  
Squeeze Flow ◽  
Two Dimensional ◽  
Flexible Fiber

FUNDAMENTALS OF THE SQUEEZE-FLOW BETWEEN A HEAT SINK AND A FLIP-CHIP

2008 ◽  
Vol 32 (3-4) ◽  
pp. 467-486 ◽  
Author(s):  
M.A. Marois ◽  
M. Lacroix
Keyword(s):  
Heat Sink ◽  
Flip Chip ◽  
String Model ◽  
Thermal Interface Material ◽  
Squeeze Flow ◽  
Back Side ◽  
Two Dimensional ◽  
Particle Volume ◽  
Volume Fractions ◽  
Drop Flow

The paper presents the fundamentals of the squeeze-flow of the thermal interface material (TIM) that takes place during the pressing of a heat sink to the back side of a flip-chip is studied. A two-dimensional string model is developed for predicting the time-varying plate separation and squeeze-rate in terms of the squeeze force. The predictions are compared to a one-dimensional string model and to a squeeze-drop flow model. Results indicate that the flow resulting from the squeezing of a string of TIM between two rigid plates is truly two-dimensional. The effect of surface tension and of the heat transfer is found to be negligible under the assembly conditions. The flow behaviour of the TIM with suspensions of high thermal conductivity particles is also investigated. It is shown that the fluid remains Newtonian for particle volume fractions smaller than 30%. For volume fractions larger than 30%, the fluid becomes Non-Newtonian during the early stages of the squeezing process, i.e. for t ≤ 1s. In the later stages however (t > 10s), the fluid may be considered Newtonian.

The two-way interaction between anisotropic flow and fiber orientation in squeeze flow

1997 ◽  
Vol 41 (3) ◽  
pp. 491-511 ◽  
Author(s):  
K. A. Ericsson ◽  
S. Toll ◽  
J.-A. E. Månson
Keyword(s):  
Fiber Orientation ◽  
Squeeze Flow ◽  
Anisotropic Flow

Evaluating Rigid and Semiflexible Fiber Orientation Evolution Models in Simple Flows

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Gregory M. Lambert ◽  
Donald G. Baird
Keyword(s):  
Simple Shear ◽  
Fiber Orientation ◽  
Squeeze Flow ◽  
Model Parameters ◽  
Mold Design ◽  
Random Initial Condition ◽  
Complex Flow ◽  
Planar Extension ◽  
Rod Model ◽  
Simple Flows

As American vehicle fuel efficiency requirements have become more stringent due to the CAFE standards, the auto industry has turned to fiber reinforced polymer composites as replacements for metal parts to reduce weight while simultaneously maintaining established safety standards. Furthermore, these composites may be easily processed using established techniques such as injection molding and compression molding. The mechanical properties of these composites are dependent on, among other variables, the orientation of the fibers within the part. Several models have been proposed to correlate fiber orientation with the kinematics of the polymer matrix during processing, each using various strategies to account for fiber interactions and fiber flexing. However, these all require the use of empirical fitting parameters. Previous work has obtained these parameters by fitting to orientation data at a specific location in an injection-molded part. This ties the parameters to the specific mold design used. Obtaining empirical parameters is not a trivial undertaking and adds significant time to the entire mold design process. Considering that new parameters must be obtained any time some aspect of the part or mold is changed, an alternative technique that obtains model parameters independent of the mold design could be advantageous. This paper continues work looking to obtain empirical parameters from rheological tests. During processing, the fiber–polymer suspension is subjected to a complex flow with both shear and extensional behavior. Rather than use a complex flow, this study seeks to isolate and compare the effects of shear and extension on two orientation models. To this end, simple shear and planar extension are employed, and the evolution of orientation from a planar random initial condition is tracked as a function of strain. Simple shear was imparted using a sliding plate rheometer designed and fabricated in-house. A novel rheometer tool was developed and fabricated in-house to impart planar extension using a lubricated squeeze flow technique, where a low-viscosity Newtonian lubricant is applied to the solid boundaries to minimize the effect of shearing due to the no-slip boundary condition. The Folgar–Tucker model with a strain reduction factor is used as a rigid fiber model and compared against a bead–rod model (a semiflexible model) proposed by Ortman. Both models are capable of predicting the data, with the bead–rod model performing slightly better. Orientation occurs at a much faster rate under startup of planar extension and also attains a much higher degree of flow alignment when compared with startup of steady shear.

Obtaining short-fiber orientation model parameters using non-lubricated squeeze flow

2017 ◽  
Vol 29 (12) ◽  
pp. 121608 ◽  
Author(s):  
Gregory Lambert ◽  
Peter Wapperom ◽  
Donald Baird
Keyword(s):  
Fiber Orientation ◽  
Short Fiber ◽  
Squeeze Flow ◽  
Model Parameters ◽  
Orientation Model

scholarly journals Coupling anisotropic viscosity and fiber orientation in applications to squeeze flow

2018 ◽  
Vol 62 (3) ◽  
pp. 669-679 ◽  
Author(s):  
Drew E. Sommer ◽  
Anthony J. Favaloro ◽  
R. Byron Pipes
Keyword(s):  
Fiber Orientation ◽  
Squeeze Flow ◽  
Anisotropic Viscosity

Measuring Collagen Fiber Orientation: A Two-Dimensional Quantitative Macroscopic Technique

1998 ◽  
Vol 120 (4) ◽  
pp. 537-540 ◽  
Author(s):  
J. P. Dickey ◽  
B. R. Hewlett ◽  
G. A. Dumas ◽  
D. A. Bednar
Keyword(s):  
Fiber Orientation ◽  
Collagen Fiber ◽  
Polarized Light ◽  
Design Evaluation ◽  
Two Dimensional ◽  
Orientation Data ◽  
Collagen Fiber Orientation ◽  
System Validation ◽  
Pixel Brightness ◽  
New System

This paper describes the design, evaluation, and application of a new system for quantifying two-dimensional collagen fiber orientation in soft tissue. Series of transmitted polarized light images were collected using a custom-designed macroscope. Combined analysis of pixel brightness, and hue from images collected with a compensator plate, permitted the assignment of each pixel into the appropriate orientation band. Experiments were performed to quantify the linearity and noise of the system. Validation was performed on a specimen composed of strain-birefringent plastic strips at various orientations. Preliminary collagen fiber orientation data is presented from a tendon specimen. This study demonstrates the utility of this approach for studying collagen fiber orientation across large areas.

Two-dimensional long-flexible fiber simulation in simple shear flow

2015 ◽  
Vol 37 (8) ◽  
pp. 2425-2433 ◽  
Author(s):  
Gleb Meirson ◽  
Andrew N. Hrymak
Keyword(s):  
Shear Flow ◽  
Simple Shear ◽  
Simple Shear Flow ◽  
Two Dimensional ◽  
Flexible Fiber
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