Comparing fiber orientation evolution between startup of shear and nonlubricated squeeze flow

2020 ◽  
Author(s):  
Gregory M. Lambert ◽  
Peter Wapperom ◽  
Donald Baird
Keyword(s):  
Fiber Orientation ◽  
Squeeze Flow

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

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

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

Evaluating Rigid and Semi-Flexible Fiber Orientation Evolution Models in Simple Flows

2016 ◽  
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 fiberpolymer 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 semi-flexible 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.

Development of On-line Fiber Orientation Meter Based on the Light Guide Effect

2004 ◽  
Vol 58 (2) ◽  
pp. 220-225
Author(s):  
Yuji Abe ◽  
Hidenobu Todoroki
Keyword(s):  
Fiber Orientation ◽  
Light Guide ◽  
On Line

scholarly journals Modeling of Bridging Law for Bundled Aramid Fiber-Reinforced Cementitious Composite and its Adaptability in Crack Width Evaluation

Materials ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 179
Author(s):  
Daiki Sunaga ◽  
Takumi Koba ◽  
Toshiyuki Kanakubo
Keyword(s):  
Fiber Orientation ◽  
Crack Width ◽  
Volume Fraction ◽  
Characteristic Point ◽  
Crack Opening ◽  
Aramid Fiber ◽  
Cementitious Composite ◽  
Fiber Reinforced ◽  
Cross Sectional ◽  
Bridging Law

Tensile performance of fiber-reinforced cementitious composite (FRCC) after first cracking is characterized by fiber-bridging stress–crack width relationships called bridging law. The bridging law can be calculated by an integral calculus of forces carried by individual fibers, considering the fiber orientation. The objective of this study was to propose a simplified model of bridging law for bundled aramid fiber, considering fiber orientation for the practical use. By using the pullout characteristic of bundled aramid fiber obtained in the previous study, the bridging laws were calculated for various cases of fiber orientation. The calculated results were expressed by a bilinear model, and each characteristic point is expressed by the function of fiber-orientation intensity. After that, uniaxial tension tests of steel reinforced aramid-FRCC prism specimens were conducted to obtain the crack-opening behavior and confirm the adaptability of the modeled bridging laws in crack-width evaluation. The experimental parameters are cross-sectional dimensions of specimens and volume fraction of fiber. The test results are compared with the theoretical curves calculated by using the modeled bridging law and show good agreements in each parameter.

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