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

scholarly journals Static ultrasonic welding of carbon fibre unidirectional thermoplastic materials and the influence of heat generation and heat transfer

2021 ◽  
pp. 002199832097681
Author(s):  
F Köhler ◽  
IF Villegas ◽  
C Dransfeld ◽  
A Herrmann
Keyword(s):  
Cross Sections ◽  
Weld Line ◽  
Welding Process ◽  
Ultrasonic Welding ◽  
Thermoplastic Composites ◽  
Squeeze Flow ◽  
Anisotropic Flow ◽  
Lap Shear ◽  
Anisotropic Thermal Conductivity ◽  
Edge Defects

Ultrasonic welding is a promising technology to join fibre-reinforced thermoplastic composites. While current studies are mostly limited to fabric materials the applicability to unidirectional materials, as found in aerospace structures, would offer opportunities for joining primary aircraft structures. However, due to the highly anisotropic flow of a molten unidirectional ply undesired squeeze flow phenomena can occur at the edges of the weld overlap. This paper investigates how the fibre orientation in the plies adjacent to the weld line influences the welding process and the appearance of edge defects. Ultrasonic welding experiments with different layups and energy director configurations were carried out while monitoring temperatures at different locations inside and outside the weld overlap. The joints were characterized by single lap shear tests, analysis of corresponding fracture surfaces and microscopic cross-sections. Results showed that the anisotropic flow and the anisotropic thermal conductivity of the plies adjacent to the weld line have a distinct effect on the appearance and location of edge defects. By using energy directors that cover only part of the weld overlap area a new approach was developed to mitigate edge defects caused by the highly directional properties of the unidirectional plies.

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 Modification to the Hawking temperature of a dynamical black hole by a flow-induced supertranslation

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Hsu-Wen Chiang ◽  
Yu-Hsien Kung ◽  
Pisin Chen
Keyword(s):  
Black Hole ◽  
Coordinate Transformation ◽  
Information Loss ◽  
Hawking Temperature ◽  
Asymptotic Region ◽  
Unruh Effect ◽  
Anisotropic Flow ◽  
Information Loss Paradox ◽  
History Of ◽  
Entire History

Abstract One interesting proposal to solve the black hole information loss paradox without modifying either general relativity or quantum field theory, is the soft hair, a diffeomorphism charge that records the anisotropic radiation in the asymptotic region. This proposal, however, has been challenged, given that away from the source the soft hair behaves as a coordinate transformation that forms an Abelian group, thus unable to store any information. To maintain the spirit of the soft hair but circumvent these obstacles, we consider Hawking radiation as a probe sensitive to the entire history of the black hole evaporation, where the soft hairs on the horizon are induced by the absorption of a null anisotropic flow, generalizing the shock wave considered in [1, 2]. To do so we introduce two different time-dependent extensions of the diffeomorphism associated with the soft hair, where one is the backreaction of the anisotropic null flow, and the other is a coordinate transformation that produces the Unruh effect and a Doppler shift to the Hawking spectrum. Together, they form an exact BMS charge generator on the entire manifold that allows the nonperturbative analysis of the black hole horizon, whose surface gravity, i.e. the Hawking temperature, is found to be modified. The modification depends on an exponential average of the anisotropy of the null flow with a decay rate of 4M, suggesting the emergence of a new 2-D degree of freedom on the horizon, which could be a way out of the information loss paradox.

Sign in / Sign up

Export Citation Format

Share Document