Orthotropic closure approximations for flow‐induced fiber orientation

1995 ◽  
Vol 39 (6) ◽  
pp. 1095-1122 ◽  
Author(s):  
Joaquim S. Cintra ◽  
Charles L. Tucker
Keyword(s):  
Fiber Orientation ◽  
Closure Approximations

scholarly journals Modeling and Simulation of Fiber Orientation in Injection Molding of Polymer Composites

2011 ◽  
Vol 2011 ◽  
pp. 1-14 ◽  
Author(s):  
Jang Min Park ◽  
Seong Jin Park
Keyword(s):  
Finite Element ◽  
Injection Molding ◽  
Fiber Orientation ◽  
Flow Model ◽  
Three Dimensional ◽  
Coupled Analysis ◽  
Injection Molding Process ◽  
Molding Process ◽  
Orientation Tensor ◽  
Closure Approximations

We review the fundamental modeling and numerical simulation for a prediction of fiber orientation during injection molding process of polymer composite. In general, the simulation of fiber orientation involves coupled analysis of flow, temperature, moving free surface, and fiber kinematics. For the governing equation of the flow, Hele-Shaw flow model along with the generalized Newtonian constitutive model has been widely used. The kinematics of a group of fibers is described in terms of the second-order fiber orientation tensor. Folgar-Tucker model and recent fiber kinematics models such as a slow orientation model are discussed. Also various closure approximations are reviewed. Therefore, the coupled numerical methods are needed due to the above complex problems. We review several well-established methods such as a finite-element/finite-different hybrid scheme for Hele-Shaw flow model and a finite element method for a general three-dimensional flow model.

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.

scholarly journals Fibers Effects on Contract Turbulence Using a Coupling Euler Model

2021 ◽  
Vol 11 (15) ◽  
pp. 7126
Author(s):  
Wei Yang ◽  
Pei Hu
Keyword(s):  
Boundary Layer ◽  
Velocity Profile ◽  
Fiber Orientation ◽  
Bottom Layer ◽  
Orientation Distribution ◽  
Industrial Applications ◽  
Dynamics Simulation ◽  
Fiber Concentration ◽  
Fibers Orientation ◽  
Process Strategy

Fiber additive will induce the rheological behavior of suspension, resulting in variation in velocity profile and fiber orientation especially for the non-dilute case. Based on the fluid-solid coupling dynamics simulation, it shows that the fiber orientation aligns along the streamline more and more quickly in the central turbulent region as the fiber concentration increases, especially contract ratio Cx > 4. However, fibers tend to maintain the original uniform orientation and are rarely affected by the contract ratio in the boundary layer. The fibers orientation in the near semi-dilute phase is lower than that in the dilute phase near the outlet, which may be the result of the hydrodynamic contact lubrication between fibers. The orientation distribution and concentration of the fibers change the viscous flow mechanism of the suspension microscopically, which makes a velocity profile vary with the phase concentration. The velocity profile of the approaching semi-dilute phase sublayer is higher than that of the dilute and semi-dilute phases on the central streamline and in the viscous bottom layer, showing weak drag reduction while the situation is opposite on the logarithmic layer of the boundary layer. The relevant research can provide a process strategy for fiber orientation optimization and rheological control in the industrial applications of suspension.

A Review of the Collagen Orientation in the Articular Cartilage

Cartilage ◽  
2021 ◽  
pp. 194760352098877
Author(s):  
Roy D. Bloebaum ◽  
Andrew S. Wilson ◽  
William N. Martin
Keyword(s):  
Surface Layer ◽  
Articular Cartilage ◽  
Fiber Orientation ◽  
Collagen Fiber ◽  
Articular Surface ◽  
Imaging Techniques ◽  
Collagen Fibers ◽  
Deep Zone ◽  
Collagen Fiber Orientation ◽  
Critical Point Drying

Objective There has been a debate as to the alignment of the collagen fibers. Using a hand lens, Sir William Hunter demonstrated that the collagen fibers ran perpendicular and later aspects were supported by Benninghoff. Despite these 2 historical studies, modern technology has conflicting data on the collagen alignment. Design Ten mature New Zealand rabbits were used to obtain 40 condyle specimens. The specimens were passed through ascending grades of alcohol, subjected to critical point drying (CPD), and viewed in the scanning electron microscope. Specimens revealed splits from the dehydration process. When observing the fibers exposed within the opening of the splits, parallel fibers were observed to run in a radial direction, normal to the surface of the articular cartilage, radiating from the deep zone and arcading as they approach the surface layer. After these observations, the same samples were mechanically fractured and damaged by scalpel. Results The splits in the articular surface created deep fissures, exposing parallel bundles of collagen fibers, radiating from the deep zone and arcading as they approach the surface layer. On higher magnification, individual fibers were observed to run parallel to one another, traversing radially toward the surface of the articular cartilage and arcading. Mechanical fracturing and scalpel damage induced on the same specimens with the splits showed randomly oriented fibers. Conclusion Collagen fiber orientation corroborates aspects of Hunter’s findings and compliments Benninghoff. Investigators must be aware of the limits of their processing and imaging techniques in order to interpret collagen fiber orientation in cartilage.

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