scholarly journals Analysis and Evaluation of Fiber Orientation Reconstruction Methods

2019 ◽  
Vol 3 (3) ◽  
pp. 67 ◽  
Author(s):  
Kevin Breuer ◽  
Markus Stommel ◽  
Wolfgang Korte
Keyword(s):  
Maximum Entropy ◽  
Spherical Harmonics ◽  
Fiber Orientation ◽  
Planck Equation ◽  
Short Fiber ◽  
Computational Effort ◽  
Bingham Distribution ◽  
Reconstruction Methods ◽  
Numerical Effort ◽  
Orientation Tensors

The calculation of the fiber orientation of short fiber-reinforced plastics with the Fokker–Planck equation requires a considerable numerical effort, which is practically not feasible for injection molding simulations. Therefore, only the fiber orientation tensors are determined, i.e., by the Folgar–Tucker equation, which requires much less computational effort. However, spatial fiber orientation must be reconstructed from the fiber orientation tensors in advance for structural simulations. In this contribution, two reconstruction methods were investigated and evaluated using generated test scenarios and experimentally measured fiber orientation. The reconstruction methods include spherical harmonics up to the 8th order and the method of maximum entropy, with which a Bingham distribution is reconstructed. It is shown that the quality of the reconstruction depends massively on the original fiber orientation to be reconstructed. If the original distribution can be regarded as a Bingham distribution in good approximation, the method of maximum entropy is superior to spherical harmonics. If there is no Bingham distribution, spherical harmonics is more suitable due to its greater flexibility, but only if sufficiently high orders of the fiber orientation tensor can be determined exactly.

A Statistical Method to Obtain Material Properties From the Orientation Distribution Function for Short-Fiber Polymer Composites

Materials ◽  
2005 ◽  
Author(s):  
David A. Jack ◽  
Douglas E. Smith
Keyword(s):  
Distribution Function ◽  
Orientation Distribution Function ◽  
Material Properties ◽  
Fiber Orientation ◽  
Orientation Distribution ◽  
Short Fiber ◽  
Expectation Values ◽  
Order Tensor ◽  
Fiber Orientation Distribution ◽  
Orientation Tensors

Material behavior of short-fiber composites can be found from the fiber orientation distribution function, with the only widely accepted procedure derived from the application of orientation/moment tensors. The use of orientation tensors requires a closure, whereby the higher order tensor is approximated as a function of the lower order tensor thereby introducing additional computational errors. We present material property expectation values computed directly from the fiber orientation distribution function, thereby alleviating the closure problem inherent to orientation tensors. Material properties are computed from statistically independent unidirectional fiber samples taken from the fiber orientation distribution function. The statistical nature of the distribution function is evaluated with Monte-Carlo simulations to obtain approximate stiffness tensors from the underlying unidirectional composite properties. Examples are presented for simple analytical distributions to demonstrate the effectiveness of expectation values and results are compared to properties obtained through orientation tensors. Results yield a value less than 1.5% for the coefficient of variation and suggest that the orientation tensor method for computing material properties is applicable only for the case of non-interacting fibers.

scholarly journals Evaluation of Fiber Orientation in Short Fiber Reinforced Metals.

1992 ◽  
Vol 18 (3) ◽  
pp. 129-133
Author(s):  
Y. IMAI ◽  
I. SHIOTA ◽  
Y. SHINOHARA ◽  
S. IKENO
Keyword(s):  
Fiber Orientation ◽  
Short Fiber ◽  
Fiber Reinforced

Fast Solutions for the Fiber Orientation of Concentrated Suspensions of Short-Fiber Composites Using the Exact Closure Method

2010 ◽  
Author(s):  
Stephen Montgomery-Smith ◽  
David A. Jack ◽  
Douglas Smith
Keyword(s):  
Distribution Function ◽  
Orientation Distribution Function ◽  
Fiber Orientation ◽  
Orientation Distribution ◽  
Equation Of Motion ◽  
Fiber Composites ◽  
Short Fiber ◽  
Second Order ◽  
Orientation Tensor ◽  
Kinetics Of

The kinetics of the fiber orientation during processing of short-fiber composites governs both the processing characteristics and the cured part performance. The flow kinetics of the polymer melt dictates the fiber orientation kinetics, and in turn the underlying fiber orientation dictates the bulk flow characteristics. It is beyond computational comprehension to model the equation of motion of the full fiber orientation probability distribution function. Instead, typical industrial simulations rely on the computationally efficient equation of motion of the second-order orientation tensor (also known as the second-order moment of the orientation distribution function) to model the characteristics of the fiber orientation within a polymer suspension. Unfortunately, typical implementation forms of any order orientation tensor equation of motion requires the next higher, even ordered, orientation tensor, thus necessitating a closure of the higher order expression. The recently developed Fast Exact Closure avoids the classical closure problem by solving a set of related second-order tensor equations of motion, and yields the exact solution for pure Jeffery’s motion as the diffusion goes to zero. Typical closures are obtained through a fitting process, and are often obtained by fitting for orientation states obtained from solutions of the full orientation distribution function, thus tying the closure to the flows from which it was fit. With the recent understandings of the limitations of the Folgar and Tucker (1984) model of fiber interactions during processing, it has become clear the importance of developing a closure that is independent of any choice of fitting data. The Fast Exact Closure presents an alternative in that it is constructed independent of any fitting process. Results demonstrate that when diffusion exists, the solution is not only physical, but solutions for flows experiencing Folgar-Tucker diffusion are shown to exhibit an equal to or greater accuracy than solutions relying on closures developed via a curve fitting approach.

Robotic Manufacturing of Near-Net Shaped Short-Fiber Reinforced Composites With Functional Properties

2009 ◽  
Author(s):  
Antony Paul ◽  
Jeffery M. Gallagher ◽  
Raymond J. Cipra ◽  
Thomas Siegmund
Keyword(s):  
Mechanical Properties ◽  
Fiber Orientation ◽  
Fiber Composite ◽  
Imaging Techniques ◽  
Short Fiber ◽  
Robotic Arm ◽  
Fiber Reinforced ◽  
Fiber Reinforced Composite ◽  
Geometric Data ◽  
Reinforced Composite

Fiber reinforced composite materials are now frequently being used over conventional materials for their ability to achieve tailored properties and performance characteristics. With the recent advancements in manufacturing techniques, short-fiber composites are coming into prominence in this sector, with their cost advantage and their capability for large throughput. Randomness of fiber orientation is inherent to short fiber composite manufacturing processes. In order to effectively manipulate the mechanical properties of a short-fiber reinforced composite, it is imperative to adequately control the orientation of the fibers during the deposition stage. A process is currently developed to acquire geometrical data of the target object and to utilize it to create a short-fiber reinforced component with controlled fiber orientation. The topological data acquisition of the object is made possible using non-contact 3D imaging techniques. The geometric data is then transferred to a commercial CAD package for the added capability to manipulate the geometry as may be required for specific applications. Subsequently, geometric data constitutes the basis of path planning for the tooling processes. In our process, a novel rapidly re-configurable tooling and molding technology is employed by which a 6-axis robotic arm is used to sculpt a pin-device vacuum surface. After the tooling is completed, the robotic arm will use a deposition nozzle to orient a steady stream of initially random short-fiber from a feeder into a unidirectional output, onto the tool surface. By controlling the position and orientation of the deposition nozzle, it is possible to control the orientation and density of fiber in each section of the near-net shaped composite pre-form. The fiber pre-form is then impregnated with a suitable matrix medium and cured to create the required component. The outlined process is thus capable of manufacturing a near-net shaped short-fiber reinforced component with highly specific mechanical properties. One of the many applications envisaged using this process is the manufacture of custom form-fitting braces, masks and guards for use in healthcare products. A patient intervention can have his or her features acquired using stereo-imaging and have corrective measures incorporated into the device prior to manufacturing. By controlling the orientation and density of the fiber at different portions of the device, it is possible to provide adequate support at specific areas or to restrict movement in specific directions while providing compliance to movement in the others.

Particle-level simulation for the prediction of short fiber orientation in injection molding

2020 ◽  
Vol 139 ◽  
pp. 106115
Author(s):  
Toshiki Sasayama ◽  
Norikazu Sato ◽  
Yoshihide Katagiri ◽  
Yuko Murayama
Keyword(s):  
Injection Molding ◽  
Fiber Orientation ◽  
Short Fiber ◽  
Particle Level
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