On the use of orientation tensors to represent prepreg platelet orientation state and variability

2020 ◽  
Vol 64 (3) ◽  
pp. 517-527 ◽  
Author(s):  
Anthony J. Favaloro ◽  
Drew E. Sommer
Keyword(s):  
Orientation State ◽  
Orientation Tensors

Coupling of Mold Flow Simulations with Two-Scale Structural Mechanical Simulations for Long Fiber Reinforced Thermoplastics

2015 ◽  
Vol 825-826 ◽  
pp. 655-662 ◽  
Author(s):  
Fabian Buck ◽  
Barthel Brylka ◽  
Viktor Müller ◽  
Timo Müller ◽  
Andrew N. Hrymak ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fiber Orientation ◽  
Mechanical Analysis ◽  
Fiber Reinforced ◽  
Micro Computed Tomography ◽  
Simulation Process ◽  
Orientation State ◽  
Orientation Tensors ◽  
Reinforced Thermoplastics ◽  
Fiber Reinforced Thermoplastics

The entire simulation process for long fiber reinforced thermoplastics is examined to determine the effective mechanical properties which are influenced by the microstructural fiber orientation state. Therefore, flow and fiber orientation simulations are conducted and the obtained fiber orientation tensors are used in two-scale structural simulations. The fiber orientation distributions as well as the mechanical properties are compared with micro-computed tomography data and results from threepoint bending tests performed by dynamical mechanical analysis (DMA), respectively. The validated results show that prediction of the essential mechanical properties is possible with the applied combinated methods and that the knowledge of the fiber orientation and its gradients is of crucial importance for the entire simulation process.

Assessing the Use of Tensor Closure Methods With Orientation Distribution Reconstruction Functions

Materials ◽  
2003 ◽  
Author(s):  
David A. Jack ◽  
Douglas E. Smith
Keyword(s):  
Distribution Function ◽  
Fourth Order ◽  
Lower Order ◽  
Series Representation ◽  
Orientation Distribution ◽  
Higher Order ◽  
Interaction Coefficients ◽  
Order Tensor ◽  
Orientation Tensor ◽  
Orientation Tensors

Orientation tensors are widely used to describe fiber distri-butions in short fiber reinforced composite systems. Although these tensors capture the stochastic nature of concentrated fiber suspensions in a compact form, the evolution equation for each lower order tensor is a function of the next higher order tensor. Flow calculations typically employ a closure that approximates the fourth-order orientation tensor as a function of the second order orientation tensor. Recent work has been done with eigen-value based and invariant based closure approximations of the fourth-order tensor. The effect of using lower order tensors tensors in process simulations by reconstructing the distribution function from successively higher order orientation tensors in a Fourier series representation is considered. This analysis uses the property that orientation tensors are related to the series expansion coefficients of the distribution function. Errors for several closures are investigated and compared with errors developed when using a reconstruction from the exact 2nd, 4th, and 6th order orientation tensors over a range of interaction coefficients from 10−4 to 10−1 for several flow fields.

Simulation and Experimental Measurement of Liquid Crystal Polymer Orientation During Injection Molding

MRS Advances ◽  
2018 ◽  
Vol 3 (39) ◽  
pp. 2311-2316
Author(s):  
Anthony Sullivan ◽  
Anil Saigal ◽  
Michael A. Zimmerman
Keyword(s):  
Liquid Crystal ◽  
Melt Processing ◽  
Engineering Properties ◽  
Liquid Crystal Polymers ◽  
Director Field ◽  
X Ray Scattering ◽  
Molecular Ordering ◽  
Orientation State ◽  
Degree Of Order ◽  
Good Agreement

AbstractLiquid crystal polymers (LCP’s) comprise a class of materials that derive desirable, but anisotropic, engineering properties from long-range molecular ordering. The ability to model the polymer texture is essential to the design of manufacturing processes for isotropic material production. Previous efforts to model LCP directionality have been primarily restricted to structured grids and simple geometries that demonstrate the underlying theory, but fall short of simulating realistic manufacturing geometries. In this investigation, a practical methodology is proposed to simulate the director field in full-scale melt-processing domains and wide-angle x-ray scattering (WAXS) is used to experimentally validate modeling results. It is shown that the model generates good agreement with experimental measurements of both the orientation state and degree of order.

Accuracy of Intersection Counting Method in Measurement of Fiber Orientation Angle Distribution Using Image Processing

2006 ◽  
Vol 324-325 ◽  
pp. 415-418
Author(s):  
Jin Woo Kim ◽  
Dong Gi Lee
Keyword(s):  
Image Processing ◽  
Fiber Orientation ◽  
Orientation Angle ◽  
Angle Distribution ◽  
Counting Method ◽  
Fiber Aspect Ratio ◽  
Reinforced Composite ◽  
Orientation Function ◽  
Orientation State ◽  
Fiber Orientation Angle

While mold fiber reinforced composite material to problem of occasion that high temperature compression molding, flow length in mold is overlong or when flow meets with resistance in side of mold, fiber orientation happens and big change occurs in strength or quality. Thus, in compression molding that use fiber reinforced composite material, orientation state of fiber in moldings is the most basic element that quotes various properties of matter values. Therefore, to clear orientation state of fiber establishing measurement of fiber orientation angle distribution is very important while give correction of molding condition decision, mechanical quality of moldings and guide about material design. In the study, the fiber orientation distribution of simulation figure plotted by PC is measured using image processing in order to examine the accuracy of intersection counting method. The fiber orientation function measured by intersection counting method using image processing is compared with the calculated fiber orientation function. The results show that the measured value of fiber orientation function using intersection counting method is lower than the calculated value, because the number of intersection between the scanning line and the fiber with smaller fiber aspect ratio is counted less than with larger fiber aspect ratio.

FASTensor: A tensor framework for spatiotemporal description

2019 ◽  
Author(s):  
Virgı́nia F. Mota ◽  
Jefersson A. dos Santos ◽  
Arnaldo De A. Araújo
Keyword(s):  
Cancer Cell ◽  
Data Augmentation ◽  
Human Action Recognition ◽  
Human Action ◽  
Research Field ◽  
Small Data ◽  
Learning Tools ◽  
Melanoma Cancer ◽  
Orientation Tensors ◽  
Spatiotemporal Representation

Spatiotemporal description is a research field with applications in various areas such as video indexing, surveillance, human-computer interfaces, among others. Big Data problems in large databases are now being treated with Deep Learning tools, however we still have room for improvement in spatiotemporal handcraft description. Moreover, we still have problems that involve small data in which data augmentation and other techniques are not valid. The main contribution of this Ph.D. Thesis 1 is the development of a framework for spatiotemporal representation using orientation tensors enabling dimension reduction and invariance. This is a multipurpose framework called Features As Spatiotemporal Tensors (FASTensor). We evaluate this framework in three different applications: Human Action recognition, Video Pornography classification and Cancer Cell classification. The latter one is also a contribution of this work, since we introduce a new dataset called Melanoma Cancer Cell dataset (MCC). It is a small data that cannot be artificially augmented due the difficulty of extraction and the nature of motion. The results were competitive, while also being fast and simple to implement. Finally, our results in the MCC dataset can be used in other cancer cell treatment analysis.

scholarly journals Variety of fiber orientation tensors

2021 ◽  
pp. 108128652110576
Author(s):  
Julian Karl Bauer ◽  
Thomas Böhlke
Keyword(s):  
Fiber Orientation ◽  
Mechanical Response ◽  
Transversely Isotropic ◽  
Orientation Tensor ◽  
Isotropic State ◽  
Orientation Tensors ◽  
Linear Invariant ◽  
Parameter Ranges ◽  
Independent Parameters

Fiber orientation tensors are established descriptors of fiber orientation states in (thermo-)mechanical material models for fiber-reinforced composites. In this paper, the variety of fourth-order orientation tensors is analyzed and specified by parameterizations and admissible parameter ranges. The combination of parameterizations and admissible parameter ranges allows for studies on the mechanical response of different fiber architectures. Linear invariant decomposition with focus on index symmetry leads to a novel compact hierarchical parameterization, which highlights the central role of the isotropic state. Deviation from the isotropic state is given by a triclinic harmonic tensor with simplified structure in the orientation coordinate system, which is spanned by the second-order orientation tensor. Material symmetries reduce the number of independent parameters. The requirement of positive-semi-definiteness defines admissible ranges of independent parameters. Admissible parameter ranges for transversely isotropic and planar cases are given in a compact closed form and the orthotropic variety is visualized and discussed in detail. Sets of discrete unit vectors, leading to selected orientation states, are given.

scholarly journals A plausible mechanism for longitudinal lock-in of cortical microtubule array after light-induced reorientation

2020 ◽  
Author(s):  
Marco Saltini ◽  
Bela M. Mulder
Keyword(s):  
Alternative Hypothesis ◽  
Cortical Microtubule ◽  
Selective Advantage ◽  
Consensus Model ◽  
Microtubule Array ◽  
Orientation State ◽  
Cortical Array ◽  
Plausible Mechanism ◽  
Lock In

The light-induced reorientation of the cortical microtubule array in dark-grown A. thaliana hypocotyl cells is a striking example of the dynamical plasticity of the microtubule cytoskeleton. A consensus model, based on katanin-mediated severing at microtubule crossovers, has been developed that successfully describes the onset of the observed switch between a transverse and longitudinal array orientation. However, we currently lack an understanding of of why the newly populated longitudinal array direction remains stable for longer times, when the initial trigger for the reorientation has died out, and re-equilibration effects would tend to drive the system back to a mixed orientation state. Using both simulations and analytical calculations, we show that the assumption of a small orientation-dependent shift in microtubule dynamics is sufficient to explain the long term lock-in of the longitudinal array orientation. Furthermore, we show that the natural alternative hypothesis that there is a selective advantage in severing longitudinal microtubules, is neither necessary nor sufficient to achieve cortical array reorientation, but is able to accelerate this process significantly.

scholarly journals Direct Fiber Simulation of a Compression Molded Ribbed Structure Made of a Sheet Molding Compound with Randomly Oriented Carbon/Epoxy Prepreg Strands—A Comparison of Predicted Fiber Orientations with Computed Tomography Analyses

2020 ◽  
Vol 4 (4) ◽  
pp. 164
Author(s):  
Jan Teuwsen ◽  
Stephan K. Hohn ◽  
Tim A. Osswald
Keyword(s):  
Computed Tomography ◽  
Detailed Comparison ◽  
Micro Computed Tomography ◽  
Molding Compound ◽  
Sheet Molding Compound ◽  
Discontinuous Fiber ◽  
Orientation Tensors ◽  
Fiber Sheet ◽  
Local Fiber ◽  
Good Agreement

Discontinuous fiber composites (DFC) such as carbon fiber sheet molding compounds (CF-SMC) are increasingly used in the automotive industry for manufacturing lightweight parts. Due to the flow conditions during compression molding of complex geometries, a locally varying fiber orientation evolves. Knowing these process-induced fiber orientations is key to a proper part design since the mechanical properties of the final part highly depend on its local microstructure. Local fiber orientations can be measured and analyzed by means of micro-computed tomography (µCT) and digital image processing, or predicted by process simulation. This paper presents a detailed comparison of numerical and experimental analyses of compression molded ribbed hat profile parts made of CF-SMC with 50 mm long randomly oriented strands (ROS) of chopped unidirectional (UD) carbon/epoxy prepreg tape. X-ray µCT scans of three entire CF-SMC parts are analyzed to compare determined orientation tensors with those coming from a direct fiber simulation (DFS) tool featuring a novel strand generation approach, realistically mimicking the initial ROS charge mesostructure. The DFS results show an overall good agreement of predicted local fiber orientations with µCT measurements, and are therefore precious information that can be used in subsequent integrative simulations to determine the part’s mesostructure-related anisotropic behavior under mechanical loads.

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