scholarly journals A Flow-Dependent Fiber Orientation Model

2020 ◽  
Vol 4 (3) ◽  
pp. 96
Author(s):  
Susanne Katrin Kugler ◽  
Argha Protim Dey ◽  
Sandra Saad ◽  
Camilo Cruz ◽  
Armin Kech ◽  
...  
Keyword(s):  
Fiber Orientation ◽  
Mechanical Performance ◽  
Mechanistic Model ◽  
Elongational Flow ◽  
Simulation Software ◽  
Fiber Reinforced Polymers ◽  
Macroscopic Model ◽  
Fluid Viscosity ◽  
Fiber Reinforced ◽  
Elongational Flows

The mechanical performance of fiber reinforced polymers is dependent on the process-induced fiber orientation. In this work, we focus on the prediction of the fiber orientation in an injection-molded short fiber reinforced thermoplastic part using an original multi-scale modeling approach. A particle-based model developed for shear flows is extended to elongational flows. This mechanistic model for elongational flows is validated using an experiment, which was conducted for a long fiber reinforced polymer. The influence of several fiber descriptors and fluid viscosity on fiber orientation under elongational flow is studied at the micro-scale. Based on this sensitivity analysis, a common parameter set for a continuum-based fiber orientation macroscopic model is defined under elongational flow. We then develop a novel flow-dependent macroscopic fiber orientation, which takes into consideration the effect of both elongational and shear flow on the fiber orientation evolution during the filling of a mold cavity. The model is objective and shows better performance in comparison to state-of-the-art fiber orientation models when compared to μCT-based fiber orientation measurements for several industrial parts. The model is implemented using the simulation software Autodesk Moldflow Insight Scandium® 2019.

scholarly journals Fiber Orientation Predictions—A Review of Existing Models

2020 ◽  
Vol 4 (2) ◽  
pp. 69 ◽  
Author(s):  
Susanne Katrin Kugler ◽  
Armin Kech ◽  
Camilo Cruz ◽  
Tim Osswald
Keyword(s):  
Fiber Orientation ◽  
Mechanical Performance ◽  
Historical Review ◽  
Fiber Reinforced Polymers ◽  
Strong Impact ◽  
Fiber Reinforced ◽  
Reinforced Polymers ◽  
Virtual Engineering ◽  
Rotary Diffusion ◽  
Orientation Phenomenon

Fiber reinforced polymers are key materials across different industries. The manufacturing processes of those materials have typically strong impact on their final microstructure, which at the same time controls the mechanical performance of the part. A reliable virtual engineering design of fiber-reinforced polymers requires therefore considering the simulation of the process-induced microstructure. One relevant microstructure descriptor in fiber-reinforced polymers is the fiber orientation. This work focuses on the modeling of the fiber orientation phenomenon and presents a historical review of the different modelling approaches. In this context, the article describes different macroscopic fiber orientation models such as the Folgar-Tucker, nematic, reduced strain closure (RSC), retarding principal rate (RPR), anisotropic rotary diffusion (ARD), principal anisotropic rotary diffusion (pARD), and Moldflow rotary diffusion (MRD) model. We discuss briefly about closure approximations, which are a common mathematical element of those macroscopic fiber orientation models. In the last section, we introduce some micro-scale numerical methods for simulating the fiber orientation phenomenon, such as the discrete element method (DEM), the smoothed particle hydrodynamics (SPH) method and the moving particle semi-implicit (MPS) method.

scholarly journals Simulating Fiber-Reinforced Concrete Mechanical Performance Using CT-Based Fiber Orientation Data

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 717 ◽  
Author(s):  
Vladimir Buljak ◽  
Tyler Oesch ◽  
Giovanni Bruno
Keyword(s):  
Reinforced Concrete ◽  
Fiber Orientation ◽  
Control Experiment ◽  
Mechanical Performance ◽  
Damage Model ◽  
Fiber Reinforced Concrete ◽  
Material Behavior ◽  
Bending Test ◽  
Structural Level ◽  
Fiber Reinforced

The main hindrance to realistic models of fiber-reinforced concrete (FRC) is the local materials property variation, which does not yet reliably allow simulations at the structural level. The idea presented in this paper makes use of an existing constitutive model, but resolves the problem of localized material variation through X-ray computed tomography (CT)-based pre-processing. First, a three-point bending test of a notched beam is considered, where pre-test fiber orientations are measured using CT. A numerical model is then built with the zone subjected to progressive damage, modeled using an orthotropic damage model. To each of the finite elements within this zone, a local coordinate system is assigned, with its longitudinal direction defined by local fiber orientations. Second, the parameters of the constitutive damage model are determined through inverse analysis using load-displacement data obtained from the test. These parameters are considered to clearly explain the material behavior for any arbitrary external action and fiber orientation, for the same geometrical properties and volumetric ratio of fibers. Third, the effectiveness of the resulting model is demonstrated using a second, “control” experiment. The results of the “control” experiment analyzed in this research compare well with the model results. The ultimate strength was predicted with an error of about 6%, while the work-of-load was predicted within 4%. It demonstrates the potential of this method for accurately predicting the mechanical performance of FRC components.

scholarly journals Model Calibration and Data Set Determination Considering the Local Micro-Structure for Short Fiber Reinforced Polymers

2021 ◽  
Vol 5 (2) ◽  
pp. 40
Author(s):  
Andreas Primetzhofer ◽  
Gabriel Stadler ◽  
Gerald Pinter ◽  
Florian Grün
Keyword(s):  
Fiber Orientation ◽  
Model Calibration ◽  
Short Fiber ◽  
Fiber Reinforced Polymers ◽  
Fiber Reinforced ◽  
Micro Structure ◽  
Data Set ◽  
Reinforced Polymers ◽  
Whole Life Cycle ◽  
Local Fiber

To ensure the usability of parts made of fiber-reinforced polymers, a lifetime assessment has to be made in an early stage of the development process. To describe the whole life cycle of these parts, continuous simulation chains can be used. From production to the end of the service life, all influences are mapped virtually. The later material strength is already given after the manufacturing process due to the process dependent fiber alignment. To be able to describe this fiber orientation within the lifetime assessment, this paper presents an approach for model calibration and data set determination to consider the local micro-structure. Therefore, quasi-static and cyclic tests were performed on specimens with longitudinal and transversal fiber orientation. A supplementary failure analysis provides additional information about the local micro-structure. The local fiber orientation is determined with µCT (micro computer tomography)-measurements, correlated to the extraction positions of the specimen, and implemented in a dataset. With an attached lifetime calculation on a demonstrator, a major influence of the local micro-structure on the calculation results can be shown. Therefore, it is indispensable to consider the local fiber orientation in the data set determination of short fiber reinforced polymers.

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