Download or read book Investigation of Dense Suspension Rotary Diffusion Models for Fiber Orientation Predictions During Injection Molding of Short fiber Reinforced Polymeric Composites written by Babatunde O. Agboola and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: There is a need for physics-based mathematical models for the design of industrial short-fiber reinforced composites (SFRC) to predict the fiber orientation within the part. Traditional models for fiber interactions use the isotropic rotary diffusion model of Folgar and Tucker, but there is considerable interest to use the Phelps and Tucker anisotropic rotary diffusion model. Both models predict the flow induced orientation, which directly determines the resulting stiffness of an injection molded part. These two models are investigated in the present work. A number of fourth order orientation tensor closure approximations are investigated for both diffusion models, with the goal being to suggest the more effective and efficient closure approximation for a variety of flow conditions. Differences in the resulting elastic properties predicted from the two rotary diffusion models are observed. These observations raise questions as to which diffusion model should be used commercially for injection molded SFRCs.

Download or read book Improved Fiber Orientation Predictions for Injection Molded Composites written by Jin Wang and published by . This book was released on 2007 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: Short fibers are commonly utilized to reinforce the polymer matrix for injection molded parts. Fibers suspended in the molten polymer matrix are oriented by the flow during the mold filling process, and acquire a preferential orientation pattern in the final part. The fiber orientation introduces anisotropy to the mechanical and thermal properties of the material, including the elastic modulus, the tensile strength, and the thermal expansion. A final part is stronger and stiffer in the direction along which the most fibers align, while it is weaker and more compliant in the other directions. An accurate prediction of fiber orientation in injection molding is crucial for designing a mold and controlling part properties. The well-established Folgar, Advani, and Tucker model is widely used to predict fiber orientation. However, recent experiments indicate that this theory overestimates the change rate of the fiber orientation tensor, and therefore predicts a similar orientation pattern in injection-molded parts regardless of the flow length, the part thickness, or the mold filling speed. A strain reduction factor (SRF) was introduced by Huynh (2001) to decrease the change rate of orientation tensor. Though it produces an excellent agreement with experimental data, the SRF model is not objective and encounters difficulty in complex flows. Inspired by the idea of reducing the growth rates of the eigenvalues of the orientation tensor by a scalar factor, a new orientation model was built, in which we modified the closure and fiber-fiber interactions terms accordingly. A possible approach to reduce the rotation rates of the eigenvectors was also explored, but no successful model with this feature was found. A finite difference program was developed and used to simulate the filling process for two simple geometries: end-gated strips and center-gated disks. The program is based upon the Hele-Shaw approximation to solve the velocity field, and implements the new orientation model to predict the fiber orientation. The results using the same scalar factor as the SRF model show an excellent agreement with experimental measurements, for both strips and disks, in small thicknesses and at different filling speeds. A special treatment was proposed for thick strips, to account for the radial flow front that is observed in short-shot experiments and is different from the almost flat flow front in thin strips. The finite difference program was also extended to simulate the filling process of injection molds with rotation, compression, and expansion (RCEM). The comparison of the predicted and measured fiber orientation demonstrates again the usefulness of our new orientation model. The new orientation theory was further implemented to model complex flows where the full equations of motion must be solved. The solver of fiber orientation equations was added to FIDAP(TM), a commercial finite element software, through user subroutines. The final program is able to solve for velocity, temperature, pressure, and fiber orientation in any two- or three-dimensional geometry. Flow through the gate of our end-gated strips was simulated, and the fiber orientation was calculated. The orientation results were compared to the measured values at a region just inside the gate, and then were used as inlet conditions for the finite difference program to successfully predict the downstream orientation. Our new orientation model is aphenomenological theory, and the value of the scalar factor to reduce the orientation change rate is determined by matching experimental data. Since the rheology of a fiber suspension is affected by the fiber orientation, a rheological experiment measuring the shear viscosity and the normal stress difference is one approach to determine the phenomenological parameters. The formulations were worked out for the shear stress and the normal stress difference with respect to the fiber orientation in a parallel-disk rotational rheometer, and the model was fit to the measured values in a least square sense by adjusting the model parameters. This provides a convenient and viable route for determining the parameters of the orientation model.

Download or read book Flow Induced Alignment in Composite Materials written by T. D. Papathanasiou and published by Woodhead Publishing. This book was released on 1997-10-21 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of aligning short fibers in a fiber-reinforced material is to improve the mechanical properties of the resulting composite. Aligning the fibers, generally in a preferred direction, allows them to contribute as much as possible to reinforcing the material. In some cases, the mechanical properties of these aligned, short-fiber composites can approach those of continuous-fiber composites, with the advantages of lower production costs and greater ease of production. Since its publication, this book has been consistently recognized as one of the most important contributions to this field.

Download or read book A Study of Fiber Orientation in Particle loaded Suspensions Using a Direct Simulation Method with Collision Strategy written by Xiaoqing Li and published by . This book was released on 2016 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt: Short-fiber reinforced composite materials are widely in use in the manufacturing industries to bridge the property gap between continuous-fiber composites and unreinforced materials. Short-fiber composites can effectively strengthen the matrix materials along the fiber length direction, and can still be processed by highly-automated and economical methods such as injection or compression molding. It’s essential to understand and predict the fiber orientation and its influence on the mechanical properties of the composite. However, the hydrodynamic interactions between the matrix and the fibers, and the inter-fiber interactions are not fully understood yet. Sometimes circular particles are added to the matrix for toughening and this may also influence the orientation of the short fibers during flow. In this thesis, we adopt a two-dimensional direct simulation method to investigate, for the first time, the effect of the presence of circular particles on the fiber orientation of short-fiber suspensions. To deal with the collision between fibers or fibers and particles, an ad-hoc method is proposed and developed. We predict the time-evolution of the elliptical fiber orientation as the volume fraction and aspect ratio increases, and compare it with that of the fiber-particle suspensions. The interaction coefficient C1 is calculated and compared with existing models. It is found that the presence of circular particles increases the rotary diffusion of a fiber suspension, and that, as the content of circular particles increases, the fiber alignment in the direction of shear is less pronounced.

Download or read book Flow induced Micro and Nano fiber Suspensions in Short fiber Reinforced Composite Materials Processing written by Dongdong Zhang (Engineer) and published by . This book was released on 2013 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: Short-fiber reinforced polymer composites enjoy widespread industrial applications due to their high strength-to-weight ratios and versatile manufacturing processes. The mechanical, electrical and thermal properties of short- fiber reinforced composite systems are tremendously dependent on fiber orientations within the polymer matrix during the manufacturing process. However, the commonly used melt flow simulation tools employ simplified empirically-derived models that have recently been shown to over-predict the rate of fiber alignment. Therefore, a physical understanding of fiber suspensions during the injection molding process is critical. The main objective of this research project is to develop a systematic methodology to predict fiber orientations during the manufacture of polymer composites through the numerical simulation. The focus is to address such issues as the effect of fiber shape, fiber- fiber interactions, Brownian motions of nano- fibers and fiber suspensions in various solvents, such as inhomogeneous flows. We develop a stand-alone Finite Element Method (FEM) for calculating hydrodynamic forces and torques exerted on fibers. For nano- fibers, the Brownian forces and torques are modeled using a Gaussian distribution function. Our approach seeks fibers' velocities that zero the net torques and forces acting on the fibers by the surrounding bulk fluid. Fiber motions are then computed using a 4th-order Runge-Kutta method to update fiber positions and orientations as functions of time. The successful completion of this project provides a systematic computational approach capable of addressing issues that are currently unresolved in the critical area of manufacturing. Extension of the approach to other areas such as drug delivery and blood cell motion is an additional benefit of this research work.

Download or read book Proceedings of the International Congress on Rheology written by and published by . This book was released on 1996 with total page 914 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Polypropylene Handbook written by József Karger-Kocsis and published by Springer. This book was released on 2019-03-18 with total page 648 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book extensively reviews Polypropylene (PP), the second most widely produced thermoplastic material, having been produced for over 60 years. Its synthesis, processing and application are still accompanied by vigorous R&D developments because the properties of PP are at the borderline between those of commodity and engineering thermoplastics. Readers are introduced to various tacticities and polymorphs of PP, and their effects on structural properties. Further, the book addresses the control of optical properties using nucleants, provides strategies for overcoming the limited cold/impact resistance of PP, examines in detail the effects of recycling, and presents guidelines for the property modification of PPs through foaming, filling and reinforcing with respect to target applications. Special attention is paid to descriptions and models of properties as a function of morphological variables. Last but not least, the book suggests potential practical applications of PP-based systems, especially in the packaging, appliances, building/construction, textile and automotive sectors. Each chapter, written by internationally respected scientists, reflects the current state-of-art in the respective field and offers a vital source of information for students, researchers and engineers interested in the morphology, properties, testing and modeling of PP and PP-based systems. The content is indispensable to the appropriate application of PPs and related composites.

Download or read book Proceedings XIIth International Congress on Rheology August 18 23 1996 Quebec City Quebec Canada written by Abdellatif Aït Kadi and published by Quebec City : Chemical Engineering Department, University of Laval. This book was released on 1996 with total page 898 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Heat Transfer in Polymer Composite Materials written by Nicolas Boyard and published by John Wiley & Sons. This book was released on 2016-03-28 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses general information, good practices and examples about thermo-physical properties, thermo-kinetic and thermo-mechanical couplings, instrumentation in thermal science, thermal optimization and infrared radiation.

Download or read book Analysis of Natural Fiber Orientation in Polymer Composites Produced by Injection Molding Process written by Rajasekaran Karthikeyan and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Short fiber reinforced polymer composites (SFRPC) produced by injection molding process have established a commercial utilization in all sectors due to low cost and lower weight of the components. The polymers are reinforced with natural fibers to improve their performance. The orientation of short natural fibers in the polymer composite influences the mechanical performance. This research thus focused on the prediction of natural fiber orientation using a theoretical model and then studied the mechanical properties of natural fiber reinforced composites. The theoretical model was derived by incorporating the shape factor of natural fibers into the angular velocity of the fluid element in order to predict the orientation during the injection molding process. The ANSYS- FLUENT software was used to find the velocity distribution in the fluid domain, from which the angular velocity of the fluid element and the orientation angle were found numerically. This numerical orientation result was then compared to the experimental data. The orientation angle of rigid particles rotating at a fixed distance from the inlet gate was measured by an experimental method where a transparent cavity was filled through an injection molding process An experimental setup was developed to study the orientation behavior of short natural fibers in the flowing viscous fluid. Two experimental case studies were conducted to validate the orientation angles of natural fibers using the derived equation. The case study was performed in two molds with one of varying section, and another wide area section and the experimental orientation angles were compared with the numerical predictions. The numerical results of the flow front and velocity distribution obtained from simulation software were compared with digitized images of the flow front from the experimental method. The natural fibers have improved the strength and modulus of the composites. The composite specimens were produced for different compositions of sisal fiber using compression-molding process and the mechanical properties of the composites were studied. An increase in tensile strength, tear strength, and improved hardness was observed in sisal fiber composites. The morphological study using X-ray tomography and Scanning electron microscopy (SEM) has shown the defects, and the fiber orientation. Short fiber reinforced polymer composites (SFRPC) produced by injection molding process have established a commercial utilization in all sectors due to low cost and lower weight of the components. The polymers are reinforced with natural fibers to improve their performance. The orientation of short natural fibers in the polymer composite influences the mechanical performance. This research thus focused on the prediction of natural fiber orientation using a theoretical model and then studied the mechanical properties of natural fiber reinforced composites. The theoretical model was derived by incorporating the shape factor of natural fibers into the angular velocity of the fluid element in order to predict the orientation during the injection molding process. The ANSYS- FLUENT software was used to find the velocity distribution in the fluid domain, from which the angular velocity of the fluid element and the orientation angle were found numerically. This numerical orientation result was then compared to the experimental data. The orientation angle of rigid particles rotating at a fixed distance from the inlet gate was measured by an experimental method where a transparent cavity was filled through an injection molding process An experimental setup was developed to study the orientation behavior of short natural fibers in the flowing viscous fluid. Two experimental case studies were conducted to validate the orientation angles of natural fibers using the derived equation. The case study was performed in two molds with one of varying section, and another wide area section and the experimental orientation angles were compared with the numerical predictions. The numerical results of the flow front and velocity distribution obtained from simulation software were compared with digitized images of the flow front from the experimental method. The natural fibers have improved the strength and modulus of the composites. The composite specimens were produced for different compositions of sisal fiber using compression-molding process and the mechanical properties of the composites were studied. An increase in tensile strength, tear strength, and improved hardness was observed in sisal fiber composites. The morphological study using X-ray tomography and Scanning electron microscopy (SEM) has shown the defects, and the fiber orientation.

Download or read book Fiber dependent injection molding simulation of discontinuous reinforced polymers written by Wittemann, Florian and published by KIT Scientific Publishing. This book was released on 2022-11-18 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work presents novel simulation techniques for injection molding of fiber reinforced polymers. These include approaches for anisotropic flow modeling, hydrodynamic forces from fluid on fibers, contact forces between fibers, a novel fiber breakage modeling approach and anisotropic warpage analysis. Due to the coupling of fiber breakage and anisotropic flow modeling, the fiber breakage directly influences the modeled cavity pressure, which is validated with experimental data.

Download or read book Analysis and Performance of Fiber Composites written by Bhagwan D. Agarwal and published by Wiley-Interscience. This book was released on 1990-10-08 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt: Having fully established themselves as workable engineering materials, composite materials are now increasingly commonplace around the world. Serves as both a text and reference guide to the behavior of composite materials in different engineering applications. Revised for this Second Edition, the text includes a general discussion of composites as material, practical aspects of design and performance, and further analysis that will be helpful to those engaged in research on composites. Each chapter closes with references for further reading and a set of problems that will be useful in developing a better understanding of the subject.

Download or read book Science and Engineering of Short Fibre Reinforced Polymer Composites written by Shao-yun Fu and published by Woodhead Publishing. This book was released on 2019-08-24 with total page 470 pages. Available in PDF, EPUB and Kindle. Book excerpt: Science and Engineering of Short Fibre Reinforced Polymer Composites, Second Edition, provides the latest information on the ‘short fiber reinforced composites' (SFRP) that have found extensive applications in automobiles, business machines, durable consumer items, sporting goods and electrical industries due to their low cost, easy processing and superior mechanical properties over parent polymers. This updated edition presents new developments in this field of research and includes new chapters on electrical conductivity, structural monitoring, functional properties, self-healing, finite element method techniques, multi-scale SFRCs, and both modern computational and process engineering methods. Reviews the mechanical properties and functions of short fiber reinforced polymer composites (SFRP) Examines recent developments in the fundamental mechanisms of SFRP's Assesses major factors affecting mechanical performance, such as stress transfer and strength Includes new chapters on electrical conductivity, structural monitoring, functional properties, self-healing, finite element method techniques, multi-scale SFRCs, modern computational methods, and process engineering methods

Download or read book Discontinuous Fiber Composites written by Tim A. Osswald and published by MDPI. This book was released on 2019-01-15 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a printed edition of the Special Issue "Discontinuous Fiber Composites" that was published in J. Compos. Sci.

Download or read book Polymer Matrix Composites and Technology written by Ru-Min Wang and published by Elsevier. This book was released on 2011-07-14 with total page 570 pages. Available in PDF, EPUB and Kindle. Book excerpt: Given such properties as low density and high strength, polymer matrix composites have become a widely used material in the aerospace and other industries. Polymer matrix composites and technology provides a helpful overview of these materials, their processing and performance.After an introductory chapter, part one reviews the main reinforcement and matrix materials used as well as the nature of the interface between them. Part two discusses forming and molding technologies for polymer matrix composites. The final part of the book covers key aspects of performance, including tensile, compression, shear and bending properties as well as impact, fatigue and creep behaviour.Polymer matrix composites and technology provides both students and those in industry with a valuable introduction to and overview of this important class of materials. Provides a helpful overview of these materials, their processing and performance incorporating naming and classification of composite materials Reviews the main reinforcement and matrix materials used as well as the nature of the interface between them including damage mechanisms Discusses forming and molding technologies for polymer matrix composites outlining various techniques and technologies

Download or read book Composite Reinforcements for Optimum Performance written by Philippe Boisse and published by Woodhead Publishing. This book was released on 2020-10-22 with total page 730 pages. Available in PDF, EPUB and Kindle. Book excerpt: Composite Reinforcements for Optimum Performance, Second Edition, has been brought fully up to date with the latest developments in the field. It reviews the materials, properties and modelling techniques used in composite production and highlights their uses in optimizing performance. Part I covers materials for reinforcements in composites, including chapters on fibers, carbon nanotubes and ceramics as reinforcement materials. In Part II, different types of structures for reinforcements are discussed, with chapters covering woven and braided reinforcements, three-dimensional fibre structures and two methods of modelling the geometry of textile reinforcements: WiseTex and TexGen. Part III focuses on the properties of composite reinforcements, with chapters on topics such as in-plane shear properties, transverse compression, bending and permeability properties. Finally, Part IV covers the characterization and modelling of reinforcements in composites, with chapters focusing on microscopic and mesoscopic approaches, X-ray tomography analysis and modelling reinforcement forming processes. With its distinguished editor and international team of contributors, Composite Reinforcements for Optimum Performance, Second Edition, is an essential reference for designers and engineers working in the composite and composite reinforcement manufacturing industry, as well as all those with an academic research interest in the subject. Discusses the characterization and modeling of reinforcements in composites, focusing on such topics as microscopic and mesoscopic approaches, X-ray tomography analysis, and modeling reinforcement forming processes Provides comprehensive coverage of the types and properties of reinforcement in composites, along with their production and performance optimization Includes sections on NCF (non-crimp fabrics), natural fiber reinforcements, tufting composite reinforcements, sustainability, multiscale modeling, knitted reinforcements, and more

Download or read book Composite Materials written by Kamal K. Kar and published by Springer. This book was released on 2016-10-14 with total page 694 pages. Available in PDF, EPUB and Kindle. Book excerpt: Composite materials are used as substitutions of metals/traditional materials in aerospace, automotive, civil, mechanical and other industries. The present book collects the current knowledge and recent developments in the characterization and application of composite materials. To this purpose the volume describes the outstanding properties of this class of advanced material which recommend it for various industrial applications.