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 Improved Fiber Orientation Predictions for Injection Molded Composites written by Henry Minh Huynh and published by . This book was released on 2001 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aspects of Fiber Orientation Prediction for Injection molded Composites written by Brent E. Verweyst and published by . This book was released on 1996 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 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 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 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 Rheology of Filled Polymer Systems written by A.V. Shenoy and published by Springer Science & Business Media. This book was released on 1999-01-31 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt: The rheology of filled polymer systems is an ever expanding field in the polymer industry today. Using a concise, practical and simple format this comprehensive work explains the concepts behind filled polymer systems and the rheological techniques involved in studying their behaviour. Aware that the readers of the book may come from differing background, the first three chapters familiarize the reader with the basics about polymers, fillers and physicochemical interactions between them, rheology and rheometry. Covering such topics as preparation of filled polymer systems, steady shear viscous properties and extentional flow properties, this book covers the areas of importance from an introductory level through to more complex issues.

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 Fiber Orientation in Injection Molded Composites written by Randy Scott Bay and published by . This book was released on 1991 with total page 454 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental measurements of fiber orientation are reported for two parts injection molded from nylon 6/6 reinforced with 43 weight percent of glass fibers. The parts are a center-gated disk and a film-gated strip. Orientation is measured from polished cross-sections and reported as a function of position, both across the thickness and in the flow direction. Both parts have a layered structure, with outer shell layers of flow-aligned fibers surrounding a central core of either random-in-plane (strip) or transversely aligned fibers (disk). The experiments are compared to predictions of a finite difference simulation of the mold filling problem. The simulation predicts the presence, nature and location of the layers very well. However, it overpredicts the small out-of-plane fiber orientation and places the core-shell transition too close to the midplane. A comparison with selected experimental results suggests that the major source of error is the closure approximation used by the fiber orientation equation. The simulation is exercised for a variety of cases to show the importance of material and process parameters. Injection time is an important parameter, but injection temperature and mold temperature have little effect on fiber orientation. A method is presented to predict the thermo-mechanical properties of injection molded composites. The property predictions suggest that current accuracy of orientation predictions in injection molding is not adequate to accurately predict these properties. To improve the accuracy of the orientation predictions a new closure approximation is developed. When used to predict orientation in injection moldings, this new closure approximation predicts correctly the small out-of-plane fiber orientation and places the core-shell transition further from the midplane, but the core layer is still predicted to be thinner than in the experiments. It appears that the transient behavior of the theory is limiting how accurately the location of the transition is predicted. Experimental results from the shell region of injection molded strips are compared with distribution function results; the comparison demonstrates clearly that the interaction coefficient decreases as the volume fraction of the fibers increases. An empirical model based on these results relates the interaction coefficient to the fiber concentration and aspect ratio.

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 Characterization and Simulation of Material Distribution and Fiber Orientation in Sandwich Injection Molded Parts written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, the material distribution, structure of fiber orientation and fiber attrition in sandwich and push-pull injection molded short fiber composites are investigated, regarding the effect of fiber content and processing parameters, given its direct relevance to mechanical properties. The prediction of the tensile strength of conventional, sandwich and push-pull injection molded short fiber composites are derived by an analytical method of modified rule of mixtures as a function of the area fraction between skin and core layers. The effects of fiber length and fiber orientation on the tensile strength are studied in detail. Modeling of the specialized injection molding processes have been developed and performed with the simulation program in order to predict the material distribution and the fiber orientation state. The secondorder orientation tensor (a11) approach is used to describe and calculate the local fiber orientation state. The accuracy of the model prediction is verified by comparing with corresponding experimental measurements to gain a further basic understanding of the melt flow induced fiber orientation during sandwich and push-pull injection molding processes.

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 Computer Modeling for Injection Molding written by Huamin Zhou and published by John Wiley & Sons. This book was released on 2013-03-04 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers a wide range of applications and uses of simulation and modeling techniques in polymer injection molding, filling a noticeable gap in the literature of design, manufacturing, and the use of plastics injection molding. The authors help readers solve problems in the advanced control, simulation, monitoring, and optimization of injection molding processes. The book provides a tool for researchers and engineers to calculate the mold filling, optimization of processing control, and quality estimation before prototype molding.

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 Automated Measurement of 3 D Fiber Orientation Distribution in Injection Molded Composites written by Jeffrey Milton Wille and published by . This book was released on 1993 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book American Society of Composites 28th Technical Conference written by Charles Bakis and published by DEStech Publications, Inc. This book was released on 2013-11-01 with total page 1892 pages. Available in PDF, EPUB and Kindle. Book excerpt: New and unpublished U.S. and international research on multifunctional, active, biobased, SHM, self-healing composites -- from nanolevel to large structures New information on modeling, design, computational engineering, manufacturing, testing Applications to aircraft, bridges, concrete, medicine, body armor, wind energy This fully searchable CD-ROM contains 135 original research papers on all phases of composite materials. The document provides cutting edge research by US, Canadian, and Japanese authorities on matrix-based and fiber composites from design to damage analysis and detection. Major divisions of the work include: Structural Health Monitoring, Multifunctional Composites, Integrated Computational Materials Engineering, Interlaminar Testing, Analysis-Shell Structures, Thermoplastic Matrices, Analysis Non-classical Laminates, Bio-Based Composites, Electrical Properties, Dynamic Behavior, Damage/Failure, Compression-Testing, Active Composites, 3D Reinforcement, Dielectric Nanocomposites, Micromechanical Analysis, Processing, CM Reinforcement for Concrete, Environmental Effects, Phase-Transforming, Molecular Modeling, Impact.