Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Fiber Orientation Analysis of Long-Glass-Fiber-Reinforced Polypropylene in Injection Molded Spiral-Flow
Author: Characterization of Rheology and Prediction of Three-dimensional Fiber Orientation State During Injection Molding of Long Glass Fiber Reinforced Polypropylene
Author: Andreas ReinhardtPublisher:
ISBN: 9783934930261
Category :
Languages : en
Pages : 159
Book Description
Characterization of Rheology and Prediction of Three-dimensional Fiber Orientation During Injection Molding of Long Glass Fiber Reinforced Polypropylene
Author: Andreas ReinhardtAnalysis of Natural Fiber Orientation in Polymer Composites Produced by Injection Molding Process
Author: Rajasekaran KarthikeyanPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
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.
Analysis of fiber attrition and fiber-matrix separation during injection molding of long fiber-reinforced thermoplastic parts
Author: Sara SimonPublisher:
ISBN:
Category :
Languages : en
Pages : 101
Book Description
Die Erhaltung der ursprünglichen Faserlänge bei der Verarbeitung von glasfaserverstärkten Thermoplasten ist von großem Interesse, da die Endfaserlänge die mechanischen Eigenschaften des Fertigteils bestimmt. Faserbruch im Zuge der Verarbeitung ist unvermeidlich und eine große Herausforderung, da er schwierig zu kontrollieren ist und die zugrunde liegende Physik nach wie vor noch nicht vollständig erforscht ist und verstanden wird. Um ein besseres Verständnis zu bekommen wurde die Faserschädigung von langglasfaserverstärktem Polypropylen in einer Couette Strömung untersucht. Die Ergebnisse zeigen, dass das verwendete Couette Rheometer ein geeignetes Gerät ist um die Auswirkungen von unterschiedlichen Prozessbedingungen auf den Faserbruch zu eruieren, zu isolieren und diese des Weiteren auch zu quantifizieren. Es konnte nachgewiesen werden, dass sowohl die Temperatur, als auch die Faserkonzentration, die Schergeschwindigkeit und die Verweilzeit einen großen Einfluss auf die Faserschädigung haben, die sich in einem Faserbruch von bis zu 90 % widerspiegelt. Die Faserbruchstudie wurde erweitert indem die Faserlängenverteilung entlang der Strömungsrichtung von Spritzgussteilen analysiert wurde. Ein weiterer Teil dieser Arbeit beschäftigte sich mit der Untersuchung der Faser-Polymer-Trennung in Spritzgussteilen, da auch dieses Phänomen beträchtlich zu einem heterogenen Eigenschaftsprofil in den Fertigteilen beiträgt. Zur Evaluierung dieser Faser-Matrix Separation wurden Computertomographie Scans angefertigt, die in Folge mit digitale Bildverarbeitung ausgewertet wurden. Die erhaltenen Ergebnisse zeigen eine deutliche Faser Agglomeration in der Kernschicht des Formteils, in welcher eine Erhöhung der Faserkonzentration von bis zu 40 % festgestellt werden konnte. Die experimentellen Daten aus den Couette Rheometer Experimenten wurden in weiterer Folge zur Validierung und Bewertung von verfügbaren Tools zur Vorhersage der Faserschädigung (Faserbruch Simulation) verwendet. Ein spezielles Augenmerk wurde auf das Phelps Kontinuum Modell gelegt, welches implementiert und in weiterer Folge für die Couette Rheometer Versuche angewandt wurde. Des Weiteren wurden die empirischen Modellparameter aus dem Phelps Modell als Eingangsvariablen für eine Moldex3D Simulation verwendet, um den Faserbruch in einem spritzgegossenem Fertigteil zu bestimmen. Das Phelps Modell wurde erfolgreich umgesetzt, jedoch war es mit den erhaltenen Ergebnissen nicht möglich die Materialabhängigkeit der empirischen Modellparameter zu bestätigen. Die Ergebnisse aus den Modex3D Simulationen zeigen, dass die Phelps Modell Parameter nicht verwendet werden können um den Faserbruch in Spritzgusssimulationen vorherzusagen, da die Parameter nicht übertragbar sind - auch nicht zwischen dem gleichen Material. Da Single Particle Modelle in Prozesssimulationen an Beliebtheit gewinnen, wurde ein kürzlich veröffentlichtes Single Particle Modell auf seine Vorhersagekraft für Faserbruch getestet. Es war möglich, das Modell in einem ersten Schritt qualitativ zu validieren. Jedoch sind zusätzliche Simulationen notwendig, um die Gültigkeit des Modells für ein breiteres Spektrum von Daten zu bestätigen.*****Preserving the initial fiber length of glass fiber-reinforced thermoplastics during processing is from major interest since the residual fiber length determines the mechanical properties of the finished part. Fiber length attrition during processing is still an inevitable and substantial challenge, because it is difficult to control and the underlying physics are not completely understood. In order to gain a better understanding in the phenomena of fiber breakage, the fiber degradation of long glass fiber-reinforced polypropylene in a Couette flow was studied. The results of this work show that the Couette rheometer is an important device to isolate and quantify the impact of processing conditions on the fiber breakage for long glass fiber-reinforced thermoplastics. Temperature, residence time, fiber concentration and processing speed all have a major impact on fiber attrition with breakage rates of up to 90 %.The study was expanded to injection molded parts and the fiber length distribution along the flow path was analyzed. An additional study of injection molded parts focused on the phenomena of fiber-matrix separation since it also causes highly heterogeneous properties within the finished part. This analysis was conducted using micro computed-tomography scans and digital image processing. The results clearly show a substantial fiber agglomeration in the core layer of the molded part of up to 40 % increase from the nominal value.Lastly, the experimental data obtained in this work was used to evaluate available predictive tools for fiber breakage simulation. A comprehensive study focused on the Phelps continuum model, which was implemented and applied for the Couette rheometer experiments. Additionally, the empirical model parameters from the Phelps model were used as an input for a Moldex3D simulation to determine the fiber breakage in an injection molded plaque. The Phelps model was successfully implemented. However, the results were not able to prove the material dependency of the empirical model parameters. The results from the Moldex3D simulations display that the Phelps model parameter cannot be used to accurately predict the fiber breakage in injection molding simulations since the model parameters seem to be not transferable even for the same material. As single particle models become more popular in process simulation, a recently published single particle model was tested for its ability to predict fiber breakage. It was possible to validate the single particle model in a first step, but to confirm the model ́s validity for a broader set of data additional simulations are necessary.
Fiber Orientation During Injection Molding of Glass-fiber-reinforced Thermoplastics
Author: Joseph Paul GreeneMasters Theses in the Pure and Applied Sciences
Author: Wade H. ShaferPublisher: Springer Science & Business Media
ISBN: 1461524539
Category : Science
Languages : en
Pages : 391
Book Description
Masters Theses in the Pure and Applied Sciences was first conceived, published, and disseminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS)* at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dis semination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the though that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volumes were handled by an international publishing house to assure improved service and broader dissemi nation. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 37 (thesis year 1992) a total of 12,549 thesis titles from 25 Canadian and 153 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this impor tant annual reference work. While Volume 37 reports theses submitted in 1992, on occasion, certain uni versities do report theses submitted in previous years but not reported at the time.
Author: 
Author: 
Author: 楊怡福