Application and evaluation of the method of ellipses for measuring the orientation of long, semi-flexible fibers

The method of ellipses (MoE) is a common experimental technique utilized to quantitatively determine the orientation state of a population of rigid fibers within a fiber–polymer composite. In this research, the validity of applying the MoE to long, semi-flexible fiber systems in which the majority of fibers are flexible is discussed. The components of the orientation tensor were first determined for a composite formed by a homogenous, simple shear field. The minimum acceptable image analysis width, or bin width, for the selected geometry was found to be ∼5.5 mm, or 1.4 times the average fiber length. This modified bin width was then used to determine the orientation at multiple percentages of flow within an injection-molded, center-gated disc, and compared to orientation values obtained utilizing the traditional, 0.7-mm bin width. The results show that the traditional, 0.7-mm bin width is sufficient for analysis of the center-gated geometry. This fortuitous result is attributed to the axisymmetric nature of the center-gated geometry, and the highly transverse fiber alignment seen within the samples, especially at moderate to high percentages of flow. In more complex flows, it is expected that the conventional bin width will not apply. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers

[1]  A. Zink-Sharp,et al.  Sample preparation and image acquisition using optical‐reflective microscopy in the measurement of fiber orientation in thermoplastic composites , 2012, Journal of microscopy.

[2]  P. Wapperom,et al.  Unambiguous orientation in short fiber composites over small sampling area in a center-gated disk , 2012 .

[3]  P. Wapperom,et al.  Transient shear flow behavior of concentrated long glass fiber suspensions in a sliding plate rheome , 2011 .

[4]  Q. Fu,et al.  Shear induced fiber orientation, fiber breakage and matrix molecular orientation in long glass fiber reinforced polypropylene composites , 2011 .

[5]  P. Wapperom,et al.  Fiber orientation kinetics of a concentrated short glass fiber suspension in startup of simple shear flow , 2010 .

[6]  Charles L. Tucker,et al.  An objective model for slow orientation kinetics in concentrated fiber suspensions: Theory and rheological evidence , 2008 .

[7]  Satish K. Bapanapalli,et al.  Prediction of elastic properties for curved fiber polymer composites , 2008 .

[8]  Ba Nghiep Nguyen,et al.  Fiber Length and Orientation in Long-Fiber Injection-Molded Thermoplastics — Part I: Modeling of Microstructure and Elastic Properties , 2008 .

[9]  E. Lafranche,et al.  Injection moulding of long glass fibre reinforced polyamide 6-6: guidelines to improve flexural properties , 2007 .

[10]  M. Vincent,et al.  Description and modeling of fiber orientation in injection molding of fiber reinforced thermoplastics , 2005 .

[11]  R. Yahya,et al.  Tensile, Impact and Fiber Length Properties of Injection-Molded Short and Long Glass Fiber-Reinforced Polyamide 6,6 Composites , 2004 .

[12]  Daniel J. Klingenberg,et al.  Rheology of sheared flexible fiber suspensions via fiber-level simulations , 2003 .

[13]  J. Thomason.  The influence of fibre length and concentration on the properties of glass fibre reinforced polypropylene: 5. Injection moulded long and short fibre PP , 2002 .

[14]  Tai Hun Kwon,et al.  Invariant-based optimal fitting closure approximation for the numerical prediction of flow-induced fiber orientation , 2002 .

[15]  C. Eberhardt,et al.  Fibre-orientation measurements in short-glass-fibre composites. Part I: automated, high-angular-resolution measurement by confocal microscopy , 2001 .

[16]  Peter Hine,et al.  Hydrostatically extruded glass‐fiber‐reinforced polyoxymethylene. I: The development of fiber and matrix orientation , 1996 .

[17]  N. C. Davidson,et al.  A novel technique for determining the 3D spatial distribution of glass fibres in polymer composites , 1995 .

[18]  Charles L. Tucker,et al.  Stereological measurement and error estimates for three-dimensional fiber orientation , 1992 .

[19]  Charles L. Tucker,et al.  Fiber orientation in simple injection moldings. Part I: Theory and numerical methods , 1991 .

[20]  H. Fritz,et al.  Injection molding of long fiber‐reinforced thermoplastics: A comparison of extruded and pultruded materials with direct addition of roving strands , 1991 .

[21]  W. Chin,et al.  Effects of fiber length and orientation distribution on the elastic modulus of short fiber reinforced thermoplastics , 1988 .

[22]  Suresh G. Advani,et al.  The Use of Tensors to Describe and Predict Fiber Orientation in Short Fiber Composites , 1987 .

[23]  E. Silverman.  Effect of glass fiber length on the creep and impact resistance of reinforced thermoplastics , 1987 .

[24]  C. L. Tucker,et al.  Orientation Behavior of Fibers in Concentrated Suspensions , 1984 .

[25]  G. B. Jeffery.  The motion of ellipsoidal particles immersed in a viscous fluid , 1922 .