Strength of short fiber reinforced polymers: Effect of fiber length distribution

Aykol, Muratahan
Isitman, Nihat Ali
Kaynak, Cevdet
In this study, the prediction of mechanical strength of short fiber reinforced plastics (SFRPs) is made possible by obtaining a Fiber Length Distribution (FLD) efficiency factor, eta(FLD), from the formerly known twofold discrete strengthening equation of Kelly-Tyson. The unified parameter eta(FLD) is developed involving both the effects of fiber breakage and resulting distribution, fiber volume fraction and fiber and interface properties, so that they can be incorporated into modified rule of mixtures (MROM). This procedure helps to clarify the experimentally observed loss in strengthening rate with increasing fiber fraction. By adapting a few experimentally determined distributions to a Weibull type function, the analytical solutions described in this study establish the exploration of the strength of SFRPs in the entire fiber content range or can reveal the interfacial bond strength. After investigating the effects of fiber and interface parameters on strengthening efficiency, it is found that common fiber-matrix combinations possessing intermediate critical fiber lengths show a significant decrease in strengthening efficiency with increasing fiber content at low fiber loadings. On the contrary, higher and lower critical fiber lengths yield less significant losses.


Interfacial Strength in Short Glass Fiber Reinforced Acrylonitrile-Butadiene-Styrene/Polyamide 6 Blends
Isitman, Nihat Ali; Aykol, Muratahan; Ozkoc, Guralp; Bayram, Göknur; Kaynak, Cevdet (Wiley, 2010-03-01)
The purpose of this study is to derive the apparent interfacial shear strength of short glass fiber reinforced acrylonitrile-butadiene-styrene/polyamide 6 (PA6) blends with different PA6 contents. Tensile stress-strain curves and fiber length distributions are utilized within a continuum micromechanics approach which involves a unified parameter for fiber length distribution efficiency represented as a function of strain. The unique combination of predicted micromechanical parameters is capable of accuratel...
Comparison of Natural Halloysite With Synthetic Carbon Nanotubes in Poly(lactic acid) Based Composites
Erpek, Canan Esma Yeniova; ÖZKOÇ, GÜRALP; Yılmazer, Ülkü (Wiley, 2017-11-01)
The objective of this study is to compare the mechanical properties, structure and degradability of the nanocomposites prepared with tubular nanofillers, halloysite (HNT) and carbon nanotube (CNT) in poly(lactic acid) (PLA), and thermoplastic polyurethane (TPU) toughened PLA (T-PLA) matrices. In the PLA matrix, CNT increased, whereas HNT decreased the tensile strength with increasing filler content. Also, the elongation at break and impact strength decreased with increasing CNT content, but these properties...
Fiber/matrix interface stress analysis of flax-fiber composites under transverse loading considering material nonlinearity
SABUNCUOĞLU, BARIŞ; Cakmakci, Onur; Kadıoğlu, Fevzi Suat (SAGE Publications, 2020-05-01)
Distribution of stresses in fiber/matrix interface in UD flax fiber reinforced composites is investigated under transverse loading and compared with conventional synthetic fibers. Micro-scale finite element models with representative volume elements are generated with various fiber packing types and fiber volume ratios. The study is performed for various strain values, which take into account the material nonlinearity of matrix. The results show that significantly lower stress concentrations exist in the ca...
Mechanical Performance of Resol Type Phenolic Resin/Layered Silicate Nanocomposites
Tasan, C. Cem; Kaynak, Cevdet (Wiley, 2009-03-01)
Clay addition has been shown to affect polymer resins positively in terms of several physical and chemical properties, including mechanical performance, high temperature endurance and durability. These increases are limited only to relatively low concentrations of reinforcement phase, but at these low concentrations polymer/layered silicate nanocomposites (P/LS NC) have shown to exhibit higher mechanical performance than fiber reinforced polymer composites. This is among the several reasons that make P/LS N...
Thermal characterization of glycidyl azide polymer (GAP) and GAP-based binders for composite propellants
Selim, K; Özkar, Saim; Yılmaz, Levent (Wiley, 2000-07-18)
Differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) were used to investigate the thermal behavior of glycidyl azide polymer (GAP) and GAP-based binders, which are of potential interest for the development of high-performance energetic propellants. The glass transition temperature (T-g) and decomposition temperature (T-d) of pure GAP were found to be -45 and 242 degrees C, respectively. The energy released during decomposition (Delta H-d) was measured as 485 cal/g. The effect of th...
Citation Formats
M. Aykol, N. A. Isitman, E. FIRLAR, and C. Kaynak, “Strength of short fiber reinforced polymers: Effect of fiber length distribution,” POLYMER COMPOSITES, pp. 644–648, 2008, Accessed: 00, 2020. [Online]. Available: