Modelling the effect of yarn twist on the tensile strength of unidirectional plant fibre yarn composites

The structural potential of plant fibres as reinforcing agents can only be realized when the highest reinforcement efficiency is employed. Hence, aligned plant fibre composites are of interest. However, due to the short length of technical plant fibres, the reinforcement needs to be in the form of staple fibre yarns, which have a twisted structure. Although twist facilitates yarn processability, it has several detrimental effects on the composites produced from such twisted yarn reinforcements; one of which is fibre obliquity and misalignment. This results in a drastic drop in composite mechanical properties. No analytical model currently exists to accurately predict the effect of yarn twist on aligned plant fibre composite tensile strength. In this paper, a novel mathematical model is developed. The model is based on (i) a modified rule of mixtures for plant fibre composites, (ii) well-defined structure-property relationships in an idealised twisted staple fibre yarn and (iii) the Krenchel orientation efficiency factor. The developed model includes a corrected orientation efficiency factor of cos2(2α), where α is the yarn surface twist angle. The model is validated with extensive experimental data from Goutianos and Peijs (Goutianos S, Peijs T (2003) Adv Compos Lett 12(6):237) and is found to be a near-perfect fit (R2 = 0.960). Experimental data from other studies are also used for further verification.

[1]  A. Błędzki,et al.  Cars from Bio-Fibres , 2006 .

[2]  T. Peijs,et al.  The Optimisation of Flax Fibre Yarns for the Development of High-Performance Natural Fibre Composites: , 2003 .

[3]  M. Singh,et al.  Life Cycle Impact Assessment of Flax Fibre for the Reinforcement of Composites , 2009 .

[4]  N. Naik,et al.  Twisted impregnated yarns: Elastic properties , 2000 .

[5]  W. Hall,et al.  A review of bast fibres and their composites. Part 2 - Composites , 2010 .

[6]  Lu Zhang,et al.  Commingled natural fibre/polypropylene wrap spun yarns for structured thermoplastic composites , 2010 .

[7]  Elaine Arnold,et al.  Next generation sustainable composites: Development and processing of furan-flax biocomposites , 2009 .

[8]  P. Wambua,et al.  Natural fibres: can they replace glass in fibre reinforced plastics? , 2001 .

[9]  I. Verpoest,et al.  Improving the properties of UD flax fibre reinforced composites by applying an alkaline fibre treatment , 2006 .

[10]  B. Madsen,et al.  Hemp yarn reinforced composites - I: Yarn characteristics , 2007 .

[11]  B. Madsen,et al.  Twisting of fibres in yarns for natural fibre composites , 2011 .

[12]  F. Göktepe,et al.  Packing Density of Compact Yarns , 2007 .

[13]  Stephen W. Tsai,et al.  Anisotropic strength of composites , 1965 .

[14]  Ning Pan,et al.  Development of a Constitutive Theory for Short Fiber Yams Part III: Effects of Fiber Orientation and Bending Deformation , 1993 .

[15]  R. A. Tait,et al.  Fracture mechanism of plant fibres , 1980 .

[16]  M. Karus,et al.  Natural Fibres in the European Automotive Industry , 2002 .

[17]  M. Lewin.  Handbook of Fiber Chemistry , 2006 .

[18]  J. Baets,et al.  Determination of the optimal flax fibre preparation for use in UD flax-epoxy composites , 2011 .

[19]  M. Skrifvars,et al.  Development of Flax Fibre based Textile Reinforcements for Composite Applications , 2006 .

[20]  Bo Madsen,et al.  Hemp yarn reinforced composites – II. Tensile properties , 2007 .

[21]  Mike Clifford,et al.  The tensile behavior of off-axis loaded plant fiber composites: An insight on the nonlinear stress–strain response , 2012 .

[22]  Ning Pan,et al.  Development of a Constitutive Theory for Short Fiber Yarns: Mechanics of Staple Yarn Without Slippage Effect , 1992 .

[23]  Milton M. Platt,et al.  Mechanics of Elastic Performance of Textile Materials , 1950 .

[24]  Milton M. Platt,et al.  Mechanics of Elastic Performance of Textile Materials , 1950 .

[25]  M. Clifford,et al.  Hydroxyethylcellulose surface treatment of natural fibres: the new ‘twist’ in yarn preparation and optimization for composites applicability , 2012, Journal of Materials Science.

[26]  Stanley Backer,et al.  Structural mechanics of fibers, yarns, and fabrics , 1969 .

[27]  Richard J. Farris,et al.  A modeling and experimental study of the influence of twist on the mechanical properties of high‐performance fiber yarns , 2000 .

[28]  M. Shioya,et al.  Variation of Longitudinal Modulus with Twist for Yarns Composed of High Modulus Fibers , 2001 .