Knitted fabric-reinforced composites

Ko, F.K., Oastorc, C.M., Yang, J.M. and Chou, T.W. (1986). Structure and properties of multi-layer, multidirectional warp knit fabric reinforced composites. In Composites 86 Recent Advances in Japan and the United Slates, Japan Society for Composite Materials, Tokyo. 

Gommers B, Verpoest I. Tensile behaviour of knitted fabric reinforced composites. In Proceedings of the 10th international conference on composite materials (ICCMIO), vol. IV. Canada Whistler 1995. pp. 309—16. 

Ramakrishna S. Characterization and modeling of the tensile properties of plain weft-knit fabric-reinforced composites. Compos Sci Tech 1997 57 1-22. 

Rios CR, Ogin SL, Lekakou C, Leong KH. A study of damage development in a weft knitted fabric reinforced composite part 1 - experiments using model sandwich laminates. Compos Appl Sci Ma /2007 38(7) 1173-793. 

Gommers B, Verpoest I, van Houtte P. Analysis of knitted fabric reinforced composites part 1. Fibre distribution. Compos Appl Sci Afaww/1998 29 1579-88. 

Zaixia F, Zhangyu YC, Haim L. Investigation on the tensile properties of knitted fabric reinforced composites made from gf-PP commingled yam preforms with different loop densities. J Thennoplast Compos Mater 2006 19 113—26. 

S. D. Pandita, D. Falconet, I. Verpoest (2002) Impact properties of weft knitted fabric reinforced composites, Compos. Sci. Technol. 62,1113. 

P. V. Houtte, I. Verpoest, B. Gommers (1998) Analysis of knitted fabric reinforced composites part I. Rbre orientation distribution. Composites A 29,1579. 

S. Ramakrishna, H. Hamada, K. B. Cheng (1997) Analytical procedure for the prediction of elastic properties of plain knitted fabric-reinforced composites. Composites A 28,25. 

Lim T C, Ramakrishna S and Shang S M (2000) Strain field of deep drawn knitted fabric reinforced thermoplastic composite sheets, J Mater Process Technol 97 95 99. 

Cheng, K.B., Ramakrishna, S., Lee, K.C., 2000. Electromagnetic shielding effectiveness of copper/glass fiber knitted fabric reinforced polypropylene composites. Compos. A Appl. Sci. Manuf. 31 (10), 1039-1045. http //dx.doi.org/10.1016/S1359-835X(00)00071-3. 

So far, the bulk of literature has concentrated on characterizing the mechanical properties of both thermosetting- - - and thermoplastic-based - knitted composite materials. The modeling of the mechanical properties (mainly stiffness and tensile) has also been popular. However, limited literature exists on the forming property characteristics of knitted fabric-reinforced thermoplastics - and their processing properties are still poorly understood. In fact, most of the literature on forming properties deals with unidirectional, - mostly woven and, to a lesser extent, braided reinforcements, rather than knitted reinforcements. 

The manufacture of hemispherical domes is well established, particularly in the field of composites, as a method of assessing the relative ability of the materials and processes to produce doubly curved shell components. In the case of knitted fabric-reinforced thermoplastics, some of the key parameters relevant to product manufacture are (i) material strain behavior (stretching V5. draw-in), (ii) surface finish, (iii) gross wrinkling and buckling of the sheet material, and (iv) interply shear in the laminate. 

Due to the inherent symmetry of as-produced textile fabrics, woven composite plates are orthotropic. Their stiffness can be represented by engineering constants Young s modules shear modules Gy and Poisson coefficients py, ij= 1,...,3. If the reinforcement is deformed during production of the composite, or if the preform is net shaped, or for some knitted performs, then the assumption of orthotropy does not necessarily apply and the full stiffness matrix has to be introduced. 

Wang Y, Gowayed Y, Kong X, Li J, Zhao D. Properties and analysis of composites reinforced with E-glass weft-knitted fabrics. J Compos Tech Res 1995 17 283-8. 

Three dimensional structures of multiaxial warp knitted fabrics have been recently developed for multidirectional reinforcement of composites. Multilayers of linear yams are assembled in warp (0°), weft (90°) and bias ( 0) directions to provide in-plane reinforcement in specific directions and they are stitched together by knitting yams to provide structural integrity and through the thickness reinforcement [1,2,3,4,5]. 

Fiber reinforced composites, depending on the properties needed, can be fabricated in three different ways. Very short fibers can be used as filler, short fibers can be organized with random orientation and long fibers can be laid in one direction to form unidirectional composites. Short staple fibers may also be twisted together to form continuous yams to fabricate unidirectional composite laminates similar to those made using long fibers. Several unidirectional laminates may be combined by layering in different directions to form laminar composites. Yarns may also be woven or knitted into fabrics to form similar laminar composites. 

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