Studies on textile composites

Bu tez kapsamında kompozit içerisinde takviye malzemesi olarak kullanılmak üzere tüp şeklinde örülmüş ve çözgü yatırımlarına sahip tekstil önşekilinin atkılı düz örme makinesinde üretimi üzerinde çalışılmıştır. Atkılı örme makinelerinde tüp şeklinde örülmüş kumaşa çözgü yatırımları yerleştirilebilmesi için örme makinesinde yapılması gereken değişiklikler ve eklemeler belirtilmiştir, tasarımları yapılmıştır. Tasarımlar doğrultusunda el örme makinesi üzerinde değişiklikler gerçekleştirilmiştir. Ayrıca çözgü yatırma sistemi tasarlanmıştır, imal edilmiştir ve örme makinesinin üzerine monte edilmiştir. Çözgü yatırım düzeneğine sahip geliştirilmiş olan bu el örme makinesinde tüp formunda ve çözgü yatırımlarına sahip numune de üretilmiştir. Within this thesis, the manufacture of warp inlaid tubular knitted preforms, which are to be used as the reinforcement materials in the composites, on weft knitting machine has been studied. The changes and modifications, which are needed to be done on the weft knitting machines so that warp inlaid tubular knitted preforms can be manufactured, have been indicated and designed. The changes have been done on the hand knitting machine based on the given designs. Warp inlaying system has also been designed, manufactured and has been assembled on the hand knitting machine. The tubular specimen with warp inlays have also been manufactured on this warp inlay system equipped hand knitting machine

3D geometrical modelling of tubular braids

Geometrical modelling for tubular braids of different structures is studied and a simple versatile three-dimensional model is proposed after considering the crimp of the braiding yarn together with the tubular curvature of the tubular braid structure. The proposed model is versatile and suitable not only for different braid structures, but also, with the changes in the structural parameters such as braid angle, number of yarns in a set, yarn and mandrel diameter the model is still applicable. Application and 3D drawings of the model for diamond, regular and triaxial braids are given with the aid of Visual Basic and 3DSMax Studio

Impact performances of monoaxial knitted fabric composites

This study aims to investigate the impact performances of the monoaxial knitted fabric composites to evaluate the effect of straight yarns within the reinforcement knitted fabric. Monoaxial knitted fabric composites have enhanced in-plane properties and it is important to evaluate the effect of yarn insertion on the impact performances because knitted fabric composites are preferred due to their out-of-plane properties. Bending, impact and compression after impact (CAI) tests were performed on the composites reinforced with monoaxial rib knitted fabrics. The flexural properties, the peak force, the damage area and the energy absorption capabilities under drop weight impact loadings and the compression strength after impact of the composites were evaluated comparatively. The results indicated that the monoaxial rib knitted fabric reinforcement enhances the bending and CAI performances of the composites, but it causes detrimental effects on the impact performances of the composites. The use of yarn insertion for the enhancement of the composite performance necessitates considerate planning for an optimization between the in-plane and out-of-plane properties of the knitted fabric composites

Geometrical Models for Balanced Rib Knitted Fabrics Part II: Applications of 1 x 1 Rib Model to Presser-Foot Knitted 1 x 1 Rib, Interlock and Half Milano Rib

This paper deals with the creation of geometrical models for presser-foot knitted 1 x 1 rib, interlock and half milano rib knitted fabrics as direct applications of the 1 x 1 rib model given in Part I of this series of papers. The drawings of the models using 3DS-Max are shown and observed to be similar to the real fabrics through the photographs provided. The run-in ratio between the plain course and the rib course of half milano rib fabrics is emphasized as an important parameter for obtaining a stress-free structure, especially when using these fabrics as technical textiles

Geometrical Models for Cardigan Structures Part II: Half Cardigan

A geometrical model for the half cardigan structure is presented based on the model of full cardigan structure given in Part I of this series of papers. In the model, loop and tuck stitch heads are taken as ellipses in two dimensions. The rest of the loops and tucks are taken as parabolic helices wrapped on elliptical cylinders in general. The parameters of the model were obtained by using a wash-relaxed wool fabric at medium tightness. Computer drawings of the model were created by the 3DS MAX graphical program, which gave similar loop shapes to those observed in real fabrics