BAYAN ELBİSELİK DOKUMA KUMAŞ YAPISININ EĞİLME VE DÖKÜMLÜLÜK ÖZELLİKLERI ÜZERİNE ETKİSİ

Iyi dikilebilirlik giysi ureticileri icin istenen bir ozelliktir. Kumaslarin iyi bir giyim performansi ve gorunume sahip olabilmesi icin konfeksiyon islemlerinden problemsiz gecebilmeleri gerekir. Konfeksiyonun fonksiyonelligi lif, iplik, kumas ve giysi olusum asamalarinin kombinasyonlari ile gelistirilebilir. Son yillarda bayan elbiselik kumaslari, kumas endustrisinde onemli bir yere sahip olmustur. Cogu bayan elbiseleri, estetik, tasarim, vucuda uygunluk veya performans gibi kullanicilarin tum gereksinimlerini karsilamasi icin mekaniksel, kimyasal apre prosedurleri, lif, iplik, kumas ve giysi yapisinin etkilesimi ile oldukca karmasik urunlerdir. Bayan elbiseleri icin ilk once yumusaklik, dokumluluk ve konfor istenir. Bu calismada, bayan elbiselik viskon dokuma kumas yapisinin egilme ve dokumluluk ozellikleri uzerine olan etkileri arastirilmistir.


INTRODUCTION
Women's dress fabrics should have some important properties. Yarn and fabric structural parameters affect performance of women's dresses. Improving fabric and garment drape and stiffness are very important for a good apperance.
In assessing the fabric, we used sensory characteristics such as surface friction, bending stiffness, compression, thickness and small-scale extension and shear, all of which play a role in determining handle and garment making-up and apperance during wear (Sinclair, 2015).
A bending test measures the severity of the flexing action of a material. The bending behaviour of fabrics is presented by bending rigidity. The bending rigidity, which is related to the perceived stiffness, is calculated from the bending length and mass per unit area. Fabrics with low bending rigidity may exhibit seam pucker and prone to problems in cutting out.
Drape is an important parameter in the application of body scanning, mass customisation, CAD-CAM and automatic pattern making in clothing design and manufacturing. Fabric drape is determined largely by the fabric bending and shear stiffness properties, with fabric thickness, low deformation tensile properties and weight also importance.
The drape coefficient has been developed to describe the degree of drape and drape shape. A lower drape coefficient mean the fabric is softer, and its drapability is better. In other words, the higher the drape coefficient the stiffer the fabric is (Hu, 2008). In recent years the most important properties for viscose fabrics is low drape coefficient for high drapability.
Viscose rayon is used for a wide range of apparel applications. Blouses, skirts, dresses, and shirts are often made of viscose fabrics for excellent drapability and comfortability. Viscose rayon is also blended with wool, polyester or acrclic for suits, jackets and blazers for the purpose of enhancing apperance and moisture permeability.
Although viscose rayon brings unique features of drapability, softness and moisture absorption to both formal and casual apparel products, it can also have some drawbacks. These include easy stretching with poor elastic recovery, low abrasion resistance, wet shrinkage and low wrinkle resistance (Sinclair, 2015).
Viscose rayon used for women's dress fabrics, too. Material drape and luster properties are essential consideration for fashion designers to achieve the required structural and luxurious apperance. Viscose rayon was the first man-made fiber invented for use in the textile and fashion apparel industries with the original name "artifical silk".
There are high correlation between drapability and bending properties of fabrics. Resistance to bending or flexural rigidity is called stiffness in textile test methods. The longer the bending length, the stiffer is the fabric. Fabrics with very high bending rigidity values may lead to sewing and handling problems as they are too stiff to be manipulated and controlled. Light weight fabrics usually have low bending rigidity and this makes it difficult to handle during cutting because of its flexibility and can cause seam puckering. It is recommended that light weight fabrics should have a minimum value of 5 µNm for warp and weft direction bending rigidity (Cheng, How and Yick ,1996;Hui,Chan, Yeung and Ng, 2007).
During recent years, the investigation of fabric stiffness has attracted the attention of many researchers because of the attempts to realize the clothing CAD system by introducing the fabric properties (Hu,Chung and Lo, 1997;Sun, 2008).
Fabric stiffness may not be wanted too high for a good drape in apparel fabrics. Therefore there is necessity to optimize the seam parameters such as sewing thread size, stitch density and seam allowance in order to decrease the stiffness of the fabric on the garment (Gurarda, 2009).
Increasing drape coefficient means decreasing fabric drapability (Omeroglu, Becerir and Karaca, 2010). Drape modelling, in particular 3-D visualisation of designed garments in draped form, is one of the key technologies in computer-aided garment design (CAD) (Hunter, Fan and Chau, 2009). Drape is of much importance for the selection of appropriate fabric for intended garment, and therefore the correlation between the drape and fabric properties must be known (Sharma, Behera, Roedel and Schenk, 2004).
Bending and drapability properties of fabrics are very important for a garment's aesthetic appearance and also play an important role in garment comfort and determining the fit of clothing around the human figure (Seram and Rupasinghe, 2013).
In this study, we investigated the influence of the structure of women's dress viscose woven fabrics on their bending and drapability properties.

Material
In this research, eight different types of woven fabrics with plain and twill structure, which are commonly used for production of women's dresses, were measured. The properties of fabrics used can be seen from Table 1.

Method
To investigate the stiffness of a fabric, bending length and flexural rigidity must be obtained. Bending rigidity tests were carried out according to ASTM 1388-64 and TS 1409 with using a stiffness tester according to Cantilever bending principle. Equations (1), (2)  The drapability tests of the fabric samples were performed according to ISO 9073-9 by using Cusick Drapemeter. The drape coefficient DC (%) is defined at Equation (4).
DC = Drape coefficient (%) W1 = Initial weigth of the paper ring before the drapability test W2 = Weight of the paper ring cut along the traced shadow configuration (shadow image)(ISO 9073-9). The paper ring (W1) and shaded area (W2) was shown in Figure 1 (Kenkare and May-Plumlee, 2005). The schematic view of the cusick's drapemeter was shown in Figure 2 (Chung, 1999).
Prior to the tests, all fabric samples were conditioned for 24 hours in standard atmospheric conditions (at a temperature of 20 ± 2°C and relative humidity of 65 ± 2 %) The SPSS 14.0 Statistical software package was used for conducting all statistical procedures. Completely randomized single-factor (one way) multivariate analysis of variance (ANOVA) as a fixed model was applied to data in order to investigate the statistical importance of polyester yarn type parameter on breaking strength, breaking elongation, abrasion resistance and air permeability properties of fabrics from these yarns. The means were compared by Student-Newman-Keuls (SNK) tests. The value of significance level (α) selected for all statistical tests is 0.05. The treatment levels were marked in accordance with the mean values, and levels marked by different letter (a, b, c) showed that they were significantly different.

Bending Test Results
Fabric samples' bending length, flexural rigidity and overall flexural rigidity tests results can be seen from Figure 3-5.
It can be seen from Figure 3 that the minimum warp bending length was measured for the plain fabric sample P6 as 0.95 cm while the maximum warp bending length was measured for the plain fabric sample P7 as 1.53 cm. Twill fabric samples with high warp density (T1 and T3) have high bending length as shown in Figure 3. It can be also seen from Figure 3 that the minimum weft bending length was measured for the plain fabric sample P6 as 0.85 cm while the maximum weft bending length was measured for the plain fabric sample P7 as 1.18 cm.
The bending length is a measure of the interaction between fabric weight and fabric stiffness in which a fabric bends under its own weight. It reflects the stiffness of a fabric when bent in one plane under the force of gravity, and is one component of drape. Thus bending length is also called drape stiffness. The bending length is dependent on the weight of the fabric (Hu, 2008).Fabric parameters like fabric thickness, density, weave type and weight play the main role in determining fabric bending properties. Therefore, any factor, such as weave structure and fabric relaxation, which increases the fibre and yarn freedom of movement within the fabric will decrease the fabric bending stiffness, and therefore the fabric drape coefficient.
The flexural rigidity, which is related to the perceived stiffness, is calculated from the bending length and mass per unit area. It can be seen from Figure 4 that the maximum warp and weft flexural rigidity were obtained for the plain fabric sample P7 as 55.57 mgcm and 25.74 mgcm and minimum warp and weft flexural rigidity were obtained for the plain fabric sample P6 as 9.10 mgcm and 6.47 mgcm, respectively. The stiffness of a fabric in bending is very dependent on its thickness. The thicker the fabric, the stiffer it is, if all other factors remain the same. It can be seen from Figure 4 that the maximum overall flexural rigidity was obtained for the plain fabric sample P7 as 192.14 mgcm and minimum overall flexural rigidity was obtained for the plain fabric sample P6 as 19.53 mgcm. The SNK test results given in Table 2 revealed that, warp and weft bending length, flexural rigidity and overall flexural rigidity of the plain fabric sample P7 and twill woven fabric sample T1 were significantly different from others.

Drape Coefficient Test Results
The drape coefficient (DC) has been developed to describe the degree of drape and drape shape. A lower DC value means the fabric is softer, and its drapability is better. In other words, the higher the drape coefficient the stiffer the fabric is (Hu, 2008). Fabric samples drape coefficient tests results can be seen from Figure 6.
It can be seen from Figure 6 that the maximum drape coefficient was obtained for the plain fabric sample P7 as 34.25 % and minimum drape coefficient was obtained for the plain fabric sample P6 as 25.56 %. Plain fabric P6 has the lowest thickness and weight among all fabric samples.
The SNK test results given in Table 3 revealed that, drape coefficient of the plain fabric sample P7 and twill woven fabric sample T1,T2 and T3 were significantly different from others.
At a constant weight, the fabric drape coefficient will decrease as the float length increases. Thus, for example, a twill weave fabric will have a lower drape coefficient than a plain weave fabric of the same mass per unit area (Hunter,Fan and Chau, 2009).
Increasing drape coefficient and overall rigidity of fabric means decreasing fabric drapability.
It can be observed from Table 4 that the drape coefficient has very strong positive correlation with bending length, flexurall and overall flexural rigidity.

CONCLUSION
Bending properties and drapability of fabrics have received major attention in fashion designing since designers have exploited the bending and drapability properties of fabric in creating new styles in accordance with changing fashion trends.
Fabric parameters like fabric thickness, density, weave type and weight play the main role in determining fabric bending and drapability properties. Fabric drapability is an important factor from an aesthetic point of view. The quality of "drape" is important to a designer as it influences a garment's appearance. Softness and drapability are very important for light weight women's dress fabrics.
Drape is of much importance for the selection of appropriate fabric for intended garment, and therefore relation between fabric structures and bending, drapability properties must be known.
The stiffness of a fabric in bending is very dependent on its thickness. The thicker the fabric, the stiffer it is, if all other factors remain the same.
Drape is of much importance for the selection of appropriate fabric for intended garment, and therefore the correlation between the drape and fabric properties must be known. Drape modelling, in particular 3-D visualisation of designed garments in draped form, is one of the key technologies in computer-aided garment design (CAD).
In this study, we investigated influence of the structure of light weight women's dress viscose woven fabrics on their bending and drapability properties.
Fabric parameters like fabric thickness, density, weave type and weight play the main role in determining fabric bending properties and drapability. Therefore, any factor, such as weave structure especially thickness, density and weight of the fabric samples will increase the fabric bending stiffness, and therefore the fabric drape coefficient increase, too. Increasing drape coefficient and overall rigidity of fabric means decreasing fabric drapability.
It can also be observed that the drape coefficient has very strong correlation with bending length, flexurall and overall flexural rigidity of viscose woven fabrics.

ACKNOWLEDGEMENT
We are grateful to Savcan Textile Factory Bursa-Turkey and Textile Engineer Miss Ebru Kümbetlioğlu for their help during this study.