Dokuma kumaşlarının gerilme altında kalıcı deformasyonu
Küçük Resim Yok
Tarih
1997
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Ege Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Deformasyon, sözlük anlamındaki en basit haliyle, şekil değişimi olarak tanımlanmaktadır. Tekstil materyallerinde yapılan deformasyon araştırmaların, son kullanım olan giysi halini de kapsayacak şekilde, üretim aşamalarında yer alan lif, iplik, kumaş ve bunların yan mamul formlarında, uzun zamandır yapılmaktadır. Temel teorilerin geliştirilmesi ile problemlerin tanımlanması ve özellikle bilgisayar teknolojisinin gelişmesi ile karmaşık problemlerin çözülmesi hızlandığı için, araştırmalar da hızlı bir gelişme göstermektedir. Dokuma kumaş, günlük yaşantımızda çeşitli kuvvetlerin etkisi altında kalır. Bu kuvvetler basınç, gerilme, çarpma, v.b. şeklinde olabilir. Dokuma kumaş, bir yere kadar bu kuvvetleri bünyesinde absorbe eder ve kuvvet etkisi kalkınca kumaş geriye dönüp eski halini alabilir. Dokuma kumaşın, viskoelastik özelliklere sahip olması ve krip-relaksasyon özellikleri göstermesi, bazı durumlarda, oluşan deformasyonu yenerek geriye dönüp kendi eski halini almasını önler ve kumaşta kalıcı deformasyon meydana gelir. Giysilerde, diz çıkması, dirsek çıkması, cep çıkması, topuk çıkması, kalça (basen) çıkması olarak rastlanan bu durum, dokuma kumaşlarda gerilme altında kalıcı deformasyona birer örnektir. Giysinin görüntüsü bozulduğu ve giysinin günlük kullanımı açısından önem taşıdığı için, bu konu bir kalite faktörü içermektedir ve incelenmesi gerekmektedir.V Bu çalışmanın ilgilendiği deformasyon çeşidi, mamul dokuma kumaşın kullanımı sırasındaki etkileri temsil edecek şekilde, kendi düzlemine dik yönde kuvvete maruz kalan kumaşın, uzaysal deformasyon davranışıdır. Bu davranış, model deneylerle analitik olarak incelenmiştir. Dokuma kumaş ile yüzey teması yapan, eğri bir yüzey olan yarım küre, yayılı yük uygulayacak şekilde kumaş düzlemine bastırılmış ve bu etki altında ortaya çıkan gerilmelere karşı kumaşın gösterdiği direnç ve kalıcı deformasyon sonuçlan deneysel olarak incelenmiştir. %100 Pamuk, bezayağı ve mamul haldeki tek bir kumaş çeşidi ile farklı deney cihazı parametreleri denenmiştir. Bu parametreler, kalıp şekli, kalıp boyutu, küre boyutu, bastırma mesafesi, bastırma hızı, bekletme süresi, tekrarlılık, dinlendirme süresi ve tekerrür olmak üzere dokuz çeşittir. Kalıcı deformasyonu en iyi belirleyen parametreler kombinasyonu, istatistiksel ve grafiksel incelemeler sonucunda belirlenmiştir. Böylece, en uygun test metodunun geliştirilmesi ve standart laboratuvar deneyi haline getirilmesi amaçlanmıştır. Farklı parametrelerin birbirleri ile ilişkileri, regresyon denklemleri ile ortaya konmuş, böylece bir parametrenin diğeri cinsinden ifade edilebilmesi ve hesaplanması güç olan insanın kumaşa uyguladığı kuvvetin belirlenmesi sağlanmıştır. Bu çalışma, değişik deformasyon çeşitlerinde viskoelastik özelliklerin kalıcı deformasyona etkilerinin ve bu etkilerin zamana ve basınca bağlı oluşumlarının ve değişimlerinin incelenmesi, kalıcı deformasyon geometrisinin ve mekaniğinin geliştirilerek uygun kullanım performansları sağlayan kumaşın tasarlanmasına veya bir dokuma kumaşın uygun kullanım koşullarının belirlenmesine ışık tutacak pratik bulgular sağlaması açılarından önem taşımaktadır. Anahtar sözcükler: deformasyon, kalıcı deformasyon, kumaş deformasyonu, deformasyon mekaniği, uzaysal kuvvet, basınç, viskoelastikiyet, elastikiyet, kalite, deney metodu
Deformation is defined, in its simple meaning in the dictionaries, as a change of form. Researches on the deformation of textile materials have been being carried out for a long time at the stages of the production of fibre, yarn fabric and in their semi-finished forms to include the garment form which is their final use. As progress has been achieved in the definition of problems by development of basic theories and in the solution of complex problems especially by the development of computer technology, researches also show a rapid development. Woven fabric is subjected to various forces in daily life. These forces may be in the form of pressure, stress, impact, etc. The woven fabric absorbs these forces to some extend and when the action of the force is lifted, the fabric recovers and returns to its old shape. As the woven fabric has the viscoelastic behavior and show creep-relaxation properties, this sometimes prevents the fabric from recovering and taking its original shape by overcoming the deformation occured and permenant deformation of fabric occurs. This situation encounted in garments as bagging at knees, elbows, pockets, heels, and hips are examples to permenant deformation in woven fabrics under stress. Because the appearance of the garment is affected and also because it is important from the point of view of its daily use, this subject carries a quality factor and thus should be studied.The type of deformation that this thesis is concerned with is the spatial deformation behavior of the fabric which has been subjected to a force perpendicular to its plane in a way which would simulate the effects during the use of the finished woven fabric. This behavior is studied by the model experiments. A semi-sphere having a curved surface has been pressed against woven fabric surface in contact with it in a manner to apply distributed load, and resistance and permenant deformation in reaction to stresses under this effect have been studied experimentally. Different test apparatus parameters are tried with only one kind of finished fabric which is 100% cotton, plain weave. These are 9 parameters, namely, shape of the test peice, dimensions of the test peice, dimensions of the sphere, pressing distance, pressing velocity, waiting time, type of test cycle, repeatability, resting time and number of repeats. The combination of parameters which best specifies the permenant deformation is determined by statistical and graphical analyses. By this way, the developement of the best responding test method and its conversion to a standart laboratory test were aimed at. The relations between different parameters were derived by the regression equations, thus it was achived to calculate one parameter in terms of others and the force exerted to the fabric by the human body which is very difficult to calculate. This work is important from the points of studying the effects of viscoelastic properties upon permenant deformation in different kinds of deformation and how these effects change according to time and perssure, of providing practical findings throwing light upon the desing of a fabric achieving suitable performance in use or to the determination of conditions of right use of a woven fabric, by developing a permenant deformation geometry and mechanics. Key words : deformation, permenant deformation, fabric deformation, deformation mechanics, spatial loading, pressure, viscoelasticity, elasticity, quality, test method.
Deformation is defined, in its simple meaning in the dictionaries, as a change of form. Researches on the deformation of textile materials have been being carried out for a long time at the stages of the production of fibre, yarn fabric and in their semi-finished forms to include the garment form which is their final use. As progress has been achieved in the definition of problems by development of basic theories and in the solution of complex problems especially by the development of computer technology, researches also show a rapid development. Woven fabric is subjected to various forces in daily life. These forces may be in the form of pressure, stress, impact, etc. The woven fabric absorbs these forces to some extend and when the action of the force is lifted, the fabric recovers and returns to its old shape. As the woven fabric has the viscoelastic behavior and show creep-relaxation properties, this sometimes prevents the fabric from recovering and taking its original shape by overcoming the deformation occured and permenant deformation of fabric occurs. This situation encounted in garments as bagging at knees, elbows, pockets, heels, and hips are examples to permenant deformation in woven fabrics under stress. Because the appearance of the garment is affected and also because it is important from the point of view of its daily use, this subject carries a quality factor and thus should be studied.The type of deformation that this thesis is concerned with is the spatial deformation behavior of the fabric which has been subjected to a force perpendicular to its plane in a way which would simulate the effects during the use of the finished woven fabric. This behavior is studied by the model experiments. A semi-sphere having a curved surface has been pressed against woven fabric surface in contact with it in a manner to apply distributed load, and resistance and permenant deformation in reaction to stresses under this effect have been studied experimentally. Different test apparatus parameters are tried with only one kind of finished fabric which is 100% cotton, plain weave. These are 9 parameters, namely, shape of the test peice, dimensions of the test peice, dimensions of the sphere, pressing distance, pressing velocity, waiting time, type of test cycle, repeatability, resting time and number of repeats. The combination of parameters which best specifies the permenant deformation is determined by statistical and graphical analyses. By this way, the developement of the best responding test method and its conversion to a standart laboratory test were aimed at. The relations between different parameters were derived by the regression equations, thus it was achived to calculate one parameter in terms of others and the force exerted to the fabric by the human body which is very difficult to calculate. This work is important from the points of studying the effects of viscoelastic properties upon permenant deformation in different kinds of deformation and how these effects change according to time and perssure, of providing practical findings throwing light upon the desing of a fabric achieving suitable performance in use or to the determination of conditions of right use of a woven fabric, by developing a permenant deformation geometry and mechanics. Key words : deformation, permenant deformation, fabric deformation, deformation mechanics, spatial loading, pressure, viscoelasticity, elasticity, quality, test method.
Açıklama
Anahtar Kelimeler
Tekstil ve Tekstil Mühendisliği, Textile and Textile Engineering, Deformasyon, Deformation, Dokuma kumaşlar, Woven fabrics, Gerilme, Stress
