Analysis Of Tensile Fracture Behavior On Blended Ring Spun Yarn

In textile industry, fibers of different physical properties were usually beblended in order to meet the requirements of a particular use. The tensile property of blended yarn is one of the important indicators which measure the physical and mechanical properties, and known as the raw materials affect directly the final taking performance and industrial performance of the textiles.In general, the theoretical strength of fibers in yarn are summed as the blended yarn strength, however the strength of the yarn in the process of production is usually less than the theoretical value.Therefore, how to maximize the use of fiber’s strength in the hope of yarn tensile breaking strength reaches the maximum value and meet the application needs is an urgent problem to lots of yarn manufacturers. At present, using traditional test methods of yarn strength can only detect the blended yarn breaking strength, breaking elongation and other physical parameters, not exactly judge internal reason of blended yarn low and uneven breaking strength, therefore, a new test method and analysis method is put forward. With the constant progress of science and technology, the rapid development of the Acoustic Emission testing and blind source separation technology, it provides the possibility of collecting directly the useful information during tensile failure of the yarn and fibers, and exploring the blended yarn tensile fracture mechanism and analysing the intrinsic factors of uneven.In this paper, the acoustic emission was first used to obtain the acoustic emission signal of single fiber tensile fracture process, and chose Blind Source Separation of HHT-ICA- FFT for the acoustic emission signal processing, based on the characteristics of acoustic emission frequency of various fiber breakage. Then, by comparison with the characteristic frequency of the single fiber blended and using the kernel density estimation of mathematical processing method for signal filtering, processing, the fiber breakageorder is determinedand the slip fibers are concluded, the objectives are reached.In this paper, the research content and achievements mainly involves the following six aspects:(1)The acoustic emission detection experiments of tensile fracture were conducted, on the common electronic fabrics strength meter.Thethe sampling frequency is determined through pre- experiment to meet the requirements of the subsequent analysis.On the tensile fracture of fiber acoustic emission signal processing the EMD- ICA- FFT blind source separation algorithm beenexplored out, which used to extract the yarn amplitude spectrum of tensile fracture, and established 6 kinds of fibre materials’ acoustic emission signal spectrum library of fracture characteristics includespolyester fiber, cotton fiber, A-fiber, B-fiber, C-fiber and D-fiber.(2) To verify the EMD and ICA methods, the fracture acoustic emission signal of polyester yarn and cotton yarn are used to simulate the fracture acoustic emission signal of polyester/cotton blended yarn. The simulation results show that the method used in blended yarn tensile fracture behavior of analysis with real reliability, provided the basis for subject experiment.(3)Kernel density estimation method was proposed for amplitude spectrum contains yarn tensile fault information processing. Using the kernel density estimation method to to estimate the probability density of polyester and cotton fiber, A, B, C, D in the process of drawing characteristic frequency of the acoustic emission signal.The following are conclusions: in tensile processing, the core density value of polyester fracture frequency characteristic is 1.124 x 106 Hz, the cotton is 1.104×106 Hz,A-fiber is 2.408×106 Hz,B-fiber is 2.282×106 Hz, C-fiber is 2.122×106 Hz and D-fiber is 2.21×106 Hz.(4)From all kinds of fibre materials’ acoustic emission spectrum of kernel density estimation analysis results in tensile fracture, it can be obtained: In each time period oftensile process of polyester/cotton blended yarn and four components blended yarn, the fiber characteristic acoustic emission spectrum differ from each other.Which can use the kernel density estimation of characteristic frequency to characterize each frequency band intensity.(5)From the perspective of kernel density estimation, it can explain that, in the tensile process of polyester/cotton blended yarn, cotton fiber break first than polyester, and the fracturefocus on the main fracture zone, and then there are the recurrence of fracture phenomenon; in the process of four components blended yarn tensile, A-fiber break firstly, D-fibers break secondly and its’ fracture occurred in the whole process;B-fibers rarely break; and C-fibers possibly don’t break.(6)In the analyzing process for the tensile fracture mechanism of the blended ring spun yarns made up with four components, there are combinations with experiments of fibers’ mechanics, friction and slice, by which provided a supplementary card to account for the results--in the stretching process of the blended ring spun yarns made up with four components, part of the D-fibers break firstly, then a slip between A-fibers and the other fibers occur. And with the processing of the tensile, A-fibers start breaking mainly after the main fracture zone; B-fibers mainly occur a slip and break rarely, which have a lower strength contribution; C-fibers possibly don’t break and have a certain amount of strength contribution to the strength of the blended yarns.