Contactless ultrasonic method for determining knitted fabrics tension

The values of the measured amplitudes of ultrasonic vibrations that have passed the controlled material have been obtained. These values were compared with the amplitude of the waves passing through the fabric sample when the initial tension was applied to it. After that, the total current value of the tension of each sample of the knitted fabric in its three zones was determined. The distribution of the total tension in different zones of the sample material was also determined. It has been established that the amplitude of ultrasonic waves passing through different zones of the textile material can be used to determine the tension of the knitted fabric over the entire width of its fabric. The possibility and expediency of determining the fabric tension on knitting equipment by using the ultrasonic contactless method has been shown. The tension of the knitted fabric in its manufacture is the main technological parameter, the value of which determines the physical, mechanical and consumer properties of the finished fabric, especially basis weight. The use of operational technological control of the tension of knitted fabrics directly during their production will improve the quality of finished products, and, accordingly, the reliability of use in personal protective equipment, in particular in body armour. It has been proposed to determine the tension of knitted fabrics in their production on knitting equipment by changing the amplitude of ultrasonic waves passing through the material under the action of tension, which also changes during the movement of the process equipment. The proposed contactless method is quite promising, since it has a number of significant advantages over the existing contact methods. In the course of the research, experimental measurements of the amplitude of ultrasonic waves have been carried out. These waves passed through samples of fabric of various materials while stretching. The samples of knitted fabrics were irradiated with an ultrasonic pulse signal with a wave frequency of 40 kHz. The samples of knitted fabrics from 58x2 Tex Kevlar threads and high molecular weight 44x3 Tex polyethylene yarns with double weave 1x1 elastic have been taken as a basis for the research. For textile fabrics, the structure of which does not allow stretching through pores under the action of tension, it is necessary to additionally adjust the contactless sensors in frequency and capacity depending on the corresponding sample. The values of the measured amplitudes of ultrasonic vibrations that have passed the controlled material have been obtained. These values were compared with the amplitude of the waves passing through the fabric sample when the initial tension was applied to it. After that, the total current value of the tension of each sample of the knitted fabric in its three zones was determined. The distribution of the total tension in different zones of the sample material was also determined. The dependences of the amplitude of ultrasonic waves, transmitted through the textile material in its different zones, on the value of the total tension, and on the value of the distribution of the tension of the fabric over its entire width were obtained. The deviations δP of the tension display between the determination of this parameter by the standard and ultrasonic methods are shown. The deviations δU between the amplitudes of waves passing through different zones of the controlled fabric are also determined.