Preliminary Study On The Design Of The Fabric Tensile Property Tester With Variable Rate Of Elongation

Nowadays fabric tensile property testers with constant rate of elongation are most commonly used. The measured results of fabric tensile properties can describe the mechanical properties of fabrics to a certain extent. However, these results cannot characterize the load and deformation in the actual manufacturing and using processes fully and really. In fact, the tensile forces and tensile speeds are mostly changing. Therefore, in order to measure the tensile behaviour in the actual manufacturing and using processes, designing a fabric tensile property tester with variable rate of elongation is of great practical significance for a thorough understanding of product characteristics and improving product quality.With computer control principle and software engineering as the foundation, combining the singlechip, virtual instrument and USB communication technologies, a fabric tensile property tester with variable rate of elongation is developed with the virtual instruments graphical programming language LabVIEW. This tester has data acquisition, data processing, data storage and printing functions and so on. The tester can measure the fabric tensile properties under variable rate of elongation by changing speeds of the drive motor.The main research results are as follows.(1) The design of the hardware system of the fabric tensile property tester with variable rate of elongation is completed. Functions of each part of the hardware system are realized. The hardware system is made up of the mechanical part, the testing part with singlechip microcomputer control, USB communication part and the upper computer part. The AC servo motor is chosen as the power component. The STC89C516RD+is chosen as the singlechip of testing part. And CH372 is chosen as the interface chip of the USB communication part. The USB device is drived by using the USB chip CH372 and VISA programming interface. So the communications between the upper and lower computers.are realized.(2) The design of the system software is completed with the application of virtual instrument technology, including the design of the user interface, software implementation of the USB communication module, transnission of the test parameters, data acquisition, and processing and display of the load-elongation curve. Signals of half sine, triangle and square wave are generated by the singlechip to drive the AC servo motor. Thus the required speed signals of variable rate of elongation are generated.(3 The tensile properties of woven fabrics under variable rate of elongation are measured with the tester developed in this research and compared with the tensile properties under constant rate of elongation. Effects of different wave signals and different cycles and amplitudes of the half sine wave on the tensile properties of woven fabrics are discussed. The following results are obtained. (a) The breaking strength and breaking elongation of woven fabrics under variable rate of elongation are both smaller than those under constant rate of elongation. (b) The breaking strength and breaking elongation under triangle wave signal are the smallest. The breaking strength and breaking elongation under square wave signal are the largest while those under half sine wave signal are modest. (c) The breaking strength and breaking elongation of woven fabrics increase with the increase of the cycle of half sine wave. (d) With the increase of the amplitude of half sine wave, the breaking strength and breaking elongation of woven fabrics first increase then decrease.