Measurement Based On Wavelet Transform For Testing Fabric Frictional Properties By A Rotating Method

Frictional property is one of the most important mechanical properties in the evalution of fabric hand. With increasing attention to the hand of textile products, recognizing and measuring their frictional properties, especially quantitatively characterizing, also has become more important.In most existing test methods, fabric makes a traditional linear motion, which has certain limitations for aeolotropic fabric. Accordingly, a new method, which adopts a rotating sample movement, is designed in this paper. On the basis of this method principle, we formed a measuring system, and the tribological curves were obtained from it. With wavelet transform was applied, the curve was devided into two parts—the approximation and the detail.12 samples were selected to do some tests and research on fabric frictional behavior in two different friction means. On the base of the experimental datum, some regression analysis was done for investigation. Test results were compared with KES to prove the availability of this method. the effects from different experimental conditions and structure parameters of samples were also discussed in this paper.Through the research and analysis, the following results can be derived from the experiments:1. By the rotating method, the aim to detect frictional behavior in any direction can be achieved during a revolving cycle, thus the friction information in both warp and weft directions are gained at one time.2. Through the analysis on frictional behavior between fabric surface and probe in a circuit, and based on KES's result, we formed a theoretical friction coefficient curve, which can be seen as a curve that fluctuating along the mean friction coefficient curve.3. An electrical analog signal ,which corresponds to the frictional force, was acquired from the force sensor, and then was collected by the data acquisition card and transformed into a digital signal by a A/D converter.4. The tribological curve obtained from our measuring system was consistent with the theoretical curve, that proved the effectiveness of the system. In our analysis, the long periodic waves, i.e. the low-frequency part, reflect the aeolotropic property of fabrics; while the small periodic fluctuations, i.e. high-frequency part, are caused by the bumpy texture structure.5. Through wavelet transform processing, low-frequency part and high-frequency part were effectively separated. It has solved the problem that the signal filtered out can not be reserved in traditional filtering method, thus raised the value of this testing system.6. Three parameters—the mean coefficient of friction, the aeolotropy margin of friction coefficient, and the texture deviation of friction coefficient—were set to characterized the frictional behavior of fabrics. And the results of the independence tests among them show that they have no repeatability.7. Through the comparison between the experimental results in two friction modes, we discovered that the high-frequency fluctuations caused by embossing texture structure were more obvious in the spherical contact mode, while the plane contact mode reflects more apparent aeolotropic properties. And analysis on the results in different sample velocities shows that fabric velocity is, to some extent, correlated to the frictional property of fabrics.8. All the characterized parameters of the rotating method have good correlations with the corresponding parameters of KES by comparison.