The Study On Testing The Roughness Of Fabric Surface By A Mechanical Method

In our daily life,we usually use the fabric handle to evaluate the quality of the cloth, and fabric surface friction properties is the closest item related to the fabric handle.As a result,the fabric surface friction properties becomes one of the most important items of objective evaluation to the fabric handle.At present,the surface tester KES is the most influential in all the methods of testing the fabric surface friction properties.This instrument measures the surface properties by measuring the roughness and the frictional coefficient of fabric.At the same time,when use KES to measure the fabric surface friction properties,we have to test the sample from warp direction and weft direction respectively,and in different locations of the sample at least 3 times.In this paper,we use the instrument set up by ourselves to measure the fabric surface friction properties,compared with the KES,our instrument has following advantages:1,In the process of testing,the contactor on the sample moves circumferentially,and it can test the friction properties on all the directions of the sample,compared with KES,it can save time.2,The results of the instrument response the fabric surface friction properties from the aspect of mechanics.In our daily life,we usually impose certain strength on the fabric,at the same time, stroke it by thumb in a circular track.And then evaluate the quality of the fabric. Compared with this,whatever the way of contact or the result of test,this instrument, in theory,is closer to human sense.We compare the results of this instrument with the results of KES to prove the feasibility of this instrument.The signal tested by this instrument can be seen as a mixed-signal composed of a variety of different frequencies information,because the signal we tested are affected by many different factors.It concludes the information of fabric anisotropy,fabric surface structure,as well as the machine vibration etc.Therefore,we have to process the digital signal we tested by this instrument before we do contrastive experiments.We use wavelet analysis in MATLAB to process the signal,we can decompose the signal into some layers,at the same time,we separate the different factors which affect the fabric surface friction properties.We use wavelet analysis,rather than use filter or other methods,mainly because of we won't lose any other frequency signals may be important for us after acquiring signal which we want.The student graduated last year in our group had confirmed that the friction graph of the low-frequency part which acquired after decomposition by wavelet analysis can reflect the characteristics of the anisotropic of fabric,compared with the results tested by KES,they have a good correlation.In this paper,we mainly analyze the high-frequency information after decomposition by wavelet analysis.At the same time,it's different from the graduated student last year in using the wavelet analysis,the programme is used here instead of wavelet box was used last year.The reason of programme is that other methods can't save the high frequency digital signal.We use spectrum analysis to analyze the high-frequency part information,after processing it,we found there are two peaks in the spectrum graph,and there are warp and weft direction in fabric,furthermore,the heights of two peaks have good correlation with the two roughness respectively measured by KES.Combined with the result confirmed by graduated students last year,we can know that the instrument which we set up is feasibility.