Research On The Modeling Of The Contact Warm-cool Feeling Of Woven Fabrics

Fabric contact warm-cool feeling is an important evaluation index of fabric thermal comfort.Due to the particularity of the fabric and the complexity of its internal structure,the experimental results are relatively limited.Therefore,in view of the shortcomings of the experimental test,this paper simulates and predicts two kinds of indexes to evaluate the fabric contact feeling of heating and cooling:fabric thermal conductivity and heat flow value of Qmax.In order to explore the fabric contact warm-cool feeling,6 kinds of woven fabrics were selected for experimental test.The thickness of the fabric and the thermal conductivity of the inner yarn were measured.Combined with the test results of Qmax,it is found that Qmax is affected by the fabric thickness,internal yarn thermal conductivity,yam interweaving law and other factors.The conclusions obtained from the analysis of experimental test results are relatively limited and can only be applied to the horizontal comparison between experimental test subjects.Based on the equivalent thermal conductivity of fabric,the three-dimensional geometric model of fabric was transformed into an equivalent model,and the fabric weave cycle was studied as the main body.According to the rules,the interwoven yarn is divided into 6 categories:interwoven point yarn overlap region,warp(weft)yarn alternating crossing region,warp(weft)yarn suspension region and pore region.The distribution of yarn and air in each region was analyzed,and the equivalent thermal conductivity model in each region was established based on the series and parallel equivalent thermal conductivity model of composite material.The established model is used to predict and analyze the variation law of thermal conductivity when the yarn height,spacing,width and interlace law change.It is concluded that when the yarn height and width increase,the equivalent thermal conductivity of the fabric increases.The increase of yarn spacing will decrease the equivalent thermal conductivity of the fabric.When the fabric structure changes,the larger the volume proportion of the yarn suspension area,the smaller the yarn equivalent thermal conductivity.For Qmax transient heat flow value fabric this parameters,through the establishment of fabric three-dimensional geometric model,and by using the finite element software of fabric,to simulate the state when in contact with skin and get the result of the temperature and heat flow,the results show that the calculated results of finite element simulation model has been established with the experiment test values error within the scope of the controllable,can be used to characterize the fabric contact changes in temperature.The established model was used to simulate the heat flux under different ambient temperature,coating treatment and embedded yarn with high thermal conductivity.The results show that when the temperature difference between human skin and fabric increases,the heat flow increases.When the fabric is coated with high thermal conductivity,the cool feeling of the fabric can be improved,and the coating thickness is also an important factor affecting the improvement effect of the coating on the fabric.When the high thermal conductivity yarn is embedded,the heat flow of the fabric will increase,which can improve the cool feeling of the fabric.