| Seamless knitting technology is widely used in the knitting of tight-fitting sportswear,medical clothing,body-shaping underwear and other products with the advantage of one-time molding.These products have a certain range of garment pressure requirements.These products have a certain range of clothing pressure requirements.When the garment pressure level is too high,the garment pressure may become a burden on the human body and harm the body,but if it is too low,the pressure clothing will not be effective.In fact,the realization of one-step garment of seamless knitting includes development processes such as knitting programs,setting knitting parameters.This method of developing seamless knitted pressure garments is not efficient,and the direct measurement of garment pressure is easily affected by the accuracy,volume,and quantity of pressure sensor,and could not evaluate the pressure distribution of the garment on human body.Therefore,due to simplify the development process of seamless knitted pressure garments and optimize the functionality of pressure garments,it is urgent to carry on in-depth research on the size and deformation properties of seamless knitted fabrics and the distribution of pressure exerted on human body.Firstly,in order to research on the relationship between the knitting parameters and the size of the fabric,there were 20 seamless knitting fabrics were designed by various knitting parameters,including spandex draft ratio,stitch length,and yarn feed tension according to Central Composite Face-centered design(CCF)response surface methodology in this paper.Through response surface analysis,the regression mathematical models between the knitting parameters and the coursewise/walewise density of fabric were established.It was found that spandex draft ratio,stitch length,and yarn feed tension had significant effects on the course-wise density of the fabric.The degree of effect in descending order was stitch length,yarn feed tension and spandex draft ratio.The quadratic regression equation between these three knitting parameters and the coursewise density of the fabric was established.This equation could predict the course-wise density of the fabric based on the values of the spandex draft ratio,stitch length and yarn tension.it was shown that the draft ratio and the stitch length had a significant effect on the wale-wise density of the fabric by the linear multiple regression analysis,and the spandex draft ratio was positively correlated with the wale-wise density of the fabric,and the stitch length was negatively correlated with the wale-wise density of the fabric.Secondly,the tensile test of fabrics were tested according to the deformation characteristics of seamless knitted fabrics,and Yeoh hyperelastic model was used to fit the tensile stress-strain curve of the test data.Through the K-Means cluster analysis,fabrics with similar tensile stress-strain properties were eliminated,and the Pearson correlation analysis was performed on the course-wise density and the strain order of the selected 6 fabrics.The results showed that the significance value of both sides was0.258,which was greater than 0.05,indicating that the course-wise density of seamless knitting could not be used to predict the mechanical properties of the fabric.The hyperelastic Yeoh model parameters of the 6 selected samples were used in the finite element uniaxial tensile simulation,and within 40% of fabrics elongation rate,and the simulation results were in good agreement with the test data.Thirdly,for purpose of studying the pressure distribution that the compression socks exerted human thighs,a healthy female college student,who was healthy and had no medical history on the legs,was scanned on 3D body scanner,and the 3D contour point cloud data of the left thigh of the human body was intercepted.In the reverse engineering software,the point cloud data was converted into the thigh solid,compression socks were drawn with 5 different reduction coefficients,and assemblies of compression socks and thighs were design.The finite element pressure simulation of30 model assemblies were completed,and according to the results of finite element simulation analysis,the mathematical relationships between the pressure at 12 points of3 girths on the surface of the thigh and sizes of two compression socks were established.Among the 12 points,the point where the compression sock exerts the maximum pressure on the surface of the thigh was selected,and compression socks which it's pressure of that point was set as 1000 Pa was developed according to the mathematical relationships between the surface pressure of the thigh and sizes of compression socks.The study showed that the pressure that compression socks exerted on the thigh was related to the radius of curvature of the thigh surface.The smaller the radius of curvature was,the greater the pressure value was,of which was consistent with Laplace's law describing the relationship between pressure and radius of curvature.The pressure value increases non-linearly with the decrease of compression sock's sizes,the polynomial mathematical relationship describing the pressure value of the 12 points on the surface of the thigh and the size of the compression sock were established,and the average of R squared was 98.54%.This equation could calculate the corresponding compression sock size value according to the pressure value required at the point.Fourthly,In order to judge whether the finite element pressure simulation was effective,the pressure test experiment in the real human body was carried out,and the difference between the pressure measurement and the finite element pressure simulation value was tested by the independent two-sample non-parametric Mann-Whitney test.The result showed that there was no statistically significant difference between the finite element pressure simulation value and the pressure measurement value,which showed that this approach was feasible to realize the customization of compression sock.This research proposed a seamless compression sock method based on fabric deformation and thigh pressure,which provided some new ideas for reducing the time and cost spent in the development process of customized compression garment. |
PDF Full Text Request