| With the rapidly increasing of living standards and the concept of healthy dressing deeply rooted in the hearts of the people, the requirement of clothing comfort is becoming higher and higher. In addition to heat and moisture comfort and feeling comfort, pressure comfort has gradually become one of the key indicators in measuring clothing comfort in recent years. From the present study, in various wearing parts of human body, the studying of clothing pressure on the top part of men’s socks is rare. The existing literatures about pressure on the top part of socks are mostly investigated the pressure effects of stockings for varicose vein on the human body from the angle of medicine, nevertheless, there has no reasonable interpretation and quantitative analysis of the pressure from ergonomic viewpoint. This paper regarding the top part of men’s socks as the research subject, deeply discussed the pressure effects of top part of socks on the lower leg, and then put forward a new method in studying pressure with the relationship between pressure and displacement arising therefrom. All these conclusions supply a theoretical reference for optimal design of the top part of a man’s sock, and the work fill a gap in this field.In this study, we selected 50 Chinese college students with a standard shape and between 20 and 25 as subjects. Through three-dimensional body scanning, we present a model of the cross-section of the lower leg where the top part of a man’s sock is located for the first time, and then solve the equation and girth of the cross section curve, these provide a data support for the building of mathematical model for forecasting pressure. In this study, the human body is regarded as an elastomer and the contact between the lower leg and the top part of the sock is considered to be an elastic contact, combined with the structure of human leg at the top part of socks, the position and shape of the bone, the thickness, modulus of elasticity and poisson’s ratio of skin and soft tissue, the finite element simulation model of the lower leg cross-section at the top part of socks is set up for the first time, the model assume that skin, soft tissue and bones are all liner elastic materials, and the finite element analysis software ANSYS is successfully applied to simulate the pressure and displacement distribution at the top part of socks, the pressure-displacement quadratic equation of any point on the lower leg cross-section estimated by simulated provide basic data for quantification research of the pressure comfort. Research indicates that the multiple relations of the pressure and displacement are basically the same for two socks, that is to say, the multiple of pressure values approximately equal to the displacement ones. Meanwhile, we divide the lower leg cross section into four equal regions according to angle, which are [0o, 90o] (region I)、[90o, 180o] (region II)、[180o, 270o] (region III) and [270o, 360o] (region IV), according to the simulation and analysis results of the finite element, [180o, 270o] (region III) had the largest area shrinkage mass on the cross-section of the leg, [90o, 180o] (region II) had the smallest, and [0o, 90o] (region I) and [270o, 360o] (region IV) had roughly the same. Region III has approximately treble the area shrinkage mass of region II, and double that of region I and IV. These conclusions supply a theoretical reference for optimal design of the top part of a man’s sock. This paper demonstrates an analytical method for simulating dynamic pressure and displacement at the top part of men’s socks. The dynamic pressure is divided into two parts, the first is pressure with time, and the second is pressure while walking. The pressure with time is set in six periods, these are 1h , 2h , 4h , 8h , maximum 12h , respectively, and the walking process is divided into four phases, these are described as upright position, foot backward off the ground, leg lift 10°and leg lift 30°, respectively. Research indicates that the pressure values of the top part of socks gradually decreased over the course of time. The pressure values significantly decreased within the first 1h , the rate of descender is about one third of the total, and the decreasing rates arrive at one half after 2h , and then the descent rate of pressure decreased less and less as time prolonged. The pressure values were almost stable 8 hours after putting on the socks. The gap between maximum value of pressure and the minimum became smaller gradually, and the pressure values at 72 points trended to basically the same in the end. Moreover, the larger the initial pressure arising from the socks or the more a point on the lower leg cross section is subjected to pressure, the more significant the pressure descended with time for the top part of men’s socks of the same fabric. As for the two different fabrics of the socks in this study, the descender of the the cotton top part of socks is larger than those of nylon as time prolonging. The area shrinkage mass of lower leg cross section also increase as time goes by, and region III has the most evidently change, region II is least. Region III has approximately 5 times the area shrinkage mass of region II after 12h . There has little change of the pressure values at the point of lower pressure in walking. For the same fabric, the higher pressure of the socks, the larger amplitude of variation of the pressure values, and then the pressure variation of the the cotton top part of socks is larger than those of nylon. For most regions of the lower leg cross section, the pressure was highest when the subjects were in an upright position stage during the course of walking, and the minimum occurred at the foot backward off the ground stage. The total area shrinkage mass of the four regions in different phases changed little during the course of walking. Nevertheless, the total area shrinkage mass is slightly higher in the upright position than that in the other three phases.At last, we discuss in details with the relationship among each factor which affect the pressure values, and finally established four indices which closely related to pressure level, these are elastic coefficient of top part of socks, Poisson’s ratio, elastic elongation and width of top part of socks. We obtained the regression equation among pressure and physical properties of the top part of socks though principal component regression. Chi-square and figure test indicated that the predictive values of pressure showed good agreement with the measured ones. The conclusions can provide the theory basis for the forecast of clothing pressure. |
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