Study On Clothing Contact Pressure Of Elastic Fabric And Establishment Of Evaluation On Wearing Touch And Pressure Comfort

As an important part of overall wearing comfort, wearing touch and pressure comfort is relatively new in research field. Through a large amount of studies, considerable progresses have been made in thermal and moisture comfort of clothing, however, physical mechanism of touch and pressure comfort yet needs further study. Clothing contact pressure is a crucital subjective paramenter in the research of wearing touch and pressure comfort. Currently, more study on the nature of contact pressure needs to be done and prediction model hasn't been utterly completed. Evaluation on wearing touch and pressure comfort mainly depends on wearing tests, which takes a lot of time and labor and could easily be affected by environment as well as attitude, psychological and physiological statues and experience of subjects. Therefore, further study on clothig contact pressure and wearing touch and pressure comfort were conducted in this thesis. Firstly, literature review on clothing contact pressure and wearing touch and pressure were done in the preface. Research, methodology, achievements and problems brought up in this field at home and abroad were outlined and analysed.Secondly, the defination of clothing contact pressure was given and its unit was introducted and standardized. The form of clothing contact pressure was determined for study based on its classification. Clothing contact pressure data of seven points during three actions were acquired with AMI-3037 air pack contact pressure measurement system. The effects of body point, body position, wearing time duration and garment style on wearing contact pressure were discussed. Pearson statistics analysis showed that wearing contact pressure was correlated with wearing allowance, which also featured linear regression relationship that passed residual, fitting level and significance test. Regression equations are considered of statistical and pratical meaningness. Analysis disclosed that wearing contact pressured was caused by fabric strain to fit human body.Relationship between dynamic strain of skin and fabric and wearing contact pressure was discussed in chapter three. Dynamic strain of skin and fabric in longitude, latitude and anglular direction were measured with reference to marking and drawing line methods. Close relations were found between them through analysis. Therefore, Polynomial regression equations on wearing contact pressure were obtained by SPSS and passed residual test, fitting level test(R2=0.853) and F significance test (F=130.134,p<0.01). Regression coefficients of the eqution passed the t significance at 0.01 level. In additional, results indicated that strain of fabric was affected by its own characteristics, mechanical property in particular. It was observed that wearing contact pressure and most parameters of mechanical property were correlated.In chapter four, a series of assumptions of fabrics were made at first. Fabric was assumed as an elastic shell. Accordingly, elastic mechanics, material mechanics and nonmomental theory of shell were applied to contact pressure study of the fabrics. Mathematical model on statical wearing contact pressure was established using mechanical properties analysis of fabrics. Prediction value of wearing contact pressure in the poisiton of wrist, middle of forearm and side-muscle were derived from the mathematical model. One hundered and twenty five measured data were selected to testify the predicted values. Results showed predicted values have nice consistency with measured data since Pearson coefficients were all above 0.85. Fifty measured data were chosen to testify the predicted values in elbow position. Analysis verified nice consistency between predicted values and measured ones. Pearson coefficients were all over 0.86. All analysis above showed that mathematical model on statical wearing contact pressure had agreeable prediction ability. In addition, the model is of statistical and practical meaningness. Variation of wearing contact during action changes was also discussed, of which relugations were summaried as well. Gaussian funciton was used to simulate dynamic wearing contact pressure combining with outcomes of statical mathematical model. From fitting analysis of four hundered and twenty data, fitting results were considered greatly favorable with square of fitting coefficients all over 0.97. With dynamic Gussian model, wearing contact pressure of random point during action change could be derived, along with the continuous curve of dynamic wearing contact pressure. With that, a clear idea of how wearing contact pressure changed with human body movement was obtained.In chapter five, the effect of contact pressure on clothing surface temperature and skin blood were investigated. Clothing surface temperature of fore-arm was measured by non-touch thermal infrared imaging camera. Different forms of analysis results showed that clothing surface temperature was distributed in region. Surface temperature of inside elbow and wrist were highest in fore-arm. Surface temperature of outside elbow and wrist were lowest. Observed surface temperature of the fixed point is affected by fabric material and wearing contact pressure. Clothing surface temperature of blended chemical fabric with spandex was discovered decrease firstly and increase subsequently with the enhancement of wearing contact pressure. However, clothing surface temperature of cotton and spandex blended fabric was discoved increase with the enhancement of contact pressure. Skin blood data was acquired by AMI-A0010 device during three external force operation processes using AMI-A0203 device. Blood flow changes could be divided in three steps namely as reactive hyperemia with initial pressure, blood blockage and compensation congestion phase. Blood flow increased promptly when initial pressure came to near 0.58kPa in early stage of experiment. Blood blockage occurred when external force came up to greater than 0.59kPa or maintained a higher value. Compensation congestion stage appeared when external pressure was removed quickly.Wearing trial results showed that touch and pressure sensations were closer to overall comfort than thermal and wet sensation when in comfortable environment without dramtic movement. With that discussed, multivariabe regression equations on overall wearing comfort with softness, coarseness, weightness and compression sensation were established. Equations passed residual test, fitting level test(R2=0.878) and F significance test (F=60.923,p<0.01). Regression coefficients of eqution passed t significance test at 0.01 level.In chapter six, relation between wearing touch and pressure comfort and fabric mechanical property was established with three neural computing networks. Nineteen FAST mechnical prameters of fabric were reduced to four common factors with principal component analysis by SPSS. Four principal factors, elastic modulus and wearing allowance rate were used as input variables of network model. Tightness, softness, coarseness, compression and overall comfort sensations were used as output variables of model. Three training sample sizes for Back Propagation Network (BP), Radial Basis Function Neural Network (RBF) and Generalized Regression Neural Network (GRNN) were chosen, which were 70,110 and 160. Spreads of RBF and GRNN were 0.1 and 0.2. With the combination of parameters for networks, thirteen initial network-models were established. Five models with better perfermances were selected through first testing. Then through second testing, GRNN model was determined as the final evaluation model. Correlation coefficient between values from GRNN model and experiment was more than 0.98. A series analysis showed that GRNN model had got best prediction accuracy. Accuracy rates on tightness, softness, and roughness and compression reached 96%. Accuracy rate on overall comfort was 92%. Regression coefficient of GRNN model was nearly close to 1.Finally, using.NET as developing platform, evaluation system of wearing touch and pressure comfort was developed with C# language. Objective wearing rating could be computed and obtained by the evaluation system. Theoretical value of static contact pressure could be predicted and dynamic contact pressure could be simulated as well. Basic fabric parameters, mechanical property, body size, garment size and etc could also be managed with the software. The application of this system could save a lot of labour and time by simplifying the input parameters. Moreover, it is easy and simple to work with. Computing speed of system is high with intuitive data processing and friendly application programming interface.In-depth and systematic study on wearing contact pressure and touch and pressure comfort was conducted in the thesis. The effect on wearing contact pressure was analyzed and linear regression equations were established. Static and dynamic prediction mathematical models were established separately. Relationship between wearing contact pressure and wearing surface temperature as well as skin blood flow were discussed with experiments. Comfort evaluation model based on wearing trials was acquired by GRNN. Evaluation software system was developed with C# language。The system could contribute to fabric manufacturing and garment designing and better meet the demands of consumer.