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Especially for textiles, which contain open structure pores, airflow carrying heat energy transfers from one side to another side by conduction and convection. Convective heat transfer plays a very important role in thermal transfer performance of textiles due to its porous structure. Compression sportswear are generally produced from knitted porous stretch fabrics, which get extended on wearing and remain in the extended state. Since they are worn next to skin and are direct contact with the body surface, their thermal comfort properties are effective on overall clothing comfort. Perhaps the greater contact of the garment to the skin together with the constant airflow can transfer the heat better from the body to the environment. Most of the well-known auxetic materials possess porous microstructures and the sizes of the pores of auxetic materials can vary during the compressive and tensile deformation. In this study, an investigation has been made to evaluate the auxetic effect on the thermal transfer performance of clothing. Two type fabrics having the very similar fabric properties but different knitting structures were provided from the market and producer. While one has an auxetic structure, the other has a standard warp knitting structure commonly used in market. As permeability and porosity are strongly related to each other, we compared air permeability of fabrics in extended state considering the fabric extension results taken from virtual avatar having the same body measurements as subjects in 3D simulation. Fabric surface temperature changes on different clothed body parts investigated by an infrared thermal camera and analysed in thermal camera software (Flir Tools) for thermal transfer performance according to the wearing protocol.

Virtual simulations have become a part of design and marketing from personal use to professional designs and provide virtual realism to a great extent. With rapidly developing technology, nowadays it has attracted much more attentions especially in textile processes. The 3D virtual garment simulation provides the textile producers and fashion designers with benefits in terms of product development, customization of garments and speed to market. While most of the software focuses just on visual design, some major software manufacturers (Lectra, Optitex, Gerber, etc.) try to develop programs to accurately simulate fabric behavior as well as visual modeling. When the literature studies are examined, it is seen that the simulations in which the fabric mechanical and physical properties are defined, provide virtual realism to a large extent. But this is just regarding to the ergonomic comfort of the garment and virtually no garment simulations exist for the realistic prediction of thermal comfort. The estimation of clothing thermal comfort is very helpful for designing garments, especially sports and works garments where thermal comfort plays an crucial role for the status of the wearer. To make a method to realistic solution to virtualize the thermal comfort of clothing: virtual body properties, garment design, clothing drapability, thermal characteristics of fabric and the thermoregulation of the human body according to different conditions should be considered all together.

Next-to-skin sportswear are generally produced from knitted strecth fabrics, which get extended on wearing and remain in the extended state. Since they are worn next to skin and are direct contact with the body surface, their thermal comfort properties are effective on overall clothing comfort. In this paper, an investigation has been made to evaluate the effect of garment fit and fabric extension on the thermal transfer performance of clothing. The method using the combination of infrared thermal camera and 3D virtual garment simulation has been developed considering the fabric extension and clothing surface temperature of different body parts. Two type T-shirts were produced by changing the bust and waist measurements and their thermal transfer performance were investigated in wear trials on subjects having different size. Fabric extension results were taken from virtual avatar in 3D simulation having the same body measurements as subjects. Temperatures changes on different body parts according to the wearing protocol were investigated in thermal camera software (Flir Tools). The experimental results show that compression garment fit and fabric extension influence the heat transfer and clothing surface temperatures. In the sportswear industry, Optimal garment fit should be defined for designing sportswear, especially for performance sportswear.

Compression sports garments in usage stretch up to 10% length and 60% in width, depending on the circumference variations of body. This stretch also changes the loop density, loop shape, porosity and thickness of fabrics. Especially for heat and water vapor transfer, it is expected to play a very important role. Compression sportswear are generally produced from knitted stretch fabrics, which get extended on wearing and remain under extended condition. Since they are worn next to skin and are direct contact with the body surface, their comfort properties are more effective on overall clothing comfort. As Permeability and porosity are strongly related to each other, we compared air permeability of fabrics in extended condition considering the fabric extension results taken from 3D simulation. The aim of this study was to investigate the effect of fabric extension on fabric Behaviours (air permeability, loop density and thickness of fabric) of eleven stretch knitted fabrics used largely in compression sportswear. Revised patterns in virtual garment simulation can help to use the air permeability property more effectively to improve the overall clothing comfort. The results of study show that air permeability and loop density which are strongly related, change significantly when the fabric is posed under an extended condition, especially it is more visible in warp knitted structures. Investigations on fabric Behaviours under extended condition could be the key for solution in ventilation of appropriate zones on garment.