A Design Tool for Clothing Applications: Wind Resistant Fabric Layers and Permeable Vents

A computational clothing design tool is used to examine the effects of different clothing design features upon performance. Computational predictions of total heat and mass transfer coefficients of the clothing design tool showed good agreement with experimental measurements obtained using a sweating thermal manikin for four different clothing systems, as well as for the unclothed bare manikin. The specific clothing design features examined in this work are the size and placement of air-permeable fabric vents in a protective suit composed primarily of a fabric-laminated polymer film layer. The air-permeable vents were shown to provide additional ventilation and to significantly decrease both the total thermal insulation and the water vapor resistance of the protective suit. 1. Introduction Windproof and wind resistant clothing layers are important in applications such as cold weather clothing and military chemical and biological protective ensembles. Completely windproof clothing provides protection from heat loss due to air penetration in cold conditions but can also become very uncomfortable when the wearer is working hard and generating a lot of heat and sweat. The same situation arises in protective clothing—some ventilation through the fabric layers can be very helpful in mitigating heat stress and extending wear time. Design tools that allow simultaneous assessment of factors such as wind penetration, heat transfer, moisture transport, and permeation of toxic substances can assist in developing new clothing systems that strike a good balance between protection and comfort. We have shown previously that the wind resistance and aerosol filtration properties of clothing layers can be controlled by varying the deposition of electrospun fiber membranes onto textile substrates [1], as shown in Figure 1. Figure 1: Air flow resistance of fabric layer modified by electrospun fiber coating level [1]. Since nanofiber layers make it possible to control air flow resistance over several orders of magnitude without affecting other clothing properties, we are interested in the resulting consequences of using these materials in new clothing designs. Electrospun elastomeric polyurethane membranes are now used in commercial outerwear fabrics such as “NeoShell” by Polartec, Inc., and take advantage of this ability to “tune” air flow through the fabric without significantly affecting other properties such as thermal insulation or water vapor diffusion (breathability). These materials may be used for either an entire clothing item, such as jacket or pants, or