The manikin that sweated
A manikin called Walter that can be used to test new clothes for extreme environments is described in research published today in the Institute of Physics publication Journal Measurement Science and Technology. Jintu Fan and Yisong Chen of the Institute of Textiles and Clothing at Hong Kong Polytechnic University, in Kowloon, explain in the journal how Walter`s special skin can simulate perspiration while his motorised limbs can be moved to make the manikin walk, for a more realistic test.
Comfortable clothes can be a matter of life or death in hazardous environments from wind-blasted mountain peaks and frozen Arctic wastes to space exploration. But thermal comfort also affects our everyday lives. Good insulation and breathability are keys to comfort.
According to Fan and Chen, the US Army has used manikins to test how effective their military clothing is at keeping warmth in and the cold out, but there is one factor that has been a touchy subject with the testers, until now. Sweat. Fan`s team has now created a new breed of manikin. The fabric-covered manikin can not only be dressed in real clothing but perspires when it gets too hot under the collar.
The researchers say their manikin has several characteristics that could give the older style test dummies a dressing down. First, it has a waterproof, but moisture permeable, fabric `skin` that simulates the evaporation of sweat by moisture transfer from the manikin`s insides through tiny pores in the skin. The second important characteristic of the manikin is that it can be thought of as `warm-blooded`. Water at body temperature (37 Celsius) is pumped from the centre of Walter`s body to his extremities. Thirdly, unlike most existing manikins it only takes one step to measure the two most important parameters – thermal insulation and moisture vapour resistance. The researchers can measure simultaneously heat loss and evaporative water loss from the manikin.
Finally, and critical for practical testing, the skin can be unzipped and interchanged with different versions to simulate different rates of perspiration.
“Our inexpensive walking and sweating manikin has been used to measure the thermal insulation and moisture vapour resistances of clothing ensembles, and demonstrated high accuracy and reproducibility,” says Fan. He believes Walter will find important applications in testing functional clothing including military uniforms, sportswear and even spacesuits. “The manikin will also be extremely useful for better understanding the dynamics of heat and moisture transfer from the human body to the environment,” he adds, “which is the foundation for thermal physiology and environmental engineering.”
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