Clothing physiology

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The clothing physiology is the knowledge of the planned construction of functional clothing . The aim is to optimally support the physiological processes in the body. This includes the fact that the textiles offer sufficient thermal insulation when it is cold and that when it is warm or exerted, sweat is released from the body and into the environment to help cool the body.

Carrying and sleeping comfort

Thermophysiological comfort

The ability of clothing to manage moisture and heat is known as thermophysiological comfort . Together with the sensation of textiles on the skin (skin sensory comfort), it defines the physiological comfort of clothing - or the physiological sleeping comfort of bedding and sleeping bags .

Skin sensory comfort

The skin sensory properties as well as the heat and moisture management of textiles are key aspects of wearing comfort. For example, a drop of sweat trickling down on wet skin creates an unpleasant touch stimulus and sweat-damp textiles are perceived as unpleasant on the skin.

Ergonomic comfort

The fit of the clothing, together with the physiological comfort, determine how comfortable a person feels in their clothing and how well they are accepted. The latter is an important consideration , especially when it comes to wearing professional or personal protective equipment .

Investigation methods

Research methods of thermophysiological comfort

The various aspects of wearing and sleeping comfort can be objectively quantified using scientific research methods.

Hohenstein skin model

The Hohenstein skin model was developed by Jürgen Mecheels at the Hohenstein Institute in Bönnigheim around 1956 . With its help, the thermal comfort of textile fabrics (woven and knitted fabrics) can be objectively measured and assessed. The Hohenstein skin model consists of a porous metal plate that can be electrically heated to skin temperature, to which water is supplied and which is built into a climate cabinet with variable temperature, humidity and air movement. The skin model simulates the heat and moisture emitted by the skin.

The measurements with the skin model provide specific parameters such as B. thermal insulation, water vapor resistance as a measure of the "breathability", sweat transport and sweat buffering, drying time, etc. These parameters characterize the thermophysiological quality of the textiles.

In order to be able to develop these examination methods, which are now established worldwide in the field of clothing physiology, and the associated assessment models, numerous series of measurements with human subjects were necessary, whose body functions were recorded and who had to classify their subjective wearing comfort. Test subjects are still used today when the task is to develop a completely new product or to confirm the results of the tests with a skin model and thermal manikin.

Thermal manikin

With the help of the thermal articulated mannequins "Charlie" (standard man) and "Charlene" (standard child) and "Charlotte" (standard woman) developed at the Hohenstein Institute , the thermal insulation of made-up clothes, bedding and sleeping bags can be determined. The so-called thermoregulation model of humans consists of copper or plastic and is equipped with a computer-controlled heating system with which the heat production for different body sections can be regulated separately from one another. The thermal articulated manikin is housed in a climatic chamber in which a wide variety of ambient temperatures can be simulated.

The more heat is given off on the arms or legs, for example, the worse the heat insulation of the item of clothing being examined there. Since this is heavily influenced by the ventilation effects that come about through movements, the mannequin moves when examining clothing on a rod as if it were marching briskly.

The examinations on the thermal jointed manikins are an important addition to those on the skin model, as the influence of the clothing ( fit , elastic cuffs, turtleneck , etc.) is taken into account. Because the thermal articulated manikin does not sweat, the moisture management and thus an important aspect of thermophysiological comfort can only be assessed if there are basic tests on the skin model.

Thermoregulation model 'sweaty hand' and 'sweaty foot'

In the 'sweaty hand' and the 'sweaty foot', the functional principles of the skin model and the thermal articulated manikins have been combined, ie the release of heat and moisture under controlled climatic environmental conditions. The measuring instruments can be used to assess both the thermal insulation and the breathability of gloves, socks and shoes.

Upholstery testing device

With both cooled and heated vehicle seats, it takes some time for comfortable seating to be achieved. With the help of the upholstery testing device, the temperature impression (initial heat flow) that a person feels upon first contact is determined. In addition, the effective thermal insulation of seats during long car journeys at a wide range of ambient temperatures is recorded.

Human subjects

With the help of the Hohenstein skin model and the thermal articulated manikins, thermophysiological comfort can be objectively measured and assessed. In order to be able to develop these examination methods, which are now established worldwide in the field of clothing physiology, and the associated assessment models, numerous series of measurements with human test persons were necessary. These are still used today at the Hohenstein Institutes when it comes to developing a completely new product or confirming the results of the examinations with a skin model and thermal manikin.

Examination parameters skin sensory comfort

Adhesive index

A porous, sintered glass plate, to which water is supplied by means of a motor burette, simulates the sweating skin. The textile sample, attached to a cylindrical load cell, is pulled over the plate. The force required for this is measured and results in the so-called sticking index, which can be used to assess whether the textile will stick uncomfortably to the skin when you sweat.

Contact points and surface index

Image analysis systems coupled to a surface scanner or a microscope show the number of contact points for textiles and a surface index as a measure of the contact area with the skin or the hairiness of the surface.

Bending stiffness

To determine the stiffness of a textile material, the bending angle of the fabric strip placed on a thin peg is measured in a measuring device using a laser beam. On the basis of decades of experience, specifications have been defined for various product and application areas that ensure optimum wearing comfort and exclude mechanical skin irritations due to excessive flexural rigidity.

Sorption index

Because the skin's sensitivity to mechanical irritation increases with increasing moisture, it is advantageous for sensory comfort when a textile material transports sweat away from the skin as quickly as possible. The sorption index indicates the speed with which a drop of water hitting the textile is absorbed by it.

Examination method ergonomic comfort

When testing the fit, the garments are tried on by test persons whose body measurements correspond to the size indicated on the label. As with everyday clothing, the size tables for ladies 'outerwear and men's and boys' clothing form the basis for assessing the fit of workwear. Experienced clothing technicians evaluate the garments in terms of length and width, usability, freedom of movement, function and appearance. This test is not only carried out on new items of clothing, but also after the care treatment, ie washing, cleaning and drying. Ideally, the fit of an item of clothing, as well as the condition of the material, the seams, etc., should not change.

Comfort grade

The results of the examinations on the skin model and the thermal articulated manikins (= thermophysiological comfort) flow together with the assessment of the skin sensory properties into the so-called wearing and sleeping comfort rating. This is possible because research has shown that around 66% of the wearing comfort is caused by the thermophysiological and around 34% by the skin sensory properties of the textiles.

The comfort grade is given in the “school grade system” from 1 for “very good” to 6 for “unsatisfactory” and enables the consumer to easily compare different products. In standards for the design of work clothing or personal protective equipment , z. T. minimum requirements for the comfort grade.

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