Effective Contact Temperature of Solid with Different Material Surface

The estimation of thermal sensation at the instant when a certain object is touched is becoming an important consideration in material evaluation. In a previous paper, we showed that the effective contact temperature of the object-when covered with a thin surface of a different material-could be implied from the thermal contact resistance of the nonsteady heat conduction between half infinite solids. However, when the thickness of the surface material of the contact object becomes the same depth as the thermoreceptor in the skin, the approximation by the thermal contact resistance no longer applies, and, therefore, deriving a strict analytical solution becomes difficult. We calculated the temperature distributions in the material for various material surfaces and the skin using a numerical method. We examined the influence on the effective contact temperature of the thickness and the heat properties of each surface material. As a result, deflection of effective contact temperature from the temperature of a material is determined by the temperature difference between the skin and the surface material/object, the heat properties of each, the thickness of the surface material, and the depth of thermoreceptor in the skin. This can be expressed by the relation of the nondimensional parameter function. When the thickness of surface material is thick enough, effective contact temperature is determined only by the heat property of the surface material, and it is unrelated to the thickness of the surface material and the thermal property of the object under it. The influences of the thickness of the surface material and the thermal property of the object on effective contact temperature appear when the thickness of surface material becomes very thin, and increases rapidly with a decrease in the thickness of the surface material. The criterion between thermally thick and/or thin material is quantitatively presented by the numerical simulation.