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This paper concerns a former experimental study of the Lehrstuhl für Ergonomie of TU München, where in the first step correlations between pressure and discomfort were found for the seat pan. In the second step these findings were validated for long term discomfort. Now an additional correlation for the back should be found, which is essential for later research. In this context tests conducted before should now be confirmed and validated by another seat comfort model with a higher number of subjects and a long term test, too. Interesting part of this study will be the intercorrelation between seat pan and back.

To describe feelings of discomfort while sitting, many experiments have been conducted to find a link between interface pressure on the seat and the feelings of discomfort of test subjects. Most of these experiments found no relation or correlation between discomfort and pressure while others actually found a relation. A question which arose was how sensitive the human body is to pressure differences during sitting. The attempt of this study was to determine the sensitivity to pressure for an area of the thigh. Therefore a test stand was designed allowing the variation of pressure on an area of a thigh during sitting. In parallel, the subjects were asked to judge the pressure sensation. By analyzing the frequencies of answers given by the test subjects, a curve could be derived which describes the sensitivity of pressure sensation. In this paper the test stand, the test procedure, the results and further experiments will be discussed.

The lack of measured data is a problem that often occurs when modeling physical human properties. This problem also occurs when trying to describe the human thigh with a finite element model. In this pilot study, an experimental chair was used to gather the required information. Each cushion of the chair consists of 81 pistons. Each piston is controlled individually by a computer. This experimental chair was used in two experiments. In the first experiment, the chair was used to measure the force length characteristics of deformed human thighs during unsupported sitting. In the second experiment, the measurement of the characteristics of undeformed thighs deformed by one piston was attempted. In this paper the test stand, the test procedures, the results und further experiments will be discussed.