Abstract: The bathtub has been widely used as household products. Due to the difference of height
and weight of customers, the unreasonable surface shape will lead to low comfortability as using the
product. In this paper, the pressure and the contact area are made as the evaluating parameters in
order to design a suitable bathtub for adults. The surface of bathtub was redesigned according to
percentile P5, P50, P95 of Chinese adult. The pressure and the contact area were measured by Tekscan
instrument. The data which were captured from the ten testers lying in different bathtub with the
original surface and the optimized surface was analyzed. Results shows that the peak pressure reduces
to 58.4%–87.3%, the average pressure reduces to 83.6%–99.4%, and the contact area of the optimized
surface increases to 1.50–2.78 times. The optimized surface effectively improves the comfortability
of users.

Key words: surface, optimal design, pressure distribution, Tekscan