Mechanical properties of polytetraflouroethylene elastomer membrane for dynamic cell culture testing.

A wide body of existing research on cellular injury has been conducted using cell cultures grown on flexible elastomer membranes deformed by a transient pressure pulse. However, there has been little published information on the material properties of these elastic membranes. In order to facilitate the development of a finite element model of cellular injury, the material properties of the underlying membrane must first be known. A series of static tests of an elastomer yielded a set of pressure-deflection data for applied pressures of 2.5, 5.0, 7.5, 10, 12 and 14 PSIG. Using an optimization technique, the material properties for an elastic finite element model were iteratively changed and compared to these experimental results in order to minimize the difference between experiment and simulation. The final material properties were found to be quite different from the initial guess, with a final modulus of 950,000 Pa, a Poisson's ratio of 0.499, and a density of 5.5*10-4 g/mm3. The comparison between the experimental and finite element models was conducted using a sum of squares difference for each of the six pressures, yielding an average sum of squares difference of 0.271 mm. The average percent error of the deflection measurements was 3.57%, with errors measured at each pressure ranging between 0% and 12%. Parameter sensitivity was examined and the most influential property was the modulus of elasticity. The least influential parameter was the density, having almost no effect on the maximum deflection.