Stress measurements in supported porous membranes

The observed deflection 8 is monitored as a fimction of time in a data acquisition system. To reduce the noise level the values of 50 scans are averaged, the average constituting one data point. For further details, see Voncken et al. [26]. 

The Youngs moduli of the support has been measured with four point bending tests, Poisson s ratio is taken to be equal to that of dense alumina. Values of Eg and Vg are 65 4 GPa and 0.23 respectively. To obtain measurable values of 5, dg is taken about 0.4 mm, while df is in the range of 1-10 pm. The values of 5 range from 0.05-0.15 mm. 

A typical example of a stress diagram is shown in Fig. 8.15 for two drying 

Stress measurements at high temperature were performed with a similar equipment as used in drying experiments. The clamped strip-top layer combination is placed in a small tubular furnace positioned horizontally by a suitable sliding arrangement [28]. A small hole is provided at the bottom of the furnace for the laser beam. The exit at the bottom of the furnace must be placed close to the detector and so must be provided with a radiation screen and be cooled adequately. 

Complications in the interpretation of the results arise from the presence of a porous support as shown by Kumar et al. [13,27]. Water sucked into the pores 

---