| Summary |
A new method is proposed by authors to measure membrane stresses in two different directions separately, where instead of measuring the membrane stresses directly, the natural frequencies of the membrane within fixed rectangular region resonated by sweep external excitation induced by sound is utilized. In this paper, through experiments it is proved that the newly developed equipment can be used for not only the membrane materials of the kind of A but also for the kinds of B and C, and in addition, the experimental tests of actual membrane structures are presented. In verification experiments of the membrane materials of the kinds of B and C, we obtained the results that are equivalent to those of A kind and this proved that the equipment is adoptable to any kinds of membrane by changing the area density ?k of membrane. In the practical measurement of two kinds of membrane structure we measured stress from the lower side instead measuring from the upper one. Although the difference of measurers could affect the result and there are some points where the deviation of the data is large, it is confirmed that the equipment is still useful to measure without considering the environmental conditions. On the other hands, through the practical measurement of the stress, it is proved that the proposed measurement equipment is available to stably measure the membrane stresses which exist in the membrane materials of the actual membrane structures.
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