音波を用いた膜張力測定手法における空気の付加質量の影響の評価 [in Japanese] EVALUATION OF EFFECT OF ADDED MASS OF AIR ON MEASURING METHOD OF MEMBRANE STRESS USING SOUND WAVE [in Japanese]
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One of the most important matters in keeping membrane structures in healthy condition is to maintain the proper tension distribution over the membrane. However, it is not easy to know the actually existing stress level in the membrane quantitatively after completion of the structures. Fluttering by strong wind or ponding caused by rain water may cause the severe damage of membrane structure itself and, therefore, it is very important to know magnitude of existing stress in constructed membrane structures for their maintenance and management. 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 and white noise external excitation induced by sound is utilized. The new method makes use of the resonance phenomena of the membrane which is induced by sound excitation given through audio speaker, where the effect of the added mass of surrounding air can not be ignored for high accuracy measurement. In this paper, evaluation scheme for the added mass effect of the air on vibration of the membrane is discussed, where two different approaches are adopted. It is shown that the proposed measurement scheme can be used for the prediction apparatus of the membrane tension stresses, where the accuracy of the measurement is achieved by proper consideration of the added mass effect of the surrounding air.
- Journal of Structural and Construction Engineering (Transactions of AIJ)
Journal of Structural and Construction Engineering (Transactions of AIJ) 72(612), 111-116, 2007
Architectural Institute of Japan