Analytical and Numerical Investigation of Structural Response of Compliant Wall Materials PartⅠ

摘要

Surface motion of compliant walls in drag reduction experiments has been analyzed. Critical comparison is made between the dynamic motion of the structure and the postulated mechanism of drag reduction (ref. 1). The spectrum of surface motion indicates that membranes over deep cavities respond at low frequencies and large wavelengths. The membrane over a deep cavity is therefore found not to yield the desired response predicted by the postulated mechanism. The membrane over a thin air gap is found to act as a wavelength chopper, and analysis of the nonlinear response of that compliant surface indicates its possible suitability for compliant wall experiments. Periodic structures are found to lock in the desired wavelengths of motion, and it is found that at least in Kramer's (ref. 2) initial experiments they could have produced high frequency surface motions. Laminated structures are found to be very ineffective as compliant models, except when there is no bonding between the membrane and the backing. Computer programs developed for these analyses are documented in this report.