Abstract
This investigation considers the suitability of the moiré method as a technique for determining the dynamic response of thin membranes. Specimen preparation, test apparatus and test results are reported for a circular and a rectangular membrane. The applicability of the method for measuring transient as well as periodic behavior is discussed. Theoretical and experimental values are compared for the case of periodic response.
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Abbreviations
- N :
-
tensile force in membrane (lb/in.)
- η:
-
deflection
- ρ:
-
mass density per unit area of membrane (lb sec2/in.2)
- t :
-
time (sec)
- Z :
-
total impedance of membrane and surrounding air
- Z m :
-
mechanical impedance of membrane
- Z a :
-
mechanical impedance of surrounding air
- A :
-
viscous or damping portion of air impedance
- B :
-
stiffness and mass portion of air impedance
- i :
-
square root of −1
- ω:
-
circular frequency (rad/sec)
- a :
-
length of rectangular specimen (alongx)
- b :
-
width of rectangular specimen (alongy)
- c :
-
outer radius of circular specimen
- x andy :
-
coordinates associated with rectangular specimen
- r and θ:
-
coordinates associated with circular specimen
- m :
-
number of nodal diameters in circular
- n :
-
number of nodal circles in circular specimen
- J n :
-
denotes Bessel function of first kind and orderm
- μ:
-
number of half wavelengths inx direction on rectangular membrane
- v :
-
number of half wavelengths iny direction on rectangular membrane
- α:
-
\(\sqrt {N/\rho } \)
References
Miles, D. O., “Direct Mechanical Determination of the Dynamic Response of Diaphragms,” Jnl. ASA,36 (8), (1964).
Chobotov, V. A., and Binder, R. C., “Nonlinear Response of a Circular Membrane to Sinusoidal Excitation,” Ibid. Jnl. ASA, (1), (1964).
Rule, E., Suellentrop, F.J., and Perls, T. A., “Second-Order Instrumentation Systems With Frequency-Dependent Stiffness and Damping,” Ibid. Jnl. ASA,31 (11), (1959).
Brüel and Kjaer Technical Review, “Pressure Equalization of Condenser Microphones,” No. 1 (1960).
Ligtenberg, F. K., “The Moiré Method,”Proc. SESA, XII (2),83–98 (1955).
Morse, P. M., “Vibration and Sound,” McGraw-Hill Book Co. 1948.
Handbook of Experimental Stress Analysis, Ed. M. Hetényi, John Wiley & Sons, 1950.
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Nickola, W.E. The dynamic response of thin membranes by the moiré method. Experimental Mechanics 6, 593–601 (1966). https://doi.org/10.1007/BF02326827
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DOI: https://doi.org/10.1007/BF02326827