An analysis is made of the experimental method of displaced frequencies for the determination of the generalized masses of a freely vibrating structure. Energy and receptance methods are combined to determine the changes in frequency, mode and equivalent mass caused by the addition of one or more small masses. Special attention is given to the behaviour of a system with close or equal natural frequencies and some of the properties of a system with two equal frequencies are examined in detail.
Get full access to this article
View all access options for this article.
References
1.
LeclercJ.‘Modification of the shape of a structure by the addition of small masses’, La Recherche Aeronautique1956 (No. 50), 45.
2.
KruszewskiE. T.HouboltJ. C.‘The calculation of the modes and frequencies of a modified structure from those of the unmodified structure’, Tech. Note nat. adv. Comm. Aero., Wash. No. 2132, 1950.
3.
BishopR. E. D.JohnsonD. C.The mechanics of vibration1960, chapter 3, pp. 85–171 (Cambridge University Press).
4.
GladwellG. M. L.‘Vibrating systems with equal natural frequencies’, J. mech. Engng Sci.19613 (No. 2), 174.
5.
KappusR.‘Possibilities of the generalization of the method of displaced frequencies’, La Recherche Aeronautique1960 (No. 79), 45.
6.
RayleighLordTheory of soundvol. 1, second edition, 1944, chapter 4 (Macmillan, London).
7.
CrandallS. H.StrangW. G.‘An improvement of the Holzer table’, J. appl. Mech.195724, 228.
