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Optimal weight absorber designs for vibrating structures exposed to random excitations
Author(s) -
Lee Jimmy
Publication year - 1990
Publication title -
earthquake engineering and structural dynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.218
H-Index - 127
eISSN - 1096-9845
pISSN - 0098-8847
DOI - 10.1002/eqe.4290190810
Subject(s) - beam (structure) , dynamic vibration absorber , stiffness , structural engineering , mass ratio , damping ratio , mechanics , noise (video) , physics , materials science , white noise , monotonic function , control theory (sociology) , engineering , mathematics , acoustics , vibration , mathematical analysis , computer science , statistics , control (management) , astrophysics , image (mathematics) , artificial intelligence
Optimal mass ratios that minimize the response of a laminated beam with an attached absorber are tabulated for various values of beam damping. The beam is treated as an equivalent one degree of freedom (1DOF) main system vibrating in the fundamental mode. The beam is subjected to Gaussian white noise force and Gaussian white noise base frame acceleration. Optimal absorber frequency ratios and absorber damping ratios have been tabulated by others; the results for the classical 1DOF main system with attached absorber suggest that the optimized non‐dimensional response decreases monotonically as the mass ratio increases. However, to generalize this monotonic relation may lead to inappropriate conclusions. If we define a constraint such that an increase in absorber mass leads to a proportional decrease in available beam construction material, i.e. effectively the combined mass of the beam and absorber is minimized, then variations in the mass ratio will affect the beam's parameters such as mass, stiffness and damping. Since some of these parameters are used for non‐dimensionalising the response, inspection of non‐dimensional responses may in some cases lead to inappropriate conclusions. This paper shows the optimal mass ratios for minimizing the response of a structure exposed to earthquake or fluid flow type random excitations.