Showing papers by "Earl H. Dowell published in 1987"
TL;DR: In this article, a perturbation analysis for disrodered structural systems consisting of weakly coupled component systems is presented, which allows one to obtain the localized modes of vibration of the disordered system from the modes of the individual subsystems.
282 citations
TL;DR: In this paper, the free modes of vibration of disordered multispan beams are investigated, both theoretically and experimentally, and it is shown that small deviations of the span lengths from an ideal value may have drastic effects on the dynamics of the system.
Abstract: The localization of the free modes of vibration of disordered multispan beams is investigated, both
theoretically and experimentally. It is shown that small deviations of the span lengths from an ideal value may
have drastic effects on the dynamics of the system. Emphasis is placed on the development of a perturbation
method that allows one to obtain the strongly localized modes of vibration of the disordered system without a
global eigenvalue analysis of the entire system. Such a perturbation analysis is cost-effective and accurate. More
importantly, it provides physical insight into the localization phenomenon, and allows one to formulate a
criterion that predicts the occurrence of strongly localized modes. Also, an experiment is described which has
been carried out to verify the existence of localized modes for disordered two-span beams. Theoretical and ex-
perimental results are compared in detail and excellent agreement is found, thus confirming the existence of
localized modes for such weakly coupled, weakly disordered structural systems.
130 citations
TL;DR: In this paper, a stable Duffing system is examined by numerical simulations in order to obtain a better understanding of the behavior of periodic and chaotic responses to sinusoidal excitations.
Abstract: A stable Duffing system is examined by numerical simulations in order to obtain a better understanding of the behavior of periodic and chaotic responses to sinusoidal excitations. It is found that beside the multiplicity of responses, there is a duality for both periodic and chaotic responses. Period doubling does exist and this process may originate from different basic responses even with the same forcing frequency. The evolution of chaos is shown by a sequence of Poincare maps. Finally a possible pattern for transition to chaos is suggested.
57 citations
TL;DR: In this paper, the jump phenomena in quasilinear Duffing systems under sinusoidal and narrow band random excitations are examined by numerical simulations, and the results show that the multi-level responses merge into a single level one as the bandwidth of the excitation broadens.
Abstract: In this paper the jump phenomena in quasilinear Duffing systems under sinusoidal and narrow band random excitations are examined by numerical simulations. The simulation results for sinusoidal excitations agree very well with analytical solutions obtained by the equivalent linearization method. The results showing the sensitivity of the periodic responses to the initial conditions are believed to be the first published in the literature. The simulation results for narrow band random excitations confirm that multi-level mean square responses can occur for mono-level excitations, but only for very narrow bandwidth excitations. The multi-level random responses are also sensitive to initial conditions. As the bandwidth of the excitation broadens, the multi-level responses merge into a single level one.
49 citations
TL;DR: In this article, the initial condition problem is studied for the buckled beam by using the forced Holmes-Duffing's equation, in an attempt to understand the route to chaos.
44 citations
TL;DR: In this article, the authors present criteria for selecting the centering frequency as well as for determining the number of sets of quasi-static modes that should be included in low-frequency and banded, mid-frequency response calculations.
39 citations
13 citations
TL;DR: In this paper, a random damped one-degree-of-freedom linear system subjected to white noise excitation is discussed and the time varying damping coefficient is considered either as Gaussian white noise or filtered white noise.
5 citations
TL;DR: Asymptotic modal analysis has been applied to stress analysis of a uniform thin rectangular plate under point forces that are bandlimited white noise in this paper, where the asymptotics of the temporal averages of the bending stresses and the distortion energy have been determined.
Abstract: Asymptotic modal analysis has been applied to stress analysis of a uniform thin rectangular plate under point forces that are bandlimited white noise. The asymptotic limits of the temporal averages of the bending stresses and the distortion energy have been determined. It is shown that the dependence on the center frequency of the asymptotic limits of stresses is different from that of deflection. The concentration factors with respect to various locations on the plate are discussed.
2 citations
17 Aug 1987
1 citations
TL;DR: In this paper, an equivalent linear viscous damping formula for beams with rather general dry friction support conditions is proposed, and the effect of normal force support reaction at the dry friction base on response is discussed.
Abstract: An equivalent linear viscous damping formula for beams with rather general dry friction support conditions is proposed. The effect of normal force support reaction at the dry friction support on response is also discussed. Comparisons of experimental results to those obtained from an approximate solution and numerical time integration are made. Generally good agreement is found among the several results.