Engineering topics
Publications and source records attributed to Dowell, E. H..
A review, correction, and extension of Vlasov and Leont'ev's (1966) analysis of beams, plates, and shells on elastic foundations is presented, and an improved theory for the motion of an elastic foundation is developed. The interaction of two or more plates resting on a common foundation is included. A simplified model is derived which appears useful for some applications.
The vibration of clamped and simply supported elastic panels due to subsonic and supersonic turbulent boundary-layer flows is investigated by a Monte Carlo technique. The resulting generalized random forces are simulated numerically from boundary-layer turbulence spectra, and the response analysis is performed in the time domain. The mutual interaction between panel motion and external and/or internal airflow is included. Response studies are performed with respect to rms response, probability structure, peak distribution, threshold crossing and spectral density. The effect on the response statistics of in-plane loading, static pressure differential, and cavity pressure is investigated.
This experimental investigation tested the accuracy of an analysis which predicts the natural frequencies of vibration of a plate constrained by an arbitrary number of point supports along the edges, and also determined the number of such supports which approximates an infinite number.
The method of Fourier transforms is used to determine the kernel function which relates the pressure on a lifting surface to the prescribed downwash within the framework of Dowell's (1971) shear flow model. This model is intended to improve upon the potential flow aerodynamic model by allowing for the aerodynamic boundary layer effects neglected in the potential flow model. For simplicity, incompressible, steady flow is considered. The proposed method is illustrated by deriving known results from potential flow theory.
A simple differential equation is derived to describe constrained-layer damping in nonsymmetric sandwich plates and beams composed of isotropic and homogeneous layers. The natural boundary conditions related to this equation are determined and some typical numerical results obtained by this equation are given. The equation is valid within the linear theories of elasticity and viscoelasticity in the absence of any constraints on thicknesses, positions, symmetries, and densities of the layers.
A method for the analysis of the free vibrations of an arbitrary structure in terms of component modes is presented based upon the use of the normal, free-free modes of the components in a Rayleigh-Ritz analysis with the constraint or continuity conditions
Criteria are presented for the prediction of panel flutter, determination of its occurrence, design for its prevention, and evaluation of its severity. Theoretical analyses recommended for the prediction of flutter stability boundaries, vibration amplitudes, and frequencies for several types of panels are described. Vibration tests and wind tunnel tests are recommended for certain panels and environmental flow conditions to provide information for design of verification analysis. Appropriate design margins on flutter stability boundaries are given and general criteria are presented for evaluating the severity of possible short-duration, limited-amplitude panel flutter on nonreusable vehicles.
Free vibrations of linear structure with arbitrary support by Rayleigh-Ritz method using unconstrained normal modes
Computer program for aerodynamic forces on flexible plate undergoing transient motion in shear flow, applying to panel flutter
Elastic harmonic waves propagation in composite circular elastic cylinder
Aeroelastic stability of flat plates and shells, considering panel flutter
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Flutter analysis of plates with inplane boundary support flexibility exposed to transverse pressure loading or buckled by uniform thermal expansion
Fluttering isotropic rectangular flat plate fatigue life estimation, taking into account stress, dynamic pressure, frequency, Mach number and plate thickness
Low aspect ratio plates flutter analysis for subsonic and supersonic models
Panel flutter theory applied to aeroelastic stability of flat unloaded plates and cylindrical shells
Buckled plates flutter at zero dynamic pressure, considering initial plate imperfections, including aerodynamic damping in quasi-steady supersonic approximation
Noise-flutter interrelation in flight vehicle flexible plate and shell configurations immersed in fluid flow