Free vibrations and random response of an integrally-stiffened panel

The free vibrations and random response to jet noise of an integrally-stiffened five-bay panel have been studied both theoretically and experimentally. A finite element approach was used to represent the panel for both parts of the study, and the predictions were verified by measurements on a model panel integrally machined from solid aluminum...

Finite element dynamic analysis of shallow shell structures

An efficient dynamic analysis capability for arbitrary shallow shell structures is developed and illustrated with several applications with experimental verifications. The method is based on a compatible, doubly-curved shallow shell element of arbitrary triangular shape which includes thickness variations. This element uses as generalized...

Application of the high precision triangular plate-bending element to problems with curved boundaries

The application of the high precision triangular plate-bending element to problems with curved boundaries is considered. Appropriate edge conditions for nodal points on these boundaries are derived. The error inherent in representing a curved boundary by a series of straight segments is found to be the limiting factor on accuracy, while the...

Closed form, finite element solutions for plate vibrations

The convergence rates of eigenvalue solutions using two finite plate-bending elements are studied. The elements considered are the well-known 12-degree-of-freedom, nonconforming rectangular element and the 16-degree-of-freedom, conforming rectangular element. Three problems are analyzed: a square plate simply supported on two opposite sides,...

A high precision triangular plate-bending element

A fully conforming, displacement-type, finite element of triangular shape is developed and applied to the solution of several problems in the bending of plates. The deflection is represented by a fifth degree polynomial in the Cartesian co-ordinates of the mid-plane. Six deflection parameters, namely the displacement and its first and second...

Diffusion of 51Cr into poly- and single crystals of niobium

Finite plate-bending elements in polar co-ordinates

Two finite elements for plate bending in polar co-ordinates are derived. One element is in the form of a circular sector and the other is in the form of an annular sector. The former element has nine degrees of freedom, while the latter has twelve, the degrees of freedom in each case being a displacement and two slapes at each element corner....

A finite cylindrical shell element and the vibrations of a curved fan blade

The vibration stepped cantilevered plates

A theoretical and experimental study of seven stepped cantilevered plates is presented. Four of the plates are square, wUh increasingly severe steps, and the remaining three are non-rectangular, formed by removing parts of the outboard corners. The first Dine natural frequencies and mode shapes of each of the plates are found experimentally and...

Vibration modes and random response of a multi-bay panel system using finite elements

A finite e lement approach ta the dynamic analysis of continuous skin- stringer panels is presented. The methodl is illustrated in the calculation of vibration modes and random response of a five-bay stringer-stifffened panel with all outer edges clamped.The panel skin is represented by finite plate elements and tbc stringers , which are assumed...

Profiles and power spectra of some off-runway landing areas

Profiles of three semi-prepared grass landing strips and four snowdrift-covered lakes have been measured and are analyzed by standard statistical methods. Autocorrelation functions show that the profiles are truely random when long wavelength trends are removed by a specially developed filter, and probability density calculations indicate that...