Showing papers by "Jack R. Vinson published in 1970"

Free vibrations of plates and beams of pyrolytic graphite type materials

Abstract: A set of general governing equations is derived for the study of free vibrations of rectangular plates composed of a transversely isotropic material, including the effects of transverse shear deformation and rotatory inertia. Such a formulation is necessary for even geometrically thin plates, when the ratio of in-plane modulus of elasticity to transverse shear modulus is large (i.e., 20-50) which occurs in vapor deposited materials such as pyrolytic graphite, and in many fiber reinforced composite materials. The corresponding equations for beams are also derived. The case of a simply supported plate is treated in detail. Numerical results show that significant differences occur in predicting natural frequencies for various modes when the present theory is used compared to the use of classical methods for plates of these material systems. Classical methods can predict frequencies that are erroneous by a factor of nearly three.

Computer program for calculating the stresses in shallow spherical shells of composite materials subjected to localized loads.

Abstract: : The computer program listed can be used to calculate the stresses anddeflections in a specially orthotropic shallow or nonshallow spherical shellof revolution subjected to a normal concentrated load in the apex region ofthe shell. The effect of transverse shear deformation is included suchthat any ratio of elastic modulus/shear modulus is possible. The programis written in ASA FORTRAN IV compatible with the scientific data system9300 computer. (Author, modified-PL)

Stresses in shallow spherical shells of composite materials subjected to localized loads.

Abstract: : Methods of analysis are developed to provide the stresses (both bending and membrane) and deformations in specially orthotropic shallow and nonshallow spherical shells of revolution subjected to localized loads at the apex. An accurate shell theory is employed including effects of circular orthotropy and transverse shear deformation. The governing equations are reduced to a single, second order complex differential equation. Solutions are obrained in terms of modified Bessel functions of non-integer order and complex argument. These functions are transformed into a set of infinite series, and upon proper non- dimensionalization, these series are shown to be uniformly and very rapidly convergent. Expressions are obtained for bending, membrane and shear stresses as well as lateral and inplane deflections everywhere in the shell. Comparisons and design curves are obtained for large variations in orthotropy and matrix shear properties which cover almost all known composite materials. Various boundary conditions, degrees of shallowness, and loading conditions are also systematically explored and reported. (Author, modified-PL)