Vibration of bimodular sandwich beams with thick facings: A new theory and experimental results

This study deals with both analytical and experimental investigations of three-layer beams with cores of polyurethane foam and facings of unidirectional cord-rubber. Both of these materials are bimodular (i.e., having different behavior in compression as compared to tension). The new theory presented is a shear-flexible laminate version of the well-known Timoshenko beam theory, which, due to the bending-stretching coupling present in the bimodular case, results in a coupled sixth-order system of differential equations. In this theory, a separate derivation is presented for the shear correction factor. Due to the discontinuities in the normal stress distribution and the bimodularity, the shear correction factor is much different than the classical homogeneous material value of $\text{5}\text{6}$. Theoretical and experimental results are presented for the frequencies of the first three modes of vibration for a pin-ended beam without axial restraint. This work is believed to be the first devoted to vibration of bimodular materials in a sandwich configuration.     

Coordination chemistry in zeolites

Researchers have devised several procedures for synthesizing transition metal ion (TMI) complexes in zeolite cavities and channels. Two main routes have been envisaged: synthesis with a preformed complex and complex assembly in the zeolite. An overview of the different preparation methods and of the TMI-complexes, encaged in zeolites, is given. These complexes have been mainly studied in zeolite Y. The zeolite is a non-coordinating anion, a solvent, or a ligand. It reduces the mobility of the complexes and provides chemisorption sites. Future developments will comprise the use of widepore zeolites and zeotypes (e.g., VPI-5, MCM-41, hexagonal faujasite) and the design of optically active surfaces. Furthermore, there is a need for quantification in general and for selectively synthesizing one type of complex.     

Displacements in a polar-orthotropic disk of varying thickness

Zusammenfassung Es werden allgemeingültige Gleichungen für die Verschiebungen kreisrunder Scheiben mit radialer Änderung der Dicke und mit polar-orthotropen Elastizitätsmoduln abgeleitet. Dabei wird angenommen, dass es keine Unstetigkeiten in den Spannungskomponenten gibt. Volterra-Dislokationen, die Verschiebungs-, aber keine Spannungsunstetigkeiten haben, werden auch betrachtet. Anscheinend ist dies die erste Behandlung ebener Dislokationen, die Steifigkeitsveränderungen in Betracht zieht.

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This paper is based in part on a portion of a dissertation presented by the author to the Department of Engineering Mechanics at The Ohio State University in August, 1961, in partial fulfillment of the requirements for the degree of Doctor of Philosophy.