in this paper, the nonlinear free vibrations of thin symmetric and non-symmetric cross-ply composite plates subjected to biaxial initial stresses are investigated. because of their excellent properties such as specific strength and specific stiffness, composite plates have wide applications in aerospace and mechanical structures. based on von-karman's strain-displacement relations and using gal...

In the article ‘Illuminating Resolution’ (GEO ExPro Vol. 8, No. 3) we described the evolution of seismic acquisition technologies that aim to achieve the geophysicists’ goals of illumination and resolution. One development featured in the article is the concept of extending the frequency content or bandwidth of seismic signals, especially at the low-frequency end, in order to achieve better ver...

In this study, the non-linear creep behaviour of a thick-walled cylinder made of stainless steel 316 is investigated using a semi-analytical method. The thick-walled cylinder is under a uniform internal pressure and a non-axisymmetric thermal field as a function of the radial and circumferential coordinates. For the high temperature and stress levels, creep phenomena play a major role in stress...

1. The first type of noise excitation originates from time varying forces acting on solids. These forces provoke mechanic vibrations (structure bound sound) within the solid parts which propagate until the outer surface of the bodies. At this outer boundary the vibrations are partly transferred to the adjacent fluid as a result of a fluid-structure-interaction (FSI). 2. The second type of noise...

Stretching process of sheet metals in both cases of axisymmetric and non-axisymmetric is analyzed. A rigid-plastic, normal anisotrop material is assumed and large strain formulation is applied. Triangular elements are used and stiffness equations of elements are obtained from virtual work principle. These nonlinear equations are linearized by Newton-Raphsons method and are solved by Gaussian el...

The vibrations of ordered counterions around rightand left-handed DNA double helix are studied. To determine the modes of DNA conformational vibrations the structure of the double helix with counterions is considered as ionic lattice (ion-phosphate lattice). Using the developed approach the frequencies and Raman intensities for right-handed B -form and left-handed Z -form of the double helix wi...

Terahertz laser VRT spectra of the water dimer consisting of 731 transitions measured with an average precision of 2 MHz and involving four ~D2O!2 intermolecular vibrations ~one previously published! have been measured between 65 and 104 cm. The precisely determined energy level patterns differ both qualitatively and quantitatively from the predictions of several dimer potentials tested, and re...