X-ray emission spectroscopic study of chloride solid compounds using synchrotron radiation

An x-ray emission spectrometer, developed at beamline 9.3.1 of the Advance Light Source (ALS), Lawrence Berkeley National Laboratory (LBNL), will allow performing measurements of x-ray emission from molecules and materials in gas, liquid and solid phases with energy, angle and polarization dependence. A two-dimensional position-sensitive detector system with data acquisition software is developed for the spectrometer that allows collecting a complete x-ray emission spectrum simultaneously. Mechanical supports for detector mounting and a holder for solid samples are designed and manufactured. Energy calibration, resolution, and performance of the detector system and the spectrometer are tested by studying a solid potassium chloride (KCl) sample with photon energies in the vicinity of Cl K edge. A detectable energy range of 55--60 eV with a resolution of 0.2 eV are obtained and reported. The detector system and data acquisition software are suitable for x-ray emission measurements

Microscopic and spectroscopic studies of metal deposition on carbon-based materials

This dissertation is focused on studying the atomic and electronic structure of carbon-based materials, namely highly-ordered pyrolytic graphite (HOPG), single-walled carbon nanotubes (SWNT), and C60 fullerenes, with and without metal (Ti and Li) deposition. The work is motivated by ongoing efforts to understand and improve the hydrogen storage capability of carbon-based nanomaterials as well as their potential applications for developing novel electronic devices; Ti and Li deposition on the surface of SWNT, C60, and HOPG samples have been performed in ultra-high vacuum. The morphology and local geometric and electronic structure of the samples was investigated by scanning tunneling microscopy and spectroscopy (STM and STS). The chemical and electronic structure of the samples was studied by X-ray and UV photoelectron spectroscopy (PES). Changes in the carbon core- and valence-electronic levels upon metal deposition were observed and correlated with detailed morphological and electronic characteristics. The results give detailed information about the interaction between metal adatoms and carbon-based materials. In addition, several important aspects related to the deposited metals, such as the formation of oxides, were studied. The results provide fundamental insight into metal-carbon interactions and help to develop approaches to improve the performance of carbon-based materials for hydrogen storage and novel electronic devices

SOUND TRANSMISSION ACROSS A FINITE SIMPLY SUPPORTED DOUBLE-LAMINATED COMPOSITE PLATE WITH ENCLOSED AIR CAVITY

ABSTRACTSound transmission across a finite orthotropic laminated double-composite plate with enclosed air cavity on an infinite acoustic rigid baffle is investigated analytically. Sound velocity potential method combined with simply supported boundary conditions is used instead of traditional methods, has good scalability and is important for studies of acoustic vibration of structures. The sound transmission loss is calculated from the ratio of incident to transmitted acoustic powers. Specifically, the focus is placed on the effects of several key system parameters on sound transmission including the plate dimensions, the laminate configurations, the boundary conditions, and the composite materials are systematically examined

Hygrothermo-mechanical behaviour of layered composite plates

In this paper, a hygrothermo-mechanical behaviour of simply supported, composite layered rectangular plates is presented. The analysis is based on use of the Finite Element (FE) method and the full third-order displacement theory. Numerical examples are presented for symmetrically in-axis (0° /90° /90° /0°) and off-axis ( 45° / - 45° / -45° / 45°) layered rectangular plates

Static and Dynamic Analysis of Piezoelectric Laminated Composite Beams and Plates

In this chapter, the mechanical behavior analysis of piezoelectric laminated composite beams and plates is influenced subjected to static, dynamic, and aerodynamic loads. Algorithm for dynamic, stability problem analysis and vibration control of laminated composite beams and plates with piezoelectric layers is presented. In addition, numerical calculations, considering the effect of factors on static, dynamic, and stability response of piezoelectric laminated composite beams and plates are also clearly presented. The content of this chapter can equip readers with the knowledge used to calculate the static, dynamic, and vibration control of composite beams, panels made of piezoelectric layers applied in the field different techniques

FREQUENCY OPTIMIZATION AND TRANSIENT ANALYSES OF STIFFENED FOLDED LAMINATE COMPOSITE PLATE USING GENETIC ALGORITHM

In  this  study,  frequency  optimization  of  stiffened  folded  laminate  composite  plate  is investigated with  respect  to  fiber orientations by using genetic algorithm  (GA). The first order shear deformation theory was used for direct frequencies calculations. The Matlab programming using rectangular isoparametric plate element with five degrees of freedom per node was built to solve  the  problems. The modulus  of  selection,  crossover  and mutation were  used  as  standard sub-modulus.  The  effects  of  obtained  optimal  fiber  orientation  on  transient  response  of  the folded plate have been investigated with difference boundary conditions. A good agreement was found between the results of this technique and other published results available in the literature

Static and dynamic analysis of laminated composite plates with integrated piezoelectrics

A Finite Element model based on First-order Shear Deformation Theory is developed for the static shape control and vibration control of la minated composite plates integrated with piezoelectric sensors and actuators. A nine-node isoparametric rectangular element with 45 degrees of freedom for the generalized displacements and 2 electrical degrees of freedom is implemented for the static and dynamic analyses. The model is validated by comparing with existing results documented in the literature. Some numerical results are presented. It is concluded that the shape of the piezoelectric laminated composite plates can reach the desired shape through passive control or active control. The influence of stacking sequence of composite plates and position of piezoelectric layers and sensors/actuators patches on the response of the piezoelectric composite plates is evaluated

Finite element analysis of laminated composite plates using high order shear deformation theory

A rectangular non-conforming element based on Reddy's higher-order shear deformation plate theory is developed. Although the plate theory is quite attractive but it could not be exploited as expected in finite-element analysis. This is due to the difficulties associated with satisfaction of inter-elemental continuity requirement and satisfy zero shear stress boundary conditions of the plate theory. In this paper, the proposed element is developed where Reddy's plate theory is successfully implemented. It has four nodes and each node contains 7 degrees of freedom. The performance of the element is tested with different numerical examples, which show its precision and range of applicability

Bending and vibration analysis of multi-folding laminate composite plate using finite element method

This paper deals with the bending and vibration analysis of multi-folding laminate composite plate using finite element method based on the first order shear deformation theory (FSDT). The algorithm and Matlab code using eight nodded rectangular isoparametric plate element with five degrees of freedom per node were built for numerical simulations. In the numerical results, the effect of folding angle on deflections, natural frequencies and transient displacement response for different boundary conditions of the plate were investigated