We report measurements of the thermoelectric power ~TEP! S and electrical resistance R of thin films of tangled ropes of single-walled carbon nanotubes. Experiments at 300 K under applied force normal to the plane of the film revealed a ;10–20 % decrease in the four-probe resistance, indicating that the contact resistance between ropes had improved. The TEP, however, was not affected by the app...

The structure of single walled armchair and zig-zag carbon nanotubes having 70 atoms and two carbons replaced by boron or nitrogen is obtained at minium energy using HF/6-31G* molecular orbital theory. The calculations show that the ground state of the zig-zag tubes is a triplet state while for the armchair tubes it is a singlet. In the zig-zag tubes the density of states at the Fermi level is ...

Experimentally determined natural frequencies and modes shapes are presented for an elastically point-supported isotropic plate with attached masses under impulsive loading. These results are compared to frequencies and to modes shapes determined from the Rayleigh–Ritz method and a finite element analysis using COMSOL. Accelerometers mounted at three locations on the plate, provide input for ME...

Thin-walled tube bending is still to be considered a new and advanced technique. The process has been adopted into several industries such as aero and automotive. This process may produce a wrinkling, bulking and tearing phenomenon if the process parameters are inappropriate, especially for tubes with large diameter and thin wall thickness. Push bending process is one of the methods used for be...

This paper presents a procedure to determine an element-length dependent strain and stress relation until fracture that is suitable for implementation in finite element models. This material relation is obtained experimentally with an optical measuring system. The strain until fracture is calculated from the measured surface displacements. The stress is derived from the measured force and the c...

Background: The presence of heavy metals in the environment especially in water supplies have caused many concerns because of their toxicity and non-degradability. Hexavalent Chromium (Cr) is one of the most toxic metals which is used in many industries, so it is essential to remove it from industrial wastewater. In this study, we made a comparison between different adsorption isotherms in the ...

The present paper presents a three-dimensional composite damage model for predicting the crush response of thin-walled structures, i.e., cylindrical tubes, manufactured employing fibre-reinforced polymer–matrix composites. This computational is based upon Continuum Damage Mechanics (CDM) approach and accounts both intralaminar interlaminar as well nonlinear behaviour that occur in materials. Ex...

Abstract To improve the crashworthiness and energy absorption of thin-walled tube structures, a bionic was designed based on structural characteristics antler osteon principle bionics had same inner outer diameters gradient thickness as osteon. A nonlinear finite element method is used to simulate with equal variation (EGTTS) under axial oblique loads. The EGTTS-7 (Egtts 7 layers) evaluated usi...