In this paper the interior noise level of a vehicle due to structural vibration, named structure borne noise, as a part of NVH analysis has been investigated. First structural analysis is performed and vibrational behavior of structure carried out due to power plant excitations. Then interior acoustic cavity response for such excitation and resultant noise is determined. Vibrational analysis is performed on three dimensional structure and internal cavity, by considering all the effective components and vibrational tracks in the cabin. Finally, the acoustical behavior of the cavity in different frequencies predicted by cavity normal modes, and results are used to reduce noise level through passive noise control methods. Manuscript profile

Determination of the mechanical properties of carbon nanotubes is an essential step in their applications from macroscopic composites to nano-electro-mechanical systems. In this paper we report the results of a series of molecular dynamics simulations carried out to predict the elastic constants, i.e. the elements of the stiffness tensor, and the elastic moduli, namely the Young’s and shear moduli, of various single walled carbon nanotubes. Poisson’s ratios were also calculated. Three different methods were used to run the simulations: applying a predetermined strain and reading the resulted stress, applying forces and constraints to the end atoms and calculating the moduli by assuming an equivalent continuum tube, and lastly applying a predetermined stress and reading the consequent deformation. In each case, the effect of nanotube chirality and diameter was studied. In addition, loading conditions were altered in each method to study the effect of nonlinearity of interatomic interactions. The results of the three methods are compared, with each other as well as with the literature, and discussed to obtain reasonable concluding remarks. Manuscript profile

Determination of the mechanical properties of carbon nanotubes is an essential step in their applications from macroscopic composites to nano-electro-mechanical systems. In this paper we report the results of a series of molecular dynamics simulations carried out to predict the elastic constants, i.e. the elements of the stiffness tensor, and the elastic moduli, namely the Young’s and shear moduli, of various single walled carbon nanotubes. Poisson’s ratios were also calculated. Three different methods were used to run the simulations: applying a predetermined strain and reading the resulted stress, applying forces and constraints to the end atoms and calculating the moduli by assuming an equivalent continuum tube, and lastly applying a predetermined stress and reading the consequent deformation. In each case, the effect of nanotube chirality and diameter was studied. In addition, loading conditions were altered in each method to study the effect of nonlinearity of interatomic interactions. The result of the three methods are compared, with each other as well as with the literature, and discussed to obtain reasonable concluding remarks. Manuscript profile