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Vibration control of mechanical systems divided into two types active and passive, this case study illustrates other approach of passive control of the cantilever plate by using double layers of the viscoelastic material (Dyad 606) one in the upper face of the Al substrate (5051) and the second one in the lower face. This layers are affected by axial uniform distributed force by applying tension load, the damping level depend on the value of this axial force where the vertical component of this force consistently the other way of the vibrating element that reduce vibration amplitude in this direction by about (95%) of the original amplitude without damping layers. Computational analysis using ANSYS program are used firstly to verify that the results from the software are compatible with that obtained from analytical and experimental evaluation by comparing the values of natural frequencies. Then using ANSYS model to calculate the reduction occurs in the lateral vibration with changing of the axial loads on the viscoelastic plates. The benefits of this model are enhancing the reliability and reducing the cost.

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Present typescript encompasses the influences of functionalization on the carbon nanotubes (CNTs) using acid oxidation which has been widely reported not only as a purification process but also as functionalization process because it is an effect on the outer surface on CNTs. Therefore, using strong acid effect and high power sonication in addition to the nature of the acid mixture (H2SO4/HNO3) with CNTs confirm that adequate volume of carboxyl groups decorate the outer surface, this functionalization process improve the dispersibility of the CNT in the response of the final dimension of the CNTs. Because of using a high temperature for a long time more than 6 hours. This work interested in the aspect ratio (L/D) and the final shape of the tubes by using a mild temperature process 50°C with concentration acid for not long time 5 hours, in an attempt to make experimental condition which guarantees good functionalization of the surface of MWNTs with minimizing the CNTs damage, The results were confirmed by Thermogravimetry Analysis (TGA), Raman Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) analysis. In addition to the functionalization process we try to save the loss in the weight during the filtration step, in addition to decrease the time during filtration of the materials after sonication. Where the results show that actually functionalization has been done with an adequate amount at this condition, and the dilution for 2 days before filtration have been approved to be easier and faster than direct filtration after treatment.

In transversely isotropic piezoelectric bi-materials, a theoretical analysis is followed to calculate the dynamic stress intensity factors (DSIFs) due to existence of a permeable interfacial crack, near the edge of a circular cavity. The model is subjected to dynamic incident anti-plane shearing (SH-wave) and Green's function method is the base of formulation. Conjunction and crack-simulation techniques are applied to obtain DSIFs at the crack’s inner tip. Calculations are prepared based on FORTRAN language program. For calibration of program, a comparison is accomplished between the present model and another with a crack emerging from the cavity edge. Calculating results clarified the influences of the physical parameters, the structural geometry and the wave frequencies on the dimensionless DSIFs and how those affected the efficiency of piezoelectric devices and materials.