Department of Mechanical Engineering

University of Technology

Final Defense of PH. D Degree Dissertation

Titled “Characterization of Porous Functionally Graded Materials in Vibration and Buckling of Sandwich Plates”

By:  Imad Kazem Najm

Members of the examining committee:

Chair:

          Prof. Dr. Ibtihal Abdel Razzaq Mahmoud

 Members:

          Prof. Dr. Bashar Awaid Badawi

Prof. Dr. Mohsen Abdullah Abdul-Hussein

Asst. Prof. Dr. Abdulsattar J. M. Hassan

Asst. Prof. Mohsen Nouri Hamza

By Supervision:

Asst. Prof. Dr. Sadiq Hussein Bakhi

Asst. Prof. Dr. Muhannad Lafta Shalaka

Mr. Imad Kazem Najm discussed his dissertation, which aimed to study the properties of composite panels manufactured from functionally graded materials that include pores changing in a specific direction of the structure. Where a mathematical model has been proposed to describe the free vibration, buckling, and bending based on the traditional plate theory (CPT) for composite panels. The outcomes of this work can be applied to the simulation of aircraft wings, rotary machines, and life medicine under various boundary restrictions.

The major conclusions of this study are:

• Based on the results of the analysis using the experiment design program (DOE), that the optimal conditions for the highest frequency (769.78 Hz) were: the ratio of pores equal to (0.29857) and the height of the hollow equal to (0.019988 m), the thickness of the upper and lower plates equal to ((0.025 m), while the exponent of the functional gradient equals (k = 0.000945).
• In the buckling analysis, it was found that the optimum load was (785.788 kN) occurring at a pore ratio equal to (0.299), a hollow height equal to (0.01978m), the thickness of the upper and lower plates equals to (0.025 m), while the functional gradient exponent equals k=3).
• Based on the analytical results, the natural frequency increased by 2.6% when changing the porosity ratio from 10 to 20% at k = 0.5, hollow height 10 mm, and lamina 0.65 mm.

The major recommendations of this study are:

• Using the other plate theories, such as first-order deformation theories and high order theory to make theoretical analysis more efficient
• Using the mechanical convection for free vibration and buckling experiments of a composite structure made of functionally graded materials containing the pores of PFGMs.
• Employing the 3D printing method to manufacture samples can be used to describe the behavior of samples manufactured from functionally graded materials subjected to moving and static loads.

Congratulations! To our student Mr. Imad Kazem Najm