1. Materials Technology and Forming Techniques, Dept. of Production Engineering, Alexandria Univ., Alexandria 21544, EG.
2. Dept. of Advanced Materials, Central Metallurgical Research and Development Institute, P.O. Box 87 Helwan, Cairo 1142, EG.
3. Machinery Dynamics and Diagnostics, Dept. of Production Engineering, Alexandria Univ., Alexandria 21544, EG (Corresponding author), e-mail: mostafa.yakout@alexu.edu.eg; yakout_mostafa@yahoo.com
4. Machinery Dynamics and Diagnostics, Dept. of Production Engineering, Alexandria Univ., Alexandria 21544, EG.