Shishay Amare Gebremeskel
Indian Institute of Technology Delhi, India
Shishay Amare Gebremeskel has completed his BSc degree in Mechanical Engineering in 2008 and his MTech degree in Manufacturing Engineering in 2010 at ages of 22 and 24 respectively. He has two years of teaching experience as Lecturer at Bahir-Dar University in Ethiopia. He is now a 2012 entry PhD research scholar at Indian Institute of Technology Delhi (IITD) under the guidance of Prof. Naresh Bhatnagar in the Department of Mechanical Engineering. So far, he has published three international journal papers.
Except for a few attempts to show the high impact load effect, the difference in level of contribution of nanoclay on polymers at their quasi-static and dynamic mechanical behaviors is a lacuna in the available literature. Quasi-static and dynamic responses of a high impact copolymer polypropylene (PP) in its neat and nanoclay-filled forms are presented in this study. The study helped in percentage quantification of differences in nanoclay effect, imposed by the very nature of loadings. The PP-nanoclay nanocomposite (PP+5wt%nc) is prepared by melt compounding of 5wt% nanoclay (nc) with PP using twin screw extruder. Tensile specimens for UTM were prepared using injection molding machine. Dynamic loading specimens were made for Split Hopkinson Pressure Bar (SHPB) using an extruded sheet. The experiments were performed at strain rates of 10-2 s-1 and 2.2*104s-1 for quasi-static and dynamic loadings respectively. As a result, the contribution of 5wt% nanoclay on PP at quasi-static loading is shown to be 2.6%, 10.8% and 13% on Yield stress, Young’s modulus and toughness, respectively. However, significantly different results are observed after dynamic loading experiments. Intense improving contributions of 506% and 53% in impact modulus and impact toughness respectively are observed. While, minor reduction (3.5%) in plateau (Yield) stress is experienced in the case of dynamic impact loading.