Deformation and Failure Mechanisms in Carbon Nanotube–Metal Matrix Composites at High Strain Rates

Purdue University, West Lafayette IN

Investigators

Abstract

Carbon nanotube-metal matrix composites are a new class of material systems with desirable properties, such as higher strength, hardness, and impact resistance, making them suitable for applications in aerospace, automotive, construction, sports, space, and other industries. High- rate of deformation is encountered, e.g., in manufacturing processes or during service of the composite structures or parts, such as in dynamic sports contact and automobile collisions. The operative deformation mechanisms during high-rate loading of carbon nanotube-metal matrix composites, however, have not been adequately quantified and understood. This award supports integrated experimental and computational research at multiple scales to develop this fundamental understanding based on hypotheses. The knowledge gained will promote product quality, reliability, safety, and use of carbon nanotube-metal matrix composites applications. Furthermore, the award supports curriculum improvements, underrepresented minority student participation in summer research programs and long-term projects, and hands-on demonstrations at a public facility for STEM activities. The objective of this project is to understand how carbon nanotubes influence the mechanical properties and behavior of carbon nanotube-metal matrix composites at high strain rates, as compared to the base metal. To achieve this objective, multiple inter-related research tasks will be performed. Task 1 is to synthesize the base metal and the composite specimens by laser-based additive manufacturing and conduct quasi-static mechanical characterizations. Task 2 is to: (i) conduct Kolsky bar experiments to obtain stress-strain relations, (ii) perform in-situ X-ray imaging to observe cracks, and (iii) characterize microstructural changes due to Kolsky bar impacts. Task 3 is to: (i) conduct projectile impact experiments to measure Hugoniot elastic limit, dynamic strengths, and shock responses, (ii) characterize impact-induced structural changes, and (iii) & (iv) conduct hydrodynamic and molecular dynamic modeling to understand shock responses and dissipation mechanisms at the macro and atomic scale, respectively. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.