Pushing the boundaries of micro and nanomechanics

Pushing the boundaries of micro and nanomechanics

  • Date: Oct 22, 2019
  • Time: 01:30 PM - 02:30 PM (Local Time Germany)
  • Speaker: Dr. Rajaprakash Ramachandramoorthy
  • Laboratory of Mechanics of Materials and Nanostructures, EMPA, Thun, Switzerland
  • Location: Max-Planck-Institut für Eisenforschung GmbH
  • Room: Large Conference Room No. 203
  • Host: Prof. Gerhard Dehm
Current level of miniaturization in everyday devices indicates that micro and nano architectures have become functional elements in electronics and diminutive mechanical-based systems. Yet, the potential of such multiscale functional elements is not fully realized due to incomplete understanding of their deformation mechanisms in application relevant loading conditions such as high strain rates (mimicking drops and impacts) and high/cryo temperatures. Even the state-of-the-art micro/nano mechanical testers are currently incapable of conducting experiments in such harsh loading environments. Thus, the mechanical properties of micro and nano scale materials are largely unknown at strain rates beyond 0.1/s and temperatures beyond 250°C or below room temperature. This premise forms the motivation of my research vision: “To investigate the small scale plasticity and failure mechanisms under extreme conditions, using novel micro/nano mechanical experimental platforms”. In this presentation, I will highlight three aspects from my previous research: i) Instrumentation and protocols for conducting extreme micro and nanomechanical testing, ii) Case studies of micro/nano scale metals and amorphous materials tested at high strain rates and high temperature combinations and iii) Sample manufacturing techniques for high through-put micro/nanomechanical testing. Specifically, I will present the work on in situ nanomechanical testing at high strain rates enabled by a custom-built hybrid piezo and microelectromechanical systems (MEMS) based testing system and the case-study on silver nanowires tested at strain rates upto ~200/s. Further, the instrumentation and protocols for micromechanical testing at combinations of high strain rates and extreme temperatures will be explained, with a case study on fused silica and silicon micropillar compression at strain rates upto 1000/s and temperatures upto 400°C. The final part of the talk will focus on my recent work with unique manufacturing methods: two-photon lithography/electrodeposition combination and localized electrodeposition, which are capable of manufacturing ideal damage-free test-beds of metallic micro/nano architectures including arrays of micropillars, microsprings and complex microlattices.
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