Prof. Ramesh Singh

Associate Professor

Mechanical Engineering Department

IIT Bombay, Mumbai, India

Education:

Research Interests:

  • High-speed micromachining
  • The microscale manufacturing poses unique challenges with respect to both machine tool design and development and the process dynamics. Scaling down the macro processes, such as milling and drilling is extremely difficult due to the orders of magnitude lower stiffness of the tool. This low stiffness could result in catastrophic failure of the micro-tool, especially, during cutting of high strength materials, such as hard steels and Ti/Ni alloys. To address these issues, two approaches can be used: firstly, high speed micromilling (spindle speeds > 100,000 rpm) can be used to reduce the chip load and cutting forces to prevent the tool failure, secondly, localized thermal softening can be induced via laser. The research in this area has culminated in development of first high-speed micromachining center in India which is capable of creation of submicron features with nanometric accuracy. This tool has been used for creation of features for biomedical applications and high precision components for defense. In addition, scientific studies on dynamic stability of high speed micromilling of Ti have been carried out to enhance the productivity and determine the stable operation domain.
  • Flexible reconfigurable fiber laser based materials processing
  • This work is focused on developing reconfigurable platforms on fiber laser. A specialized optics setup has been developed and patented which can give a combination of spot sizes and intensity distributions. This flexible reconfigurable system has been used for laser-assisted machining, localized hardening and cladding. Laser cladding has been further explored for repair and restoration of dies and aerospace structures. Laser cladding is a complex phenomena and it comprises of thermal, mechanical and metallurgical changes. A 3-D finite model based on element birth technique and moving heat source which captures differential contraction due to mismatch in coefficients of thermal expansion has been developed and integrated with Tanners Law for estimating the spreading of the molten pool. The volume dilation and transformation plasticity due to metallurgical changes along with differential contraction have been modeled to predict the residual stresses in the restored portion. A lab sacle deposition set up is functional and project is underway for developing in-situ robotic restoration system which could do automatic damage assessment and free form deposition for repair dies and aerospace structures.
  • Novel finishing techniques and functional characterization of precision finished surfaces
  • Finishing at micro/meso scales for profiled surfaces can be cumbersome because rigid grinding methods can be very difficult to implement and diamond turning is expensive so innovative finishing techniques need to be developed. To address these issues, novel solutions for finishing hard and brittle materials at the microscale are required. A new process and machine tool for conformal hydrodynamic nanopolishinghas been patented and a functional machine to polish single crystal sapphire has been delivered to BARC.
  • Finite element modeling
  • One of key interest areas is finite element modeling of different manufacturing processes, such as machining, flow forming, ring rolling, pilgering and electromagnetic forming. Another active field in modeling is multiscale modeling of damage evolution in composites. A new RVE-based approach called multi-fiber multi-layer representative volume element (M2RVE) to capture all the main damage mechanisms have been developed. We are also interested in modeling the tool-tissue interactions when different tissues are punctured or indented with a surgical tool.

Other Interests:

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