Harshavardhan Kalathur Assistant Professor Department of Mechanical Engineering

Dr. Harshavardhan Kalathur is an Assistant Professor in the Mechanical Engineering Department at Mahindra École Centrale College of Engineering. Dr. Harshavardhan Kalathur did his Ph.D in Engineering Mechanics, University of Wisconsin in Madison, U.S.A.

  • Education
    1. PhD in Engineering Mechanics, University of Wisconsin in Madison, U.S.A.
      Thesis: Enhancement of Viscoelastic and Piezoelectric Properties in Materials and Structural Systems with Negative Stiffness: Experiment.
      Advisor: Roderic Lakes http://silver.neep.wisc.edu/~lakes/
      Committee: Walter Drugan, Michael Plesha, Mathew Allen, Donald Stone
      Minor: Business, with entrepreneurship focus
    2. 2010 MS in Engineering Mechanics, University of Wisconsin in Madison, U.S.A.
    3. 2009 BTech in Mechanical Engineering, Jawaharlal Nehru Technological University in Hyderabad, India.
  • Research
    1. Developing advanced materials that exhibit extreme behavior by combining mutually exclusive properties, such as high stiffness and high damping, high strength and high toughness.
    2. Paradigms such as negative stiffness, bio-inspired architectured materials and supersonic impact of single crystal metallic cubes, were used and studied.
    3. Hands-on experience with brand new research lab startup that included purchasing, coordinating with various departments/stakeholders and preparation of experimental protocols and lab safety manuals.
    4. Supervising/mentoring undergraduate and graduate students.
    5. My PhD dissertation work involved experimentally obtaining enhanced viscoelastic and piezoelectric properties by designing and investigating novel materials and structural systems with negative stiffness. Viscoelastic properties were enhanced using negative stiffness under small oscillations in a lumped system, via snap-through hysteresis. Negative incremental stiffness was responsible for achieving the figure of merit, | Eeff | tan δeff of at least 1.6 GPa, a value typically never exceeded in conventional materials. The strain range can be comparable to that associated with use of nonlinear high damping metals such as copper manganese alloys, but with superior energy absorbing characteristics. This was a DARPA project who credited this paradigm as the best solution for a specific military application. Piezoelectric properties such as effective piezoelectric sensitivity d, was enhanced using a lattice based on composite rib elements. The effective piezoelectric sensitivity of the lattice was several orders (10,000 times) of magnitude greater than that of material in the ribs. A piezo-mechanical hybrid paradigm yielded an enhancement in effective piezoelectric sensitivity by almost 40,000 times. In this design, a piezoelectric strip actuator was used in conjunction with a buckled brass strip that entailed negative stiffness. The negative stiffness was tuned to approach the positive bend stiffness of the actuator cantilever. A novel potassium sodium niobate (KNN) based ceramic composite with barium titanate (BaTiO3) inclusions was synthesized and the effective piezoelectric d33 sensitivity showed an enhancement of 21% at 9oC compared to the value at room temperature. This enhancement is due to the phase transformation of BaTiO3 thus causing negative stiffness that is constrained by the surrounding matrix material.
  • Publications
    1. Kalathur, H., Lakes, R.S., "Enhancement in piezoelectric sensitivity via negative structural stiffness", J. Intell. Mat. Sys. and Struc., 27(18) 2568-2573 (2016).
      Abstract: Effective piezoelectric sensitivity of bimorph strip actuators was enhanced by negative structural stiffness. Negative stiffness was achieved in brass strips post-buckled in compression to an 'S' shape; the brass strip was placed in series with the bimorph. The negative stiffness was tuned by adjusting the brass strip length. The effective piezoelectric sensitivity in units of displacement per volt input, increased as the inverse of the overall stiffness of the series element. The maximum observed enhancement in effective piezoelectric sensitivity was at least a factor of six, at 1 Hz in comparison to the value when no negative stiffness was used. This corresponds to a maximum effective sensitivity of about 36 μm/V in comparison to the baseline effective sensitivity of about 6.1 μm/V, at 1 Hz. The value is several orders of magnitude (almost 40,000 times) higher than the typical value of sensitivity for the material comprising the individual bimorph strip actuator.
    2. Rodriguez, B., Kalathur, H. and Lakes, R. S., "A sensitive piezoelectric composite lattice: experiment", Physica Status Solidi, 251(2) 349-353 (2014).
      Abstract: Lattice structures based on bimorph rib elements are fabricated and studied experimentally. The effective piezoelectric sensitivity d is observed to be much larger, by a factor of at least 10,000, in magnitude than that of material comprising the lattice ribs. Bending of the ribs in response to input voltage is responsible for the large sensitivity.
    3. H. Kalathur, T. M. Hoang, R. S. Lakes and W. J. Drugan, "Buckling Mode Jump at Very Close Load Values in Unattached Flat-End Columns: Theory and Experiment", J. Appl. Mech. 81(4), 041010 Sept. (2013).
      Abstract: Buckling of compressed at-end columns loaded by unattached at platens is shown, theoretically and experimentally, to occur first at the critical load and associated mode shape of a built-in column, followed extremely closely by a second critical load and different mode shape characterized by column end-tilt. The theoretical critical load for secondary or end tilt buckling for a column geometry tested is shown to be only 0.13% greater than the critical load for primary buckling, in which the ends are in full contact with the compression platens. The experimental value is consistent with this theoretical one. Interestingly, under displacement control, the first buckling instability is characterized by a smoothly-increasing applied load, whereas the closely-following second instability causes an abrupt and large load drop (and hence exhibits incremental negative stiffness). The end tilt buckling gives rise to large hysteresis that can be useful in structural damping but that is non-conservative and potentially catastrophic in the context of design of structural support columns.
    4. Kalathur, H., Lakes, R. S., "Column dampers with negative stiffness: high damping at small amplitude", Smart Materials, 22, 084013 (8pp) (2013).
      Abstract: High structural damping combined with high initial stiffness is achieved at small amplitude via negative stiffness elements. These elements consist of columns in the vicinity of post-buckling transition between contact of at surfaces and edges of the ends for which negative incremental structural stiffness occurs. The column configuration provides high initial structural stiffness equal to the intrinsic stiffness of the column material. Columns of the polymers polymethyl methacrylate (PMMA)and polycarbonate were used. By tuning the pre-strain, a very high mechanical damping, was achieved for small amplitude oscillations. The product of effective stiffness and effective damping as a figure of merit | Eeff | tan δeff of about 1.5 GPa was achieved for polymer column dampers in the linear domain and about 1.62 GPa in the small amplitude nonlinear domain. For most materials this value generally never exceeds 0.6 GPa.
  • Experience

    WORK EXPERIENCE

    2018 Entrepreneurial Intern, TandemLaunch, Montreal, CANADA

    • Technical Advisor Intern at a startup; provided technical support in understanding and improving the surface mechanical performance of their electronics display glass.
    • Provided a solution roadmap for optimized display glass performance.

    2018 Associate Lecturer, University of Wisconsin, Madison USA

    • Temporarily covered initial several lectures in Mechanics of Materials for a tenured Professor, who was on leave. Class size was over 100 students.
    • Assigned and scheduled weekly online homework on WileyPLUS, an online course integration software.
    • Received excellent feedback from students.

    2017-2018 Research Associate, University of Wisconsin, Madison USA

    • Assisted in establishing the new `Innovative Structured Materials for Extreme Mechanical Properties Lab' for creating and studying materials with extreme properties.
    • Built a complex laser based micro-ballistic experimental apparatus for creating nanostructured metals.
    • Majorly involved with the purchase of high value equipment such as class 4 lasers, optical elements and components, microscope and cameras, with a total cost > $200,000.
    • Coordinated with the purchasing department for preparing POs, assisted in drafting RFBs and Simplified bids.
    • Created real time equipment inventory and prepared equipment operation and lab safety manuals.

    2016-2017 Postdoctoral Fellow, McGill University, Montreal, Canada

    2015-2016 Volunteer, University of Wisconsin in Madison

    • Study of the mechanics and structure of biological systems.
    • Design, fabrication and testing of bio-inspired materials for high performance.
    • Methods: High-speed imaging, electro-mechanical test frames, impact testing, Solid-Works, digital image correlation
      • Set up and installation of 3-D printing lab for metals and polymers.
      • Design of the "Maker Space" for the college of Engineering.

    GRADUATE RESEARCH EXPERIENCE

    2012-2015 Research Assistant, University of Wisconsin in Madison

    • Design, fabrication, synthesis and testing of structural systems and materials involving negative stiffness
    • Report writing and publications
    • Poster presentations
    • Supervision of undergraduate intern in fabrication and data collection
    • Instrumentation Experience:
         - Specimen preparation: surface grinding, polishing and etching, ball milling.
         - Optical Microscopy, High Voltage Power Supply, Digital Function Generator, Dual Mode Charge Amplifier Digital Multimeters, Digital oscilloscopes, LVDT, Load cells, Optical sensors, Lock in Amplifiers, Resonance Ultrasound, Servo hydraulic machines, Miscellaneous lab tools.
    • Logistics Experience:
         - Materials and equipment purchasing for research.
         - Managing finances allocated for research purchases.
    • Computer Skills:
         - Technical graphing software, Kaleidagraph
         - Computational software, MATLAB (basic)
         - Finite Element Model developing and analyzing software, ANSYS (basic)
         - Typesetting software, LATEX
         - Microsoft Office tools
         - Platforms such as Mac and PC

    GRADUATE TEACHING EXPERIENCE

    2015 Teaching Assistant for Dynamics, University of Wisconsin in Madison

    • Kinematics, force-mass-acceleration relations, work and energy, impulse and momentum, moments of inertia and mass.
    • Conducting regular discussion sessions. Reinforced concepts covered by the instructor in lectures via more problem solving.
    • Graded exams.

    2011-2012 Teaching Assistant for Statics, University of Wisconsin in Madison

    • Principles of mechanics, force systems, equilibrium, structures, distributed forces, moments of inertia of areas, and friction.
    • Conducted regular discussion sessions. Reinforced concepts covered by the instructor in lectures via more problem solving. Provided guidance in design projects and technical report writing, etc.
    • Graded exams.

    2011 Teaching Assistant for Practicum in Finite Elements, University of Wisconsin in Madison

    • Use of finite elements (FE) for solving practical problems in mechanics. Elementary theory of FE is discussed. A commercial computer program is used for applications. Major emphasis is on behavior of FE, modeling, and evaluation of results for correctness.
    • Provided assistance to the instructor in trouble shooting and overall guidance for students in developing FE models using ANSYS.

    2010 Teaching Assistant for Engineering Measurements and Instrumentation Lab, University of Wisconsin in Madison

    • Theory of modern instrumentation, the design and execution of experiments and the analysis of experimental data. Laboratory provides direct experience with concepts in the context of experimental design for hypothesis testing, for product evaluation and for control system design.
    • Conducted regular lab sessions. Supervised student assigned lab tasks and projects, provided guidance in technical report writing, etc.
    • Graded lab reports and exams.