Research Areas
Here are the main Research areas that I work in
Delay Coupled Self-Oscillating Dome Shaped MEMS
- Limit cycle MEMS, showing broadband synchronization can be coupled using Surface Acoustic Waves they generate in the subsrate.
- This forms a delay type system, which is more stable and can show broadband response compared to single osciallator and hence useful as a time keeping device etc.
- Model these devices using coupled nonlinear ODE's to determine the behavior and optimized design.
- Fabricate and test devices in vacuum using a laser based setup.
Optimization of flow based nonlinear energy harvester
- Aero elastic flutter as a means of harvesting energy from ambient fluid flow is studied
- The energy harvested in the manner described above can be used to power continuously operating remote MEMS sensors with application in structural health monitoring, smart dust, body prosthetics etc.
- Systematic design of this system, using full and reduced order CFD based numerical analysis, determine the best design in providing the most turbulent flow.
- The designs are validated using coupled Fluid structure based simulations performed in Abaqus.
- Use FEA and simplified model based study to determine the dynamic compressive response of hexagonal honeycombs with defects in the form of missing cell walls for various impact velocities.
- The influence of the defect locations on the deformation bands, the local accelerations,the contact-induced, and the deformation-induced bulk and boundary stresses is determined.
- Senstivity of relative proportion and location of defects towards energy absorption capacity at various impact velocities is determined.
- Study the effect of fluid on impact absorbtion capability of honeycomb
Constitutive Modeling of Nonlinear Materials
Nonlinear viscoelastic multi-configurational rate type material model for tire rubber
- Implementaion of a nonlinear viscoelastic multi-configurational rate type material model within the general framework of the commercial finite element package Abaqus (UMAT).
- Use perturbation based consistent material Jacobian for multi-configurational models to be used in the global Newton iterations.
- Couple the numerically approximated Jacobian and TR-BDF2 integrator, to develop an efficient numerical scheme.
- Validate against predictions for results of a Grosch wheel/Rolling tire test .
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Rate Independent Cohesive Zone Model for Modeling Failure in Quasi-Brittle Materials
- Rate independent cohesive zone model that can simulate cracking, slipping, and crushing of planes through a traction-separation law implemented in Abaqus (UMAT).
- A single surface hyperbolic failure criterion, extending Coulomb friction criterion with cut-off in tension and cap-off in compression implemented with Euler backward integration scheme together with a global-local Newton solver compatible with a substepping strategy.
- The proposed model is then used for simulating shear wall panels and is validated against experimental results available in literatures.
Reduced Order Modeling(ROM)
Generally the behavior of physical systems can be modeled using partial differential equations,that might be difficult to solve for all geometries and boundary condition. Hence for many systems, especially involving multiphysiscs analysis and complex nonlinearities such as contact, performing analysis using a full order high fidelity model is not feasible. Hence reduced order modeling (ROM) strategies are used to obtain the answers pertaining to the system behavior, which will not be feasible with the full order high fidelity approaches. There are several approach to generate the ROM for systems such as Volterra series representations, the proper orthogonal decomposition, and harmonic balance.
ROM of a fully coupled Fluid Structure Interaction(FSI) based problem.