Projects

Matrix-free FEA for Additive Manufacturing

PI: Professor Krishnan Suresh (Dept. of Mechanical Engineering, University of Wisconsin-Madison)

The focus of this work is on one aspect of AM simulation, namely, part-level elasto-plastic simulation for residual stress and distortion predictions. This is one of the crucial steps in AM process optimization, but is computationally expensive, often requiring the use of large computer clusters. The primary bottleneck in elasto-plastic simulation is the repeated solution of large linear systems of equations. While there is a wide range of linear solvers, most cannot exploit the unique structured nature of the mesh underlying AM. Here, we revisit a specific matrix-free solver, namely rigid-body deflated solver that has been very successful for solving large linear-elastic problems in such scenarios. The salient feature of this solver is that the stiffness matrix is never assembled, thereby reducing the memory requirements significantly, leading to large computational gains. We extend the above solver to elasto-plasticity by efficiently updating the element tangent matrices, and the corresponding deflation matrix. The performance of the proposed method is evaluated on a benchmark problem using multi-core CPU and GPU architectures, and compared against ANSYS. Then, part-level residual stresses and distortion prediction are predicted using the proposed solver. The present work is restricted to associative plasticity with von-Mises yield criteria, but can be extended to other plasticity models.

Contact Stress Parameter Evaluation using Digital Photoelasticity

Sponsored By: Indian Space Research Organization (ISRO)

Project Associate, IIT Madras

PI : Professor K. Ramesh (Dept. of Applied Mechanics, IIT Madras)

I have developed analytical solution resulting into explicit expressions for whole-field stresses in conformal and non-conformal contacts using Mushkelishvili complex stress function which could be directly employed for photoelastic experiments. The results were validated experimentally through digital photoelasticity. The manuscript of this work is under preparation and we expect it to be published in a reputed international journal. (Please refer the publications section for related conference presentation).

Topology Optimization of Compliant Mechanisms

Research internship as SN Bose Scholar

PI: Professor Krishnan Suresh (Dept. of Mechanical Engineering, University of Wisconsin-Madison)

I spent summer of 2015 at the University of Wisconsin-Madison as S. N. Bose scholar. I worked with Prof. Suresh on designing 3 dimensional compliant mechanisms with topology optimization using finite element (FE) based level set method. I achieved the increase in compliance of mechanisms by 10⁵ orders of magnitude.

I also analyzed the behavior of number of microstructural assemblies of the compliant structures to get the optimum configuration considering various constraints. The microstructural optimization was achieved with the patterned stacking in order to obtain desired mechanical properties like compliance, negative Poisson ratio and strength. I enjoyed the challenge of learning the advanced topics on my own.

Design and Manufacturing of Air bearing and Helmholtz cage for satellite ACS Testbed

Senior Thesis, Guide: Professor D. W. Pande, Dean R&D, Faculty Adviser, Structures Subsystem, CSAT

Testbed would provide near-zero friction, torque-free and controlled magnetic field atmosphere so that it could simulate the space-like conditions experienced by satellite. With innovative in-house design and manufacturing of air bearing and Helmholtz cage, we build the testbed at just $100 which was 20 times more economical than commercially available items (which costed no lesser than $2000). We also characterized the airbearing with respect to various loads and determined pressure distribution using ANSYS FLUENT. This effort won us the prestigious "Best Project Award" among all the senior theses in COEP. The outcomes of this work were presented at the 29th Space Simulation Conference, 2016 at Maryland, USA (for details regarding publication, please refer to the Publications section)

Development of 1-U picosatellite -Swayam