Research

Metal Mechanics

 

  1. Crystal plasticity (Multi-scale)

 

  1. Material point models

 

  1. Single crystal plasticity: anisotropy, strain-rate and temperature dependence

 

BCC single crystal tensile behavior at 298 K – Effect of crystal orientation

 

  1. Polycrystal plasticity (texture simulations)

Simulation of texture evolution for random initial orientations for uniaxial tension load case: Texture pole figures along <110> and <111> crystallographic directions.

 

  1. Physics based constitutive modeling

 

Temperature and orientation dependence of FCC materials: a better fit can be obtained through physical models in comparison temperature independent classical models.

 

  • Single crystal finite element model

Goss compression of an FCC single crystal a. before deformation, b. after deformation.

 

  1. Polycrystal finite model (RVE)

 

Polycrystal simulation of an Aluminum sample with large grains –Each color represents a grain.

 

Crystal plasticity simulation of metal forming process using a simplified polycrystal RVE for DP600 steel material.

 

 

 

  1. Thermomechanical finite element process simulation for Metal Additive Manufacturing

 

  1. Powder bed fusion process

 

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Thermal simulation of powder bed fusion process as a metal 3D printing process.

 

 

  1. Directed energy deposition process

 

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Thermal simulation of directed energy deposition process a metal 3D printing process.

 

 

  1. Single crystal micro machining model

 

Simulation of turning process for FCC single crystals and cutting force fluctuations for different crystallographic turning zone axes a. <100>, b. <110>, c. <111>, d. schematic sketch for the turning zone axis.

 

 

  1. Residual stress analysis method

 

  1. Hole drilling method (experimental)

 

Vishay RS200 to measure residual stresses using hole drilling method according to the ASTM Standard E837.

 

 

  1. X-ray Diffraction (at Cornell University – with Prof. P.R. Dawson)

Two scale analysis methodology to find the macro scale stress distributions from lattice strain measurements (Images are taken from the reference: Demir E., Park J.S., Miller M.P. and Dawson P.R., Computer Methods in Applied Mechanics and Engineering, vol. 265, pp. 120-135, 2013.)

 

 

  1. Micromechanics

 

  1. Size dependence and GNDs (at Max Planck Institute for Iron Research with Prof. D. Raabe)

 

A method to compute geometrically necessary dislocations is developed and applied analyze Electron Backscattered Diffraction (EBSD) maps underneath indents to explain indentation size effect

 

  1. Micro scale experiments (at Max Planck Institute for Iron Research with Prof. D. Raabe)

 

Various single crystal Copper samples prepared by Focused Ion Beam (FIB) milling method: Beams with round cross-section, cantilever beam during manufacturing, Bauschinger test sample and its EBSD map (from left to right).

 

 

Composite Mechanics

 

  1. Design of variable stiffness composites

 

  1. Strain Energy Minimization

Design methodology for variable stiffness composites: optimization for compliance using lamination parameters as the variables, conversion of lamination parameters to fiber angles, application of curvature constraints to find manufacturable fiber angle distribution for a simply-supported plate with a pressure load.

 

  1. Buckling load maximization

Preliminary results of buckling optimization to find best fiber angles for an axially compressed plate with fixed edges.

 

  • Application to 3D printing of PLA material with chopped carbon fibers (collaboration with Dr. Thomas Cender)

 

Variable stiffness design of an open hole tension specimen followed by path planning and 3D printing, respectively.

 

 

 

 

 

 

 

 

 

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