Shahmeer Baweja | Argonne National Laboratory (original) (raw)

Thesis Chapters by Shahmeer Baweja

STATISTICAL ANALYSIS OF HCP POLYCRYSTALS USING CRYSTAL PLASTICITY MODELING AND SIMULATION, 2019

Three-dimensional crystal plasticity finite element modeling and simulation of polycrystalline ma... more Three-dimensional crystal plasticity finite element modeling and simulation of polycrystalline magnesium (Mg) alloys is performed. The focus of this work is on extracting the relation between the initial texture and the mechanical behavior of a polycrystalline Mg microstructure under uniaxial loading, particularly along principal directions of a rolled material - rolling (L), in-plane transverse to rolling (T), and out-of-plane transverse (S) to L and T. Starting with an initial rolled texture of an Mg alloy as a basis, the effect of deviations in the initial texture on the macroscopic and microscopic characteristics is analyzed through quantitative analysis of the deviations in the overall stress-strain behaviors, activities of the slip and twinning mechanisms, and textural evolution.

Papers by Shahmeer Baweja

Mechanics of Materials, Jan 31, 2024

The minerals, metals & materials series, 2021

The remarkable crystallographic plastic anisotropy of magnesium and its alloys reflects in its po... more The remarkable crystallographic plastic anisotropy of magnesium and its alloys reflects in its polycrystal response via texture. While texture-strength linkages have been studied, the role of textural variability on damage remains elusive. The challenge is to obtain relevant metrics that relate the net plastic anisotropy to macroscopic modes of damage. A possible approach is to adopt mechanistic descriptions of the damage. Motivated by the recent experimental and theoretical works in this direction, here we appeal to the Hill yield function to characterize the net plastic anisotropy of polycrystalline magnesium via the Hill plastic anisotropy tensor 𝕙. Metrics based on the components of 𝕙 offer a way to predict damage as a possible damage predictor. Using the results from our recent extensive three-dimensional crystal plasticity simulations for a wide range of textures, we map the net plastic anisotropy on to the coefficients of 𝕙, separately for the tensile and compressive responses. Metrics based on these coefficients serve as indicators for the propensity of textured polycrystals to damage by: (i) porosity evolution, or (ii) shear instability. An attempt is made to understand the potential roles textural variability and crystallographic plastic anisotropy play in damage under different loading conditions.

Journal of Dynamic Behavior of Materials, Aug 4, 2020

We report a preliminary computational study of the rate-dependent behavior of a polycrystal magne... more We report a preliminary computational study of the rate-dependent behavior of a polycrystal magnesium alloy under varying levels of stress triaxiality conditions. Smooth and notched round bar specimens with a strong initial texture are considered to achieve different levels of stress triaxiality. Full three-dimensional crystal plasticity simulations are conducted, which mimic tensile Kolsky bar experiments. The results indicate that the material rate sensitivity couples with the stress state to produce qualitatively different macroscopic responses that are governed by the interacting microscale deformation mechanisms. While the smooth specimens show macroscopic strain localization resulting in stress softening immediately following the initial yield, notched bars exhibit increasingly stable responses with increasing notch acuity. Deformation anisotropy is tempered with increasing stress triaxiality and strain rate. A micromechanical analysis of the deformation activities is presented to explain the macroscale responses. Stress triaxiality distributions in the notch regions provide insights into probable damage mechanisms as a function of the imposed strain rate.

Journal of Magnesium and Alloys, Feb 11, 2023

This work systematically investigates the microstructure-property relationship in Mg alloys. Emph... more This work systematically investigates the microstructure-property relationship in Mg alloys. Emphasis is placed on understanding, through high resolution crystal plasticity modeling, how grain size and texture collectively impact material strengthening and hardening, net plastic anisotropy, and tension-compression asymmetry. To achieve this, 528 fully three-dimensional finite element calculations are performed, which comprise eleven textures, four grain sizes, six loading orientations, and two uniaxial loading states (tension and compression). The grain size effect follows Hall-Petch relation that depends on both, loading orientation and initial texture. The reduction in extension twinning with grain size refinement is influenced by texture as well. Below a threshold textural strength, grain size refinement leads to an appreciable reduction in the net plastic anisotropy at yield, quantified using Hill anisotropy, and reduced tension-compression asymmetry. Using a micromechanical basis, the effect of grain size and texture on material ductility is predicted to be non-monotonic. The computational predictions serve as synthetic data sets for experimental validation and reduced-order modeling.

International Journal of Plasticity, 2020

This work systematically investigates the texture-property linkages in hexagonal close-packed (he... more This work systematically investigates the texture-property linkages in hexagonal close-packed (hexagonal) materials using a three-dimensional computational crystal plasticity approach. Magnesium and its alloys are considered as a model system. We perform full-field, large-strain, micromechanical simulations using a wide range of surrogate textures that sample several experimental datasets for a range of Mg alloys. The role of textural variability and the associated sensitivity of deformation mechanisms on the evolution of macroscopic plastic anisotropy and strength asymmetry is mapped under uniaxial tensile and compressive loading along the material principal and off-axes orientations. To assess the role of crystallographic plastic anisotropy, two distinct material datasets are simulated, which represent pure and alloyed magnesium. The results provide insights into experimental observations reported for magnesium alloys over a range of material textures. We further discuss potential implications on the damage tolerance from the aggregate plastic anisotropy arising from intrinsic crystallographic and textural effects.

Magnesium Technology 2020, 2020

Microstructure , material properties, and macroscopic stress state closely interact in determinin... more Microstructure , material properties, and macroscopic stress state closely interact in determining the strength and fracture resistance of ductile metals. While a fair understanding of the microstructure -stress interaction on strength, deformation stability, and damage has been achieved for common engineering alloys, the same is not true for magnesium (Mg) alloys. A fundamental understanding of how the net plastic anisotropy influences the macroscopic load-deformation characteristics and deformation stability will potentially aid the development of high-performance Mg alloys . A concerted multi-scale computational effort is essential in providing a deeper understanding of the deformation micromechanics of Mg alloys . In this paper, we investigate the microstructure -property linkages under tensile and compressive loading states through high-fidelity crystal plasticity modeling and simulation. Extended investigations along this path should enable the development of guidelines for damage-tolerant design of Mg alloys .

Direct metal deposition (DMD) is now becoming part of a new trend in rapid and additive manufactu... more Direct metal deposition (DMD) is now becoming part of a new trend in rapid and additive manufacturing. It involves rapidly generating three-dimensional (3-D) physical prototypes of the components from their computer-aided design (CAD) models. The various materials deposited by DMD have far reaching applications in medicine, technology, and industry. The current literature attempts to make up for the dearth of research in the microstructural, mechanical and metallurgical properties of materials that are developed and enhanced by the DMD process and focuses on the influence of the laser parameters on shaping those properties. A comprehensive review of the DMD process and its categories, equipment, materials and applications is presented in this article.

This document provides design, analysis and evaluation of a compound reverted geartrain with resp... more This document provides design, analysis and evaluation of a compound reverted geartrain with respect to loading, stress and safety factors to obtain specifications for gears, shafts and bearings which satisfy the customer requirements for the desired power and torque.

Some thousands of years ago, humans took inspiration from the flawless flight of several birds an... more Some thousands of years ago, humans took inspiration from the flawless flight of several birds and began dreaming of capturing the sky. Manned kites, hot-air balloons and airships were some of the earliest developments in aviation. Modern aviation began with the first successful fully controllable, powered flight of a heavier-than-air plane by Orville and Wilbur Wright in December 17, 1903. Design of modern aircrafts such as Boeing and Airbus are based upon the design and concept of the Wright brothers' successful aircraft. The first commercial flight was made around 1914. Airplanes are transportation devices designed to move people and cargo from one place to another. They come in a variety of shapes and designs depending on the mission of the aircraft. Commercial aircrafts are the biggest planes and frequently used by millions of people all around the world to travel to places for vacations, businesses and conferences. The aero industry is one of the largest industry in the world with millions of dollars generating from thousands of commercial flights a day. This paper will discuss in details the design of a modern commercial aircraft as seen in the 21st Century.

Simulations of flow over a 2D axisymmetric cylinder was performed at different Reynolds number to... more Simulations of flow over a 2D axisymmetric cylinder was performed at different Reynolds number to obtain values of drag coefficient (CD) and lift coefficient (CL) which were then validated with velocity and pressure contour plots. Further validation was achieved with obtaining plots of pressure coefficient (CP) at these different Reynold number and then compared with the data from the literature. Simulation of flow over a non-rotating NACA 0012 airfoil was performed at different Reynold's number and angle of attacks (AOA) and validated by comparison of values of CL and CP with the chosen literature and, for simulation of flow over a rotating NACA 0012 airfoil performed at varying angles of attacks, the results was validated with plots of CL with varying AOA to achieve an understanding of the effects of stall accompanied with hysteresis on the values of CD and CL when the airfoil is rotated within a range of AOA incident to the incoming flow.

Electric Vehicles (EVs) powered by batteries were first introduced in 1834 by Robert Anderson of ... more Electric Vehicles (EVs) powered by batteries were first introduced in 1834 by Robert Anderson of Scotland, but mass production of relatively cheaper and longer range gasoline vehicles by Henry Ford in 1910 gradually displaced EVs from the market. [3] However, concerns over rising global temperatures owing to a two-fold increase in greenhouse gas emissions (GHGs), mainly 𝐶𝑂2, in the last 30 years from 1970 to 2005 and an increase in demand for the nearly-depleted oil led back to developing clean, carbon-free energy sources, particularly for the transportation sector. [1] In 2005, the transportation sector was responsible for approximately 15% of global GHG emissions to which road transport contributed 73%. [9] The International Energy Agency (IEA) estimated, in 2012, that 20% of global primary energy use and 25% of energy-related carbon dioxide (𝐶𝑂2) emissions are attributable to this sector. [7] These emissions are controlled through full hybrid electric vehicles (HEVs) and/or plug-in hybrid vehicles (PHEVs) and altogether removed through full Battery Electric Vehicles (BEVs). [1] The well-to-wheel energy consumption and emissions for EVs utilizing lithium-ion batteries (Li-ions) are the lowest at 314-374 𝑊ℎ 𝑘𝑚−1 and 76-90 𝑔𝐶𝑂2𝑒𝑞𝑘𝑚−1 compared to 450-760 𝑊ℎ 𝑘𝑚−1 and 150-170 𝑔𝐶𝑂2𝑒𝑞𝑘𝑚−1 for gasoline vehicles. [7] Several battery technologies other than Li-ions are also currently being used and developed for EVs. The main challenges ahead lie in simultaneously meeting battery requirements in specific energy, specific power, efficiency, cycle life, safety and costs in the short, medium or even long term. It is deemed that only Li-ions will attain all required conditions in the medium term and possibly long term. Since Li-ions currently represent the largest share of commercial batteries for BEVs, they are expected to dominate the market in the medium and possibly even long term. [9] The paper focuses on the issues and solutions surrounding the development of Li-ions