Announcements – Page 41 – Mechanical Engineering Graduate Office (meGRAD)

2021 ExxonMobil LOFT Fellowship Program

Post author By Darius Isaiah Craig
Post date June 11, 2021

ExxonMobil Corporation, the largest publicly traded international energy company, has partnered with the Hispanic Heritage Foundation (HHF) to create fellowship opportunities in the STEM fields (Science, Technology, Engineering, and Math) for Hispanic college students. Through HHF’s Latinos On Fast Track (LOFT) program, ExxonMobil seeks to nurture motivated college students across the country, with a passion for Engineering and Science.

Selected students will be exposed to a top-quality company by participating in this signature mentoring program. Each student will be paired up with an ExxonMobil professional to learn how their knowledge and skills are applied in a corporate setting.

Fellowship Components
The Fellowship consists of five 1-hour meetings with a mentor (virtual or in person), participation in the Harvard-certified ExxonMobil mentee program (on-line), an exclusive curriculum to introduce Fellows to ExxonMobil and career opportunities, and a $1,000 educational grant. In addition, there exists the possibility to interview for ExxonMobil positions (internships/full-time) upon successful completion of the Fellowship.

Fellowship Requirements
This opportunity is highly competitive and open to rising sophomores, juniors, Seniors, and Graduate Students attending a 4-year college or university.
Fellowship applicants with the following majors will be given priority:

· Civil Engineering

· Chemical Engineering

· Computer Engineering

· Electrical Engineering

· Geoscience

· Material Science and Engineering

· Mechanical Engineering

Applicants with these majors will be considered also: Chemistry, Computer Science Environmental Engineering, Industrial Engineering, Mathematics, Petroleum Engineering, and Physics.

Other Requirements:

· Must plan to pursue a career in the fields/majors listed above

· Have a GPA of 3.5 or higher

· Be a U.S. citizen or legal permanent resident of the United States with a valid Social Security Number at the time of application. All legal permanent residents must submit a copy of their valid permanent resident card or passport stamped I-551 (not expired).

For the 2021 ExxonMobil LOFT Fellowship

If you have questions please contact Julian@hispanicheritage.org. Please use “ExxonMobil LOFT Fellowship ” in the subject line.

Announcements Fellowships & Scholarships

NSF Post-Doc Engineering Fellowships

Post author By Darius Isaiah Craig
Post date June 10, 2021

Recognizing that many universities put their faculty hiring on hold due to uncertainties created by the pandemic, NSF has launched a new postdoctoral program for recently-graduated PhD students who want to stay in academia. Applications will be accepted from June 21 through July 6, 2021. We hope that this new Engineering Postdoctoral Fellows (eFellows) program enables highly qualified PhDs to gain more experience in academic research and be competitive for future faculty positions. Diverse candidates are encouraged to apply. Note that this program complements the Innovative Postdoctoral Entrepreneurial Research Fellowship (I-PERF) program that gives recent PhD graduates an opportunity to do a postdoc in an NSF-funded startup or small business. For details, see https://iperf.asee.org/ and https://efellows.asee.org/

Announcements

CAMPUS RETURN TO IN-PERSON INSTRUCTION – FALL 2021

Post author By Darius Isaiah Craig
Post date June 8, 2021

Based on the current decision from the Provost, UMD is returning to normal in-person instructional mode, starting in Fall 21.

To be consistent with this transition, Graduate School has instructed that Thesis and Dissertation Defense exams should also resume their traditional in-person format.

Details of their guidelines can be found here: https://gradschool.umd.edu/resumption-person-thesis-and-dissertation-defenses

Since we have traditionally followed Graduate School Defense format as guidance for Ph.D. Qualifier Exams and Dissertation Proposal Presentations, those events will also resume their traditional in-person format starting in Fall 21. Waivers for special situations will require prior approval and will be based on the guidelines provided by Graduate School in their website above.

Proposal Presentations and Defenses scheduled in Summer 2021 can be conducted in either format or in a hybrid mode, depending on the situation. Prior approval is not needed for any of these formats in Summer 2021.

Announcements Defenses

Dissertation Defense – Aditya N. Sangli

Post author By Darius Isaiah Craig
Post date June 7, 2021

Title: Fluid Dynamics of Extensional Deformation and Capillary-Driven Breakup of Drops at Low Reynolds Number.

Author: Aditya N. Sangli

Day/Time: June 22nd, 12:00 pm – 2:00 pm

List of committee members
Professor David I. Bigio, Chair & Advisor
Professor Amir Riaz
Professor James H. Duncan
Professor Kenneth Kiger
Professor Richard V. Calabrese, Dean’s Representative

Abstract:
In this dissertation, extensional deformation and capillary-driven breakup of drops at low Reynolds number is investigated using a combination of theoretical, experimental, and numerical techniques. The dissertation introduces a new non-dimensional measure for drop deformation, rationalizes previously unseen drop breakup behavior, and extends our overall understanding of the fluid dynamics behind drop deformation and breakup.
First, non-stagnant extensional deformation of Silicone oil drops in Castor oil is experimentally studied over a wide range of capillary numbers by injecting the drops along the centerline of a flow through a hyperbolic converging channel. The unique design of the channel is capable of imposing a constant extensional rate and is validated using lubrication theory. Based on a careful analysis of drop deformation at both small and large capillary numbers compared to the critical capillary number, a new measure called the semi-minor capillary number is introduced to characterize drop behavior. Critical semi-minor capillary number is presented for a wide range of viscosity ratios and the significance of the new measure over the conventional capillary number measure is discussed.
During the course of the experiments, it was observed that drops undergoing non-stagnant extension exhibited a lag in velocity compared to the background flow velocity at the same point. This lag in velocity is attributed to flow induced deformation of the drops and the phenomenon is rationalized for a wide range of capillary numbers.
When drops are injected offset of the centerline of the channel, an anomalously large degree of deformation is observed even at low flow rates. A careful investigation of the phenomenon revealed that the strain rates along offset lines were at least an order of magnitude larger than the extensional rates along the centerline. A model is developed based on lubrication theory to predict the large deformation of drops and is successfully validated with experimental measurements.
Finally, when slender drops are allowed to develop under the effect of interfacial tension, they either retract into a sphere or breakup into multiple drops. This phenomenon is investigated using direct numerical simulations in a previously unexplored part of the parametric space where both inertial and viscous effects in the outside fluid are considered. A stability diagram is presented that shows a transition of drop states from asymptotically unstable to asymptotically stable states at different viscosity ratios. The drop behavior in different regimes is discussed and the significance of the balance between inertial and viscous forces is thoroughly described.

Defenses

Upcoming Dissertation Defense – Ramin Moradi

Post author By Darius Isaiah Craig
Post date June 2, 2021

Systematic Integration of PHM and PRA for Risk and Reliability Analysis of Complex Engineering Systems

Author: Ramin Moradi

Date/Time: Wednesday, June 16th. | 2 pm – 4 pm

Examining Committeee:
Dr. Katrina Groth, Chair/Advisor
Dr. Mohammad Modarres
Dr. Enrique Lopez Droguett
Dr. Michelle Bensi
Dr. Shapour Azarm
Dr. Greg Baecher, Dean’s Representative

“Complex Engineering Systems (CES) such as power plants, process plants,
manufacturing plants, etc. have numerous, interrelated, and heterogeneous subsystems with different characteristics and risk and reliability analysis requirements. On the other hand, with the advancements in sensing and computing technology, abundant monitoring data is being collected which is a rich source of information for a more accurate assessment and management of these systems. The current risk and reliability analysis approaches and practices are inadequate in incorporating various sources of information, providing a system-level perspective, and performing a dynamic assessment of the operation condition and operation risk of CES.

In this dissertation, this challenge is addressed by integrating techniques and models from two of the major subfields of reliability engineering, which are Probabilistic Risk Assessment (PRA) and Prognostics and Health Management (PHM). PRA is very effective at modeling complex hardware systems, and approaches have been designed to incorporate the risks introduced by humans, software, organizational, and other contributors into quantitative risk assessments. However, PRA has largely been used as a static technology and in the design stage of the systems. On the other hand, PHM has developed powerful new algorithms for understanding
and predicting mechanical and electrical devices’ health. Yet, PHM lacks the system-level perspective, relies heavily on the operation data, and its outcomes are not risk-informed.

We propose a novel framework at the intersection of PHM and PRA which provides a forward-looking, model- and data-driven analysis paradigm for assessing and predicting the operation risk and condition of CES. We operationalize this framework by developing two mathematical architectures and applying them to real-world systems. The First architecture is focused on enabling online system-level condition monitoring. While the second architecture improves upon the first and realizes the objectives of using various sources of information and monitoring
operation condition together with operational risk.”

Jobs/Internships

R&D ENGINEER POSITION – INTEL Corp.

Post author By Darius Isaiah Craig
Post date May 27, 2021

Job Description: Assembly and Test Technology Development (ATTD) Experimental Mechanics Lab deals with thermo-mechanical challenges in the development of advanced packaging technologies. The personnel in this R&D lab use a variety of tools to study the behavior of electronic packages and their material constituents under different mechanical and/or thermal loading conditions: like dynamic warpage of packages using optics-based tools; interfacial adhesion strength using Double Cantilever Beam test; fracture toughness of bulk materials using three-point bend test; material CTE using Digital Image Correlation method; and defect (or crack) detection & classification using optical (or acoustic emission) sensors and AI/ML codes. Employees also develop new metrologies and software capabilities for use with next-gen packaging technologies.

An ideal candidate is one with a strong background in Experimental Mechanics, along with problem solving and programming skills.

Qualifications

You must possess the below minimum qualifications to be initially considered for this position.

Preferred qualifications are in addition to the minimum requirements and are considered a plus factor in identifying top candidates.
Relevant experience can be obtained through school work, classes and project work, internships, military training, and/or work experience.

Minimum Qualifications:

Possess a master’s degree and 6+ months of experience or PhD degree and 1+ years of experience in one of the following majors: Mechanical Engineering, Aerospace Engineering, Materials Science and Engineering, or related field.
Must have the required degree or expect the required degree by December 2021.

Preferred Qualifications:

6+ months of experience (master’s degree) or 1+ years of experience (PhD degree) with one or more of the following:

Material characterization, load frames, DAQs, PID controllers, basic optics, 3D CAD, silicon photonics, Cu-Cu hybrid bonding, and/or structural health monitoring.
LabView, Matlab, and/or Python programming.

Interested candidates should email their resume to Dr. Pramod Malatkar (pramod.malatkar@intel.com).

Defenses

Dissertation Defense – Qian Jiang

Post author By Darius Isaiah Craig
Post date May 27, 2021

Anisotropic Multi-scale Modeling for Steady-state Creep Behavior of Polycrystalline Coarse-grain SnAgCu (SAC) Solder Joints

Author: Qian Jiang

Day/Time: June 10, 12:00 noon – 2:00 pm

List of committee members
Professor Abhijit Dasgupta, Chair
Professor Hugh Alan Bruck
Professor Teng Li
Professor Patrick McCluskey
Professor Lourdes G. Salamanca-Riba, Dean Representative

Abstract:
Heterogeneous integration is leading to unprecedented miniaturization of solder joints. The overall size of solder interconnections in current-generation microelectronics assemblies has length-scales that are comparable to that of the intrinsic heterogeneities of the solder microstructure. In particular, there are only a few highly anisotropic grains in each joint. This makes the mechanical response of each joint quite unique. Rigorous mechanistic approaches are needed for quantitative understanding of the response of such joints, based on the variability of the microstructural morphology.

The discrete grain morphology of as-solidified coarse-grain SAC (SnAgCu) solder joints is explicitly modeled in terms of multiple length scales (four tiers of length scales are used in the description here). At the highest length-scale in the joint (Tier 3), there are few highly anisotropic viscoplastic grains in each functional solder joint, connected by visoplastic grain boundaries. At the next lower tier (Tier 2), the primary heterogeneity within each grain is due to individual dendrites of pro-eutectic β-Sn. Additional microscale intermetallic compounds of Cu₆Sn₅ rods are located inside individual grains. Packed between the dendrite lobes is a eutectic Ag-Sn alloy. The next lower length-scale (Tier 1), deals with the microstructure of the Ag-Sn eutectic phase, consisting of nanoscale Ag₃Sn IMC particles dispersed in a β-Sn matrix. The characteristic length scale and spacing of the IMC particles in this eutectic mix are important features of Tier 1. Tier 0 refers to the body-centered tetragonal (BCT) anisotropic β-Sn crystal structure, including the dominant slip systems for this crystal system.

The objective of this work is to provide the mechanistic framework to quantify the mechanical viscoplastic response of such solder joints. The anisotropic mechanical behavior of each solder grain is modeled with a multiscale crystal viscoplasticity (CV) approach, based on anisotropic dislocation mechanics and typical microstructural features of SAC crystals. Model constants are calibrated with single crystal data from the literature and from experiments. This calibrated CV model is used as single-crystal digital twin, for virtual tests to determine the model constants for a continuum-scale compact anisotropic creep model for SAC single crystals, based on Hill’s anisotropic potential and an associated creep flow-rule.

The additional contribution from grain boundary sliding, for polycrystalline structures, is investigated by the use of a grain-boundary phase, and the properties of the grain boundary phase are parametrically calibrated by comparing the model results with creep test results of joint-scale few-grained solder specimens. This methodology enables user-friendly computationally-efficient finite element simulations of multi-grain solder joints in microelectronic assemblies and facilitates parametric sensitivity studies of different grain configurations.

This proposed grain-scale modeling approach is explicitly sensitive to microstructural features such as the morphology of: (i) the IMC reinforcements in the eutectic phase; (ii) dendrites; and (iii) grains. Thus, this model is suited for studying the effect of microstructural tailoring and microstructural evolution. The developed multiscale modeling methodology will also empower designers to numerically explore the worst-case and best-case microstructural configurations (and corresponding stochastic variabilities in solder joint performance and in design margins) for creep deformation under monotonic loading, for creep-fatigue under thermal cycling as well as for creep properties under isothermal aging conditions.

Announcements Defenses

Dissertation Defense – Benjamin Knisely

Post author By Darius Isaiah Craig
Post date May 25, 2021

Title: Integrating Human Performance Models into Early Design Stages to Support Accessibility

Author: Benjamin Knisely

Day/Time: June 8th, 1-3 pm

List of committee members
Assistant Professor Monifa Vaughn-Cooke, Chair
Assistant Professor Mark Fuge
Professor Jeffrey Herrmann
Assistant Professor John Dickerson
Professor Michel Wedel, Dean Representative

Day/Time: June 8th, 1-3 pm

Abstract:
Humans have heterogeneous physical and cognitive capabilities. Engineers must cater to this heterogeneity to minimize opportunities for user error and system failure. Human factors considerations are typically evaluated late in the design process, risking expensive redesign when new human concerns become apparent. Evaluating user capability earlier could mitigate this risk. One critical early-stage design decision is function allocation – assigning system functions to humans and machines. Automating functions can eliminate the need for users to perform risky tasks but increases resource requirements. Engineers require guidance to evaluate and optimize function allocation that acknowledges the trade-offs between user accommodation and system complexity. In this dissertation, a multi-stage design methodology is proposed to facilitate the efficient allocation of system functions to humans and machines in heterogeneous user populations. The first stage of the methodology introduces a process to model population user groups to guide product customization. User characteristics critical to performance of several generalized product interaction tasks are identified and corresponding variables from a national population database are clustered. In stage two, expert elicitation is proposed as a cost-effective means to quantify risk of user error for the user group models. Probabilistic estimates of user group performance are elicited from internal medicine physicians for generalized product interaction tasks. In the final stage, the data (user groups, performance estimations) are integrated into a multi-objective optimization model to allocate functions in a product family when considering user accommodation and system complexity. The methodology was demonstrated on a design case study involving self-management technology use by diabetes patients, a heterogeneous and safety-critical population. The population modeling approach produced quantitatively and qualitatively validated clusters. For the expert elicitation, experts provided internally validated, distinct estimates for each user group-task pair. To validate the utility of the proposed method (acquired data, optimization model), engineering students (n=16) performed the function allocation task manually. Results indicated that participants were unable to allocate functions as efficiently as the model despite indicating user capability and cost were priorities. This research demonstrated that the proposed methodology can provide engineers valuable information regarding user capability and system functionality to drive accessible early-stage design decisions.

Jobs/Internships

AKATECH – STEM Career Opportunities

Post author By Darius Isaiah Craig
Post date May 24, 2021

Announcements Defenses

Thesis Defense – Harsha Bharadwaj

Post author By Darius Isaiah Craig
Post date May 20, 2021

TITLE: Morphology evolution of droplets in a polymer based extensional flow.

Date/Time: Friday, May 28 – 2PM-4PM

Committee Members:
Dr. David Bigio (Advisor)
Dr. James Duncan
Dr. Ryan Sochol

Zoom Link: https://umd.zoom.us/j/93032464600

Abstract: Fused Deposition Modelling (FDM) is one of the most widely used Additive Manufacturing (AM) methods to bring products to life. This thesis examines the incorporation of liquid additives into the nozzle region of an FDM system and attempts to understand their behavior in the polymer melt flow. The current computational work provides a background for a novel method wherein liquid additives can be injected into the melted polymer. A converging nozzle providing a near constant extension rate along the center-line is modelled. The deformation of droplets inside a polymer undergoing a purely extensional flow is studied for a range of exit (V) to platen velocities (U) and viscosity ratios (λ). It is observed that the behavior of droplets for a λ = 1 is found to be drastically different from that of lower λ’s, which is attributed to the balance of shear stresses at the interface of the inner and outer flow fields. Finally, the morphology of the deposited plastic strands is also predicted. It is seen that as the velocity ratio is increased the cross-section of the deposited strand changes from being almost spherical to an oblong.