About

Huck Beng Chew is a Professor, Associate Head, and Director of Graduate Studies at the Department of Aerospace Engineering at the University of Illinois Urbana-Champaign. His research focuses on areas within aerospace engineering, including aerospace materials, structures, and systems design and simulation. He is involved in advancing knowledge and education in these fields, contributing to the department's academic and research missions.

Research topics

• Composite material
• Materials science
• Condensed matter physics
• Nanotechnology
• Physics
• Geometry
• Optics
• Optoelectronics

Selected publications

• Sticking Coefficient Effects on the Carbon Deposition Rates in an Electric Propulsion Testing Chamber

  2025-01-03

  articleSenior author

  Ground testing is essential for understanding carbon sputtering caused by interactions between thruster beam ions and chamber walls. These interactions lead to back-sputtered carbon particles, which can contaminate the thruster. This study employs kinetic simulations with two distinct sputter models to analyze the deposition rate of back-sputtered carbon at the thruster exit. Previous studies have shown that yield models and angular distributions significantly influence sputtering behavior, often without considering the effects of sticking coefficients. In this work, we emphasize the role of energy distribution in determining deposition rates. Sticking coefficients, derived from molecular dynamics simulations as functions of incident energy and angle, are incorporated through post-processing the numerical results. While sticking coefficients from two different models are similar at normal incidence, our findings highlight a critical difference at high angles of incidence, we found that the Sigmund-Thompson energy distribution results in lower sticking coefficients compared to those derived from molecular dynamics based energy distributions. This discrepancy indicates that in future full chamber simulations using MD-based sticking coefficients, secondary carbon emissions from the sidewalls are likely to influence the deposition rate on the thruster.

  PublisherDOI

• In situ synchrotron X-ray diffraction and crystal plasticity studies of the deformation and fatigue crack growth behavior in a TRIP-assisted advanced high strength steel

  Acta Materialia · 2025-05-06 · 9 citations

  articleOpen access
  PublisherOA PDFDOI

• Threshold energy for sputtering of monoatomic surfaces with noble gas ions

  Scripta Materialia · 2025-02-06 · 2 citations

  articleOpen accessSenior authorCorresponding

  Sputtering has revolutionized nano- and micro-scale manufacturing, but can cause wear in crucial components in contact with plasmas. To control sputtering, a critical but elusive quantity is the threshold energy for sputtering initiation, often obtained from empirical extrapolation of sputtering yield data that have large uncertainties at low ion energies. Using molecular dynamics simulations, we quantify the sputtering threshold energies of monoatomic surfaces under the bombardment of noble gas ions at normal incidence angle across a broad range of ion-target combinations. We relate the resulting threshold energies to the ion-target properties through an evolutionary algorithm for symbolic regression, and show a strong functional dependence on the nucleus charge governing ion-target repulsion and the target density, in addition to the heat of sublimation and ion-target mass ratio in prior semi-empirical models. This new data-driven formulation improved predictions by an order-of-magnitude, and is applicable to crystalline and amorphous targets.

  PublisherDOI

• Metal passivation strengthens the interface in titanium composites reinforced with boron nitride nanotubes

  Materialia · 2025-02-08 · 1 citations

  articleCorresponding
  PublisherDOI

• Molecular Dynamics Modeling of the Forces on [EMIM][BF4] Ion Emissions and Emission Rates Due to Applied Electric Fields

  2025-01-03

  articleSenior author

  Ionic liquids are stable propellants that are candidates for use with electrospray propulsion systems. Ionic liquids such as [EMIM][BF4] can be ionized by electric fields to produce emissions through various mechanisms including fragmentation. Processes like fragmentation can lead to reduced efficiency or erosion and need to be modeled at high-fidelity to develop a relationship between operating parameters such as the strength of the applied electric field and the resulting plume composition. By introducing a nanopore that allows us to maintain a curved liquid-vacuum interface, we are able to replicate the meniscus that forms at the tip of an electrospray emitter where ion emissions are produced when the applied electric field is able to overcome the surface tension of the liquid. Using ensembles of molecular dynamics simulations, it is possible to quantify the emissions produced by applying uniform electric fields of 1, 2, 4, or 6 V/nm for over 2 ns. These simulations reveal that the number of emissions and cumulative charge increase with the applied electric field. As the magnitude of the electric field increases from values of 1 or 2 V/nm to 4 or 6 V/nm, the predominant emission mechanism changes from heavier species such as dimers to lighter monomers. This atomistic model shows that as the electric field increases, it becomes easier to overcome the surface tension forces on the oscillating chains of ions that emerge at the liquid-vacuum interface to produce ion emissions. Lighter monomers can be cleaved from these chains more easily with stronger applied electric fields leading to fewer dimer and trimer emissions overall. The emissions counts and cumulative charge profiles computed from these simulations reveal that by controlling the applied electric field, it is possible to bias the ion emissions toward fewer dimer or trimer emissions. This is crucial to preventing the emission of heavier ion species that may fragment to create charged products that move at reduced velocities or neutral [EMIM][BF4] that cannot be accelerated further by the electric field.

  PublisherDOI

• Electric field control of monomer and dimer emissions in the EMIM–BF4 ionic liquid

  The Journal of Chemical Physics · 2025-07-10

  articleSenior author

  Achieving fine control over the thrust and specific impulse from electrospray thrusters requires fundamental understanding of the microscale mechanisms governing the types of ion emissions at the emitter tips. Using all-atom molecular dynamics (MD) simulations, we model the pressurized flow of 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM-BF4) ionic liquid out of a nanopore to form a convex meniscus, representative of the liquid surface at the emitter-tip, which in turn is subjected to a uniform electric field. Results show that most emitted species are dimers at low electric fields (∼1 V/nm), transitioning to combined monomer and dimer emissions at intermediate electric fields (∼2-4 V/nm), with predominantly monomer emissions at high electric fields (∼6 V/nm). This dimer-to-monomer transition with electric field strength is correlated with the corresponding increase in per-atom stress fluctuations along single interconnected molecular chains of alternating cations and anions at the tip of the Taylor cone, allowing for scission of shorter chains to emit monomers at higher electric fields and scission of longer chains to emit dimers and trimers at lower electric fields. Our coarse-grain MD simulations reveal qualitatively similar emission mechanisms to the all-atom MD simulations, with comparable instantaneous currents during steady-state ion emissions (∼1-8 nA) under electric field strengths of relevance to experiments.

  PublisherDOI

• Comparison of molecular dynamics informed particle-in-cell carbon sputter simulations with ground facility experiments

  Journal of Applied Physics · 2025-08-13

  articleOpen accessSenior author

  Accurate tracking of sputtered carbon species is crucial in assessing the lifetime of critical components in high-power electric propulsion systems. This study investigates carbon sputtering in high-power electric propulsion (EP) systems through comparison of numerical modeling and measurements obtained based on a new experimental technique that utilizes isotopic tracking. Sputter yield and differential yield models from molecular dynamics (MD) simulations were integrated into macroscopic particle-in-cell (PIC) plume simulations to predict carbon transport and deposition observed during the experiment. By coarse-graining the MD results from the atomistic length-scale to the meoscale PIC length scale, the study shows that the high-fidelity sputtering model captures the experimental trends. Comparison of experimentally measured carbon fluxes with predictions was found to be in agreement within a factor of two and with similar spatial distribution. Additional factors that might account for the difference between experiment and predictions, such as the roughness of the carbon target as well as the possible tilt relative to the ion beam axis, were considered. It was found that tilt effects lowered the discrepancy by up to 58%, depending on the probe location. Comparison of different sputter models revealed that the choice of angular and energy distributions significantly affects the results, emphasizing the need for accurate physics-based modeling. These results demonstrate the capability of the proposed numerical model to simulate carbon sputtering in EP testing facilities, providing a robust framework for future studies.

  PublisherOA PDFDOI

• Microscale strain field predictions from grain microstructure of polycrystalline metals using fully convolutional networks

  International Journal of Solids and Structures · 2025-12-04 · 1 citations

  articleOpen accessSenior author
  PublisherDOI

• Atomistic investigation of interface-dominated deformation mechanisms in nanolayered Cu–Ag eutectic alloy

  Journal of Materials Science · 2024-08-01 · 3 citations

  article
  PublisherDOI

• Carbon Transport in Electric Propulsion Testing – I: Multiscale Computations for Carbon Sputtering by Low Energy Ion Bombardment

  2024-01-04 · 2 citations

  articleSenior author

  A quantitative assessment of carbon transport during ground-based testing of high-power electric propulsion (EP) thrusters is essential for accurate lifetime assessment. Novel experimental carbon tracking techniques based on isotopic labeling of 13C, in concert with Direct Simulation Monte Carlo (DSMC) plasma simulation techniques, have added the capability to elucidate the effects of carbon contamination on critical EP surfaces. Here, a multiscale sputtering simulation framework is used to inform and validate these carbon transport experimental-simulation models. Specifically, molecular dynamics (MD) simulations, upscaled to Monte Carlo (MC) simulations are adopted to quantify the relevant macroscopic sputtering properties (sputter yield, angle, and energy) of carbon under krypton ion bombardment at 300 eV. The multiscale sputtering simulation is able to capture the smoothening behavior observed from post-sputtered surface analysis of a 13C pellet from a hall thruster. The sputtering properties from our MD-MC models will be used to inform the boundary conditions of the DSMC-based carbon transport model.

  PublisherDOI

Recent grants

• Collaborative Research: Mechanics of Tough and 3D Printable Ceramic Nanocomposites

  NSF · $315k · 2024–2027

• Collaborative Research: Experimental and Computational Nanomechanics of the Load Transfer Mechanisms at the Graphene Polymer Interface

  NSF · $203k · 2015–2019

• Collaborative Research: Exploiting Nanoscale Interfaces to Enhance Bulk Mechanical Response of Additively Manufactured Boron Nitride Nanotube-Metal Composites

  NSF · $336k · 2020–2024

• Collaborative Research: Fracture Toughness of Lithium-Ion Battery Electrodes: An Integrative Experimental and Computational Study

  NSF · $181k · 2013–2016

• Collaborative Research: EAGER: Active Self-Strengthening and Reinforcement of Additively Manufactured Metal Nanocomposites in a Corrosive Environment

  NSF · $150k · 2024–2027

Frequent coauthors

• T.F. Guo

  Gannan Medical University

  14 shared

• Kyung–Suk Kim

  Brown University

  14 shared

• Li Cheng

  University of Alberta

  13 shared

• Haoran Wang

  10 shared

• Abhilash Harpale

  University of Illinois Urbana-Champaign

  9 shared

• Ruizhi Li

  Beihang University

  9 shared

• Deborah A. Levin

  9 shared

• Huy Tran

  8 shared

Labs

• Experimental Robotics LabPI

Awards & honors

• Fellow of the Institute of Mechanical Engineers, FIMechE (si…
• College of Engineering at Illinois Alumni Award for Distingu…
• Alumni Award for Distinguished Service