About

Hongyi Xiao is an Assistant Professor in the Department of Mechanical Engineering at the University of Michigan. He holds a Ph.D. in Mechanical Engineering from Northwestern University, obtained in 2018, and a B.E. in Thermal Engineering from Tsinghua University, earned in 2014. His research group focuses on granular materials composed of discrete particles that can collectively behave like a solid, liquid, or gas. His work aims to reveal the solid and fluid mechanics as well as the statistical physics of these materials through a combination of 2D and 3D experiments, discrete particle simulations, and machine-learning informed modeling. His current research emphasizes understanding how granular materials deform from a structure-property perspective, with the goal of designing particle interactions and dynamics at the microscopic scale to achieve novel collective behaviors at the material scale. Additionally, he investigates how animals and robots interact with granular matter as a soft and yielding medium. His research areas include fluids, mechanics & materials, and multi-scale computation, contributing to the broader understanding of complex behaviors in granular systems and their applications.

Research topics

• Materials science
• Mechanics
• Composite material
• Statistical physics
• Geology

Selected publications

• Reciprocal swimming in viscoelastic granular hydrogels

  Journal of Fluid Mechanics · 2026-04-27

  articleOpen access1st authorCorresponding

  We experimentally study a scallop-like swimmer with reciprocally flapping wings in a nearly frictionless, cohesive granular medium consisting of hydrogel spheres. Significant locomotion is found when the swimmer’s flapping frequency matches the inverse relaxation time of the material. Remarkably, the swimmer moves in the opposite direction compared with its motion in a cohesion-free granular material of hard plastic spheres. At higher or lower frequencies, we observe no motion of the swimmer, apart from a short initial transient phase. X-ray radiograms reveal that the wing motions create low-density zones, which in turn give rise to a hysteresis in drag and propulsion forces. This time-dependent effect, combined with the swimmer’s inertia, accounts for locomotion at intermediate frequencies.

  PublisherOA PDFDOI

• Research on Optical Fiber Vibration Identification Technology Based on Big Data Analysis in Optical Cable Operation and Maintenance Early Warning

  Procedia Computer Science · 2025-01-01

  articleOpen access

  This paper aims to develop an optical fiber vibration identification system based on big data analysis to realize the real-time monitoring and data analysis of the running state of optical cable. The goal is to reduce the impact of sudden failures on the network by accurately analyzing fiber vibration data. Big data technology is adopted to process and analyze fiber vibration data, and data-driven method is used to provide decision support, including collecting large amounts of fiber vibration data, applying data mining technology to identify vibration patterns, and using to make fault prediction with machine learning algorithms. The implementation effect of the system shows that through real-time data monitoring and analysis, the stability of the network can be effectively improved, the ledger management and query method can be improved, the network panorama presentation and real-time monitoring can be realized, and the impact of sudden faults on the network operation can be significantly reduced. Through these measures, the system not only improves the reliability of the network, but also optimizes the fault management and early warning mechanism, providing strong support for the network maintenance and operation.

  PublisherDOI

• Locomotion of a scallop-inspired swimmer in granular matter

  Physical Review Applied · 2025-09-18

  article1st authorCorresponding
  PublisherDOI

• Disorder enhances the fracture toughness of 2D mechanical metamaterials

  PNAS Nexus · 2025-01-28 · 20 citations

  articleOpen access

  Abstract Mechanical metamaterials with engineered failure properties typically rely on periodic unit cell geometries or bespoke microstructures to achieve their unique properties. We demonstrate that intelligent use of disorder in metamaterials leads to distributed damage during failure, resulting in enhanced fracture toughness with minimal losses of strength. Toughness depends on the level of disorder, not a specific geometry, and the confined lattices studied exhibit a maximum toughness enhancement at an optimal level of disorder. A mechanics model that relates disorder to toughness without knowledge of the crack path is presented. The model is verified through finite element simulations and experiments utilizing photoelasticity to visualize damage during failure. At the optimal level of disorder, the toughness is more than 2.6× of an ordered lattice of equivalent density.

  PublisherOA PDFDOI

• DEM Simulation of the Powder Application in Powder Bed Fusion

  Springer tracts in additive manufacturing · 2025-01-01

  book-chapterOpen access

  Abstract The packing behavior of powders is significantly influenced by various types of inter-particle attractive forces, including adhesion and non-bonded van der Waals forces [4, 7, 8, 19, 41, 43]. Alongside particle size and shape distributions, the inter-particle interactions, particularly frictional and adhesive forces, play a crucial role in determining the flow behavior and consequently the packing density of the powder layer. The impact of various types of attractive forces on the packing density of powders with different materials and particle size distributions remains largely unexplored and requires further investigation. Accurately comprehending these effects through experiments while considering specific particle size distributions and material properties poses significant challenges.

  PublisherOA PDFDOI

• Locomotion of a Scallop-Inspired Swimmer in Granular Matter

  arXiv (Cornell University) · 2024-12-06

  preprintOpen access1st authorCorresponding

  Understanding swimming in soft yielding media is challenging due to their complex deformation response to the swimmer's motion. We experimentally show that a scallop-inspired swimmer with reciprocally flapping wings generates locomotion in granular matter. This disagrees with the scallop theorem prohibiting reciprocal swimming in a liquid when its inertia is negligible. We use X-ray tomography and laser profilometry to show that the propulsion is created by the combined effects of jamming and convection of particles near the wings, which break the symmetry in packing density, surface deformation, and kinematics of the granular medium between an opening and a closing stroke.

  PublisherOA PDFDOI

• Combined thermal and particle shape effects on powder spreading in additive manufacturing via discrete element simulations

  Powder Technology · 2024-07-23 · 11 citations

  articleOpen access

  The thermal and mechanical behaviors of powders are crucial for additive manufacturing. In powder bed fusion, capturing temperature profiles and packing structures before melting is challenging due to diverse heat transfer pathways and powder properties. This study tackles this challenge with a discrete element model simulating non-spherical particles with thermal properties during powder spreading. Thermal conduction and radiation are integrated into a multisphere particle formulation to model heat transfer among irregular-shaped powders with temperature-dependent elastic properties. The model is utilized to simulate the spreading of pre-heated PA12 powder over a hot substrate representing the part under manufacturing. Variances in temperature profiles are observed in the spreading cases based on particle shapes, spreading speed, and temperature-dependent elastic modulus. Particle temperature beneath the spreading blade is influenced by the kinematics of the particle heap and temperature-dependent properties.

  PublisherOA PDFDOI

• Structural fluctuations in thin cohesive particle layers in powder-based additive manufacturing

  Granular Matter · 2024-03-13 · 6 citations

  articleOpen access

  Abstract Producing dense and homogeneous powder layers with smooth free surface is challenging in additive manufacturing, as interparticle cohesion can strongly affect the powder packing structure and therefore influence the quality of the end product. We use the Discrete Element Method to simulate the spreading process of spherical powders and examine how cohesion influences the characteristics of the packing structure with a focus on the fluctuation of the local morphology. As cohesion increases, the overall packing density decreases, and the free surface roughness increases, which is calculated from digitized surface height distributions. Local structural fluctuations for both quantities are examined through the local packing anisotropy on the particle scale, obtained from Voronoï tessellation. The distributions of these particle-level metrics quantify the increasingly heterogeneous packing structure with clustering and changing surface morphology.

  PublisherOA PDFDOI

• Infinitely rugged intra-cage potential energy landscape in metallic glasses caused by many-body interaction

  Materials Today Physics · 2024-11-07 · 9 citations

  articleOpen access
  PublisherOA PDFDOI

• Combined thermal and particle shape effects on powder spreading in additive manufacturing via discrete element simulations

  arXiv (Cornell University) · 2024-02-23

  preprintOpen access

  The thermal and mechanical behaviors of powders are important for various additive manufacturing technologies. For powder bed fusion, capturing the temperature profile and the packing structure of the powders prior to melting is challenging due to both the various pathways of heat transfer and the complicated properties of powder system. Furthermore, these two effects can be coupled due to the temperature dependence of particle properties. This study addresses this challenge using a discrete element model that simulates non-spherical particles with thermal properties in powder spreading. Thermal conduction and radiation are introduced to a multi-sphere particle formulation for capturing the heat transfer among irregular-shaped powders, which have temperature-dependent elastic properties. The model is utilized to simulate the spreading of pre-heated PA12 powder through a hot substrate representing the part under manufacturing. Differences in the temperature profiles were found in the spreading cases with different particle shapes, spreading speed, and temperature dependence of the elastic moduli. The temperature of particles below the spreading blade is found to be dependent on the kinematics of the heap of particles in front, which eventually is influenced by the temperature-dependent properties of the particles.

  PublisherOA PDFDOI

Frequent coauthors

• D. J. Durian

  26 shared

• Paul B. Umbanhowar

  Northwestern University

  19 shared

• Richard M. Lueptow

  19 shared

• Robert Ivancic

  National Institute of Standards and Technology

  18 shared

• Andrea J. Liu

  15 shared

• Julio M. Ottino

  13 shared

• Robert A. Riggleman

  University of Pennsylvania

  9 shared

• Vasileios Angelidakis

  Queen's University Belfast

  9 shared

Education

• PHD student, Mechanical Engineering

  Northwestern University