About

Hyonny Kim earned a Ph.D. in 1998 from UC Santa Barbara and became a postdoctoral researcher at UCSB from 1999 to 2001. He then joined the faculty at Purdue University. His research focuses on impact effects on composite materials and structures with aerospace and other applications, multifunctional materials, nano-materials, and adhesive bonding. He is active in the American Society for Composites, serving as the editor for the society, and participates in revisions of the Composites Mil-handbook 17.

Research topics

• Materials science
• Composite material
• Computer Science
• Engineering
• Electrical engineering
• Optoelectronics
• Metallurgy
• Geometry
• Structural engineering
• Acoustics

Selected publications

• Effect of Manufacturing-Induced Geometric Imperfections on the Compressive Response of Aluminum Honeycomb Cores

  SSRN Electronic Journal · 2025-01-01

  preprintOpen access
  PublisherDOI

• Damage Identification of Composite Laminate Impact Delaminations with Dual-Tone Steady-State Ultrasonic Excitation and Nonlinear Signature Analysis

  2025-09-09

  articleOpen access

  Composite layered materials offer many engineering advantages including high strength-to-weight ratio, tailorable material properties, and high fatigue resistance. Detection of small intra-layer delaminations that occur during manufacturing or while in the service environment are critical to ensure that the structure maintains its designed performance. Nondestructive evaluation (NDE) methods, such as ultrasonic testing, can identify hidden defects and damage, but detection can be challenging because the separated layers often remain in physical contact and prevent ultrasonic waves from scattering. Simultaneous multi-frequency excitation has the ability to incite contact acoustic nonlinearities and unique ultrasonic scattering patterns which can be observed within the ultrasonic signatures of the harmonics and mixing frequencies. Acoustic steady-state excitation spatial spectroscopy (ASSESS) is a full-field ultrasonic NDE inspection technique. ASSESS implements a steady-state ultrasonic excitation using a transducer and rapidly measures a structure’s surface velocity response using a laser Doppler vibrometer (LDV). The measurement product is a complex-valued wavefield response mapped to the surface geometry. This research investigates the presence of nonlinear signatures in a dual tone ASSESS measurement of a composite laminate panel with three impact delaminations. From a single measurement, complex velocity wavefield maps are calculated at the two excitation frequencies and additional harmonic and mixing frequencies. Contact acoustic nonlinearity signatures are identified as changes in response amplitude over certain frequencies. Spatial and temporal frequency and image processing methods are applied to individual wavefield images to identify damage locations.

  PublisherOA PDFDOI

• Special Issue on Impact and Dynamic Response

  Journal of Composite Materials · 2024-12-16

  articleSenior author
  PublisherDOI

• An ultrasonic scanning system for damage detection in composite built-up panels by inversion of guided wave dispersion curves

  2023-04-18

  article

  This paper proposes an ultrasonic scanning system for the inspection of stiffened composite panels used in modern aircraft construction. Conventional ultrasonic scanning systems usually track individual features of the propagating waves (e.g. amplitude, velocity, etc. at specific frequencies). The proposed scanning system, instead, is able to track the full dispersion curve across a significant frequency range, and, through an inversion process, to identify the elastic constants of the panel at each scanning position for an enhanced inspection. The proposed scanning system utilized a “single-input-dual-output" (SIDO) scheme whereby ultrasonic guided waves are excited by an impact and detected by two air-coupled ultrasonic sensors. At each scanning point, the system extracts the phase velocity dispersion curves of the panel via a phase spectral analysis of the measured waveforms. The measured dispersion curve is then fed to an inversion algorithm that identifies the composite engineering constants through an optimization loop. The Semi-Analytical Finite Element (SAFE) method is used as the forward model in the inversion procedure. Validation experiments were performed on a stiffened skin-to-stringer CFRP panel with impact-type damage present on the hat shape stringer cap. The system showed an ability to detect the internal damage with access only to the outer skin. The ability to track the elastic constants of the test part is quite relevant to the ultimate goal of determining the part residual strength using the ultrasound scanning system.

  PublisherDOI

• Interaction of compression failure mechanisms in composites with ply waviness defects

  Composite Structures · 2023-04-28 · 4 citations

  articleSenior author
  PublisherDOI

• Ultrasonic Guided Waves Generated by Parametrized Novel Mini Impactor with Application to a Composite Structure

  Conference proceedings of the Society for Experimental Mechanics · 2022-01-01 · 1 citations

  book-chapterSenior author
  PublisherDOI

• Experimental Investigations of Carbon-Epoxy Composites with Ply Waviness Under Cyclic Bending

  AIAA SCITECH 2022 Forum · 2022-01-03 · 1 citations

  articleSenior author

  View Video Presentation: https://doi.org/10.2514/6.2022-0667.vid This article presents results from an experimental investigation of composite laminates manufactured with ply waviness defects and tested in a sandwich beam configuration. The sandwich beam specimens with composite facesheets are loaded under quasi-static and fully reversed cyclic loading in a four-point bend configuration. The manufacturing variability of the ply waviness defect characteristic features (misalignment angle, waviness length and amplitude, and ply thickness changes) was analyzed, and a correlation between the waviness features and failure response was established. High-resolution imaging and digital image correlation (DIC) analysis are used for monitoring the strain fields developing near the wavy ply region, and explanations of the failure mechanisms nucleating in the material are presented. Under quasi-static loading, the peak load associated with compression failure shows a strong correlation with the ply waviness misalignment angle and waviness length. Under fully reversed cyclic loading, the initiation, interaction, and evolution of failure mechanisms are significantly different compared to those observed in quasi-static loading conditions. Possible explanations on the sequence of fatigue damage events, informed by DIC analysis and optical microscopy are presented.

  PublisherDOI

• Non-destructive damage localization in built-up composite aerospace structures by ultrasonic guided-wave multiple-output scanning

  Composite Structures · 2022-05-04 · 17 citations

  articleSenior author
  PublisherDOI

• IMPACT DAMAGE AND INJECTION REPAIR STRENGTH RESTORATION

  2021-09-20

  articleSenior author

  Impact damage to composite structures can lead to a range of damage modes. Of interest is modest damage composed of delaminations less than 50 mm in size, and no visible impact-side fiber breakage. While resin injection is a current-practice repair technique that can be used to address these damage modes in a manner that is much less invasive than bonded scarf patch repair, the injection technique is not currently credited as one restoring strength back to laminate. Issues of quantifying the removal of any internal contamination, assessing degree of resin fill, and demonstration of how much strength is restored are being addressed within the scope of this research activity. Resin injection will be conducted and the resulting strength restoration assessed in local fracture tests (end-notch flexure). The formation of actual impact damage morphologies, namely multiple planes of delamination interconnected with matrix cracks, is a critical aspect of this problem. Three 25-ply composite panel types having varying percentage of 0o fiber content have been impacted under low velocity at a range of energy levels. Resulting force vs. time and ultrasonic mapping of damage extent. Damage produced by such impacts will be used in subsequent injection repair studies. Intentional contamination will be introduced, and then removal will be achieved via injected solvents and atmospheric plasma, with monitoring of contaminant presence achieved by in-line quantitative chemical analysis.

  PublisherDOI

• Characterization and Modeling of Cell Wall Imperfections in Aluminum Honeycomb Cores using X-ray CT Imaging

  AIAA Scitech 2021 Forum · 2021-01-04 · 4 citations

  article

  View Video Presentation: https://doi.org/10.2514/6.2021-1620.vid Honeycomb cell imperfections, may significantly affect the failure of sandwich composites in core crushing and shear modes. Identification and quantification of the different types of imperfections and evaluation of their effects on the mechanical response of honeycomb cores in flatwise compression is presented. X-Ray computed tomography (CT) scans of honeycomb cores in co-cured composite sandwich panels were performed. Image analysis methods are applied to characterize and quantify core cell geometry and cell wall waviness. An approach is developed for extracting cell wall mid surface planes and waviness for constructing finite element models using shell elements. Analysis results from models with the as-manufactured imperfections are compared to results from models with idealized geometries to evaluate the effect of the as-manufactured imperfections on the initiation of cell wall buckling and subsequent core crushing.

  PublisherDOI

Frequent coauthors

• Jennifer Rhymer

  9 shared

• Francesco Lanza di Scalea

  University of California, San Diego

  9 shared

• Daniel Whisler

  8 shared

• Andrew Ellison

  8 shared

• Keith T. Kedward

  University of California, Santa Barbara

  6 shared

• Zhenhua Song

  Central South University

  6 shared

• Benjamin J. Katko

  University of California, San Diego

  6 shared

• Gabriela K. DeFrancisci

  University of California, San Diego

  5 shared

Education

• Ph.D.

  UC Santa Barbara

  1998

• Other

  UC Santa Barbara

Awards & honors

• Gareth Thomas Materials Excellence Award