Kyriakos Komvopoulos

Prof. Kyriakos Komvopoulos

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Academic Career Length

42Years (1985-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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18 September 2007 in Nano Letters
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Journal Article
Closed access
KBKaitlin M. Bratlie
Kaitlin M. Bratlie
HLHyunjoo Lee
Hyunjoo Lee
KKKyriakos Komvopoulos
Kyriakos Komvopoulos
PYPeidong Yang
Peidong Yang
GSGabor A. Somorjai
Gabor A. Somorjai
1 October 1998 in Journal of Applied Physics
Verified
Journal Article
Closed access
WYW. Yan
W. Yan
KKKyriakos Komvopoulos
Kyriakos Komvopoulos
Rough surfaces are characterized by fractal geometry using a modified two-variable Weierstrass–Mandelbrot function. The developed algorithm yields three-dimensional fractal surface topographies representative of engineering rough surfaces. This surface model is incorporated into an elastic-plastic contact mechanics analysis of two approaching rough surfaces. Closed form solutions for the elastic and plastic components of the total normal force and real contact area are derived in terms of fractal parameters, material properties, and mean surface separation distance. The effects of surface topography parameters and material properties on the total deformation force are investigated by comparing results from two- and three-dimensional contact analyses and elastic and elastic-perfectly plastic material behaviors. For normal contact of elastic-perfectly plastic silica surfaces and range of surface interference examined, the interfacial force is predominantly elastic and the real contact area is approximately one percent of the apparent contact area or less, depending on the mean interfacial distance. The analysis can be easily modified to account for anisotropic fractal surfaces and different material behaviors.
14 June 2021 in Frontiers in Bioengineering and Biotechnology
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Journal Article
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MMMaria Ines Echeverria Molina
Maria Ines Echeverria Molina
KMKaterina G. Malollari
Katerina G. Malollari
KKKyriakos Komvopoulos
Kyriakos Komvopoulos
Numerous surgical procedures are daily performed worldwide to replace and repair damaged tissue. Tissue engineering is the field devoted to the regeneration of damaged tissue through the incorporation of cells in biocompatible and biodegradable porous constructs, known as scaffolds. The scaffolds act as host biomaterials of the incubating cells, guiding their attachment, growth, differentiation, proliferation, phenotype, and migration for the development of new tissue. Furthermore, cellular behavior and fate are bound to the biodegradation of the scaffold during tissue generation. This article provides a critical appraisal of how key biomaterial scaffold parameters, such as structure architecture, biochemistry, mechanical behavior, and biodegradability, impart the needed morphological, structural, and biochemical cues for eliciting cell behavior in various tissue engineering applications. Particular emphasis is given on specific scaffold attributes pertaining to skin and brain tissue generation, where further progress is needed (skin) or the research is at a relatively primitive stage (brain), and the enumeration of some of the most important challenges regarding scaffold constructs for tissue engineering.
14 June 2016 in Nature Communications
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Journal Article
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FSFeifei Shi
Feifei Shi
ZSZhichao Song
Zhichao Song
PRPhilip N. Ross
Philip N. Ross
GSGabor A. Somorjai
Gabor A. Somorjai
RRRobert O. Ritchie
Robert O. Ritchie
KKKyriakos Komvopoulos
Kyriakos Komvopoulos
Long-term durability is a major obstacle limiting the widespread use of lithium-ion batteries in heavy-duty applications and others demanding extended lifetime. As one of the root causes of the degradation of battery performance, the electrode failure mechanisms are still unknown. In this paper, we reveal the fundamental fracture mechanisms of single-crystal silicon electrodes over extended lithiation/delithiation cycles, using electrochemical testing, microstructure characterization, fracture mechanics and finite element analysis. Anisotropic lithium invasion causes crack initiation perpendicular to the electrode surface, followed by growth through the electrode thickness. The low fracture energy of the lithiated/unlithiated silicon interface provides a weak microstructural path for crack deflection, accounting for the crack patterns and delamination observed after repeated cycling. On the basis of this physical understanding, we demonstrate how electrolyte additives can heal electrode cracks and provide strategies to enhance the fracture resistance in future lithium-ion batteries from surface chemical, electrochemical and material science perspectives.
1 December 1996 in Wear
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Journal Article
Closed access
KKKyriakos Komvopoulos
Kyriakos Komvopoulos
1 September 2003 in Journal of Applied Physics
Verified
Journal Article
Closed access
LKL. Kogut
L. Kogut
KKKyriakos Komvopoulos
Kyriakos Komvopoulos
A general electrical contact resistance (ECR) theory for conductive rough surfaces was derived from first principles. The analysis is based on fractal geometry for the surface topography description, elastic-plastic deformation of contacting asperities, and size-dependent constriction resistance of microcontacts. Relations for the ECR in terms of contact load and apparent contact area are obtained for isotropic, homogeneous, conductive surfaces with known material properties and surface topography. Useful design guidelines for electrical contacts are extracted from the numerical results. A general relation between the dimensionless real contact area and the dimensionless ECR is introduced for lightly loaded contacts that depends only on the electron mean free path. Approaches for determining the surface roughness, material properties, and real contact area are discussed in the context of relatively simple ECR measurements.