Most important Publications

My publication standards are relatively high, as I prioritize quality over quantity. On average, each of the articles for which I am the main author has generated  130,000 in research funding.

THERE foundation

V. N. Khiêm, M. Jabareen, R. Poudel, X. Tang & M. Itskov (2024). “Modeling of textile composite using analytical network-averaging and gradient damage approach”, Journal of the Mechanics and Physics of Solids, 193, 105874.

In collaboration with Prof. Mahmood Jabareen (Technion – Israel Institute of Technology), I developed a thermodynamic regularization methodology (THERE) applicable to a wide range of materials with distinct thermodynamic behavior, while ensuring the physical interpretability of both parameters and results. I used this article, which presents the first theory capable of describing both fiber sliding and fiber bending in textile reinforcements, to demonstrate the performance of THERE in strictly positive internal dissipative materials. Based on this, I developed a successful Newton International Fellowship proposal that secured funding for my own research at Swansea University (DSLgene project, with a total funding volume ≈ 350,000€)

SIC discovery

V. N. Khiêm & J.-B. Le Cam (2024). “A comprehensive exploration of strain-induced crystallization through surface calorimetry and thermodynamics analysis’, Constitutive Models for Rubbers XIII

Here, I initiated my first steps in data collection by a collaboration with Prof. Jean-Benoît Le Cam (University of Rennes). We are the first who accurately discovered strain-induced crystallinity in cyclic loading of natural rubbers using quantitative surface calorimetric data, thereby circumventing the complexity and cost of traditional X-ray diffraction measurements. This research facilitates microstructural observations of natural rubbers in small laboratories and companies.

Microbubble dynamics

M. Xuan, J. Fan, V. N. Khiêm, M. Zou, K.-O. Brenske, A. Mourran, R. Vinokur, L. Zheng, M. Itskov, R. Göstl & A. Herrmann (2023) “Polymer Mechanochemistry in Microbubbles”, Advanced Materials, 35(47), 2305130.

This study arised from my collaboration with chemists, I was solely accountable for physical modeling and data analysis. I determined that, for a given shell thickness, tailoring microbubble diameters and crosslink densities can optimize chain scission during sonication, a vital aspect in enhancing drug delivery efficacy under ultrasonication. This collaboration resulted in a successful research proposal that secured funding for our research groups (ACTISONO project, total funding volume 3,666,000€, in which 200,000€ was allocated to RWTH Aachen University).

Unequilibrium theory of SIC

V. N. Khiêm, J.-B. Le Cam, S. Charlès & M. Itskov (2022), "Thermodynamics of strain-induced crystallization in filled natural rubber under uni- and biaxial loadings, Part II: Physically-based constitutive theory", Journal of the Mechanics and Physics of Solids, 159, 104712.

In this work, the previous equilibrium theory of SIC (JMPS 2018) was extended to address phase transitions occurring outside of thermodynamic equilibrium. This is the first theory capable of predicting SIC in equibiaxial tension of filled natural rubber.

Ah extension to thermodynamics of internal variables

V. N. Khiêm, T.-T. Mai, K. Urayama, , J. P. Gong & M. Itskov (2019), “A Multiaxial Theory of Double Network Hydrogels", Macromolecules 52(15), 5937-5947

This is the first theory capable of interpreting the newly observed damage cross-effect, a distinctive feature of modern soft materials like multiple-network hydrogels.

Local model for NCF

V. N. Khiêm, H. Krieger, M. Itskov, T. Gries & S. E. Stapleton (2018) "An averaging based hyperelastic modeling and experimental analysis of non-crimp fabrics", International Journal of Solids and Structures, 154, 43-54.

The first local constitutive theory for non-crimp fabrics (NCF) was proposed which accounts for multiple mesoscopic characteristics of NCF such as fiber volume fraction, fiber dispersion as well as fabric bending stiffness. A simplified version of this model was utilized by Audi. Based on this paper, I took the initiative to develop a comprehensive research proposal that secured funding from German Research Foundation for the department (DFG project number 408311698, allocated budget to RWTH Aachen University ≈200,000€) during my PhD.

Ah + AI extension to mechanoluminescence

V. N. Khiêm & M. Itskov (2018). Analytical network-averaging of the tube model: Mechanically induced chemiluminescence in elastomers. International Journal of Plasticity, 102, 1–15.

In this paper, I introduced the first theory that explains and identifies the classically mysterious internal variables in continuum mechanics through bond scission (damage) -induced light emission in mechanoresponsive elastomers. Based on this, I developed a successful research proposal that secured funding for my own research group (DFG project number 492017525, with a total funding volume ≈760,000€, in which 300,000€ was allocated to RWTH Aachen University.

Ah + AI extension to phase transition

V. N. Khiêm & M. Itskov (2018) "Analytical network-averaging of the tube model: Strain-induced crystallization in natural rubber", Journal of the Mechanics and Physics of Solids, 116, 350-369.

I proposed novel concepts regarding internal energy and two types of crystallites to elucidate the mechanisms of heat generation and absorption in natural rubbers. Based on this paper, I developed a successful research proposal that secured funding for the department (DFG project number 500476685, total funding volume ≈240,000) during my postdoc.

AI foundation

V. N. Khiêm & M. Itskov (2017) "An averaging based tube model for deformation induced anisotropic stress softening of filled elastomers", International Journal of Plasticity, 90, 96–115.

Here, I developed an analytical inelasticity theory (AI) based on a single potential (Helmholtz free energy), representing the first theory applicable to any irreversible process in continuum mechanics. I demonstrated the AI method through an example involving deformation-induced anisotropic damage in filled elastomers. A simplified version of this model was subsequently used by Porsche.

Ah foundation

V. N. Khiêm & M. Itskov (2016) "Analytical network-averaging of the tube model: Rubber elasticity", Journal of the Mechanics and Physics of Solids, 95, 254–-269.

Here, I established a unique analytical homogenization scheme Ah (named analytical network-averaging) applicable to various materials, which consistently yields analytical representations of microscopic strain measures. Its performance was illustrated by integration into a statistical-mechanically based isotropic constitutive model.