Prof. Soh Ai Kah
Head of Discipline (Mechanical Engineering)
School of Engineering
Constitutive theory and toughening mechanisms of advanced materials; micro/nano mechanics of deformation and fracture; electromagnetic solid mechanics; multi-scale modelling
Published more than 270 ISI journal papers; obtained more than US$3 million competitive research funding for studying advanced functional materials.
(i) Visiting Professor; Singapore university of technology and design; Year of award: 2016
(ii) Visiting Professor; The University of Hong Kong; Year of award: 2013
(iii) Fellow, C.Eng.; Institute of Mechanical Engineering (UK); Year of award: 2012
(iv) Advisory Board Member; Acta Mechanica (SCI Journal); Year of award: 2010
(v) Visiting Professor; Brown University; Year of award: 2010
(vi) Handling Editor and Editorial Board Member; Functional Materials Letters (SCI Journal); Year of award: 2009
(vi) Visiting Professor; National University of Singapore; Year of award: 2008
(vii) Fellow; Hong Kong Institute of Engineers; Year of award: 2005
(viii) Universitas 21 Fellowship; The University of Hong Kong; Year of award: 2005
(ix) Senior Visiting Professor; ‘Failure Mechanics’ Lab. (Key Lab.) of Tsinghua University; Year of award: 2000
- Doctor of Philosophy, University of Surrey, 1980
- Degree in Engineering, National University of Singapore, 1975
Member of International Professional Bodies
- IMechE, FIMechE; CEng
Constitutive theory and toughening mechanisms of advanced materials; micro/nano mechanics of deformation and fracture; electromagnetic solid mechanics; multi-scale modelling.
Title: Development of spintronics and energy storage and conversion devices using nanostructured multiferroic materials
Multiferroics (MFs) possess two or more types of order parameters simultaneously that couple the electric, magnetic and elastic responses. The magnetoelectric (ME) coupling of such materials has attracted increasing attention due to possible manipulation of magnetization by applied electric field or polarization by magnetic field. It has been found that the increase of interfacial effects of such materials, by reducing the material or component size to nano-scale, would not only significantly increase the ME coupling effect, but also evoke the emergence of many novel properties due to the interactions of the charge, spin, lattice and orbital degrees of freedom at interfaces. Thus, we propose to study interface dominated multiferroic nanostructures (IDMNS). Since IDMNS are still hardly available due to the difficulty of fabrication, the fabrication method for IDMNS will be evaluated first. Subsequently, by combining the results of first principles calculations and experimental characterization, the components and structures of IDMNS will be optimized for attaining larger ME coupling and other possible unique properties. A multi-scale modeling framework will be established to investigate the ME coupling behavior of MF nano-composites (MNCS). At nanoscale, the existing mesoscopic phase field method will be modified to make it suitable for evaluating the evolution of domain structure and polarization of the system. At micro-scale, an energy approach will be used to study the interfacial influence on the ME effect of the system.
Upon successful completion of the project, the interfacial effects on the ME coupling behavior and the induced novel properties will be better understood. Moreover, the approach to optimize the IDMNS for maximizing the ME coupling effect and/or other unique properties will also be established. The potential applications of IDMNS, especially in the scope of spintronics and energy storage and conversion devices, will also be explored and developed.
Title: Impact of stress generation on insertion battery performance under intercalation dynamics
High power rechargeable Li-ion battery with long cycle life is one of the most promising candidates to power batteryelectric vehicles. Usually high power state needs high rate operation which produces significant diffusion-induced stress, and thus leads to mechanical degradation associated with a limited cyclic life. Electrode microstructural engineering has been found to be a promising way for reducing mechanical degradation and improving cyclability.
However, to-date no quantitative models have been devised for elucidating the influences of the electrode microstructure and electrochemical reaction on the diffusion-induced stress and, hence, the mechanical degradation upon cyclic intercalation. Thus, the main objective of the proposed project is to achieve a better understanding of the influence of electrode microst ructure and different charging/discharging operations on the stress-coupled intercalation dynamics through computational modeling and simulation study and, hence, exploring the approaches for withstanding the stress in different nanostructured electrodes. In the proposed project, a thermodynamically consistent phase field model is adopted to study the interplay among stress generation, Li-ion concentration evolution and electrode microstructure. A systematic computational modeling and simulation study will be carried out to ascertain the approaches for withstanding the stress in different electrode microstructures, and to determine the optimal electrode microstructure that can support high rate operation with superior cyclic life. Some layered nanocomposite electrode thin films will be fabricated and characterized to provide experimental data for validating the results obtained from the established theoretical modeland numerical simulation.
Upon successful completion of the proposed project, the following achievements would have been made:
1. Establishment of a phase field modeling framework to systematically investigate the effect of electrode microstructure on stress bearing.
2. Determination of optimized electrode microstructures for improving the cyclability of nanostructured electrodes.
MEC3455 - Solid Mechanics
Jin, Chuan Jian; Li, Hao Liang; Song, Yi Cheng; Lu, Bo; Soh, A. K.; Zhang, Jun Qian (2019) On stress-induced voltage hysteresis in lithium ion batteries: Impacts of surface effects and interparticle compression, Science China Technological Sciences, (1357-1364), Volume: 62, Issue Number: 16747321, 10.1007/s11431-018-9491-6
Ma, Long; Liu, Xuepeng; Soh, Ai Kah; He, Linghui; Wu, Changzheng; Ni, Yong (2019) Growth of curved crystals: Competition between topological defect nucleation and boundary branching, Soft Matter, (4391-4400), Volume: 15, Issue Number: 1744683X, 10.1039/c9sm00507b
Song, Y. C.; Soh, A. K.; Zhang, J. Q. (2016) On stress-induced voltage hysteresis in lithium ion batteries: impacts of material property, charge rate and particle size, Journal of Materials Science, (9902-9911), Volume: 51, Issue Number: 00222461, 10.1007/s10853-016-0223-y
Song, Y. C.; Li, Z. Z.; Soh, A. K.; Zhang, J. Q. (2015) Diffusion of lithium ions and diffusion-induced stresses in a phase separating electrode under galvanostatic and potentiostatic operations: Phase field simulations, Mechanics of Materials, (363-371), Volume: 91, Issue Number: 01676636, 10.1016/j.mechmat.2015.04.015
- Theoretical and experimental studies in support of the GaN-on-GaN light-emitting diodes (LED) national project led by CREST, Soh Ai Kah, Hung Yew Mun, etc., 2017-2019, CRM, Monash University Malaysia, RM200k
- Investigating the micron-scale cyclic plastic constitutive model based on strain gradient theories, Liu Jinxing, Soh Ai Kah, 2017 - 2020, NSFC (China), RM387k
Kueh Tze Cheng
MD simulations to study micro heat transfer
Monash University Malaysia
More than 25 students from The University of Hong Kong who undertook Ph.D. and M.Phil. successfully graduated with projects relating to micro-/nano-mechanics on ferroelectric and ferromagnetic materials from 2000 - 2013.
- FImechE (Professional qualification), CEng - IMechE
- FHKIE (Professional qualification) - Hong Kong Institute of Engineers (HKIE)