HKU ME
Alfonso Ngan's
 𝚈𝚘𝚞𝚝𝚞𝚋𝚎
1053

Dislocation Density Function Dynamics DDFD

DDFD's Website Banner

In dislocation density function dynamics (DDFD), developed by Alfonso H.W. Ngan of the University of Hong Kong, the evolution of “all-dislocation” density (ADD) is governed by a simple kinematic evolution equation [13]:

ρ̇ ( r,θ ) = - ( ρ v ) r θ̂ movement - ( ρ ω ) θ tilting
All-dislocation kinematic equation

DDFD Presentation Slides HKU Mech Engg

1 / 36
Page 1
2 / 36
Page 2
3 / 36
Page 3
4 / 36
Page 4
5 / 36
Page 5
6 / 36
Page 6
7 / 36
Page 7
8 / 36
Page 8
9 / 36
Page 9
10 / 36
Page 10
11 / 36
Page 11
12 / 36
Page 12
13 / 36
Page 13
14 / 36
Page 14
15 / 36
Page 15
16 / 36
Page 16
17 / 36
Page 17
18 / 36
Page 18
19 / 36
Page 19
20 / 36
Page 20
21 / 36
Page 21
22 / 36
Page 22
23 / 36
Page 23
24 / 36
Page 24
25 / 36
Page 25
26 / 36
Page 26
27 / 36
Page 27
28 / 36
Page 28
29 / 36
Page 29
30 / 36
Page 30
31 / 36
Page 31
32 / 36
Page 32
33 / 36
Page 33
34 / 36
Page 34
35 / 36
Page 35
36 / 36
Page 36
P. 1
P. 2
P. 3
P. 4
P. 5
P. 6
P. 7
P. 8
P. 9
P. 10
P. 11
P. 12
P. 13
P. 14
P. 15
P. 16
P. 17
P. 18
P. 19
P. 20
P. 21
P. 22
P. 23
P. 24
P. 25
P. 26
P. 27
P. 28
P. 29
P. 30
P. 31
P. 32
P. 33
P. 34
P. 35
P. 36





[1] H.S. Leung and A.H.W. Ngan, J. Mech. Phys. Solids 91, 172–203 (2016). (DOI: 10.1016/j.jmps.2016.03.008)
[2] A.H.W. Ngan, MRS Commun. 7 (3), 583–590 (2017). (DOI: 10.1557/mrc.2017.66)
[3] Alireza Kalaei, Yang Xiang, and Alfonso H.W. Ngan, Int. J. Plast. 158, 103433 (2022). (DOI: 10.1016/j.ijplas.2022.103433)

About Professor Alfonso Ngan Hing Wan顏慶雲教授
 Professor Alfonso H.W. Ngan (顏慶雲教授) is currently Kingboard Professor in Materials Engineering, Chair Professor of Materials Science and Engineering, as well as Head of Department of Mechanical Engineering, at the University of Hong Kong. He obtained his BSc (Eng) degree from the University of Hong Kong (HKU) in 1989 as the Williamson Prizeman (top Engineering graduate), and PhD from the University of Birmingham in the U.K. in 1992. After a year of postdoctoral training at Oxford University, he joined HKU in 1993, and was promoted through the ranks to Chair Professorship in 2011.
 Professor Alfonso Ngan is a leading authority in the microstructural basis of properties of engineering materials, in particular, crystalline defects and their modeling, and nanomechanics including applications to biological systems. He has published over 200 ISI papers, and co-authored two books. His main contributions include a method, the so-called “Feng-Ngan equation”, for correcting viscoelastic effects in nanoindentation measurements of soft materials, which has been used by peer researchers in their work as reported in more than 100 ISI publications by now. His research-related honours include the prestigious Rosenhain Medal and Prize from the Institute of Materials, Minerals and Mining, U.K., in 2007—he is the only non-British national so far to have received this award since its establishment in 1951. He was also awarded a higher doctorate (DSc) from his alma mater the University of Birmingham in 2008, the Croucher Senior Research Fellowship in 2009, Fellow of the Hong Kong Academy of Engineering Sciences (FHKEng) in 2014, Changjiang Professorship from the Chinese Ministry of Education in 2019, the Guanghua Engineering Science and Technology Prize of the Chinese Academy of Engineering (CAE) in 2020, and in 2021 he was elected International Fellow of the Royal Academy of Engineering (FREng). In 2024, he received the prestigious Hong Kong Institution of Engineers (HKIE) Grand Award for his “Rate-jump Method for Nanomechanical Testing”.
 Professor Alfonso Ngan is an expert advisor to the Hong Kong Government's Water Supplies Department, solving problems including lead-leaching in potable-water systems and corrosion in Hong Kong's unique sea-water flushing system, and is a Trustee of the Croucher Foundation. He has played advisory roles in a number of government committees and tertiary institutions. He is serving on the Gordon Research Conference Board for Hong Kong Conferences. He served as one of five Meeting Chairs in the Materials Research Society (MRS) 2017 Spring Meeting held in Phoenix, Arizona, USA, on 17–21 April 2017. 

Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, P.R. China

Novel Thin-film Actuating Materials Group (Alfonso's Experimental Research) @hku-mechanicalactuatingmat7569

Croucher Scholar Page: Alfonso Hing-wan Ngan - 顏慶雲 教授

HKAES Distinguished Lecture (2023) by Guanghua Award recipient Prof. A.H.W. Ngan

HKIE Grand Award for Invention category (2024) project article by Prof. A.H.W. Ngan []