Completed Research Work

Following are the projects completed during 2004-2011.
 
1. Mechanical properties of lead-free solder materials.
This project is to characterize the mechanical properties of the lead-free solder balls, the solder balls are in the size range of microns and attached on substrate, therefore, direct access their mechanical properties is difficult. In this project, nanoindentation is the major characterization tools to measure the mechanical properties of the solder balls. This project was done by Mr. B.S.S.Chandra Rao, he has been award Ph.D degree on Mechanical Engineering in 2013.
 
Some Recent Publications:
 
1. B.S.S.Chandra Rao, J.Weng, L.Shen, T.K.Lee and K.Y.Zeng, "Morphology and mechanical properties of intermetallic compounds in SnAgCu solder joints",
    MICROELECTRONIC ENGINEERING, 87, (2010), 2416 - 1422
2. B.S.S.Chandra Rao, K.Mohan Kumar, V.Kripesh and K.Y.Zeng, "Tensile deformation behavior of nano-sized Mo particles reinforced SnAgCu solders",
    MATERIALS SCIENCE AND ENGINEERING A, 528, (2011), 4168-4172. 

Ph.D Thesis:

1. Siva Suri Chandra Rao Bhesetti: Micromechanical Behavior of Lead-free Solder Joints Developed for 3D-Packaging Applications. Doctor of Philosophy, Department of Mechanical Engineering, National University of Singapore (2013).
  
 
2. Mechanical properties of piezoelectric single crystal materials.
This research area is to characterize the mechanical properties of PZN-PT piezoelectric single crystals. The effects of in-plane and out-plane poling are also studied. Nanoindentation, microindentation and Piezo-response Force Microscopy (PFM) are used to study the mechanisms of deformation before and after poling, PFM is used to study the domain structure and domain switch mechanisms in this materials. This project was done by Mr. Wong Meng Fei, he has been award Ph.D degree on Mechanical Engineering in 2012.
 
Some Recent publications:
 
1. M.F.Wong and K.Y. Zeng, "Mechanical polishing effects toward surface domain evolution in Pb(Zn1/3Nb1/3)O3-PbTiO3 single crystals".
   JOURNAL OF THE AMERICAN CERAMIC SOCIETY, 94, (2011), 1079-1086 
2. M.F.Wong and K.Y.Zeng, "Elastic-plastic Deformation of Pb(Zn1/3Nb2/3)O3-(6-7)%PbTiO3 Single Crystals during 
Nanoindentation",
   PHILOSOPHICAL MAGAZINE, 90, (2010),1685 - 1700.
3. K.Y.Zeng, Y.L.Ng, L.Shen, K.K.Rajan and L.C.Lim, "Deformation and Fracture Behavior of [011]-poled Pb(Zn1/3Nb2/3)O3-7%PbTiOSingle Crystals",
    MATERIALS SCIENCE AND ENGINEERING A, 498, (2008), 457‑463.
4. M.F.Wong and K.Y.Zeng, "Deformation Behavior of PZN‑6%PT Single Crystal during Nanoindentation".
    PHILOSOPHICA MAGAZINE, 88, (2008), 3105‑3120.
5. M.F.Wong, X.Heng and K.Y.Zeng, "Domain Characterization of Pb(Zn1/3Nb2/3)O3‑(6‑7%)PbTiO3 Single Crystals using Scanning Electron Acoustic Microscopy". 
   JOURNAL OF APPLIED PHYSICS, 104, (2008), 074103.
6. K.Y.Zeng, Y.S.Pang, L.Shen, K.K.Rajan and L.C.Lim, "Elastic modulus, hardness and fracture behavior of Pb(Zn1/3Nb2/3)O3‑PbTiOsingle crystal". 
    MATERIALS SCIENCE AND ENGINEERING A, 472, (2008), 35‑42.
 
Thesis:
 
1. Wong Meng Fei: "Micromechanical properties and domain structures of PZN-PT piezoelectric single crystals", Doctor of Philosophy, Department of Mechanical Engineering,
    NUS, 2011. 
 
 
3. Interfacial mechanics
This research area is to focus on determination the interfacial mechancial properties through indentation experiments and finite element analysis. The interfacial delamination processing, interfacial energy and interfacial strength are characterized and determined through the analysis of the nanoindentation experiments by using the wedge shape tip. This project was done by two students, Mr. Yeap Kong Boon and Mr. Chen Lei, Mr. Yeap Kong Boon was mainly doing experiments and has been award Ph.D degree on Mechanical Engineering in 2010, whereas Mr. Chen Lei was doing computational simulation and has been award Ph.D degree on Mechanical Engineering in 2012.
 
Some Recent publications:
 
1. L.Chen, K.B.Yeap, K.Y.Zeng, C.M.She and G.R.Liu, "Interfacial delamination cracking shapes and stress states during wedge indentation in a soft-film-hard-substrate
    system - computational simulation and experimental studies", JOURNAL OF MATERIALS RESEARCH, 26 (19), (2011), 2511-2523.
2. L.Chen, K.B.Yeap, K.Y.Zeng, and G.R.Liu, "Determination of the Interfacial Adhesion Properties by Wedge Indentation: Finite Element Simulation and Experiment",
    PHILOSOPHICAL MAGAZINE 89, (2009), 1395-1413.
3. K.B.Yeap, K.Y.Zeng, and D.Z.Chi, "Wedge Indentation Studies of Low-k Films at Inert, Water and Ambient Environments", 
    MATERIALS SCIENCE AND ENGINEERING, A, 518, (2009), 132-138.
4. K.B.Yeap, K.Y.Zeng and D.Z.Chi, "Determining the Interfacial Toughness of low‑k films on Si Substrate by Wedge Indentation: Further Studies". 
    ACTA MATERIALIA, 56, (2008), 977‑984.
5. K.B.Yeap, K.Y.Zeng, H.Y.Jiang, L.Shen and D.Z.Chi, "Determining interfacial properties of submicron low‑k films on Si substrate by using wedge indentation technique".
    JOURNAL OF APPLIED PHYSICS, 101, (2007), 123531.
 
Other Related Publications:
 
1. C.M.She, Y.W.Zhang, K.Y.Zeng, "A three-dimensional finite element analysis of interface delamination in a ductile film/hard substrate system induced by wedge
    indentation", 
    ENGINEERING FRACTURE MECHANICS, 76, (2009), 2272-2280. 
2. P. Liu, Y.W.Zhang, K.Y.Zeng, C.Lu and K.Y.Lam, "Finite element analysis of interface delamination and buckling in thin film systems by wedge indentation". 
    ENGINEERING FRACTURE MECHANICS, 74, (2007), 1118-1125.
3. Y.W. Zhang, K.Y.Zeng and R.Thampurun, "Interface delamination generated by indentation in thin film systems ‑ a computational mechanics study".
    MATERIALS SCIENCE AND ENGINEERING A, 319‑321, (2001), 893‑897.
 
Thesis:
 
1. Yin Yousheng: "A simulation by using cohesive zone model for indentation test in thin-film/substrate systems", Master of Engineering, Department of Mechanical
    Engineering, NUS, 2007.
2. Yeap Kong Boon: "Characterization of interfacial mechanical properties using wedge indentation method", Doctor of Philosophy, Department of Mechanical Engineering, NUS,
    2010.
3. Chen Lei: "Development of smoothed numerical methods for fracture analysis and interfacial toughness characterization in thin film systems", Doctor of Philosophy,
    Department of Mechanical Engineering, NUS, 2012. 
 
 
4. Processing and characterization of polymer-based nanocomposites.
This project is to processing and characterizing the micromechanical properties of epoxy matrix composite reinforced with nano-size Alumina particles. The effects of particle shapes, sizes, and surface chemistry have been studied. The micromechanical properties are studied by nanoindentation and correlated with the macroscopic properties such as fracture mechanics testing and fractography. This project was done by Ms. Lim Sheau Hooi, she has been award Ph.D degree on Mechanical Engineering in 2011.
 
Some Recent Publications:
 
1. S.H.Lim, K.Y.Zeng and C.B. He, "Preparation, Morphology and Mechanical Properties of Epoxy Nanocomposites with Alumina Fillers",
    INTERNATIONAL JOURNAL OF MODERN PHYSICS B, 24, (2010), 136-147.
2. S.H.Lim, K.Y.Zeng and C.B.He, "Morphology, tensile and fracture characteristics of epoxy-alumina nanocomposites",
    MATERIALS SCIENCE AND ENGINEERING A, 527, (2010), 5670 - 5676.
 
Thesis:
 
1. Lim Sheau Hooi: "Synthesis and micro-mechanical properties of epoxy-alumina nanocomposite", Doctor of Philosophy, Department of Mechanical Engineering, NUS, 2010. 
 
 
5. Analysis of nanoindentation of thin films
This project is to develop methodologies to analysing nanoindentation load/displacement curves for ultra-thin films. The substrate effects will be considered. The methodologies should be applicable to both soft-films-on-hard-substrate and hard-film-on-soft-substrate. The elastic modulus and hardness are then extracted from the analysis of the indentation load/displacement data. This project was initially done by Mr. Amit Kumar. Mr. Amit Kumar was award Ph.D degree on Mechanical Engineering in 2012.
 
Some Recent Publications:
 
1. A.Kumar and K.Y.Zeng, "Alternative methods to extract the hardness and elastic modulus of thin films from nanoindentation load-displacement data",
    INTERNATIONAL OURNAL OF APPLIED MECHANICS, 2, (2010), 41-68.
2. A.Kumar and K.Y.Zeng, "Measurement of the hardness of ultra-thin films by the first derivative of load-displacement curve from nanoindentation data", 
    INTERNATIONAL JOURNAL OF MODERN PHYSICS B, 24, (2010), 256-266. 
 
 
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