Scientific Program

Conference Series Ltd invites all the participants across the globe to attend 3rd International Conference on Smart Materials & Structures Orlando, Florida, USA.

Day 1 :

Keynote Forum

Rafal Abdank-Kozubski

Jagiellonian University in Krakow, Poland

Keynote: Chemical ordering phenomena in nanostructured FePt: Monte Carlo simulations

Time : 09:20-09:55

Smart Materials 2017 International Conference Keynote Speaker Rafal Abdank-Kozubski photo
Biography:

Rafal Kozubski has completed his PhD from the Jagiellonian University in Kraków in 1984. He has worked as a Post-doctorate at the Strasbourg Institute of Physics and Chemistry of Materials (IPCMS), France (1987 to 1988). He was an Academic Visitor in the Institute for Applied Physics, Swiss Federal Institute of Technology, Zurich, Switzerland (1988 and 1990). He also stayed at the Institute for Solid State Physics, University of Vienna, Austria as a Lise-Meitner Fellow from 1993 to 1995. After completing his Habilitation (DSc) from the Jagiellonian University in Kraków in 1997, he has worked there as an Associate Professor (1997-2006) and in 2006, he was appointed as Full Professor at the same university. His international experience includes International Fellowship at the Queen’s University in Belfast (2006-2008) and Visiting Professorships at the L.Pasteur University in Strasbourg/University of Strasbourg, France (2007, 2008, 2009, 2010 and 2011). In 2016, he was appointed as a Conjoint Professor of the University of Newcastle, Australia. He has published over 100 scientific papers in international reviewed journals and is an author of over 150 communications on international conferences.

Abstract:

Monte Carlo (MC) simulation studies of free-surface-induced selective destabilization of L10 superstructure variants in FePt nanolayers, nanowires and nanoparticles were carried out. The system was modeled with nn and nnn interatomic pair interactions deduced from ab initio results for Fe-Pt. The heterogeneous nucleation of a- and b-L10 variant domains reported previously for FePt nanolayers was induced by the (100)-type surfaces limiting the nanostructures. While the initial c-variant L10 superstructure of nanowires transformed totally to the L10 a-variant with Fe and Pt monoatomic planes perpendicular to the wire axis and to both (010) and (001) surfaces, in the case of nanocubes the competition between the a- and b-variant L10 domains nucleating at the (100), (010) and (001) surfaces resulted in suppression of their growth. As a consequence, most of the cube volume remained untransformed and showed the c-variant L10 chemical long-range order (LRO) with a degree lowered by homogeneously creating antisite defects. The results quantified by the calculated a- and b-L10 domain penetration depth and the LRO and SRO degree in particular cases are important for the development of magnetic storage media technologies requiring stable L10 superstructure variants determining easy magnetization directions.

Keynote Forum

Pradeep K. Rohatgi

University of Wisconsin-Milwaukee, USA

Keynote: Development of self-healing metallic materials and composites

Time : 09:55-10:30

Smart Materials 2017 International Conference Keynote Speaker Pradeep K. Rohatgi photo
Biography:

Pradeep K. Rohatgi, is a Professor of Materials Engineering, and Director of the Center for Composites at the University of Wisconsin-Milwaukee. He is a pioneer in the field of composite materials, particularly metal matrix composites. Dr. Rohatgi has coauthored twelve books and over 400 scientific papers. He has 20 U.S. patents and has received numerous awards for excellence in research. He has received numerous awards for excellence in research and has been elected to fellowships of several organizations including TMS, ASM, ASME, SAE, TWAS, SME, AAAS, MRS. His initial research on cast metal composites has been listed as a major landmark in the 11000 year history of metal casting and TMS has organized an honorary symposium to honor his contribution to metal matrix composites. Recently he has extended his work to make matrix nano composites, syntactic foams, self-lubricating and self-healing metal matrix composite castings.

Abstract:

Self-healing materials are inspired from natural biological materials that they can heal themselves when injured or bleed. All complex biological organisms have the ability to repair minor damage. Incorporating the self-repair function into inorganic systems is seeing growing interest of materials scientists. Most recent studies were concentrated on polymers and ceramics because it is easier to synthesize them than metallic materials. It can be classified the self-healing materials into two titles: autonomous self-healing materials and non-autonomous self-healing materials. Grain boundary migration, self-healing of nano-voids at the nanoscale repairing can be evaluated as autonomous self-healing. Non-autonomous self-healing is required an external driving force such as heating. Most recent studies about the self-healing metals and metal matrix composites are non-autonomous healing. Most of the studies were performed on the aluminum alloy, zinc alloy and Sn-Bi alloys about the self-healing metallic materials. Self-healing metals and metal matrix composites can be categorized by shape Memory Alloy (SMA) based healing, microencapsualtion based healing and precipitation healing. An approach to obtaining self-healing castings is made by incorporating shape memory alloy (SMA) reinforcements in a cast matrix. Another proposed mechanism is to incorporate a low melting alloy within hollow microcapsules that are embedded in a high melting alloy. An advancing crack breaks the microcapsule, allowing the low melting alloy to be liquefied and flow into the crack.  Self-repairing capabilities can also be imparted to metal castings by aging precipitation during casting the alloy which provides closure of voids making stronger materials preventing the formation of initial cracks. Self-healing metallic materials are very promising for future. But currently, it has several constraints for practical application. It has needed developing new self-healing agents or mechanisms to resist high temperature. Researches are continuously improving self-healing metallic materials in order to use this material in near future.

Keynote Forum

Kim Meow Liew

City University of Hong Kong, Hong Kong

Keynote: Nanocomposite materials: Trends and challenges

Time : 10:30-11:05

Smart Materials 2017 International Conference Keynote Speaker Kim Meow Liew photo
Biography:

K M Liew is the Head of Department of Architecture and Civil Engineering and Chair Professor of Civil Engineering, City University of Hong Kong. Earlier, he was appointed as the Chair Professor of Building and Construction, City University of Hong Kong, a tenured Professor at Nanyang Technological University, Singapore and the Founding Director of Nanyang Center for Supercomputing and Visualization. He was a Visiting Professor of MIT, University of Southern California, University of Toronto and Tsinghua University. His research interests encompass computational mechanics, materials modeling, nanotechnology, plates and shells, engineering optimization and fire simulation. Over his academic career, he has published over 700 SCI journal articles. He is listed by the Institute for Scientific Information (ISI) as a Highly Cited Researcher in Engineering. His publications have been cited over 22000 times and his current H-index is 75 (Google Scholar).

Abstract:

Carbon nanotubes (CNTs) have found to possess high strength and stiffness as well as high aspect ratio and low density, making them a strong candidate for the reinforcement in polymer composites. Existing research has reported that the mechanical and physical properties of CNTs are superior to those of carbon fibers. Therefore, in recent years, CNTs have been used for the reinforcement in composite, forming the CNT-reinforced composite. This CNT-reinforced composite can be used in the form of beam, plate or shell structural component. With the increasing research works devoted to this topic, it will be important to know the current trends and challenges of nanocomposite materials.

Break: Group Photo @ Hall-B
Coffee Break - 11:05-11:30 @ Foyer

Keynote Forum

Lu-Wen Zhang

Shanghai Jiao Tong University, China

Keynote: Carbon nanocomposites and materials

Time : 11:30-12:05

Smart Materials 2017 International Conference Keynote Speaker Lu-Wen Zhang photo
Biography:

Dr. Zhang is the Distinguished Research Professor of mechanics in Shanghai Jiao Tong University. She received her PhD in 2010 from Shanghai University and continued her postdoctoral study in Shanghai University and City University of Hong Kong. Dr. Zhang’s main research trust is focused on computational mechanics, multi-scale modeling, Nano composite materials and optimization. Her research areas are on theoretical development and application of numerical algorithms and computational methods for problems in mechanics and nano materials. Dr. Zhang has published over 70 SCI journal articles and her publications have been cited over 1,200 (ISI). Her current h-index is 19 (ISI). She is Editor of Journal of Modeling in Mechanics & Materials (De Gruyter), Guest Editor on a Special Issue of Mathematical Problems in Engineering Journal (Hindawi Publishing) on Computational Methods for Engineering Science in 2014, and Editorial board member of Polymer Science (iMedPub). 

Abstract:

Understanding the mechanical behavior of nanocomposites and materials remains one of the most difficult challenges in the field of material science. In this talk, we will present a multi-scale framework for computational modeling of the mechanical behavior of carbon nanotube (CNT) reinforced cement composites. The geometry of a cylindrical representative volume element (RVE) of composites is considered in which the CNT and matrix are used as elastic continua. In a macroscopic scale treatment, reinforcement is assumed to be embedded in the overall domain in the corresponding volume fraction. Accounting for the volume fraction, orientation and arrangement of the reinforcing components, CNTs and a matrix are simulated by different nonlinear constitutive models to represent the composites; CNTs are considered as one-dimensional and distributed in a uniform orientation. A mesoscopic scale description is considered in order to depict the mesostructured morphology of the reinforced composites and the bond-slip of its mutual interaction. Two length-scale systems of equations are coupled together using a staggered technique and the modified Newton-Raphson method is adopted to solve the nonlinear system equations in order to track the full load-displacement path of the composites. Several carefully selected case studies and benchmark problems will be presented in the talk.

  • Smart Materials and Technologies
    Smart Biomaterials (A)
Location: Hall - B
Speaker

Chair

Elias Siores

University of Bolton, UK

Speaker

Co-Chair

Kim Meow Liew

City University of Hong Kong, Hong Kong

Speaker
Biography:

Patrice Woisel has obtained his PhD in Organic Chemistry at the University of Lille, France in 1996 and was appointed as a Lecturer at the University of Dunkerque, France. In 2007, he became a Professor at the National School of Engineering Chemistry (ENSCL), France. He currently leads a research group of around 10 people and has written over 90 publications in major international journals.

Abstract:

There is no doubt that the creation of high performance polymeric materials relies directly on our ability to manipulate these smart materials in a controllable, predictable and orchestrated fashion from nano to macro-scale. Recently, architectures where the individual polymer blocks are connected through supramolecular interactions such as hydrogen bonding, metal-ligand and pseudorotaxane like interactions have received significant attention. The inherent features of the molecular recognition-driven self-assembly confer significant advantages over their covalently linked brethren in terms of facilitating modularity and self-healing properties. Moreover, through careful design smart polymeric systems have been developed with stimuli-responsive structures and properties. Here, we report the successful engineering of new multi-stimuli responsive and colored macromolecular assemblies based on well-defined functionalized polymer building blocks incorporating both electro-deficient (CBPQT4+) and electron-rich units (tetrathiafulvalene, naphthalene) moieties. The architectures of these materials have been constructed by specifically holding together complementary well-defined polymer building blocks (prepared by Controlled Radical Polymerization) with specially designed host/guest motifs attached in specific locations on polymer backbones. The inherent reversibility of supramolecular architectures has allowed on demand modular and tunable modification of structures and properties of materials. More particularly, we have exploited the presence of colored CBPQT4+ based interactions to create smart micelles and hydrogels and reprogrammable supramolecular temperature and pH sensors with memory function. An important practical aspect of these new functional materials is that all relevant phenomena (self-assembly and disassembly processes, reading/reprogramming of temperature, memory function) have an associated visible readout, thereby affording convenient and quantifiable systems with applications spanning the physical and biological sciences.

Speaker
Biography:

Dong Joo Kim has his expertise in the development and evaluation of high performance cement based construction materials with high tensile strength, ductility and energy absorption capacity in addition to self-sensing or self-healing capability. He has obtained his PhD degree from the University of Michigan, Ann Arbor in 2009 and since then he has been an Assistant and Associate Professor in Sejong University, South Korea.

Abstract:

In this study, the change of electrical resistivity in Ultra-High-Performance Fiber-Reinforced Concrete (UHPFRCs) in tension was investigated. UHPFRCs have shown significant reduction in their electrical resistivity after first cracking until post cracking tensile strength point during their unique tensile strain-hardening. An experimental program was designed to investigate the change in the electrical resistivity of UHPFRCs blending 1 vol.% long (L=30 mm, D=0.3 mm) and 1 vol.% short (L=19 mm, D=0.2 mm) smooth steel fibers. To measure the electrical resistivity, a layer of silver paste was first applied onto the surface of specimens and then copper tapes were attached on the silver paste. The distance between two outsides electrodes for input current (10 µA) was 110 mm while that between two electrodes for voltage measurement was 50 mm. The specimen was subjected to direct tension using a universal testing machine (UTM). The speed of the machine displacement was 1.0 mm/min. The reduction in the electrical resistivity of UHP-FRCs under direct tension until post cracking tensile strength was 437.7 kΩ∙cm, and it was found to be significantly higher than those (13.7 and 149.7 kΩ∙cm) of strain hardening steel-fiber reinforced concretes (SH-SFRCs) with lower strength matrices (117 and 152 MPa), respectively. The potential damage-sensing capacity of UHPFRCs, in addition to the high mechanical resistance of UHPFRCs, would be considerably favorable for future structural health monitoring system as well.

Speaker
Biography:

Liying Jiang is an Associate Professor at the Department of Mechanical and Materials Engineering, University of Western Ontario, Canada. She has received her PhD from the University of Alberta in 2005. Her research interests and activities cover a wide range of applied mechanics. Her expertise is theoretical and numerical simulation to develop mechanics and physics models for challenging problems related to material’s behavior ranging from traditional composites to smart materials and to nanostructured materials.

Abstract:

As a category of electroactive polymers, dielectric elastomers (DEs) exhibit physical response to electrical stimuli and transduce electrical energy to mechanical energy. On the other hand, when acting in a generator mode, they can also convert mechanical energy from different sources, such as winds, ocean waves and human movement into electrical energy. Due to their flexibility and high energy density, dielectric elastomer generators (DEGs) have recently attracted much attention from the research community. It has been demonstrated in experiments that DEGs can achieve energy densities more than 10 times higher than those of piezoelectric and electromagnetic generators. Although some DEGs have shown very promising results, their performance is in fact affected by multiple failure modes and the material viscoelasticity. Particularly, the material viscoelasticity of the DE membrane embedded in a DEG could cause high energy dissipation of the generator and exert a strong influence on the design of its harvesting scheme. To uncover possible approaches to improve the performance of DEGs, this work presents a framework to comprehensively evaluate the harvested energy and conversion efficiency of DEGs with the consideration of the finite-deformation viscoelasticity of the material. Also, different possible energy harvesting schemes are explored in this work. From our simulation results, it is found that choosing a suitable voltage level of the power supply (or a suitable bias voltage) could markedly raise both the harvested energy and conversion efficiency of DEGs. The general framework and results in this work are expected to provide insight into optimizing the design of dielectric elastomer generators.

Break: Lunch Break 13:20-14:20 @ Restaurant
Speaker
Biography:

Elias Torres Alonso has a background in Physics with a specialisation in Physics of Materials in the Complutense University in Madrid. After that, he obtained an Erasmus fellowship to spend one year in Lund University in Sweden, where he worked with III-V Nanowires. At the moment, Elias is working towards his PhD in Physics/Engineering at the University of Exeter, United Kingdom, where he uses various 2D materials to create flexible, wearable and scalable next-generation electronic and optoelectronic devices within the group of Prof Monica Craciun and Prof Saverio Russo.

Abstract:

The concept of smart-textiles is witnessing a rapid development with recent advances in nanotechnology and materials engineering. Bearing in mind that the concept of textiles is much wider than clothes and garments, the potential is immense. While most current commercial applications rely on conventional hardware simply mounted onto fibers or fabrics, a new approach to e-textiles consisting in using functionalized textiles for several technological applications has the potential to change the paradigm of wearable electronics completely. Conducting fibers are an important component of any e-textile, not only because they can be used as wiring for simple textile-based electronic component, but also because they can be used to build electronic devices directly on textile fibers. We have reported a new method to coat insulating textile fibers with monolayer graphene to make them conductive while preserving their appearance. There are a number of factors that can greatly influence the sheet resistance achieved by graphene-coated textile fibers. In order to understand the influence of the topography of the fibers on the effectiveness of the graphene coating, an extensive study encompassing microscopy techniques like Atomic Force Microscopy and Scanning Thermal Microscopy, as well as Raman spectroscopy was performed. This method has proven to be a versatile tool to achieve flexible, transparent and conducting fibers of different materials, sizes and shapes. The first applications of electronic devices built on such fibers are demonstrated with an alternating current electroluminescent device, following previous work in our group on similar devices in flexible substrates. This opens up the way for the realization of wearable devices on textiles.

Speaker
Biography:

Nusrat Jahan has completed her MSc from Tuskegee University, USA and currently pursuing PhD in Ecole Polytechnique de Montreal, Canada. She has published 5 papers in journals and in a couple of proceedings.

Abstract:

Polyvinylidene fluoride (PVDF) has relatively high thermal stability (~120 °C) with moderate piezoelectric coefficient (d33~30pC/N) while cellular polymers such as polypropylene (PP) has higher d33 value (120-600 pC/N) with poor thermal stability (up to around 50 °C) which limited their applications in high temperature transduction. Therefore, a three-phase composite has been studied where organoclay has been added to enhance polar β phase and CaCO3 to introduce cellular structure in PVDF to get the advantage from both source of piezoelectricity with thermal stability. The samples were prepared by mixing PVDF, organically modified nanoclay (1-12 wt%) and CaCO3 (30-40 wt%) into a twin screw extruder and subsequent calendaring of films with thickness around 100 μm. FTIR result showed that although the supplied CaCO3 is not surface modified, still it results in around 30% of β phase in PVDF in absence of nanoclay and a gradual increase was observed in β phase with increasing amount of CaCO3 and this increment was further elevated by adding surface modified organoclay. Though various percentage of clay was used, 3 wt% of them seems to contribute maximum β phase (~55%) due to better dispersion and DSC as well as XRD confirmed the results further. Maximum 87% β phase was found in PVDF/40 wt% CaCO3/3 wt% nanoclay sample after stretching at a ratio (R=final length/initial length) of 4.5 at 90 °C. Seemingly, increased stretching ratio not only improved the β phase content but also created harmonious voided structure around CaCO3 particles in the sample. SEM on stretched film showed the presence of such lenses shaped voided structure inside the film.

Speaker
Biography:

Ihsan Burak Temelturk has received his BS degree in Mechanical Engineering in 2012 and completed Master of Science degree from Aerospace Engineering Department in Middle East Technical University in Ankara, Turkey. He is currently a System Design Engineer in Turkey. His research interests include design, modeling and control of electromechanical systems. He has studied piezo materials, piezo actuators and its applications.

Abstract:

Servovalves are critical sub components of hydraulic systems which are used in many fields such as aerospace and defense technologies. Conventional servovalves have torque motor which has a shortcoming of narrow bandwidth and long response time which result in a bulky behavior of the overall system. Usage piezoelectric actuator is a novel way to overcome this problem. In this study, design of a first stage flapper of a two stage servovalve involving a mechanically amplified piezo-stack actuator instead of a torque motor is done. In the design problem, flapper displacement and the force developed at the nozzle location are set as the design objectives. Thickness and the height of the flexure are the design variables regarding the flexure. Finite element method and mathematical modeling of piezo actuators and structures are utilized to build a model of the first stage of the servovalve with piezoelectric actuator. Design parameters of amplification mechanism of piezo actuator are verified by finite element analyses and experimental results. Dynamic behavior of flapper mechanism with piezo actuator is characterized using Bouc-Wen model and displacements of flapper is controlled and monitored with both laser displacement sensor and strain gage and also control methods with voltage amplifier are tested in Bouc-Wen model hysteresis compensator, close loop with PI controller and hybrid control in test setup. The hysteresis errors are compared with each others.

Break: Panel Discussion: 15:20-15:35
Coffee Break 15:35-15:50 @ Foyer
  • Smart Materials and Technologies
    Smart Biomaterials (B)
Location: Hall - B
Speaker

Chair

Rafal Abdank-Kozubski

Jagiellonian University in Krakow, Poland

Speaker

Co-Chair

Lu-Wen Zhang

Shanghai Jiao Tong University, China

Session Introduction

Igor Y Denisyuk

ITMO University, Russia

Title: Nano-biocomposites for biomedical application

Time : 15:50-16:15

Speaker
Biography:

Igor Y Denisyuk has his expertise in field of nanoparticles, non-linear molecular crystals, polymer material, photonics, phodegradable nanocomposites and biomedical nanocomposites.

Abstract:

Silver, gold, selenium and metal oxides nanoparticles in polymer matrix intensively investigated in biomedical application due to the plenty of unique properties of antimicrobial properties to Gram-positive, Gram-negative pathogens and antifungal activity is an important scientific problem to create bio-nanocomposites. Non-selective, broad spectrum antibacterial and antifungal activity against different types of microorganisms as well as the long-term effect for a few months is one of the main requirements to biopolymers. Nanocomposites with nanoparticles Ag, Au, SiO2, ZnO were prepared on the basis of two monomer compositions: (1) Acidic composition consisting of monomers: 2-Carboxyethyl and Bisphenol A glycerolate. (2) pH neutral formulation consisting of monomers: Diurethanedimethacrylate and Isodecyl acrylate and photo initiator. Methods of preparing polymer films based nanocomposites can be found in our papers. Exposure was increased 5 times from total time of polymerization for these composites; prepared samples were heated at 50 oC for 12 hours to minimize the effects of residual monomers in the experiment. As test objects were used: Strains of fungi Candida albicans (С. albicans NCTC 885-653) and Aspergillus fumigatus (clinical isolate); strains of staphylococci Community-associated Methicillin-resistant Staphylococcus aureus (CA-MRSA, penicillin-binding protein (PBP2α) - positive); Healthcare-associated Methicillin-resistant Staphylococcus aureus (HA-MRSA, penicillin-binding protein (PBP2α) - positive); Methicillin-resistant Staphylococcus epidermidis (MRSE, penicillin-binding protein (PBP2α) - positive); Methicillin-resistant Staphylococcus epidermidis (MRSE, penicillin-binding protein (PBP2α) - negative); Methicillin-resistant Staphylococcus aureus (MRSA, penicillin-binding protein (PBP2α) -negative); Methicillin-susceptible Staphylococcus aureus (MSSA); Methicillin-susceptible Staphylococcus epidermidis (MSSE). The antifungal activity of ZnO nanocomposites based on polymeric matrix 2-Carboxyethyl acrylate/Bisphenol-A-glycerolate (1 glycerol/phenol) diacrylate against C. albicans and A. fumigatus was found. Pronounced suppressive effect of ZnO nanocomposites based on polymeric matrix 2-Carboxyethyl acrylate/Bisphenol-A-glycerolate (1 glycerol/phenol) diacrylate against staphylococci was identified. The antifungal activity of polymeric matrix based on 2-Carboxyethyl acrylate/Bisphenol-A-glycerolate (1 glycerol/phenol) diacrylate against C. albicans was found.

Speaker
Biography:

Masahide Terazima has his expertise in physical chemistry for elucidating reaction mechanism. In particular, his current research interests are studies of chemical reaction dynamics of biological proteins. He has been developing new methods for direct detection of energy and conformation of reactive species in time-domain. Furthermore, he has succeeded in measurement of molecular diffusion processes in time-domain. He has discovered that the diffusion coefficient is sensitive to protein conformations, so that this technique can be used for tracing dynamical conformation change as well as intermolecular interaction changes.

Abstract:

There are many photo-response biological proteins to convert the light energy to chemical energy, or to generate light information. It may be possible to use these proteins as advanced materials to detect light. For such applications, it is necessary to understand the molecular mechanism of the light detection of these proteins. In general, revealing conformation changes and intermolecular interactions is essential for the understanding. Although optical spectroscopies developed so far have been used for detecting dynamics of chemical reactions, there are many undetectable (spectrally silent) dynamics in biological reaction systems by these methods. It is desirable to develop a method to overcome this limitation. We have succeeded in detecting many intermediate species, which cannot be detected by traditional spectroscopic methods. The principle is based on the time-resolved detection of energies, volume changes, and the diffusion coefficient changes by the time-resolved transient grating (TG) method. Here I will demonstrate the method on a reaction of a blue-light sensor protein: PixD. We found a very unique light intensity dependence of the reaction, which may be used as an advanced material for the light sensor. PixD proteins are ones of photosensors containing the BLUF domain. They include Slr1694 (SyPixD) and Tll0078 (TePixD). SyPixD regulates phototaxis of cyanobacterium. Crystallographic analyses showed that these homologous PixD proteins have oligomeric structures: a decamer comprised of two stacked pentameric rings. We found that the dissociation reaction of the decamer is a key reaction for signal transduction and it will be used for application purpose. By using the TG technique, we discovered that the conformational change of the TePixD and SyPixDdecamer depend on the intensity of the excitation light. From the excitation light intensity dependence, we found that the multiphoton excitation of this protein is essential for the reaction.

Speaker
Biography:

Nathan P Salowitz has received his BS degree in Engineering Mechanics from the University of Wisconsin Madison in 2001 and MS and PhD degrees in Aeronautics and Astronautics from Stanford University in 2006 and 2013, respectively. From 2003 to 2005, he was a Structural Analysis Engineer with The Boeing Company. From 2013 to 2014, he was a Postdoctoral Engineering Research Associate at Stanford University. Since 2014, he has been an Assistant Professor with the Mechanical Engineering Department with Adjunct Professor Appointments in the Electrical Engineering and Civil and Environmental Engineering departments at the University of Wisconsin-Milwaukee. He has more than 16 publications and is currently pursuing research in intelligent materials and structural health monitoring with particular interests in sensor design, mass sensor deployment, wireless communication and the interaction of sensors and structures.

Abstract:

Self-healing materials have innate capabilities to restore geometry and mend damage in a structure. These materials have tremendous potential to prevent catastrophic failures and overcome fatigue issues by repairing structural damage as it occurs, while in service. In order to restore bulk deformations and close macroscopic cracks self-healing materials have been developed that are essentially sparse fiber composites, composed of a structural matrix reinforced with shape memory fibers. This composition is capable of closing large cracks and restoring bulk geometry in a free, unloaded state. A significant limitation of this technique is that structures are not capable of overcoming or withstanding externally applied loads while restoring their original geometry. This is because the shape memory material used to restore geometry is currently cast in its trained geometry. Therefore, activation and recovery will only provide loads to return to that original geometry, negating plastic deformation of the matrix and any externally applied load will cause deviation, inhibiting geometric restoration. Seeking to overcome this limitation, polymer samples were created containing prestrained nickel titanium shape memory fibers that undergo constrained recovery upon activation. Actuation of the shape memory fibers generates internal/residual loads allowing the healed structure to withstand and overcome externally applied loads. Theory, experimental results, analysis and future vision for self-healing materials composed of prestrained nickel titanium shape memory fibers are discussed. A mechanics based derivation is presented relating internal/residual loads to allowable externally applied loads. Experimental results are presented from samples composed of prestrained shape memory alloy reinforced polymer with an internal framework to ensure load transfer between components. Samples were loaded in tension with a constant crosshead speed until matrix failure, then healed through thermal actuation and loaded to crack opening multiple times. Analysis of theory and experimental results are presented.

Speaker
Biography:

An-Yi Chang is currently pursuing his PhD with his major in Micro- and Nanoscale Systems at Louisiana Tech University, USA. He has earned his MS in Chemical Engineering from Louisiana Tech University, USA. His research emphasis on biological microfluidics, particularly, designing microfluidics to study cell reactions and drug release in microenvironments. Presently, he is working in Institute for Micromanufacturing (IFM) and concentrating on developing microfluidics for on-chip biosensing of neurochemical sensing with boron-doped nanocrystalline diamond microelectrodes (BDUNCD).

Abstract:

Electrochemical microsensors play an important role in investigating the effect of neurochemicals in human brain function. Abnormal levels of neurochemicals cause several neurodegenerative diseases. The current microelectrodes foul rapidly in brain microenvironment and results in significant reduction in chemical sensitivity and sensor’s useful lifetime. Here, we present boron-doped ultrananocrystalline diamond (BDUNCD) microelectrodes that could aid in long-term monitoring of neurochemicals because of their wide electrochemical potential window, extremely low background current and excellent chemical inertness. The research goal is to reduce the rate of electrode fouling arising from reaction byproducts (e.g., melanin) and extend the lifetime to several weeks, which does not exist now. We microfabricated a custom microfluidic platform to study the BDUNCD surface fouling mechanism by depositing and mapping silver particles on BDUNCD microelectrode surfaces that were fouled at different conditions. The rate of fouling was studied using Fast Scan Cyclic Voltammetry (FSCV) and Amperometry (AM) techniques. For the first time, in situ electrode cleaning methods were developed to extend the electrode lifetime by >4-fold. Finally, chemical sensitivity enhancements were investigated by modifying BDUNCD with carbon nanotubes (CNT) and polymer coatings. For this study, we developed a droplet microfluidic device to study the changes in sensitivity and response time to two neurochemicals (dopamine and serotonin) using three different microelectrode surfaces.

Peng-Sheng Wei

National Sun Yat-Sen University, Taiwan

Title: Mechanisms of mass transfer on porosity during solidification

Time : 17:25-17:45

Speaker
Biography:

Dr. Peng-Sheng Wei received Ph.D. in Mechanical Engineering Department at University of California, Davis, in 1984. He is a professor in the Department of Mechanical and Electro-Mechanical Engineering of National Sun Yat-Sen University (NSYSU), Taiwan. Dr. Wei has published more than 80 papers in reputed journals, given keynote or invited speeches in international conferences more than 60 times. He is a Fellow of American Welding Society (AWS) and American Society of Mechanical Engineers (ASME). He also received the Outstanding Research Achievement Awards from both the National Science Council (NSC), and NSYSU, the Outstanding Scholar Research Project Winner Award from NSC, the Adams Memorial Membership Award, the Warren F. Savage Memorial Award, and the William Irrgang Memorial Award from AWS. He has been the Xi-Wan Chair Professor of NSYSU since 2009, and Invited Distinguished Professor in the Beijing University of Technology, China, during 2015-2017.

Abstract:

Pore formation and its shape in solid influence not only  microstructure of materials, but also contemporary issues of various sciences of biology, engineering, foods, geophysics and climate change, etc. In order to remove and control porosity, understanding its formation is important. A pore formed in solid is a consequence of a bubble nucleated by super-saturation and entrapped by a solidification front. This work accounts for realistic mass and momentum transport across a self-consistently and analytically determined shape of the bubble cap, whose surface is in physico-chemical equilibrium beyond the solidification front. Accurate determination of contact angle from a realistic shape of the cap is required to predict the relevant shape of the pore in solid. It was systematically found that there are two different solute transport models subject to thin and thick thicknesses of concentration boundary layers on the solidification front. Case 1 accounts for species transport from the pore across an emerged cap through a thin concentration boundary layer on the solidification front into surrounding liquid in the early stage, whereas Case 2 is subject to species transport from the surrounding liquid across a submerged cap within a thick concentration boundary layer into the  pore. The analytical results find that the variation of solute gas pressure in the pore  with  time  determines development of the  pore  shape  in  solid increases in mass transfer coefficient and solidification rate decrease the pore radius. The predicted pore shape agrees with experimental  data. A realistic prediction and control of the growth of the pore shape has therefore been obtained.

Break: Panel Discussions 17:45 -18:00