Transcript New Graduate Student Orientation

New Graduate Student
Orientation
August 17, 2011
Dr. Mohammad Elahinia
This presentation can be found at:
www.eng.utoledo.edu/~pwhite
Solid Mechanics Focus Group
•
Dr. Lesley Berhan
Assoc. Professor
[email protected]
NI 4025 419 530 8220
• Dr. Mohammad Elahinia Assoc. Professor [email protected]
NI 4045 419 520 8224
• Dr. Ali Fatemi
Professor
[email protected]
NI 4029 419 520 8213
• Dr. Yong Gan
Assist. Professor
[email protected]
NI 4024 419 520 6007
• Dr. Mohamed Samir Hefzy Professor
[email protected]
NI 1016 419 520 6086
• Dr. Ahalapitiya Jayatissa Assoc. Professor [email protected]
NI 4049 419 520 8245
• Dr. Efstratios Nikolaidis
Professor
[email protected]
NI 4035 419 520 8216
• Dr. Mehdi Pourazady
Assoc. Professor
[email protected]
NI 4036 419 520 8221
• Dr. Phillip White *
Professor & Chair [email protected]
Solid Mechanics
NI 4065 419 520 4241
Focus Group
* = not adding new students at this time.
Dr. Lesley Berhan
Research Interests:
• Negative Poisson’s ratio materials
• Nanocomposites
• Composites
• Heterogeneous materials
• Fibrous networks
• Structural mechanics
• Finite element analysis
Interested in hiring one or two graduate students
Modeling electrical percolation onset in polymer nanocomposites
Composite and Fibrous Materials Laboratory | University of Toledo
Dr. Lesley Berhan
Percolation in nanocomposites is of high interest because of the
potential to create electrically and/or thermally conductive systems
with an extremely low mass of particles. At relatively low
concentrations of nanofillers the electrical conductivity of polymer
nanocomposites dramatically increases.
The study of percolation is relevant to many areas of research including
thermal management, EMI shielding, and lightning strike protection
Conventional modeling approach
•Reinforcement (e.g. graphene platelets, nanotubes,
nanoparticles, etc.) modeled as fully penetrable objects
•Relationship between excluded volume and percolation
threshold used obtain percolation threshold
Hard-core modeling approach
•Reinforcement modeled as impenetrable objects (hard
core) embedded within a soft (i.e. penetrable) shell
•Excluded volume of objects found numerically
•Relationship between percolation threshold and
excluded volume found using Monte Carlo simulations
•Analytical solution will be derived and compared with
experimental results
Dr. Mohammad Elahinia
• I am looking for one Ph.D. student. The
area of the research is biomedical
applications of shape memory materials.
• Please see next slide.
Biomedical Applications of NiTi Shape Memory Alloys:
(I) Smart pedicle screw (II) Esophagus positioner
Majid Tabesh, Amin Mohaghegh, and Mohammad Elahinia
Dynamic and Smart Systems Laboratory, MIME Department, University of Toledo
Background
Shape Memory Alloys, such as equiatomic Nickel Titanium (NiTi or
Nitinol), undergo a phase transformation in their crystal structure when cooled
from the stronger, high temperature form (Austenite) to the weaker, low
temperature form (Martensite). This inherent phase transformation is the basis
for the unique properties of :
(I) Bio-inspired Shape Memory Alloy
Pedicle Screw to Compensate for
Bone Degradation in Osteoporosis Patients
(II) Bio-inspired Shape Memory Alloy
Esophagus Positioner
for Minimally Invasive Surgeries
Pedicle Screw: a particular type of bone screw designed for implantation
into vertebral pedicle.
Can be used in instrumentation procedures for fixating rods and plates to the
spine with the purpose of:
 Dynamic stabilization of the spine
 Immobilization for Spinal Fusion
 Spinal Deformity correction, …
Atrial fibrillation: an abnormal heart rhythm
(cardiac arrhythmia).
Involves the two upper chambers (atria) of the
heart.
Patients with AF are believed to have a
significantly higher risk of stroke
Radiofrequency ablation (RFA): catheter based treatment method
For patients who do not respond to other methods.
Low voltage alternating electricity at high frequencies to
create controlled thermal injury in a group of cells near the
pulmonary veins.
RFA could cause thermal injury to the esophagus (fistula).
The esophagus and posterior left atrium (LA) wall are in close contact over a
large area that may often lie within the atrial fibrillation ablation zone
The RF could burn the esophagus tissues, causing esophageal perforation
leading to mediastinal infection, stroke, and death.
Osteoporosis and spinal instrumentation
SMA esophagus positioner
Allows a material to return to its original
shape within a strain of up to 8% by
increasing the temperature.
Allows the formation of an elastic
behavior with significant recoverable
strain (up to10%)
NiTi is also biocompatible , biomechanically compatible, MR compatible, fatigue
resistant, etc which constitute excellent medical characteristics.
Self-expanding stents
Orthopedic staples
Osteoporosis is a systemic skeletal disease
characterized by low bone mass, micro architectural
deterioration of bone tissue, and a consequent increase
in bone fragility and susceptibility to fracture.
It is a major drawback in spinal instrumentation due
to hardware loosening or pulling-out both intra and
post operation.
SMA wires, if heated, will deflect the
esophagus away from the ablation site.
Anchoring system with expandable thread inserts
Conclusions
Shape memory alloy (SMA) technology offers new capacities to medical devices,
negotiating the obstacles in:
Spinal instrumentation of osteoporotic bone and
Initially, this SMA scaffold is
pre-compressed in its martensitic
state. As the scaffold is heated, due
to the body temperature, tends to
recover its original shape, to
maintain the inner diameter of a
blood vessel or any tubular passage.
Esophageal fistula during Radiofrequency ablation (RFA).
The SMA staple, in its opened
shape, is placed at the fractured
bone site. Through heating by an
external device, this staple tends to
close, compressing the separated
parts of bone to accelerate the
healing process of bone fractures.
References
1.
The screw assembly before placement
NiTi insert. Initial low-temperature (at
insertion). and closed high temperature form
(at withdrawal).
The screw assembly after placement
2.
Final form when reached to body temperature.
A portion of the insert from both ends
expands.
3.
H. Fischer, B. Vogel, and A. Welle. “Applications of shape memory alloys in medical instruments”. Minimally
invasive therapy and allied technologies, Volume 13, Issue 4 August 2004, pages 248-253.
H. A. Yuehuei. Internal fixation in osteoporotic bone. Edited by H. A. Yuehuei. Thieme Medical Publishers, INC.
2002.
D Sanchez-Quintana et al. Anatomic Relations between the Esophagus and Left Atrium and Relevance for
Ablation of Atrial Fibrillation. Circulation, v. 112 issue 10, 2005.
Dynamic and Smart Systems Laboratory
North Engineering Room 2045
Phone: (419) 530-8130
Fax: (419) 530-8126
http://smartsys.eng.utoledo.edu/
Dr. Ali Fatemi
• Primary areas of interest: Fatigue,
Fracture Mechanics, Failure Analysis,
Materials Mechanical Behavior, Fatigue
of Elastomers, Composite Materials,
Nano-Fiber Reinforced Plastics, Damage
Mechanics, Solid Mechanics, Mechanical
Design, Experimental Mechanics.
Dr. Yong Gan
• See next slides for research areas
• He is interested in working with Ph.D.
students and is seeking funding.
Outline
• Thermal Evaporated Thin Films and Their
Temperature Sensitive Electric Property
• Silicate Glass-Based Silver Composites for
High Temperature Thermoelectric Energy
Conversions
• Preparation of Photovoltaic
(PV)/Thermoelectric (TE) Nanofiber Arrays on
Conductive Substrates
• Biophotofuel Cell Electrode Research
Thermal Evaporated CdS Thin Film on Glass
and the Temperature Sensitive Electric Property
Introduction
Morphology of CdS Film
Cadmium sulfide (CdS) is a semiconductor material [1]. The polycrystalline CdS layer is n-type
doped (as CdS invariably is) [2], and therefore provides one half of the p-n junction. It has the
optical band gap of 2.42 eV or 514.5 nm (in wavelength units) [3], which is sensitive to visible light.
Thin films of CdS have found applications as detectors of light and window materials for solar cells.
There is little work on the thermoelectricity of CdS. Recently, we have demonstrated that CdS thin
films are very sensitive to heat. The change of surface temperature of this material results in
significant increase in electrical conductivity.
I-V Curve at Different Temperatures
In this study, we focus on the heat sensitivity of CdS thin films. CdS thin film in the thickness of
about 5~10 nm was prepared by thermal evaporation at 3000C. A three-electrode system was used for
linear sweep voltammetry measurement. The three electrodes are connected with a CHI 400A
electrochemical quartz microbalance to conduct data acquisition. The three electrodes are the
reference electrode, the work electrode (cathode), and the counter electrode (anode). The width of
the specimens is 25 mm, and the distance between the counter electrode and the work electrode is
also 25 mm. The potentials were changed in a triangle waveform.
CdS I-V curve under different temperature
x 10
T=70F
T=90F
T=100F
T=120F
T=140F
T=170F
T=220F
0
-1
Current (A)
Experimental
-8
1
Summary
-2
1. When temperature increases the current increasers
significant ly. Such a heat sensitive behavior reveals the
thermoelectricity within the CdS thin film.
-3
-4
2. Future research: X-ray analyze the components of the
film.
-5
-6
0
0.1
0.2
0.3
0.4
0.5
0.6
Potential (V)
0.7
0.8
0.9
1
References
1. CdS film coated on glass with thermally-evaporating method.
2. Experiment setup includes: Multimeter with Thermocouple, Heater,
Electrochemical Analyzer, and Computer with analysis software.
[1] J.F. Shackelford, Introduction to Materials Science for Engineers, 6 th Edition, Pearson Prentice Hall,
Upper Saddle River, new Jersey, (2005), pp.13-14.
[2] Junichi Nishino, Sunao Chatani, Yukifumi Uotani, Yoshio Nosaka, Journal of Electroanalytical Chemistry
473 (1999) 217–222.
[3] J. Britt, C. Ferekides, Appl. Phys. Lett. 62 (1993) 285.
Conductive and Oxidation
Resistant Silicates-Silver
Research Objective
To develop glass-based
electrode materials for high
temperature thermoelectric
energy conversions that
exhibit the following
properties: high conductivity,
high oxidation resistance
and good bonding to TE
legs.
G.J. Snyder, et al., Nat. Mater. Vol.7, 105, 2008.
Significance and Background
Thermoelectric (TE) materials generate electricity from
thermal gradient. The electrode connecting TE elements is
critical for effective power generation. Due to the high
temperature reactions and intra-diffusion between Si and
metals, the electrical conductive behavior of most metallic
electrodes degrades. Judicious selection of electrode
materials was under-taken to develop interconnects for high
temperature TE materials.
Solution : Glass-Based Composite Materials
• Silver Solder alloys
• Glass-Based Adhesive
Electrically and Thermally
Conductive Oxidation Resistant
Preparation of PV/TE Nanofiber Arrays on
Conductive Glass
Preparation of PV/TE Nanofiber Arrays on
Conductive Glass
Liquid Solution Method:
TiO2 and CoO made
Biophotofuel Cell Electrode (anode)
CdS + hν (sunlight) → CdS + e(CdS is n-type semiconductor with band gap of 2.45 eV)
TiO2 + hν (sunlight or UV light) → TiO2 (h+) + TiO2 (e-)
O=C(NH2)2 (in biowastes) + 6h+ + H2O → CO2↑ + N2 + 6H+
2NH3 (released from biowastes) + 6h+ → N2↑ + 6H+
Dr. Yong Gan
• See next slides for research areas
• He is interested in working with Ph.D.
students and is seeking funding.
Outline
• Electrodepositing Nanostructures for
Thermoelectric and Photoelectric Energy
Conversion
• Joining High Temperature Thermoelectric
Energy Conversion Materials with Silicate
Glass-Based Silver Composites
• Synthesis of Photovoltaic
(PV)/Thermoelectric (TE) Nanofiber Arrays on
Conductive Substrates
• Preparation of Biophotofuel Cell Electrode
Electrodepositing Nanostructures for Thermoelectric
and Photoelectric Energy Conversion
Conductive and Oxidation
Resistant Silicates-Silver
Research Objective
To develop glass-based electrode materials
for high temperature thermoelectric energy
conversions that exhibit the following
properties: high conductivity, high oxidation
resistance and good bonding to TE legs.
Preparation of PV/TE Nanofiber Arrays
Preparation of PV/TE Nanofiber Arrays on
Conductive Glass
Liquid Solution Method:
TiO2/CoO composites
Biophotofuel Cell Electrode (anode)
CdS + hν (sunlight) → CdS + e(CdS is n-type semiconductor with band gap of 2.45 eV)
TiO2 + hν (sunlight or UV light) → TiO2 (h+) + TiO2 (e-)
O=C(NH2)2 (in biowastes) + 6h+ + H2O → CO2↑ + N2 + 6H+
2NH3 (released from biowastes) + 6h+ → N2↑ + 6H+
Dr. Ahalapitiya Jayatissa
• Please see next slide
Nanotechnology and MEMS Laboratory, MIME Department
Current Research Projects:
1. Graphene based multiplexed Sensors: The main thrust of this research is to improve the
sensing properties of carbon nanotube and graphene based gas sensors by understanding
the mechanism underpinning the selectivity and sensing properties.
PhD: 1 student, MS: 1 student
2. Novel Material System based on Zinc-Oxy-Nitride: The determination of the properties
of the thin films so grown by a variety of experimental techniques, leading to a crosscorrelation between the growth parameters, the resulting film structure and its physical
properties.
PhD: 2 students
3. Laser Processing of Thin Films: The objective of this research project is to investigate the
fundamental phenomena of laser irradiation on metal oxide-based thin films relevant to gas
sensor performance by employing experimental as well as computational approaches.
PhD: 2 students
All projects involve Experimental activities and
Contact:
Professor A. H. Jayatissa
Tel: 419-530-8245
Room #: 4049 NI
E-mail: [email protected]
Modeling/Simulations.
(Synthesis, coating and fabrication of thin
films, MEMS, and Sensors;
Modeling/Simulation based on finite element
analysis)
Dr. Efstratios Nikolaidis
• Research interest: Efficient Re-Analysis
Methodology for Sound and Vibration
of Large-Scale Structures
• Please see next slide
Definition and Significance
It is expensive to optimize vehicle body design by using
detailed FEM for sound and vibration
Vibratory displacement
and sound
Excitation
Uncertainty
Propagation
Monte Carlo Simulation
(10,000 replications)
Statistics of
displacement and
SPL
Design Optimization: Several MCS (e.g. 100)
Dr. Mehdi Pourazady
• Areas of interest: Applications of Finite
Element Methods in modeling and
numerical solution of problems in two
areas of Biomechanics and Nano
Engineering.
• He would like to have one MS and One
PhD student.