new graduate student orientation august 15, 2012 dr. phillip white this presentation can be found...
TRANSCRIPT
New Graduate Student Orientation
August 15, 2012
Dr. Phillip White
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 4241Focus Group
* = not adding new students at this time.
Dr. Lesley BerhanResearch 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 nanocompositesComposite and Fibrous Materials Laboratory | University of Toledo
Dr. Lesley Berhan
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
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
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.
Dynamic and Smart Systems Laboratory
North Engineering Room 2045
Phone: (419) 530-8130
Fax: (419) 530-8126
http://smartsys.eng.utoledo.edu/
Background (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
Conclusions
Allows a material to return to its original shape within a strain of up to 8% by increasing the temperature.
Shape memory alloy (SMA) technology offers new capacities to medical devices, negotiating the obstacles in:
Spinal instrumentation of osteoporotic bone and
Esophageal fistula during Radiofrequency ablation (RFA).
References1. 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 248-253.2. H. A. Yuehuei. Internal fixation in osteoporotic bone. Edited by H. A. Yuehuei. Thieme Medical Publishers, INC.
2002.3. 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.
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.
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 :
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
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.
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, …
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.
Osteoporosis and spinal instrumentation
The screw assembly before placement The screw assembly after placement
Anchoring system with expandable thread inserts
NiTi insert. Initial low-temperature (at insertion). and closed high temperature form (at withdrawal).
Final form when reached to body temperature. A portion of the insert from both ends expands.
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.
SMA esophagus positioner
SMA wires, if heated, will deflect the esophagus away from the ablation site.
Biomedical Applications of NiTi Shape Memory Alloys:(I) Smart pedicle screw (II) Esophagus positioner
Majid Tabesh, Amin Mohaghegh, and Mohammad ElahiniaDynamic and Smart Systems Laboratory, MIME Department, University of Toledo
Fatigue and Fracture of Materials and Structures
• Why an important area of research?– Between 60% and 90% of all mechanical failures are attributed
to fatigue fractures (many textbooks on fatigue)
– The cost of these fractures in the US alone is about 4% of the GNP (NIST study)
– Broad applications to many materials (metals, polymers, composites) and to many structures and industries (automotive, aerospace, power generation, etc.)
– Several journals dedicated to this topic, including International Journal of Fatigue, Journal of Fatigue and Fracture of Materials and Structures, International Journal of Fracture, Journal of Engineering Fracture Mechanics, etc.
Experimental Research Laboratory
State-of-the-Art Facilities, including:•Servo-hydraulic Systems
– Three Axial Load Frames– Torsion Load Frame – Axial-Torsion Load Frame
•Electro-mechanical Systems– Axial Load Frames (50 kN)– Rotating Bending Machines– Cantilever Non-rotating Bending
•Extensometry– Mechanical Extensometers– Video-Extensometer (Non-Contact)
•Crack Detection Systems
Related Graduate Level Courses Regularly Offered
– Advanced Mechanics of Materials– Fatigue of Materials and Structures
–Fracture Mechanics (offered this term)
– Mechanics of Composite Materials
Current Sponsored Research Projects
• Notched Fatigue Behavior under Constant and Variable Amplitude Multiaxial Loading, Funded by Funded by US Navy Air System Command US Navy Air System Command
• Development of a Axial Stress-Life Database for Gear Steels in Aircraft Engine Applications, Funded by Funded by Pratt-Whitney Pratt-Whitney (A Division of (A Division of United Technologies)United Technologies)
• Fatigue Behavior and Modeling of Polymeric Materials,, Funded Funded by by General Motors General Motors
• Axial and Bending Fatigue of Cast Iron including Stress Concentration Effects, Funded by Funded by Eaton CorporationEaton Corporation
• Experiments and Modeling of Thermo-Mechanical Fatigue of Polymeric Materials,, Funded by Funded by General Motors General Motors
• Strain-Controlled Fatigue Properties of 4037 Steel, Funded Funded by by Chrysler LLC.Chrysler LLC.
• Strain-Controlled Deformation and Fatigue Behavior of Sheet and Cast Aluminum for Structural Durability Design and Evaluation, Funded by Funded by General MotorsGeneral Motors
• Mechanical Modeling and Fatigue Damage Analysis of Annulus Fibrosus, Funded by Funded by Engineering Center for Orthopaedic Research Excellence.Engineering Center for Orthopaedic Research Excellence.
Need More Information?
–Visit Dr. Fatemi’s Website
Dr. Yong Gan
• See next slides for research areas
• He is interested in working with Ph.D. students and is seeking funding.
Outline
• Thermoelectric and Photoelectric Energy Conversion
• High Temperature Thermoelectric Energy Conversion Materials
• Synthesis of Photovoltaic (PV)/Thermoelectric (TE) Nanofiber Arrays
• Preparation of Biophotofuel Cell Electrode
Thermoelectric property
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
Biophotofuel Cell Design
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 cross-correlation 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
Contact: Professor A. H. Jayatissa Tel: 419-530-8245
Room #: 4049 NIE-mail: [email protected]
All projects involve Experimental activities and 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
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)
Definition and Significance
It is expensive to optimize vehicle body design by using detailed FEM for sound and vibration
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.