guest lecture of prof. paulo cesar at nova southeastern/jan 2015
DESCRIPTION
Guest Lecture of Prof. Paulo Cesar at Nova Southeastern/Jan 2015TRANSCRIPT
Associate ProfessorUniversity of São PauloSchool of DentistryDepartment of Biomaterials and Oral Biology
Fatigue behavior of glass-ceramics, glass-
infiltrated alumina, and zirconia (Y-TZP) for
dental applications
Paulo Francisco Cesar, PhD
Outline:
1.1. Fatigue of ceramic materials (Slow Crack Growth).
1.2. Load application modes: static, dynamic, cyclic.
1.3. Cyclic fatigue: types of laboratorial tests.
1.4. Fatigue parameters (stress corrosion coefficient, n).
http://youtu.be/U9GbhHFaTmk
1.1. Fatigue of ceramic materials (Slow Crack Growth)
Stresses below the critical level (< KIc)
Strong effect of humidity
1.2. Load Application modes
Static
Dynamic
Cyclic
Gonzaga et al.
J Biomed Mater Res B Appl Biomater. 2011, 99(2):247-57
Gonzaga et al. Dent Mater. 2011, 27(4):394-406
Callister, 2007
Cyclic fatigue
Presence of artificial saliva,
Temperature and pH variations,
Stress level and frequency similar to
in vivo situation.
Cyclic fatigue
1.3. Cyclic fatigue: types of laboratorial tests
S-N curves
Cycling at a fixed stress level
Stair-case approach
Step-stress approach
Str
ess A
mplit
ude
Number of cycles
Learnengeneering.org
S-N Curve
Studart et al. Biomaterials. 2007, 28(17):2695-705.
500 N
160 N
Cycling at a fixed stress level
Studart et al. Biomaterials. 2007, 28(17):2695-705.
Fatigue parameters obtained by cycling at a fixed stress level
Cycling at a fixed stress level
Stair-case approach
Amaral, M.; Cesar, P.; Valandro, L.; Lohbauer, U., 2013
600
650
700
750
800
850
900
-1 9 19 29 39 49 59 69 79
Stre
ss (
MPa
)
Specimen order
10^2
10^3
10^4
10^5
102
103
104
105
Stair-case approach
Str
ess
(M
Pa)
Control
Silicatization (Rocatec)
Glass film
Amaral, M.; Cesar, P.; Valandro, L.; Lohbauer, U., 2013
Step-stress
ReliaSoft ALTA 7 - www.ReliaSoft.com
Stress vs Time
Time (cycles)
Stre
ss
(M
Pa
)
0 20435340871 81741 163482100
400
160
220
280
340
Stress Profile
Step-stress
Borba et al. Dent Mater, 2013, doi: 10.1016/j.dental.2013.05.009
1.4. Fatigue parameters (stress corrosion coefficient, n)lo
g f
rac
ture
str
es
s (
MP
a)
Fra
ctu
re s
tre
ss
(M
Pa)
Log time to failure (MPa/s)
1 day 1 yr 10 yrs
2.1. Residual stress level predicted by finite element analysis
(Thermal stress analysis).
2.2. Residual stresses calculated by the “hole-drilling” technique.
2.1. Residual stress level predicted by finite element analysis
(Thermal stress analysis).
Meira et al. Dent Mater, 2013, 29(5):594-601
2.1. Residual stress level predicted by finite element analysis
(Thermal stress analysis).
Minimum
principal stress
(s3)
Meir
aet
al.
Den
t M
ate
r, 2
013, 29(5
):594-6
01
Maximum principal stress (s1)
Meira et al. Dent Mater, 2013, 29(5):594-601
Belli R, Dent Mater. 2013; 29(2):181-90
Belli et al., J Mech Behav Biomed Mater. 2013; 21:167-77
2.2. Residual stresses calculated by the
“hole-drilling” technique
- Title: Residual stress in veneering ceramic on Y-
TZP, alumina and ZTA frameworks.
- Authors: K. Fukushima, M. Sadoun, P. Cesar, A. Mainjot.
COFECUB project
Comité Français d'Evaluation de la Coopération
Universitaire et Scientifique avec le Brésil
- Aknowledgements: Grace de Souza, H. Yoshimura, H.
Goldenstein, Jean-Pierre Attal.
2.2. Residual stresses calculated by the “hole-drilling” technique
Hole-drilling technique
Mainjot et al. Dent Mater. 2011; 27(5):439-44
Hole-drilling technique
COFECUB Project: Univ. Paris-Descartes (Paris 5)
Fukushima et al., 2013 - COFECUB
Y-TZP Alumina
ZTAFukushima et al., 2013 - COFECUB
Fukushima et al., 2013 - COFECUB
3.1. Reinforcement of dental porcelain with alumina particles.
3.2. Addition of carbon nanotubes to Y-TZP.
3.1. Reinforcement of dental porcelain with alumina particles
PhD project: Reinforcement of dental porcelain with
alumina (mono and pollycristal)
PhD Student: Marina Kaizer
Advisor: Rafael Moraes
In colaboration with: Paulo Cesar
Univ. Federal de Pelotas
Kaizer, 2013
Kaizer, 2013
Kaizer, 2013
Control Polly Polly+Sil Mono+Sil Mono
Kaizer, 2013
Reinforcement of dental porcelain with alumina
(mono and pollycristal)
PhD Project: Development of the nanocomposite
Y-TZP / MWCNT-COOH for dental applications
3.2. Addition of carbon nanotubes to Y-TZP
Student: Lucas Hian da Silva
Co-advisor: Rubens Tango
Advisor: Paulo Cesar
In collaboration with the
Institute for Nuclear and
Energetic Research (IPEN):
Dolores Lazar
Walter Usui
Walter Yoshito
Carbon Nanotube (CNT)
Yu et al., 2000; Ando, 2010
MWCNT fuctionalized
Lucas Hian da Silva, 2013
Y-TZP conventional Y-TZP/MWCNT
Lucas Hian da Silva, 2013
3.2. Addition of carbon nanotubes to Y-TZP
Thank you!
Associate ProfessorUniversity of São PauloSchool of DentistryDepartment of Biomaterials and Oral Biology
Paulo Francisco Cesar, PhD
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