Evaluation and comparison of estimated
wave elastic modulus of concrete, using
embedded and surface bonded PZT
sensor/actuator systems
Presented by: Ayumi Manawadu, Ph.D. student
Zhidong Zhou, Ph.D. student
Pizhong Qiao, Professor
08-10-2017
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US infrastructure in poor shape
• ASCE score for bridges in US: C+
• 4 in every 10 bridges are 50 years or older
• Many bridges are approaching the end of their design life
• Condition assessment and continuous monitoring is important
• Non Destructive test methods available are expensive, inaccurate, or difficult to implement
• Right now there is no effective technology!
• Approach : use of ultrasonic wave based sensor systems
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Image Source: Google images
Objectives
• To study and evaluate suitability of surface bonded sensor systems to determine wave elastic modulus of concrete (E), with comparison to embedded sensor systems (over first 28 days after casting)
• To develop Finite Element models to verify the experimental results (for 28th day results)
• To study the effect of orientation of embedded sensors in the estimation of E
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Fundamentals of Piezoelectricity:
Piezoelectricity (direct effect)Development of an electric potential across boundaries when a mechanical stress (pressure) is applied (1880, Curie brothers). Converse effect also exists.
4Image Source: Google images
Source: Sirohi & Chopra, 2000), (Jordan & Ounaies, 2001)
Fundamentals of Piezoelectricity:
Piezoelectricity contd.
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Sjk : Strain [6x1]
Ei : Applied electrical field vector (volt/m) [3x1]
Tkl : Stress (N/m2) [6x1]
dijk : Piezoelectric constants (Coulomb/N or m/Volt)
𝒔𝒊𝒋𝒌𝒍𝑬 : Compliance matrix (m2/N)
𝑆𝑗𝑘 = 𝑑′𝑖𝑗𝑘𝐸𝑖 + 𝑠𝑖𝑗𝑘𝑙𝐸 𝑇𝑘𝑙 (1)
Fundamentals of Piezoelectricity:
Examples of piezoelectric material
Natural Biological Synthetic ceramics Polymers
Sucrose(table sugar)
Dry BonesLead zirconate titanate - PZT
(Pb[ZrxTi1−x]O3 with 0 ≤ x ≤ 1)
Polyvinylidene fluoride (PVDF):Quartz Tendon Barium titanate (BaTiO3)
Rochelle salt Silk Potassium niobate (KNbO3)
Topaz Enamel Sodium tungstate (Na2WO3)
Berlinite DNA Bismuth ferrite (BiFeO3)
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Experimental Program:
Outline
B#1: SA 0⁰ to beam longitudinal axis B#2: SA 45⁰ to beam longitudinal axis
B#3: SA 90⁰ to beam longitudinal axis
Smart Aggregate (SA)
Smart Aggregate (SA)
PZT
Surface Bonded PZT (in all three beams above)
r=5mm, t=0.4mm
r=9.5mm, t=19.05mm
Concrete beam: 16’x4’x3’
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Prepare SA
• Coat PZT with Epoxy
• Encase in cement mortar
• Wrap copper coils
• Cure SA
Embed SA and bond PZT
• Embed SA at 0⁰, 45⁰, 90⁰ orientations (to longitudinal Axis)
• Surface bond PZT with epoxy
• Cure
Testing
• Sensor response over first 28 days
• Time of Flight of 1st shear wave package
Experimental Program:
Procedure
Smart Aggregates : Song et.al (2008)
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Oscilloscope
Dual Channel
FilterArbitrary waveform generator
Power Amplifier
Experimental Program:
Setup
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Experimental Program:
Fundamentals of wave propagation
Image Source: Google images
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0
50
100
150
200
250
0.0000 0.0001 0.0002 0.0003 0.0004 0.0005
Sign
als
cap
ture
d b
y SA
(m
V)
Time (s)
ToFFirst Shear wave
package
Experimental Program:
Determination of Time of Flight (ToF)
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Cs – Shear wave velocity, CR – Rayleigh wave velocity, ToF – Time of flight
-1.0
-0.5
0.0
0.5
1.0
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
Am
plit
ud
e
Time (x10-5 s)
100kHz 3.5 cycles Hanning windowed sine wave
𝑓 𝑡 = 0.5(1 − cos( 2𝜋𝑡 × 100 × 103
3.5)) sin(2𝜋𝑡 × 100 × 103) 0 < 𝑡 < 3.5 × 10−5𝑠
0 𝑡 > 3.5 × 10−5𝑠(5)
(2)
(3)
(4)
𝐶𝑠 = 𝑙 𝑇𝑂𝐹
𝐶𝑠 =𝐸𝑑
2(1+𝜈)𝜌
𝐶𝑅 =0.87+1.12ν
1+ν
𝐸𝑑
2(1+ν)ρ
𝑇𝑂𝐹 ∝1
𝐶𝑠(𝑜𝑟 𝐶𝑅)∝
1
𝐸
Experimental Program:
Procedure to determine Wave Elastic Modulus (E)
• PZT: d33=320 pm/V, d31=-140 pm/V, E33=73 GPa,
E11=86 GPa, ρ=7.9 g/cm3
• Constraints:
– Surface based ties: PZT-casing (master surface: PZT)
– Coupling: Electric potential of PZT - master nodes
• Step : static general
• Boundary conditions
– PZT top : Apply Linear Electric potential
– PZT bottom : Electric Potential 0V
– Smart module bottom surface : Fixed 13
Part Element MeshPZT linear piezoelectric brick 1 mm
Mortar casing 8 node linear brick – full integration 2.5 mm
Finite Element Model – Abaqus 6.10.1:
Modelling of Smart Aggregate (SA)
Deform
Undeform
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-25
-15
-50 20 40 60 80 100
u3
dis
p. (
x 1
06
m)
Electric Potential (V)
0
2
4
6
8
0 20 40 60 80 100
u1
,u2
dis
p. (
x10
9m
)
Electric Potential (V)
Finite Element Model – Abaqus 6.10.1:
Results from static/general analysis of SA
Electric Potential
U3
• Concrete beam :
– Element : C3D8 full integration
– Mesh : 2.5 mm (at least 2.67 mm for accurate results)
– Assumed: E= 20GPa, ν=0.2, ρ=2400 kg/m3
• Step : Dynamic, implicit (time period: 3e-4 s, increment size 1e-6s)
• Field and History Output : EPOT, U
• Boundary conditions :
– Smart cement module was modelled as before
– Sinusoidal Excitation signal applied as before
– Concrete beam – free boundary conditions
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Finite Element Model – Abaqus 6.10.1:
Analysis (concrete beam+ SA)
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Finite Element Model – Abaqus 6.10.1:
Analysis (beam+ SA/PZT)- displacement contours
Embedded SA at 0⁰ Embedded SA at 45⁰
Embedded SA at 90⁰ Surface bonded PZT patches
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Finite Element Model – Abaqus 6.10.1:
Relevant response signals from FE Analysis
-8
-6
-4
-2
0
2
4
6
8
0 0.00005 0.0001 0.00015 0.0002 0.00025 0.0003A
mp
litu
de
u3
(x1
0-1
2m
)
Time (s)
First shear wave package
-10
-5
0
5
10
0 0.00005 0.0001 0.00015 0.0002 0.00025 0.0003
Am
plit
ud
e u
3 (
x10
-12
m)
Time (s)
Rayleigh wave package
Embedded SA
Surface bonded PZT patches
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Change in experimental ToF of first shear wave package on 28th day : embedded PZT patches
207202 201202
219
200201 201 201
150
160
170
180
190
200
210
220
230
1 2 3
ToF
(µs)
Beam Number
Experimental_Embedded Numerical_embedded Theoretical_embedded
Note : E= 18GPa is assumed for the FE model. Maximum difference between; experimental results is 2.99%, experimental and numerical results is 8.96%.
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Change in experimental ToF of Rayleigh wave package on 28th day : surface bonded PZT patches
Note : E= 18GPa is assumed for the FE model. Maximum difference between experimental results is 1.85%
219
220
216215
221
205
210
215
220
225
B#1 B#2 B#3 Numerical Theoretical
ToF
(µS)
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Change in experimental dynamic elastic modulus with hydration : embedded & surface bonded PZT patches
y = 14.422x0.0693
y = 17.041x0.0215
y = 13.888x0.1034
y = 15.138x0.0362
y = 16.04x0.0383
y = 13.964x0.0734
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15
16
17
18
19
20
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Wav
e M
od
ulu
s o
f El
asti
city
, E (
GP
a)
No. of days since casting
B#1_surf B#2_surf B#3_surf B#1_embed B#2_embed B#3_embed
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Comparison of experimental wave elastic modulus of embedded & surface bonded PZT patches at 28th day
Note : E= 18GPa was initially assumed for the FE model. Maximum difference between surface bonded and embedded PZTs is 10.47%
18.36
18.11
18.78
18.00
17.00
17.8518.03
16.00
17.00
18.00
19.00
B#1 B#2 B#3 FEM/Theo
Wav
e M
od
ulu
s o
f El
asti
city
, E (
GP
a)Surface Bonded (exp) Embedded (exp)
• Estimated wave modulus of elasticity (E), through surface bonded sensors is larger than the embedded sensors
• Estimated E from the two systems are in good agreement with each other (with a maximum difference of 10.47%)
• Orientation of sensors has an impact on the clarity of wave packets, but no significant effect on the estimated E (maximum difference:
• Proposed finite element models are in good agreement with theoretical and experimental results
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Summary of findings and Conclusions
Future research
• Identify the effectiveness of using surface bonded sensors to determineelastic material properties of concrete/polymer concrete in the presenceof– Cracks– Freeze/thaw attacks– Changes in beam dimensions
compared to embedded PZT sensor systems
• Study the effectiveness of using surface bonded sensors in detection ofvarious damages, over embedded sensor systems
• Build a portable device for damage detection and material propertyassessment of large scale civil infrastructure
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Thank You!
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Questions?
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