This document discusses the development and characterization of PVDF-TrFE/ZnO nanocomposite piezoelectric sensors. X-ray diffraction shows peaks corresponding to PVDF(110) and ZnO(101) crystal planes. Dielectric studies found that as ZnO concentration increased from 10wt% to 60wt%, permittivity decreased from 11.22 to 5.665, while piezoelectric voltage coefficient increased from 0.89 Vm/N to 2.64 Vm/N due to higher ZnO content. Pitch-catch measurements showed the 60wt% ZnO sensor had the highest sensitivity of 2.64 mV/Nm. Dynamic analyses found PVDF sensors had faster response and relaxation times than

2. Sensitivity comparison of PVDF and nanocomposite PVDF-
TrFE/ZnO by Pitch Catch measurement

3. Development and characterization of PVDF nanocomposite for structural
health monitoring
 PVDF poly(vinyledene difluoride)-TrFE(Trifluoroethylene)/ZnO Zinc Oxide
nanocomposite piezo sensor is developed in solvent cast method.
 PVDF-TrFE-3g
 ZnO in two different concentration 10&60wt%
1. PVDF-TrFE pellets dissolved in DMF(dimethyl Formamide) for 30minutes
2. Zinc oxide dispersion in DMF under sonication for 4hours
3. Same zinc oxide solution is then mix with PVDF-TrFE solution
4. Continuous stirring for 10minutes.
5. Cast the prepared solution on a glass mould keep it in furnce at 120degC for
2hours.

4. Characterization of PVDF-TrFE/ZnO nanocomposite film
 X-ray diffraction for structural study
 Dielectric study
 Sensitivity : pitch catch measurement

5. X-ray diffraction
Here, peak positions of reflections corresponding to PVDF(110) and
ZnO(101) are marked in the pattern which is matching with the literature
value

6. Dielectric study
For PVDF permittivity is 16.2
@10kHz, for PVDF-TrFE/ZnO at
10wt% of ZnO Permittivity is
11.22 & for PVDF-TrFE/ZnO at
60wt% of ZnO Permittivity is
5.665.

7. Piezoelectric coefficient
Sensor Freq
(Hz)
(Hz)
d33(pC/N
)
Permittivity(ε) g33(Vm/N)(g=d/ε)
(Vm/N)
PVDF 100 22 16.2 1.35
10wt%
of ZnO
100 10
11.2
0.89
60wt%
of ZnO
100 15
5.665
2.64
Further, the poled PVDF-TrFE/ZnO nano-composite samples were evaluated for piezoelectric
properties.
1.35
0.89
2.64
0
0.5
1
1.5
2
2.5
3
5 7 9 11 13 15 17
g,VoltageCoefficient(mVm/N)
Permittivity
Above graph says as the g33, sensitivity depends on the permittivity, it says sensitivity is more for the
60wt% ZnO dopant to the PVDF-TrFE, i.e2.64mVm/N at 5.665 permittivity

8. Pitch catch measurement
i) For the test, in Fig. 1, one aluminum cantilever beam is
used. On the beam one actuator (PZT) and one sensor
(PVDF) is bonded using structural epoxy.
ii) The actuator is connected to one channel of function
generator and also to one channel of CRO. Thus, input to
actuator can be seen on the CRO screen.
iii) The sensor is connected to one channel of CRO. This
channel is selected as a trigger.
Frequency 100-400Hz
Amplitude 10Vpp

9. Frequency response
 The specimens were excited using two square 13 mm PZT wafers which
were temporary adhered with araldite to the base of the specimen and
actuated out of phase by an 10 Vpp which was sent to the Piezos
through a function generator to drive them between 100 Hz and 15MHz
in first trial. Finally, how the piezos will responds for higher frequency
range has been observed. i.e., from 15Hz,15Kz and 15Mhz

10. Keeping amplitude constant and varying the frequency from 100 Hz to 400 Hz,
variation in voltage output is observed.
As the frequency increases voltage of nanocomposite sensor starts deteriorating from 7 to 5V and PVDF from
3to2V.

11. Frequency response of PVDF and Nanocomposite sensor from Hz to Mega
Hertz(MHz) range:
As the frequency increases
from 15 Hz to 15MHz range
amplitude starts decreasing
and voltage peak to peak
reduces 9V to 1 V for
nanocomposite and 4V to
736mV.

13. What is Structural Health Monitoring (SHM)
“The process of implementing a damage detection and
characterization strategy for aerospace, mechanical
and civil engineering structures”
Not a new concept
•Has been around for several decades
•Advances in electronics made it easier
to implement.
Several non-destructive evaluation (NDE) tools available for
monitoring.

14.  Health monitoring
Operational Evaluation
Data Feature Extraction
Statistical Models Development
1. Strain gages
2. Inclinometers
3. Displacement transducers
4. Accelerometers
5. Temperature gages
6. Pressure transducers
7. Acoustic sensors
8. Piezometers
9. Laser optical devices
Instrumentation used:
SHM Involves:
• Most of these sensors can be wirelessly connected.
• Technology using solar energy is very common in instrumentation.
• Latest technology even has self powered systems, i.e. no external power required.

15. Monitoring Metrics
Measure:
 Acceleration
 Strain
 Climatic Conditions
 Curvature
 Displacements
 Load
Identify:
 Corrosion
 Cracking
 Strength
 Tension
 Location of rebar
/delaminations

16. Damage Detection and Impact Prediction:
Damage detection is a problem of prime interest in aircraft
structures
Aim of current study is to analyze damage detection caused
due to impact on structure and use those observation for
prediction of impact location and energy
This study will be helpful in real-time impact detection in aircraft structures.
Real-time detection will be better than damage detection after failure. This will save lot of
time and also reduce failures caused because of damages occurred in structures.

17. Methodology:
 Impact of known energy will be made on composite structure at known
location
 Strain developed in structure will be observed with PVDF sensor
 These will be compared with conventional strain gages
 Pattern and profile for strains developed under various energies of
impact will be taken
 These profiles will be used to conversely predict the impact energy and
location based on damage occurred

18. 1. Static Analysis

19. Proportionality of Response :
PVDF sensor was fixed on composite
plate
Impact was made at a fixed distance
from the sensor with different energies
Corresponding voltage values were
recorded
Impact Position
PVDF Sensor

20. Results: Energy(J) +ve peak -ve peak Max. of abs
1 1.04188 -1.14113 1.14113
2 1.549449 -1.36849 1.549449
3 2.06722 -1.90539 2.06722
Voltage increased
proportionally with
increase in impact energy
Proportionality factor from
obtained values is
0.463V/J

21. Direction Dependence and Repeatability:
Impacts were made around
PVDF sensor in a circular path
With same energy, impacts were
made with step of 10°
2trials for 1J energy and one
trial for 2J were conducted

22. O
b
s
e
r
v
a
t
i
o
n
Angle
Trial 1_1J Trial 2_1J Trial 1_2J
+ve peak -ve peak +ve peak -ve peak +ve peak -ve peak
-90 1.091693 -1.56037 1.132474 -1.52887 1.507252 -2.33628
-80 1.150267 -1.6023 1.041477 -1.34567 2.033199 -2.38395
-70 1.140076 -1.55194 1.029984 -1.75659 1.343843 -2.02198
-60 1.270749 -1.50136 1.027031 -1.09734 1.433522 -1.30784
-50 1.553907 -2.00647 1.020616 -0.86894 1.353675 -1.25856
-40 1.495541 -1.91412 1.385657 -1.58436 1.377144 -1.63372
-30 1.743303 -2.33434 0.771667 -0.83048 1.532751 -2.08906
-20 1.362303 -1.45809 1.344471 -1.47443 1.687561 -1.86865
-10 1.475035 -1.86387 1.460196 -1.95776 1.721271 -2.13295
0 1.004034 -1.41232 1.119668 -1.48516 1.70534 -2.60267
10 1.179591 -1.90361 1.221367 -1.77897 1.20738 -1.7414
20 1.100083 -1.9348 1.256186 -1.66937 1.495461 -2.21248
30 1.182704 -1.80934 0.940167 -1.25182 1.087983 -1.60236
40 1.061459 -1.55429 1.000197 -1.32096 1.112323 -1.43387
50 1.097387 -1.33743 1.032448 -1.23148 1.679943 -2.08662
60 0.942713 -1.33263 0.859171 -1.37734 1.579155 -2.07065
70 1.113512 -1.62083 1.085304 -1.7484 1.681362 -2.69384
80 1.007912 -1.62993 1.141654 -1.74292 1.079625 -1.88151
90 1.92805 -1.6861 1.391464 -1.54187 1.299706 -1.64393

23. Impact energy : 1J

24. Impact energy 2J

25. Results: fit
Trial1
1J
Trial 2
1J
Trial
2J
+ve 1.257 1.119 1.469
-ve 1.685 1.68 1.947
max 1.697 1.46 1.959
Further Approach:
Dynamic (time-domain) analysis of PVDF sensor

27. Previously-:
PVDF sensor was tested for SHM application
•Static analysis was performed for impacts of known energies
•Repeatability and proportionality was verified for PVDF sensor
•Directional dependence of sensor to impacts was analysed
Further Approach:
 Dynamic (time-domain) analysis of PVDF sensor

28. 2. Dynamic Analysis

29. Test Set-Up
 The composite plate was fixed with 4 sensors as shown in
schematic figure
 4 strain gauge were also placed at same position for direct
comparison with sensor
 Impacts were made at various location with same energy

30. is dielectric
constant of material
Working Formulae:
The voltage generated by a piezo-sensor is given by:
where, C is capacitance of material given by:
Sensitivity of material to strain is defined as,
Conversely, strain to the sensor can be calculated as,
‘Y’ is Young’s Modulus of
elasticity
l , b , t represent the length,
breadth & thickness of sensor
resp.

31. Pre-Calculations:
 4 PVDF sensors of thickness 120µm, 25µm, 50µm and100µm were
taken and applied at respective positions on the test composite plate.
 Using the working formulae the strain developed per unit voltage
generated for the sensors was found to be:
Sensor thickness(µm) ε/V (µstrains)
120 26.7
25 128.4
50 64.24
100
32.12

32. Observations:

33. Shown below are responses of PVDF sensors and corresponding strain gauges for impact at centre
of composite plate (245,170).

34. Shown below are responses of PVDF sensors and corresponding strain gauges for impact near to
sensor1on composite plate (370,230).

35. Shown below are responses of PVDF sensors and corresponding strain gauges for impact near to
sensor2 on composite plate (125,230).

36. Shown below are responses of PVDF sensors and corresponding strain gauges for impact near to
sensor3 on composite plate (370,105).

37. Shown below are responses of PVDF sensors and corresponding strain gauges for impact near to
sensor4 on composite plate (125,105)

38. Dynamic Analysis:
 Two important features in dynamic response of sensor are response time and relaxation time.
 Since, throughout the experiment responses of sensors were recorded for a single impact
which causes strain to develop in the composite and reduces gradually afterwards.
 The rise time and settling time for strain caused due to impact as measured by strain gauge
and PVDF sensor will be compared here forth.
 Rise time: time taken for sensor output to increase from zero/offset
to maximum, corresponding to strain developed in structure.
 Relaxation time: time taken for settling of sensor output from max.
back to zero/offset (or 0.7of maximum).

39.  Shown here, is the response of RSG1 and PVDF sensror1 for impact at location 1 (75,175)

40.  Response time
TrRSG –TrPVDF =0.023sec
 Rise time
 PVDF=17msec
 RSG=61msec
 Settling time
 PVDF=12.36msec
 RSG=33.08msec
*Above values are for PVDF sensor1 and RSG1 at centre impact. Similar results
were obtained in other trials as well for all sensors.
Results:

41. Frequency Response Analysis

42.  Cantilever 1 (for RSG and PVDF)
 50cm x 1.8cm x 0.4cm
 Tip distance 4.5cm
Free Vibrations
Schematic of the setup made for comparison of frequency response of
strain gauge and FBG sensor with PVDF sensor
t
b
l
Composite Cantilever
 Cantilever 2 (for FBG and PVDF)
◦ 25cm x 4cm x 0.1cm
◦ Tip distance 4cm

43. The experiment:
 PVDF sensor and RSG were fixed on a cantilever beam of composite
material.
 The cantilever was forced to free vibrations and responses from RSG
and sensor was recorded.
 The frequency spectra of the two sensors was obtained and
compared.
 On another composite cantilever, PVDF sensor and FBG sensor were
fixed.
 Same procedure was followed for this cantilever as well, for
comparison of FBG and PVDF sensor.

44. Results:
 Shown here are the
responses for PVDF
sensor and strain gauge
along with and their
respective frequency
spectra for first trial.

45. Results:
 Shown here are the
responses PVDF sensor
and FBG along with their
respective frequency
spectra for first trial.

46. Observations:
PVDF & FBG
FBG PVDF
Trial1 18.43 18.33 37.22 50 117.8 135.6
Trial2 18.45 18.24 37.06 50 117.6 135.9
PVDF & RSG
RSG PVDF
Trial1 13.25 82.65 13 83 240
Trial2 13.64 81.82 13 82 239
Trial3 26.76 170.4 26 170 478
Trial4 26.79 26 170 478
Trial5 25 25 170 480
Trial6 25.44 26.67 51.67 168.3 478.3

47. Conclusions:
 A good agreement was found in frequency spectra of PVDF sensor
and RSGs as well as FBGs for free vibration of composite cantilever.

48. Conclusion
fit
Trial1
1J
Trial 2
1J
Trial
2J
+ve 1.257 1.119 1.469
-ve 1.685 1.68 1.947
max 1.697 1.46 1.959
Part 1: X-ray diffraction shows at(110) reflection highest peak is 20.-
-- and (101) reflection highest peak is 36.----for ZnO
Dielectric as the dielectric constant increases sensitivity decreases
as shown in the graph no----
Piezo coefficient though piezo coefficient is less for nanocomposites
its sensitivity is high
Frequency response as the frequency increases PVDF is comes in
mV and nano will be in V.
Response time
TrRSG –TrPVDF =23msec
Rise time
PVDF=17msec
RSG=61msec
Settling time
PVDF=12.36msec
RSG=33.08msec
PVDF & FBG
FBG PVDF
Trial1 18.43 18.33 37.22 50 117.8 135.6
Trial2 18.45 18.24 37.06 50 117.6 135.9
PVDF & RSG
RSG PVDF
Trial1 13.25 82.65 13 83 240
Trial2 13.64 81.82 13 82 239
Trial3 26.76 170.4 26 170 478
Trial4 26.79 26 170 478
Trial5 25 25 170 480
Trial6 25.44 26.67 51.67 168.3 478.3
Part 2:
Part 3:

49. Thank You