Active materials are rapidly expanding their variety as well as applications due to their promising high–tech potential. Composite structures of active materials enable researchers to develop mechatronic systems and devices with inherent intelligence features and increased level of integration. A composite structure consisting of piezoactive material and electrorheological fluid is proposed, and its possibilities in developing self-adjusting and adaptive systems are discusse

R. Bansevicius

R.-T. Tolocka

English

Journal of Vibroengineering

 © VIBROMECHANIKA.  JOURNAL OF  VIBROENGINEERING.  2008 JANUARY/MARCH,   VOLUME  10,  ISSUE  1,  ISSN 1392-8716 
 
52 
334. Application of Piezoactive Material/Rheological Fluid Composite  
        Structures in Engineering 
 
R. Bansevicius1, R. T. Tolocka2 
Kaunas University of Technology,  
Kestucio 27, LT- 44312, Kaunas, Lithuania  
E-mail: 1 Bansevicius@cr.ktu.lt, 2 Tadas.Tolocka@ktu.lt 
 
(Received 20  January 2008; accepted 17  March  2008) 
 
 
 
 
     
 
 
 
Abstract. Active materials are rapidly expanding their variety as well as applications due to their promising high–tech 
potential. Composite structures of active materials enable researchers to develop mechatronic systems and devices with 
inherent intelligence features and increased level of integration. A composite structure consisting of piezoactive material 
and electrorheological fluid is proposed, and its possibilities in developing self-adjusting and adaptive systems are 
discussed.  
 
Keywords: adaptive damping, composite structure, active material. 
 
 
Notation 
 
S – strain;  
Es  – compliance when the electric field is not applied; 
 T – stress; 
d – piezoelectric coupling constant;  
E – electric field strength;  
D – charge–density displacement;  
Tε – permittivity at constant stress. Superscript t stands 
for the matrix transpose;  σ
 – stress in the electrorheological fluid; 
 E – electric field strength; η  – viscosity;  
u – displacement of fluid particle; 
 y – particle coordinate; 
 t – time; 
 x(t) – PAM shear strain in the coating surface which is 
proportional to the mass m displacement;  
F(t) – excitation force;  
A – coating cross section;  
l – coating surface length. 
 
Introduction 
 
Over the past centuries the materials meeting specific 
needs for strength, durability, weight, flexibility, etc. were 
developed. With the advent of active materials, the 
components able to modify themselves in these dimensions 
came into reality. They are copying the intelligent forms of 
the living world and thus share inherent intelligence which 
allows them to respond to the changes in the environment. 
In the simplest case these materials respond directly to 
stimuli without any signal processing. More sophisticated 
systems contain their own sensors, actuators and 
computational capabilities in order to modify their 
behaviour responding to the changing environment. Such 
smart systems based on active materials are currently used 
for a growing range of commercial applications in 
structural engineering, biomedical, optical techniques, 
aerospace and other applications.  
A lot of various active materials are more or less 
widely used. Piezoactive materials, rheological fluids and 
shape memory materials have become classical in this area. 
Others, like magnetostrictive, electroplastic, electro-optic, 
electroacoustic, pyrosensitive materials, are expanding 
wide scale applications. Active material composite 
structures have the most promising high–tech potential for 
shock and oscillation suppression systems [1,2]. The 
application possibilities of an active material structure 
consisting of a piezoactive material and rheological fluid 
are discussed in the paper, which is an overview of the 
ongoing research [3-6]. 
 
Piezoactive material/rheological fluid composite 
structure and its applications 
 
Piezoactive materials (PAM) applications are based on 
the piezoeffect, which is described as follows: 
 334. APPLICATION OF PIEZOACTIVE MATERIAL/RHEOLOGICAL FLUID COMPOSITE STRUCTURES IN ENGINEERING. R. BANSEVICIUS1, R. T. TOLOCKA2 
  
 
© VIBROMECHANIKA.  JOURNAL OF  VIBROENGINEERING.  2008 JANUARY/MARCH,   VOLUME  10,  ISSUE  1,  ISSN 1392-8716 
 
53 
EdTsS tE += ,    (1) 
 
EdTD Tε+= ; 
 
  
Due to the possibilities to develop devices featuring 
rapid response, practically unlimited resolution, large force 
generation, broad operating frequency range, high stability 
and low power consumption, PAM is widely used for 
sensing as well as for actuating (Fig.1). Examples of PAM 
applications for actuation are ultrasonic motors, 
micromanipulators, laser tuning devices and other 
instrumentation. Sensing properties of PAM are exploited 
in accelerometers and oscillation suppression systems 
based on the same effect.  
Shear stress in electrorheological fluid (ERF) depends 
on the voltage applied: 
 
ty
uE ∂∂
∂+= ηασ 2 ;    (2) 
 
Thus the fluid viscosity becomes the function of the 
voltage (see Fig.1). There are two possibilities to change 
ERF viscosity: to make use (a) of voltage U alteration at 
the gap h between electrodes being h=const and (b) to 
make use of gap h alteration at voltage between electrodes 
being U = const. In the first case the electric field strength 
(and ERF viscosity as well) become directly proportional 
the voltage and in the second case – inversely proportional 
to the gap magnitude. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Fig. 1. ERF and PAM, and their composite structure properties 
 
 
Low zero-field viscosity, high ER effect, wide 
range of control and high shear stability of ERF are of 
great importance and lead to its successful applications for 
vibration suppression as well as design of simple, quiet and 
rapid-response interfaces between electronic controls and 
mechanical systems. Well known applications are for 
shock absorbers in vehicles, dampers for seats, machinery, 
centrifuges, prostheses, etc. 
Composite structures consisting of ERF and PAM 
promise possibilities to develop systems with inherent 
intelligence of higher level because they allow 
combination of sensing, control and variable parameter 
elements into structures which exhibit self-adjustment and 
adaptability properties. The possibilities of such structure 
to respond to disturbance in accordance with various 
kinematic parameters are shown in the Figure 2, a. Mass m 
is translating in the ERF, whose flow along the contact 
with mass is affected by the viscosity and shear rate of 
shear stress of ERF, which is strongly related to electrical 
charges U, taken from the electrodes of piezoelectric 
ERF PAM 
Variable viscosity 
Possibilities of viscosity 
variation 
Sensing 
Actuation 
Actuation / Sensing 
COMPOSITE STRUCTURE 
PAM 
U≠  const h = const 
U = const h ≠ const 
 Response 
 by changing viscosity   Control Signal 
    PAM    ERF 
Disturbance 
         PAM  signal 
         PAM  voltage 
 Displacement 
 Force 
 334. APPLICATION OF PIEZOACTIVE MATERIAL/RHEOLOGICAL FLUID COMPOSITE STRUCTURES IN ENGINEERING. R. BANSEVICIUS1, R. T. TOLOCKA2 
  
 
© VIBROMECHANIKA.  JOURNAL OF  VIBROENGINEERING.  2008 JANUARY/MARCH,   VOLUME  10,  ISSUE  1,  ISSN 1392-8716 
 
54 
transducers PT [3]. Depending on the position of 
piezoelectric transducer in relation to mass m and 
additional mass ma, electrical charge U is related to the 
position U(x), velocity U( x? ) or acceleration U( x?? ) of the 
moving mass m. Thus the damping characteristics of 
system can be independently controlled by any kinematic 
parameter of mass motion. 
 
 
 
 
 
 
 
 
 
 
 
   
  
  a)                                                                               b) 
 
Fig. 2. Control possibilities of the ERF - PAM composite structure (a) and its application for adaptive damping (b) 
 
The proposed composite structure has a lot of 
various useful applications. The system shown in Figure 2, 
a can be directly applied as an adaptive shock absorber as 
well as for self-adjusting force actuating in the exercising 
machines [4]. It is also suitable for adaptive damping 
system which is schematically shown in Figure 2, b [5,6]. 
The system consists of PAM coating on the structural 
element and the layer of ERF contacting with it. When 
oscillations in the structural element are excited, the 
electric charge proportional to their magnitude occurs in 
the electrodes due to the direct piezoeffect in the PAM and 
causes the electric field whose strength is:  
 
( ) ( ) ;11 ⎥⎦
⎤⎢⎣
⎡ −=
A
tF
stx
ld
E E   (3) 
 
The ERF viscosity changes in the area of ERF 
contact with electrodes in accordance with the applied 
voltage and thus damping becomes adaptive. The 
presented system exhibits both passive and active damping 
features. However, classical passive dampers can only be 
tuned best for a relatively small frequency range, whereas 
an adaptive damping system shown in Figure 2, b is 
characterized by a wide frequency range.  
Using multi-layer structures and films of PZT and 
ERF it is possible to realize adaptive damping of the 
continuous systems (rod, shaft, plate, frame, etc).  
The sectioned electrodes allow us to organize the 
adaptive response in relation to the magnitude of strain in 
the structure [3]. The example is shown in Figure 3, where 
piezoelectric layer is fixed to the vibrating structure. One 
of the electrodes of the piezoelectric layer is sectioned and 
is in contact with ERF. Ux(t) is the distribution of electric 
charge on the sectioned electrodes; σxy - are stresses in the 
active layer. It is easy to notice that damping and flow 
resistance will be directly related to the maximum value of 
the stresses in the structure without applying an external 
electrical field. 
 
 
 
 
 
 
 
 
 
 
 
Fig. 3. Adaptive damping system (a) and its dynamic behavior (b): 1 - vibrating structure; 
2 - PAM layer; 3 a - continuous electrode; 4 - sectioned electrode; 
5 - continuous electrode in the contact with the ERF layer 
 Coeficient of damping  x 
 y 
 Ux(t) 
 σxy 
 x 
 1 
 2 
 3 
 4 
 5 
 ERF 
 PT 
 PT 
 m 
 ma 
F(t) 
m 
 
PAM ERF 
  Electrodes 
 
 334. APPLICATION OF PIEZOACTIVE MATERIAL/RHEOLOGICAL FLUID COMPOSITE STRUCTURES IN ENGINEERING. R. BANSEVICIUS1, R. T. TOLOCKA2 
  
 
© VIBROMECHANIKA.  JOURNAL OF  VIBROENGINEERING.  2008 JANUARY/MARCH,   VOLUME  10,  ISSUE  1,  ISSN 1392-8716 
 
55 
Summary 
 
The composite structure consisting of piezoactive 
material and electrorheological fluid was proposed and its 
application possibilities for self-adjustable damping 
systems were analyzed. The possibilities to develop 
systems with response to different kinematic parameters of 
a moving body and strain distribution have been discussed. 
 
References 
 
[1] Bansevicius R., Tolocka R.T. Shock and impact energy 
absorbtion and control by active material based systems, in: 
Structures Under Shock and Impact VIII, ed.N. Jones &C.A 
Brebbia, Witt Press, 2004, p. 359 – 363. 
[2] Bansevicius R., Tolocka R.T. Application of Active 
Materials for Semi-Active Vibration Suppression Systems, 
in: Proceedings of EUROMECH 455 on Semiactive 
Vibration Suppression. M. Valasek, A. Preumont (Eds.). 
CTU in Prague, Czech Republic, July 5-7. 2004. (CD). 
[3] Bansevicius R., Knight J.A.G., Tolocka R.T. Self-Adaptive 
Composite Structures for Oscillations Damping, in: 
Proceedings of the 4th International Conference on Motion 
and Vibration Control ”Movic’98”, Zurich, Switzerland, 
August 25-28, 1998, Volume 2. p 629 - 633. 
[4] Grigas V., Legh A., Tolocka R.T. Active Material 
Composite Structures for Variable Resistance Facilities. 
Journal of Vibroengineering, Vol. 8, No 2, 2006, p. 68 – 69. 
[5] Bansevicius R., Tolocka R.T. Adaptive Damping of 
Composite Structures: The Cases of Harmonic and Shock 
Excitation, in: Proceedings of 2nd European Nonlinear 
Oscillations Conference. Praque.- September 9-13.- 1996, - 
p.16-20. 
[6] Bansevicius R., Tolocka R.T., Knight J.A.G Oscillations 
suppression by active structures, in: Proceedings of 
International Conference “Mechatronics 2000”, September 
21-23, 2000, Warsaw, Vol. 2, p. 501 - 502. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 


Application of piezoactive material/rheological fluid composite structures in engineering

Bansevicius, R.

Tolocka, R.-T.

Journal of Mechatronics and Artificial Intelligence in Engineering

 © VIBROMECHANIKA.  JOURNAL OF  VIBROENGINEERING.  2008 JANUARY/MARCH,   VOLUME  10,  ISSUE  1,  ISSN 1392-8716  52 334. Application of Piezoactive Material/Rheological Fluid Composite          Structures in Engineering  R. Bansevicius1, R. T. Tolocka2 Kaunas University of Technology,  Kestucio 27, LT- 44312, Kaunas, Lithuania  E-mail: 1 Bansevicius@cr.ktu.lt, 2 Tadas.Tolocka@ktu.lt  (Received 20  January 2008; accepted 17  March  2008)             Abstract. Active materials are rapidly expanding their variety as well as applications due to their promising high–tech potential. Composite structures of active materials enable researchers to develop mechatronic systems and devices with inherent intelligence features and increased level of integration. A composite structure consisting of piezoactive material and electrorheological fluid is proposed, and its possibilities in developing self-adjusting and adaptive systems are discussed.   Keywords: adaptive damping, composite structure, active material.   Notation  S – strain;  Es  – compliance when the electric field is not applied;  T – stress; d – piezoelectric coupling constant;  E – electric field strength;  D – charge–density displacement;  Tε – permittivity at constant stress. Superscript t stands for the matrix transpose;  σ  – stress in the electrorheological fluid;  E – electric field strength; η  – viscosity;  u – displacement of fluid particle;  y – particle coordinate;  t – time;  x(t) – PAM shear strain in the coating surface which is proportional to the mass m displacement;  F(t) – excitation force;  A – coating cross section;  l – coating surface length.  Introduction  Over the past centuries the materials meeting specific needs for strength, durability, weight, flexibility, etc. were developed. With the advent of active materials, the components able to modify themselves in these dimensions came into reality. They are copying the intelligent forms of the living world and thus share inherent intelligence which allows them to respond to the changes in the environment. In the simplest case these materials respond directly to stimuli without any signal processing. More sophisticated systems contain their own sensors, actuators and computational capabilities in order to modify their behaviour responding to the changing environment. Such smart systems based on active materials are currently used for a growing range of commercial applications in structural engineering, biomedical, optical techniques, aerospace and other applications.  A lot of various active materials are more or less widely used. Piezoactive materials, rheological fluids and shape memory materials have become classical in this area. Others, like magnetostrictive, electroplastic, electro-optic, electroacoustic, pyrosensitive materials, are expanding wide scale applications. Active material composite structures have the most promising high–tech potential for shock and oscillation suppression systems [1,2]. The application possibilities of an active material structure consisting of a piezoactive material and rheological fluid are discussed in the paper, which is an overview of the ongoing research [3-6].  Piezoactive material/rheological fluid composite structure and its applications  Piezoactive materials (PAM) applications are based on the piezoeffect, which is described as follows:  334. APPLICATION OF PIEZOACTIVE MATERIAL/RHEOLOGICAL FLUID COMPOSITE STRUCTURES IN ENGINEERING. R. BANSEVICIUS1, R. T. TOLOCKA2    © VIBROMECHANIKA.  JOURNAL OF  VIBROENGINEERING.  2008 JANUARY/MARCH,   VOLUME  10,  ISSUE  1,  ISSN 1392-8716  53 EdTsS tE += ,    (1)  EdTD Tε+= ;    Due to the possibilities to develop devices featuring rapid response, practically unlimited resolution, large force generation, broad operating frequency range, high stability and low power consumption, PAM is widely used for sensing as well as for actuating (Fig.1). Examples of PAM applications for actuation are ultrasonic motors, micromanipulators, laser tuning devices and other instrumentation. Sensing properties of PAM are exploited in accelerometers and oscillation suppression systems based on the same effect.  Shear stress in electrorheological fluid (ERF) depends on the voltage applied:  tyuE∂∂∂+= ηασ 2 ;    (2)  Thus the fluid viscosity becomes the function of the voltage (see Fig.1). There are two possibilities to change ERF viscosity: to make use (a) of voltage U alteration at the gap h between electrodes being h=const and (b) to make use of gap h alteration at voltage between electrodes being U = const. In the first case the electric field strength (and ERF viscosity as well) become directly proportional the voltage and in the second case – inversely proportional to the gap magnitude.                           Fig. 1. ERF and PAM, and their composite structure properties   Low zero-field viscosity, high ER effect, wide range of control and high shear stability of ERF are of great importance and lead to its successful applications for vibration suppression as well as design of simple, quiet and rapid-response interfaces between electronic controls and mechanical systems. Well known applications are for shock absorbers in vehicles, dampers for seats, machinery, centrifuges, prostheses, etc. Composite structures consisting of ERF and PAM promise possibilities to develop systems with inherent intelligence of higher level because they allow combination of sensing, control and variable parameter elements into structures which exhibit self-adjustment and adaptability properties. The possibilities of such structure to respond to disturbance in accordance with various kinematic parameters are shown in the Figure 2, a. Mass m is translating in the ERF, whose flow along the contact with mass is affected by the viscosity and shear rate of shear stress of ERF, which is strongly related to electrical charges U, taken from the electrodes of piezoelectric ERF PAM Variable viscosity Possibilities of viscosity variation Sensing Actuation Actuation / Sensing COMPOSITE STRUCTURE PAM U≠  const h = const U = const h ≠ const  Response  by changing viscosity   Control Signal     PAM    ERF Disturbance          PAM  signal          PAM  voltage  Displacement  Force  334. APPLICATION OF PIEZOACTIVE MATERIAL/RHEOLOGICAL FLUID COMPOSITE STRUCTURES IN ENGINEERING. R. BANSEVICIUS1, R. T. TOLOCKA2    © VIBROMECHANIKA.  JOURNAL OF  VIBROENGINEERING.  2008 JANUARY/MARCH,   VOLUME  10,  ISSUE  1,  ISSN 1392-8716  54 transducers PT [3]. Depending on the position of piezoelectric transducer in relation to mass m and additional mass ma, electrical charge U is related to the position U(x), velocity U( x ) or acceleration U( x ) of the moving mass m. Thus the damping characteristics of system can be independently controlled by any kinematic parameter of mass motion.                   a)                                                                               b)  Fig. 2. Control possibilities of the ERF - PAM composite structure (a) and its application for adaptive damping (b)  The proposed composite structure has a lot of various useful applications. The system shown in Figure 2, a can be directly applied as an adaptive shock absorber as well as for self-adjusting force actuating in the exercising machines [4]. It is also suitable for adaptive damping system which is schematically shown in Figure 2, b [5,6]. The system consists of PAM coating on the structural element and the layer of ERF contacting with it. When oscillations in the structural element are excited, the electric charge proportional to their magnitude occurs in the electrodes due to the direct piezoeffect in the PAM and causes the electric field whose strength is:   ( ) ( ) ;11 ⎥⎦⎤⎢⎣⎡ −=AtFstxldE E   (3)  The ERF viscosity changes in the area of ERF contact with electrodes in accordance with the applied voltage and thus damping becomes adaptive. The presented system exhibits both passive and active damping features. However, classical passive dampers can only be tuned best for a relatively small frequency range, whereas an adaptive damping system shown in Figure 2, b is characterized by a wide frequency range.  Using multi-layer structures and films of PZT and ERF it is possible to realize adaptive damping of the continuous systems (rod, shaft, plate, frame, etc).  The sectioned electrodes allow us to organize the adaptive response in relation to the magnitude of strain in the structure [3]. The example is shown in Figure 3, where piezoelectric layer is fixed to the vibrating structure. One of the electrodes of the piezoelectric layer is sectioned and is in contact with ERF. Ux(t) is the distribution of electric charge on the sectioned electrodes; σxy - are stresses in the active layer. It is easy to notice that damping and flow resistance will be directly related to the maximum value of the stresses in the structure without applying an external electrical field.            Fig. 3. Adaptive damping system (a) and its dynamic behavior (b): 1 - vibrating structure; 2 - PAM layer; 3 a - continuous electrode; 4 - sectioned electrode; 5 - continuous electrode in the contact with the ERF layer  Coeficient of damping  x  y  Ux(t)  σxy  x  1  2  3  4  5  ERF  PT  PT  m  ma F(t) m  PAM ERF   Electrodes   334. APPLICATION OF PIEZOACTIVE MATERIAL/RHEOLOGICAL FLUID COMPOSITE STRUCTURES IN ENGINEERING. R. BANSEVICIUS1, R. T. TOLOCKA2    © VIBROMECHANIKA.  JOURNAL OF  VIBROENGINEERING.  2008 JANUARY/MARCH,   VOLUME  10,  ISSUE  1,  ISSN 1392-8716  55 Summary  The composite structure consisting of piezoactive material and electrorheological fluid was proposed and its application possibilities for self-adjustable damping systems were analyzed. The possibilities to develop systems with response to different kinematic parameters of a moving body and strain distribution have been discussed.  References  [1] Bansevicius R., Tolocka R.T. Shock and impact energy absorbtion and control by active material based systems, in: Structures Under Shock and Impact VIII, ed.N. Jones &C.A Brebbia, Witt Press, 2004, p. 359 – 363. [2] Bansevicius R., Tolocka R.T. Application of Active Materials for Semi-Active Vibration Suppression Systems, in: Proceedings of EUROMECH 455 on Semiactive Vibration Suppression. M. Valasek, A. Preumont (Eds.). CTU in Prague, Czech Republic, July 5-7. 2004. (CD). [3] Bansevicius R., Knight J.A.G., Tolocka R.T. Self-Adaptive Composite Structures for Oscillations Damping, in: Proceedings of the 4th International Conference on Motion and Vibration Control ”Movic’98”, Zurich, Switzerland, August 25-28, 1998, Volume 2. p 629 - 633. [4] Grigas V., Legh A., Tolocka R.T. Active Material Composite Structures for Variable Resistance Facilities. Journal of Vibroengineering, Vol. 8, No 2, 2006, p. 68 – 69. [5] Bansevicius R., Tolocka R.T. Adaptive Damping of Composite Structures: The Cases of Harmonic and Shock Excitation, in: Proceedings of 2nd European Nonlinear Oscillations Conference. Praque.- September 9-13.- 1996, - p.16-20. [6] Bansevicius R., Tolocka R.T., Knight J.A.G Oscillations suppression by active structures, in: Proceedings of International Conference “Mechatronics 2000”, September 21-23, 2000, Warsaw, Vol. 2, p. 501 - 502.                                                    

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Application of piezoactive material/rheological fluid composite structures in engineering

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