This document discusses different types of smart composites. It defines smart composites as materials composed of smart materials embedded in polymers, metals, or concrete to sense, control, and communicate. Smart materials can change properties in response to stimuli like temperature, pressure, or electric fields. Some examples of smart materials given are piezoelectric, shape memory, and pH sensitive polymers. The document then describes four general classifications of smart composites: 1) structural composites for sensing damage, 2) composites for actuation using shape memory materials, 3) novel functional composites like self-healing, and 4) nanocomposites enabling new functions. Examples of fiber optic and piezoelectric sensors in structural composites and

1. INTRODUCTION- SMART COMPOSITES
Definition:
 As per Author- Kelly, Davidson and Uchino in 2017, Smart composites are defined as the Systemic
composition of smart materials to provide enhanced dynamic sensing, communicating, and
interacting capabilities via Interactive Connected Smart Materials (ICS Materials).
 Smart Composites can be explained simply as these are designed materials ,where smart materials
are embedded in polymer, metal or concrete etc.. to sense, control, communicate etc.
 To get the whole idea of smart composites, We need to understand what is smart material. Let we
discuss in coming slides.

2. SMART MATERIALS
 Smart materials, also called intelligent or responsive materials .
 Author Rogers, 1988- Defined Smart material are the materials which have the ability to change
their physical properties in response to specific stimulus input or environmental changes.
 These stimulus could be pressure, temperature, electric, magnetic filed ,chemical, mechanical
stress, radiation etc.

3. SOME OF THE SMART MATERIALS TYPES
 Piezo Electric Materials.- Materials that produce a voltage when stress is applied.
 Photovoltaic or Opto electronics materials- Converts Light to electrical current.
 Shape memory materials Induce deformation due to temperature, stress change.
 PH Sensitive polymers- Material which changes in volume when PH of surrounding medium changes.
 Halochromic materials-change their color as a result of changing acidity.
 Temperature response polymers-materials which undergo changes upon temperature.
 Thermo electric materials-convert temperature difference to electricity & Vice versa.
 Di Electric elastomers-produce large strains (up to 500%) under the influence of an electric field.

4. FOUR General classification of Smart composites
(1) Structural smart composites;
(2) composites for actuation;
(3) novel functional composites; and
(4) nanocomposites that are enablers of novel functions.

5. (1)STRUCTURAL SMART COMPOSITES
 Structural Smart composites are materials that have the sensing capability to detect stress, strain, fatigue and
damage. monitor the health conditions of structures that are difficult to inspect or repair, such as wind turbine
blades, underground pipes and long-span bridges.
Structural Health Monitoring With Fiber Optic Sensing - YouTube
 Embedding smart material into structural material is an integrated design that is more reliable and compact.
Several types of smart materials or sensors have been adopted in sensitive structural composites. Among them,
fiber optic sensors, piezo electric have been widely studied and adopted.
 Their features include, but are not limited to, immunity to electromagnetic interference, small size, light weight,
durability, low cost for mass production and high bandwidth.
 These features allow large numbers of Smart materials or sensors to operate in the same system and to be
integrated within thin materials.

6. (1)STRUCTURAL SMART COMPOSITES
Continued
Example-1
Optical fiber embedded CFRP composites
 Fiber optic sensors embedded in carbon fiber-reinforced polymer composites can be used to monitor the structural health
in their fabrication, and their in-service condition.
 The below figure shows the fabrication from Mr. Okabe, 2002
 Single mode optical fibers with Fiber bragg grating sensors used.
 optical fibers were coated with UV-cured resin, whose outside diameter was 250 µm.
 the FBG sensor is sensitive to the transverse cracks that run through the thickness and width of the 90◦ ply. Moreover,
since the optical fiber is embedded in 0◦ ply to be parallel to the carbon fibers, the matrix rich region around the optical
fiber is so small that it does not deteriorate the strength or stiffness of the CFRP laminates.

7. (1)STRUCTURAL SMART COMPOSITES
Continued
Example-1
Optical fiber embedded CFRP composites- Testing
 Tensile strain was measured with a strain gage attached on a surface of the specimen, and the tensile load was
measured with a load cell. The optical fiber was illuminated by a broadband edge-emitting light-emitting diode
(EELED) light source.
 The reflection spectrum was obtained by using an optical spectrum analyzer ,With an increase in the crack density ρ,
the form of the reflection spectrum will face distortion. This change in the form of the spectrum is expected to be
due to the strain distribution caused by the transverse cracks

8. (1)STRUCTURAL SMART COMPOSITES
Continued
Example-2
cement based Piezo electric ceramic composite
 Another popular option is based on piezoelectric materials .The piezoelectric effect is the ability of materials to generate
an electric charge in response to applied mechanical stress.
 By monitoring and measuring the generated electric charge, it is possible to use piezoelectric materials as sensors.
 A unique characteristic of the piezoelectric effect is that its ability to transform stress to electricity is reversible, meaning
that the materials can generate stress when an electric field is applied.
 This allows ‘smart composites’ to not only sense but also actuate (Zhang et al., 2002; Pelrine et al., 2000). This bridges
sensitive composites and another important group of smart composites, composites for actuation.
 Upcoming experiment shows the electrical responses of cement-based piezoelectric ceramic composites under
mechanical loadings

9. (1)STRUCTURAL SMART COMPOSITES
Continued
cement based Piezo electric ceramic composite Fabrication
 Lead zirconate titanate (PZT) piezoelectric ceramic powders and white cement were used to prepare cement-based
piezoelectric composites. White cement is used as matrix.
 Lead zirconate titanate (PZT) piezoelectric ceramic powders and white cement are mixed together to make 0–3 type
cement-based piezoelectric ceramic composites. In order to improve the fluidity of the fresh mixture, a superplasticizer
(W19, W. R. Grace) was used.
 Then the mixture was compacted into the 13 mm ∗ 13 mm ∗ 3 mm model. After casting, the specimens were put in the
curing room with a temperature of 65°C and relative humidity of 98% for 24 hours.

10. (1)STRUCTURAL SMART COMPOSITES
Continued
cement based Piezo electric ceramic composite- Mechanical Testing system
 The mechanic-electrical response measurement of cement-based piezoelectric ceramic composite are carried out with
MTS. The illustration of test can be seen in Figure. Different types of mechanical dynamic loadings are applied by MTS,
and the output voltage is collected by PC.
 A high-order Electrical response of cement-based piezoelectric ceramic composite exists under mechanic loads.It shows
that the composite is suitable for dynamic mechanical sensor as holding high static stability.
.

11. (2) SMART COMPOSITES FOR ACTUATION
 Materials being used as actuators were referred to as induced strain actuators in the 1980s. The actuation was based on
natural mechanisms that cause actuation strains, including thermal expansion, piezoelectricity, material phase change and
moisture absorption (Crawley and Lazarus, 1991).
 Shape-memory materials were proposed and developed based on the above mechanisms. They are materials like nitinol
etc will deform & deformation can return to their original position to certain stimuli like temperature, stress etc
 Shape-memory composites can be manufactured at a low cost; they are also lightweight and potentially biocompatible and
biodegradable, facilitating applications such as space-deployable components and structures (e.g., antennas and hinges
(Sokolowski et al., 2008), as shown in Fig. )

12. (2) SMART COMPOSITES FOR ACTUATION
Continued
 Shape-memory composites can be controlled using temperature, electricity, magnetic field and light (Liu et al., 2017),
making them flexible in their implementation. After years of development, their recovery stress, production cost and
displacement resolution have all been improved significantly.
 Fiber reinforced polymer composite with Shape memory material is in demand for weight saving application in various
engineering applications.
 Advantages are good mechanical behavior, corrosion resistance.
 FRPs brittle failure issues can be solved when integrating with Shape memory as it can absorb energy leading to better
dampening effect.

13. (3) SMART COMPOSITES WITH NOVEL FUNCTIONALITIES
 Smart composites can also be composites with unusual properties (additional to sensing and actuation).
Example -1
 Self-healing composites are composite materials that can recover automatically after damage (Wang et al., 2015b). The
mechanism of healing can be either intrinsic or extrinsic. Intrinsic healing uses materials’ intrinsic .Extrinsic healing is
based on embedded microstructures (e.g., microcapsules and microvessels) which contain liquid healing agents. In the
event of a crack, the healing agents are released to fill the gap and solidify (Pang and Bond, 2005), as shown in Fig.
 Self-healing composites’ potential applications are mostly connected with safety-critical machines and infrastructures that
may be difficult to access, inspect, maintain and repair, such as off-shore wind turbines, aircrafts and satellites.

14. (3) SMART COMPOSITES WITH NOVEL FUNCTIONALITIES
Continued
Example -2
 Artificial skins with very good stretchability and sensing capability have grown rapidly in the last decade. They are soft and
stretchable materials with embedded electronic sensing components.
 For example, conductive elastomeric composites incorporating carbon nanotubes (Roh et al., 2015) can be stretchable,
transparent, ultrasensitive and patchable, making them suitable for use as human-machine interfaces .
 Artificial skins can sense touch, temperature, humidity and biological variables .The color of electronic skins can also be
tuned by embedding organic electrochromic devices .There has also been work on skins with self-powering capability (e.g.,
through triboelectric mechanisms) (Shi et al., 2016) shown in figure.

15. (3) SMART COMPOSITES WITH NOVEL FUNCTIONALITIES
Continued

16. (4)NANO COMPOSITES ENABLING NOVEL FUNCTIONS
 Many actuation, sensing and other functions discussed above are enabled by the incorporated nanoparticles.
 Functional nano composites are also occasionally referred to as smart composites.
 For example, synthesized Fe3O4-multiwalled carbon nanotubes are a type of smart composite as they can be used to
fabricate intelligent microwave-absorber materials (Lu et al., 2015).
 Nanocapsules containing functional substances may also be regarded as smart composites when they are applied to the
fabrication