Smart materials

Question 1

Define a smart material.

Answer 1

A material that changes its properties in a useful, predictable way when exposed to a stimulus (e.g., heat, light, stress, electricity, magnetism).

Question 2

Give three common stimuli for smart materials.

Answer 2

Temperature, light (UV/visible), and mechanical stress/pressure. Others include moisture, pH, electricity, and magnetic fields.

Question 3

What is a shape memory alloy (SMA)?

Answer 3

A metal alloy that can be deformed cold and then returns to a pre‑set shape when heated above its transformation temperature (e.g., Nitinol).

Question 4

Name two uses of SMAs.

Answer 4

Self‑opening heat‑activated fasteners and temperature‑responsive actuators (e.g., valves).

Question 5

What is superelasticity in SMAs?

Answer 5

The ability to undergo large elastic strains and spring back at a given temperature without heating, useful for flexible components.

Question 6

What is a shape memory polymer (SMP)?

Answer 6

A polymer programmed to hold a temporary shape and return to its original shape when heated or exposed to a trigger (e.g., light).

Question 7

State one advantage of SMPs over SMAs.

Answer 7

They are lighter, cheaper, and easier to form into complex shapes (but generally exert lower forces).

Question 8

Define thermochromic pigment.

Answer 8

A pigment that changes colour with temperature; often used in temperature indicators and safety labels.

Question 9

Give a workshop example of thermochromic use.

Answer 9

Heat‑warning labels on machines that change colour if surfaces are hot.

Question 10

Define photochromic pigment.

Answer 10

A pigment that changes colour when exposed to UV light (darkens outdoors, lightens indoors).

Question 11

Common product using photochromic material?

Answer 11

Photochromic sunglasses that darken in sunlight and clear indoors.

Question 12

Define phosphorescent material.

Answer 12

Stores light energy and glows in the dark after the light source is removed (delayed re‑emission).

Question 13

Give a use for phosphorescent materials in the workshop.

Answer 13

Safety signs or markers that are visible during power cuts.

Question 14

What is a piezoelectric material?

Answer 14

A material that generates a voltage when mechanically stressed and can deform when a voltage is applied (sensor/actuator).

Question 15

Two applications of piezoelectric materials.

Answer 15

Contact microphones/vibration sensors and precise positioning actuators.

Question 16

Define electroluminescent (EL) material.

Answer 16

Emits light when an electric field is applied (e.g., EL panels/wire for backlighting).

Question 17

Where might EL materials be used?

Answer 17

Thin backlights for displays or safety/edge lighting on equipment.

Question 18

What is a thermoelectric material?

Answer 18

Generates electricity from a temperature difference (Seebeck effect) or provides cooling/heating when powered (Peltier effect).

Question 19

Give one use of thermoelectrics in engineering.

Answer 19

Localised electronic cooling using Peltier modules.

Question 20

Define magnetorheological (MR) fluid.

Answer 20

A fluid that rapidly changes viscosity/stiffness when a magnetic field is applied (smart damping).

Question 21

Define electrorheological (ER) fluid.

Answer 21

A fluid that changes viscosity when an electric field is applied (controllable clutches/dampers).

Question 22

What is QTC (quantum tunnelling composite)?

Answer 22

A rubber‑like material whose electrical resistance drops dramatically under pressure, used as a pressure/touch sensor.

Question 23

Give a simple QTC use in a school project.

Answer 23

A squeeze or touch‑sensitive on/off switch for a small electronic device.

Question 24

Define electroactive polymer (EAP).

Answer 24

A polymer that changes size or shape when an electric field is applied, functioning as a soft actuator.

Question 25

State one challenge with EAPs.

Answer 25

Often require high voltages or careful control to produce useful motion.

Question 26

What is a hydrochromic material?

Answer 26

Changes colour or transparency when exposed to water or moisture (e.g., leak indicators).

Question 27

What is a thermistor and is it a smart material?

Answer 27

A temperature‑sensitive resistor used as a sensor. It responds to temperature, but it’s usually classed as an electronic component rather than a smart structural material.

Question 28

Smart material vs modern material—difference?

Answer 28

Smart materials change properties with a stimulus; modern materials are newly developed or improved materials (e.g., carbon fibre composites) and may not respond to stimuli.

Question 29

Name two benefits of using smart materials in manufacture.

Answer 29

Built‑in sensing/actuation can reduce part count and enable self‑adjusting products.

Question 30

Name two drawbacks of smart materials.

Answer 30

Higher material cost and the need for control systems/power for some types.

Question 31

Give two safety considerations when handling smart pigments/powders.

Answer 31

Avoid inhalation/skin contact and follow the material safety data sheet (use PPE, good ventilation).

Question 32

How can smart materials support sustainability?

Answer 32

They can improve energy efficiency (e.g., adaptive lighting/cooling) and reduce waste via condition monitoring and responsive control.

Question 33

Which smart material would you choose for a temperature warning label and why?

Answer 33

Thermochromic pigment—changes colour at a set temperature for a clear visual warning.

Question 34

Which smart material suits a silent, precise micro‑movement?

Answer 34

Piezoelectric actuator—offers very fine, fast motion with no gears.

Question 35

Which smart material for adjustable damping in a machine mount?

Answer 35

MR fluid device—stiffness/viscosity can be tuned using a magnetic field.

Question 36

Give one classroom test to demonstrate photochromic behaviour.

Answer 36

Expose a coated sample to a UV lamp or sunlight and observe colour change vs. shade.

Question 37

Name a processing consideration for SMAs in products.

Answer 37

They require heat‑setting to program the 'memory' shape and careful temperature control in service.

Question 38

Explain how a smart material could reduce Overprocessing (TIMWOOD).

Answer 38

A self‑indicating coating (thermochromic) shows when the correct heat has been applied, avoiding unnecessary extra passes.

Question 39

Explain how smart sensing can cut Defects (TIMWOOD).

Answer 39

Embedded sensors (piezo/thermistors) can detect misalignment or overheating early so processes stop before scrap is made.

Question 40

Scenario: You need a night‑visible safety label without power. Which material?

Answer 40

Phosphorescent pigment—charges under normal light and glows in the dark.

Question 41

Scenario: A part must return to its original shape after being bent during installation. Which material?

Answer 41

Shape memory alloy or shape memory polymer triggered by heat.

Question 42

Scenario: Create a soft, thin backlight for a control panel. Which material?

Answer 42

Electroluminescent panel for uniform low‑profile lighting.