Module E: Presentation
Identifying Elements of Materials
and Structural Design
Department of Defense Education Activity
Robotics Engineering – CTE502
Career and Technical Education
Robotics Engineering (CTE502) – DoDEA Career and Technical Education
Module A: Presentation – Setting Expectations for Student Success
Revised 14 July, 2012
History of Architecture
Branches of Engineering
• Architectural Engineering- focus on safety, cost, and
construction methods of designing buildings
• Civil Engineering- build bridges, dams, buildings, roads and other
large structures often, incorporating the use of concrete.
• Industrial engineering focuses on organizing the people, information,
energy, materials, and machines involved in the production process.
• Manufacturing engineering is a branch that deals with the design,
plan, develop, improve, and manage the machinery, processes, and
systems that produce these products.
• Material engineers study the properties of existing materials, find
new ways to work with them and develop new materials.
• Metallurgical and materials engineers extract, process, refine,
combine, and manufacture natural substances to create new
materials that are stronger and resist corrosion.
• Plastics engineers study the properties of polymer materials. They
also design machines used to manipulate and shape plastics.
Objects
When initiating a design project of any kind, two
components to focus on are:
Structure and Function
It is essential to take the shape and purpose of the
item into consideration when choosing materials.
These will lead to identifying the constraints of
the design project.
Structures
• Bridges: Truss, Arch, Suspension
• Domes: masonry, cast-iron, Geodesic
• Skyscrapers: towers, columns, trusses
• Dams: Arch, Buttress, Embankment,
Gravity
• Tunnels: Soft-ground, Rock, Underwater
Materials
• Non-metallic
– Properties
• Brittle
• Do not conduct electricity
– Examples
• Wood
• Ceramics
– Properties
» Brittle
» Hard
» Strong in
compression,
» Weak in shearing
and tension
• Plastics
– Properties
» Flexible
» Lightweight
» Strong in
compression and
tension
» Long lasting
• Metallic
– Properties
• Conduct electricity
• Malleable
• Ductile
– Examples
• Mined
– Copper
– Aluminium
– Iron
• Alloys
– Mixtures of
metals/nonmetals
» Bronze = Cu + Sn
» Brass= Zn + Cu
» Steel= Fe + C
Plastics
• Thermosetting plastics
– Retain their shapes
– Cannot return to their
original form once cooled
and hardened
– Hard and durable.
– Uses: auto parts, aircraft
parts and tires.
– Examples include
polyurethanes,
polyesters, epoxy
resins and phenolic
resins
• Thermoplastic
– Can soften upon heating
– Return to their original
form.
– Easily molded
– Uses: extruded into films,
fibers and packaging.
– Examples include
polyethylene (PE)-,
polypropylene (PP) and
polyvinyl chloride (PVC).
Common Polymers
•
Polyethylene terephthalate (PET or PETE)
–
•
Teflon was made in 1938 by DuPont. The polymer is stable, heat-resistant, strong, resistant to many chemicals and
has a nearly frictionless surface. Teflon is used in plumbing tape, cookware, waterproof coatings, and bearings.
Dow makes Saran resins, that can be drawn into films and wraps that are impermeable to food odors. Saran wrap
is a popular plastic for packaging foods.
Polyethylene, LDPE and HDPE:
–
•
A thermoplastic that when made, it's brittle, so manufacturers add a plasticizer liquid to make it soft and
moldable. PVC is commonly used for pipes and plumbing because it's durable, can't be corroded and is cheaper
than metal pipes. Over long periods of time, however, the plasticizer may leach out of it, rendering it brittle and
breakable.
Polyvinylidine Chloride (Saran):
–
•
and TVs),
it forms Styrofoam.
Polytetrafluoroethylene (Teflon):
–
•
Can form a hard impact-resistant plastic for furniture, cabinets (for computer monitors
glasses and utensils. When polystyrene is heated and air blown through the mixture,
Styrofoam is lightweight, moldable and an excellent insulator.
Polyvinyl Chloride (PVC):
–
•
(like
Polystyrene (Styrofoam):
–
•
A thermoplastic that can be pulled into fibers (like Dacron) and drawn into films
Mylar). It's the main plastic in food storage bags.
The most common polymer in plastics is polyethylene, It was first used to insulate electrical wires, but today it's
used in films, wraps, bottles, disposable gloves and garbage bags (LDPE). HDPE was first introduced in the hula
hoop, but today it's mostly used in containers.
Polypropylene (PP):
–
Used in car trim, battery cases, bottles, tubes, filaments and bags.
www.science/howstuffworks.com/plastic.html
How Plastics are Shaped
•
Extrusion:
– Pellets are heated and mechanically mixed, forced through a small
opening and cooled with air or water.
– This method is used to make plastic films.
•
Injection molding:
– Pellets are heated and mechanically mixed and then forced under high pressure into
a cooled mold.
– This process is used for containers like butter and yogurt tubs.
•
Blow molding:
– This technique is used in conjunction with extrusion or injection molding. Pellets are
heated and compressed into a liquid tube, like toothpaste. The resin goes into the
chilled mold, and compressed air gets blown into the resin tube. The air expands the
resin against the walls of the mold.
– This process is used to make plastic bottles.
•
Rotational molding:
– Pellets are heated and cooled in a mold that can be rotated in three dimensions. The
rotation evenly distributes the plastic along the walls of the mold.
– This technique is used to make large, hollow plastic items (toys, furniture, sporting
equipment, septic tanks, garbage cans and kayaks).
www.science/howstuffworks.com/plastic.html
Forces
• Tension
– Stretches materials apart
• Compression
– Squeezes materials together
• Torsion
– Twists materials
Shapes
• What happens when you apply a force to each of
these shapes?
• Activity: Using only one file folder, balance as
many textbooks as possible. Books must be at
least 10 cm off the table. What shape supports
the most books? Why?
Trusses
• What makes them so strong?
Fasteners
•
•
•
•
•
Nuts and Bolts
Screws
Nails
Rivets
Glue