Department of Defense Education Activity Robotics Engineering – CTE502 Career and Technical Education

1. 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

2. History of Architecture

3. 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.

4. 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.

5. Structures • Bridges: Truss, Arch, Suspension • Domes: masonry, cast-iron, Geodesic • Skyscrapers: towers, columns, trusses • Dams: Arch, Buttress, Embankment, Gravity • Tunnels: Soft-ground, Rock, Underwater

6. 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

7. 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).

8. Common Polymers • Polyethylene terephthalate (PET or PETE) • A thermoplastic that can be pulled into fibers (like Dacron) and drawn into films (like Mylar). It's the main plastic in food storage bags. • Polystyrene (Styrofoam): • Can form a hard impact-resistant plastic for furniture, cabinets (for computer monitors and TVs), glasses and utensils. When polystyrene is heated and air blown through the mixture, it forms Styrofoam. Styrofoam is lightweight, moldable and an excellent insulator. • Polyvinyl Chloride (PVC): • 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. • Polytetrafluoroethylene (Teflon): • 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. • Polyvinylidine Chloride (Saran): • 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: • 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

9. 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

10. Forces • Tension • Stretches materials apart • Compression • Squeezes materials together • Torsion • Twists materials

11. 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?

12. Trusses • What makes them so strong?

13. Fasteners • Nuts and Bolts • Screws • Nails • Rivets • Glue