Chapter 5: Materials and Drawings Flashcards
What is a constraint?
A constraint is an external force that when applied to a material, tends to deform it. The deformation may or may not be visible.
What are the five main different types of constraints?
1) Compression (crush)
2) Tension (stretch)
3) Torsion (twist)
4) Deflection (bend)
5) Shrearng (cut)
Why will a mateiral deform?
The force being applied is too big.
What are the three types of deformations?
1) Elastic (temporary change in shape that returns to its original shape on its own when the force is removed)
2) Plastic (permanent change in shape that can return to its original shape is another force is applied)
3) Fracture (broken)
List all ten properties of materials and define each.
(Chemically Deformed Fruits grow on a TREE in Helen’s Slimey Moat.)
1) Hardness: the ability to resist penetration or scratching/denting
2) Resilience: the ability to resist impact/shock
3) Stiffness: the ability to resist deformation
4) Elasticity: the ability to return to its original shape after it has been subjected to restraints
5) Malleability: the ability to be flattened into a sheet without breaking
6) Ductility: the ability to be stretched into a wire without breaking
7) Resistance to corrosion: the ability to resist oxidation (chemically neutral - doesn’t react with acid) - RUSTING
8) Fragility: the ability to break easily without first being deformed
9) Electrical conductivity: the ability to allow an electrical current to flow
10) Thermal conductivity: the ability to allow heat energy to flow
What are the two families of wood?
1) Wood: directly from the tree
2) Modified wood: processed with adhesive - ex: plywood, particle board, etc.
Degradation - Rots
Protection
1) Varnish/wax
2) Paint
3) Chemically treated
What are the two families of plastics?
1) Thermoplastics
Characteristics: soften/melt when heated (low heat resistance), recyclable, softer, usually used for disposable items, resistant to corrosion.
2) Thermosetting Plastics
Characteristics: more heat resistant (don’t melt - disintegrate), not recyclable, more rigid, usually used for longer lasting objects, resistant to corrosion.
Degradation: exposure to sun (UV rays)
Protection:
1) Pigments
2) Chemical
**Add both while manufacturing
What are the traits of ceramics?
Inorganic matter containing various compounds
Ex: glass, porcelain, ceramic, clay, etc.
Very hard and not very resilient
Degradation - does not degrade
No protection required
What are the traits of composites?
A composite is when we mix two diffrent materials (the matrix and the reinforcement).
Matrix - main
Reinforcement - additive to modify some of the properties (added during the manufacturing of the material)
Degradation: seperation of the matrix and reinforcement
Protection - varies from case to case
How do metals degrade and how can we protect them?
Degradation: Oxidation
Protection:
1) Paint
2) Grease/oil
3) Galvanization (coat of zinc)
4) Quenching + tempering (heat treatment)
What is the play?
The amount of space between two parts.
Can two pieces fit together if they’re the same size?
Yes, but there will be no movement.
What are the four different types of drawings?
1) Isometric projection (3D drawing)
2) Orthogonal/multiview projection (three views - front, right side and top)
3) Exploded view diagram (shows all the parts seperated - technical analysis)
4) Developments (unfolded view)
