Material_Properties

shawlaskewvilleUrban and Civil

Nov 29, 2013 (3 years and 6 months ago)

98 views


-

1
-





Activity 2.1.1



Strength of Materials


Name: ____________________________________



Use the information from the Materials Lab

at

http://www.pbs.org/wgbh/buildingbig/lab/materials.
html

to
answer the following
:


I.
Metals


Type of
Material

Strength in
Tension
(Stretching)

Strength in
Compression
(Squeezing)

Cost

Weight

Pros and
Cons

Applications

Aluminum












Steel













1. Based on your results, in which loading cond
ition (tension or compression) are metals strongest?





2. Steel is among the strongest
, toughest

engineering materials there is. Why don’t engineers use
steel to solve problems like the Aloha Airlines fuselage explosion over Hawaii?





3.
In this invest
igation, you should have noticed that aluminum is just as strong as steel (when mixed
with other metals), yet aluminum is much lighter and does not rust. If this is the case, why do we still
use steel
?




4. Even though steel is an exceptionally strong met
al, why wouldn’t it be a good choice for use inside
jet engines?











-

2
-


II.
Polymer
s


Type of
Material

Strength in
Tension
(Stretching)

Strength in
Compression
(Squeezing)

Cost

Weight

Pros and
Cons

Applications

Plastic













5. As noted in the i
nvestigation, plastics are strong and very light, both of which are desirable
characteristics to engineers. However, watch carefully as you apply tension and compression to the
plastic. Note how it behaves. Based on your observations, would plastic be a su
itable alternative to
aluminum for airplanes
, or steel for buildings
? Why or why not?





III.
Ceramics


Type of
Material

Strength in
Tension
(Stretching)

Strength in
Compression
(Squeezing)

Cost

Weight

Pros and
Cons

Applications

Brick













6. Bas
ed on your observations, in which method of loading (tension or compression) are ceramics
strongest? In your opinion, why do you think ceramics behave this way?





7. Since ceramics can be so s
trong (
and relatively inexpensive
)
, why aren’t they used to m
ake aircraft
or other transportati
on machines? Why do we only see

them used in buildings or structures?







8. Why wouldn’t brick be used to make the cables which hold up a suspension bridge?









-

3
-

IV.
Composites


Type of
Material

Strength in
Tension
(S
tretching)

Strength in
Compression
(Squeezing)

Cost

Weight

Pros and Cons

Applications

Wood










Reinforced
Concrete










9)

a.
Note the arrangement of the steel rods in the reinforced concrete and the fibers of the wood. Why
were these materials

strongest pulled along the fibers?





b. In your opinion, what would have happened if we would have pulled on the wood/reinforced
concrete from the top and bottom instead of the sides? Why?





10. Click on the regular concrete and perform a tension/comp
ression test. How does adding the steel
rods improve the strength of the concrete (and in which mode, tension or compression)? Explain.





11.
As noted in the investigation, wood and reinforced concrete are relatively strong and inexpensive.
Why don’t we
use these particular composite materials to construct aircraft or other transportation
vehicles?