UNIT 4 TOPICS 1-7 REVIEWx - Magrath High School

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25 Νοε 2013 (πριν από 3 χρόνια και 8 μήνες)

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TOPIC 1: TYPES OF STRUCTURES


ALL STRUCTURES ARE EITHER NATURAL OR MANUFACTURED




TYPES OF STRUCTURES:


MASS STRUCTURES


FRAME STRUCTURES


SHELL STRUCTURES


MIXTURE (FOOTBALL HELMET)

WHAT TYPE OF STRUCTURE AM I?


BACKPACKING TENT


POP CAN


CONCRETE BARRIER IN A PARKING LOT


HOUSE


SEASHELL


TURTLE’S SHELL


CLAY POT


BICYCLE


SKELETON

TOPIC 2: DESCRIBING STRUCTURES


Six categories: “For All Students Must Jump Far”


Function


Aesthetics


Materials


Joints


Fasteners

FUNCTION


What it is used for. Describes what the structure is supposed to do. For example,
the function of a bridge is to transport trains across a particular area.


Words to describe function:


Containing


Transporting


Sheltering


Supporting


Lifting


Fastening


Separating


Communicating


Breaking


Holding

AESTHETICS

Aesthetics definition: the study of beauty in art and nature



Think of the types of material used, or the colors a material might be painted.


Marble columns, clothing designs, arched doorways, etc.


Interesting textures, repeating patterns


Carefully chosen materials and design to make a structure look good


Think about it, a product that looks good on the shelf is more likely to sell right?

SAFETY

MARGIN OF ERROR:
EXTRA STRENGTH THAT ALLOWS A
STRUCTURE TO WITH STAND MUCH LARGER LOADS
THAN IT WOULD NORMALLY NEED TO CARRY.


BALANCING SAFETY WITH COST:
GOOD DESIGN IS A
CAREFUL BALANCE BETWEEN HAVING A GOOD MARGIN
OF SAFETY AND REASONABLE COST.

MATERIALS


What is the structure made out of?


Cement, Steel, Wood, etc.




COMPOSITE MATERIALS: made from more than one kind of material.


Example: reinforced concrete

steel bars inside to help support

ƒ
Example: Fiberglass cloth embedded in rigid plastic is molded into boat hulls


ƒ
LAYERED MATERIALS: thin sheets or layers of materials, usually pressed or
glued together.


Example: safety glass of a car window helps prevent shattering when glass breaks.

ƒ
Example: tissue paper contains multiple layers of very thin paper.


ƒ
LAMINATE:
LAYERS OF DIFFERENT MATERIALS


CHOOSING MATERIALS

WHEN DESIGNERS ARE DECIDING WHICH TYPE OF MATERIALS TO USE IN THEIR
STRUCTURE, THEY WILL CONSIDER THE FOLLOWING:


COST


APPEARANCE


ENVIRONMENTAL IMPACT


ENERGY EFFICIENCY

JOINTS

--
ALL JOINTS ARE EITHER RIGID OR MOBILE

RIGID=DO NOT ALLOW MOVEMENT

MOBILE=ALLOWS MOVEMENT


SOME OTHER TYPES OF JOINTS ARE:


FASTENERS


INTERLOCKING SHAPES


TIES


ADHESIVES


MELTING

TYPES OF JOINTS: 1
-
FASTENERS


nails
, bolts, screws, rivets, dowels


--
downside to fasteners is that they weaken
material as they must
poke




TYPES OF JOINTS: 2
-
INTERLOCKING SHAPES

Clothing hem, paving stones, sheet metal, woodworking, dental fillings, etc.






TYPES OF SEAMS:


DOVETAIL JOINT




TYPES OF JOINTS: 3
-
TIES

EXAMPLE OF TIES
: thread, string, rope that fasten things together; example
-
clothing
seam, shoelace, jacket hood.



TYPES OF JOINTS: 4
-
ADHESIVES

ADHESIVES: sticky substances that hold things together.
Thermosetting=heat
Solvent
-
based=air
dry


THERMOSETTING





SOLVENT
-
BASED



TYPES OF JOINTS: 5
-
MELTING


MELTING: Turn structures material into liquid and join with another piece.

ƒ
Must be carefully cleaned

ƒ
Must cool properly


TOPIC 3: MASS AND FORCES

YOUTUBE VIDEO “EUREKA!”


TERMS TO KNOW:


Mass:
the amount of matter (stuff) an object has in it.
NEVER CHANGES


Weight
: a force that is caused by the gravitational pull between one object and
another object.
CAN CHANGE


HOW DOES AN OBJECT’S WEIGHT CHANGE?


CAN CHANGE WHEN THE OBJECT’S LOCATION CHANGES TO A PLACE WHERE
THERE ISN’T AS MUCH GRAVITATIONAL PULL, FOR EXAMPLE, IN SPACE.




Newton:
SI unit of force


1 Newton=enough force to stretch a rubber
-
band


10 N=enough force to lift a carton of milk


200 N=the force of a hard
-
thrown baseball hitting your hand


MASS AND FORCE:


When converting:


Kilograms to
Newtons
=multiply by 10


Grams to Kilograms=multiply by 1,000


Grams to
Newtons
=divide by 100


Newtons

to Grams=multiply by 100



1 Kilogram=10
Newtons

1 Newton=100 Grams

1 Kilogram=1,000 Grams

1 Gram=0.01
Newtons

TOPIC 3 TERMS TO KNOW CONTINUED:


Forces: stresses such as pushes and pulls


Kilogram: same amount of mass as 1,000 grams


Milligram: 1000
miligrams
=1 gram


Balance: type of measuring instrument used to determine an object’s

mass


TOPIC 4: FORCES, LOADS, AND STRESSES

Types of force:


-
Shear force


-
Torsion force


-
Tension force


-
Compression force

TENSION FORCE

Stretch

a material by pulling ends apart.


-
Tensile strength: largest tension force the material can stand before breaking.

COMPRESSION FORCE

-
ability to withstand crushing or squeezing together


Compressive strength: measures largest compression force the material can stand
before losing its shape or breaking into pieces.

SHEAR FORCE

-
Bend or tear a material by pressing different parts in opposite
directions at the same time.



*Shear strength: measures the largest shear force material can
stand before ripping apart.

TORSION FORCE:

Twist a material by turning ends in opposite directions.



*Torsion strength: measures the largest torsion force the
material can stand and still spring back to its original shape.

TOPIC 4 ADDITIONAL TERMS:

Dead load: permanent force acting on a structure. Includes weight of actual structure.


Live load: a changing, non
-
permanent force acting on a structure.


External forces: forces acting on structure from outside


Internal forces: forces acting on structure from within the materials of structure, which
can cause structure to change shape or size.


Deformation: change internally of structure’s shape or size.





TOPIC 4: RESISTING STRESS

-
Steel: high tensile strength, strong force pulling particles together

-
Graphite: low shear strength, particles arranged in layers, which is why its used for
led pencils.

-
Rubber: high torsion strength, particles attract each other in all directions; which is
why they hold together when twisted.

REVIEW:

What is the name for something that serves a specific function and resists forces?



building

design

load

structure


STRUCTURE

REVIEW

A person's weight is really a measure of the gravitational force between that person
and Earth.



True

False


TRUE!

REVIEW:

Rigid joints are used in a structure to allow joined materials to move easily.



True

False


FALSE!

REVIEW

What are the four types of structures?

1
-
Frame

2
-
Shell

3
-
Mass

4
-
Mixed

REVIEW

The Patterson family hired the Quick Fix Renovation Company to do some renovations
in their home. They wanted doors placed into some walls and other walls
removed in order to make the house more functional for their needs. Several
weeks after the renovations were completed, Mrs. Patterson noticed that the
ceiling was cracking and sagging where a wall had been removed. What is the
most likely explanation for the sagging?



A. Cheap
materials were used.

B. The
removed wall helped to support the weight of the roof.

C. The
removed wall originally divided two rooms.

D. The
removed wall was poorly constructed.


ANSWER:

B

REVIEW

Which of the following is a composite material?



A. corrugated
cardboard

B. wool

C. reinforced
concrete

D. steel
beams


C. Reinforced Concrete

REVIEW:

Lucy, an architect with a Calgary firm, is responsible for designing a new public library.
She has been told what the function will be and she knows the safety regulations.
As well as function and safety, she wants the building to be beautiful. What is
another word for "looking good" in structure design?



A. balanced

B. composition

C. symmetry

D. aesthetics


D. Aesthetics

REVIEW

What is the name for the process of melting two pieces of the same material
together?



A. welding

B. soldering

C. adhering

D. brazing


A. Welding

REVIEW

What is the correct unit of measurement for weight?



pound

gram

kilogram

newton


GRAM

REVIEW

Spider silk has a great deal of what type of strength?



Tensile (tension)

compressive

shear

torsion


TENSION!