Properties of Materials

Question 1

Materials of Engineering

Answer 1

refers to selecting the correct materials for the application in which the engineered part is being used.

Question 2

Materials can be divided into a number of groups such as;​

Answer 2

Metallic and Non- Metallic Materials

Question 3

Metallic Materials

Answer 3

Iron​

Copper​

Aluminum​

Magnesium​

Nickel​

Titanium​

Lead​

Tin​

Zinc​

*Alloys of these Metals;​

Steel​

Brass​

Bronze​

​

​

Question 4

Non-Metallic Materials​

Answer 4

Wood​

Ceramics​

Concrete​

Glass​

Rubber​

Plastics​

Question 5

When selecting a material for an engineering application, a primary concern is to assure that its properties will be adequate for the anticipated operating conditions

Answer 5

• These may include:​

– Mechanical characteristics​

– Physical characteristics​

• Ability to operate under extremes of temperature​
• Resist corrosion​

Question 6

Mechanical Characteristics​

Answer 6

Strength

Rigidity

Resistance to fracture

Ability to withstand vibrations or impacts

Elasticity

Plasticity

Ductility

Malleability

Brittleness

Toughness

Hardness

Softness

Question 7

Strength

Answer 7

is the ability to withstand stress without breaking

Question 8

Rigidity

Answer 8

is a quality found in objects that don’t bend

Question 9

Elasticity

Answer 9

is the ability of a stressed material return to its original shape when the load is removed.

Question 10

Plasticity

Answer 10

is the reverse of elasticity and is the property of a material to retain any deformation produced by loads after the load has been removed.​

Question 11

Ductility

Answer 11

is the ability in a material to be drawn out by tensile forces beyond its elastic limit without breaking.​

Question 12

Malleability

Answer 12

is a similar property to ductility except that the material is deformed beyond elastic limit by compressive forces, such as rolling or hammering​

Question 13

Brittleness

Answer 13

a material is brittle where fractures occur with little or no deformation.​

Question 14

Toughness

Answer 14

is the ability to withstand shock loads.​

Question 15

Hardness

Answer 15

is the ability of a material to resist penetration, abrasion, indentation and wear.

Question 16

Softness

Answer 16

obviously , is the opposite property to hardness.

Question 17

Physical Characteristics​

Answer 17

Weight (density)​

Electrical properties –electrical conductivity​

appearance​

Question 18

Physical Properties​

Answer 18

Density (weight)​

• Melting point- the temperature at which a given solid will melt​
• Optical properties​

– Transparency​

– Opaqueness- not transparent​

– Color​

• Thermal properties (specific heat)​
• Thermal conductivity​
• Electrical conductivity​
• Magnetic properties​

Question 19

The Choice​

Answer 19

In many cases, metals and nonmetals are viewed as​

competing materials​

• The selection is being based on how well each is​capable of providing the required properties​
• When both perform adequately, total cost often becomes​

the deciding factor:​

– The cost of material​

– Plus the cost of fabricating the desired component​

​

Question 20

Material Selection​

Answer 20

Based on a comparison of the established design​

  requirements and the tabulated record results that​

 describe how common materials respond to various​

  standard test​

• It is important to know:​

– Which properties are significant?​

– How the test values were determined?​

– What restrictions or limitations should be placed on their use?​

– Various test procedures, their capabilities and their limitations​

​

Question 21

Strain

Question 22

Unit Strain

Answer 22

• the amount of elongation for each unit length

Question 23

Tension

Answer 23

tensile stresses and strains

Question 24

compression

Answer 24

compressive stresses and strains

Question 25

shear

Answer 25

shear stresses and strains

Question 26

compression

Answer 26

pushing (buckling, a more common failure in compression)

Question 27

tension

Answer 27

pulling

Question 28

shear

Answer 28

shoving/ sliding

Question 29

torsion

Answer 29

twisting

Question 30

bending

Answer 30

tension (below neutral axis) and compression (above) Fatigue - combination of these stresses

Question 31

static

Answer 31

forces applied to a material are constant

Question 32

dynamic

Answer 32

forces applied to a material are changing during the time period

Question 33

Static Properties

Answer 33

A number of standardized tests have been developed to determine them: - Tensile test: * Strength properties * Ductility and brittleness * Toughness * True Stress - True Strain Curves * Strain Hardening and the Strain- Hardening Exponent Damping Capacity Compression tests Hardness Testing * Brinell Hardness Test * The Rockwell Test Vickers Hardness Test * Microhardness Test

Question 34

tensile test

Answer 34

are simple, relatively inexpensive, and fully standardized. By applying a force on a material using a uniaxial load, the reaction of the material can be readily recorded and analyzed.

Question 35

hardness testing

Answer 35

-brinell hardness test -the rockwell test -Vickers hardness test -Microhardness test

Question 36

hardness

Answer 36

measure of a materials resistance to penetration

Question 37

2 most common stationary hardness tests

Answer 37

brinell- stress test rockwell- strain test

Question 38

other hardness tests

Answer 38

-scleroscope -mohs -vickers and knoop

Question 39

scleroscope

Answer 39

rebound of a tup or hammer

Question 40

mohs

Answer 40

scratch test

Question 41

vickers and knoop

Answer 41

similar to brinell but microhardness