Page 78 - Manufacturing Engineering and Technology - Kalpakjian, Serope : Schmid, Steven R.

Section 2.2 Tension 57

TABLE 2.l
Relative Mechanical Properties of Various Materials at Room Temperature, in Decreasing Order. Metals are in
Their Alloy Form.

Strength Hardness Toughness Stiffness Strength/Density
Glass fibers Diamond Ductile metals Diamond Reinforced plastics
Carbon fibers Cubic boron nitride Reinforced plastics Carbides Titanium
Kevlar fibers Carbides Thermoplastics Tungsten Steel
Carbides Hardened steels Wood Steel Aluminum
Molybdenum Titanium Thermosets Copper Magnesium
Steels Cast irons Ceramics Titanium Beryllium
Tantalum Copper Glass Aluminum Copper
Titanium Thermosets Ceramics Tantalum
Copper Magnesium Reinforced plastics
Reinforced thermosets Thermoplastics Wood
Reinforced thermoplastics Tin Thermosets
Thermoplastics Lead Thermoplastics
Lead Rubbers

2.2 iierisioni

The tension test is the most common method for determining the mechanical prop-
erties of materials, such as strength, ductility, toughness, elastic modulus, and strain-
hardening capability. The tension test first requires the preparation of a test
specimen, as shown in Fig. 2.1a. Although most tension-test specimens are solid and
round, they can also be flat or tubular. The specimen is prepared generally according

Elastic <_I-» Plagtig
Stress
uts -f--
Y -
I Y _ TFracture
/
' t;n~1E:
->II<-Offset O ef ?;ain (for /0=1)
/0-l-> eo eu

AO /Q-»e

if

Original Uniform elongation
1
gage 'U
len th,/
Q ° /f Neck
L
`L
5 Fracture
4 TOta| ek-,zgation Post-ujform elongation
E §§ ;1=: I
_ A,
(H) (D)

FIGURE 2.l (a) A standard tensile-test specimen before and after pulling, showing original
and final gage lengths. (b) Stages in specimen behavior in a tension test.