Chapter 2

MATERIALS AND PROCESSES

67

 

 

Important Equations Used in This Chapter

See the referenced sections for information on the proper use of these equations.

 

2

Axial tensile stress (Section 2.1):

 

 

 

 

 

P

=

 

(2.1 a)

Ao

 

 

 

 

Axial tensile strain (Section 2.1):

 

l l

=

o

(2.1 b)

lo

 

Modulus of elasticity (Young’s modulus) (Section 2.1):

 

E = 

(2.2)

 

 

Modulus of rigidity (Section 2.1):

 

 

E

 

G =

(2.4)

2(1 + )

 

Ultimate shear strength (Section 2.1):

steels :

S

us 0.80 Sut

 

(2.5 b)

other ductile metals :

S

us 0.75 Sut

 

 

 

Shear yield strength (Section 2.1):

 

 

 

 

 

U =   d

(2.6)

0

 

 

Modulus of resilience (Section 2.1):

1 S 2

 

y

U

(2.7)

R

2 E

Modulus of toughness (Section 2.1):

S +

y Sut

U

(2.8)

T



2

f

 

Arithmetic mean (Section 2.2):

n

1

 

 

 =  x

(2.9b)

i

 

n i =1

 

Standard deviation (Section 2.2):

n

 

1

2

Sd =

( x

(2.9c)

i )

n - 1 i =1

Image 176

 

68

MACHINE DESIGN -

An Integrated Approach

 

Ultimate tensile strength as a function of Brinell hardness (Section 2.4): S

 

ut 500 HB  30 HB psi

2

(2.10)

S

ut 3.45 HB  0.2 HB MPa

 

 

2.10 REFERENCES

1 E. B. Haugen and P. H. Wirsching, “Probabilistic Design.” Machine Design, v. 47, nos.

10-14, Penton Publishing, Cleveland, Ohio, 1975.

2 H. E. Boyer and T. L. Gall, eds. Metals Handbook. Vol. 1. American Society for Metals: Metals Park, Ohio, 1985.

3 M. F. Ashby, Materials Selection in Mechanical Design, 2ed., Butterworth and Heinemann, 1999.

 

 

2.11 WEB REFERENCES

The web is a useful resource for up-to-date material property information at these and other sites that can be found with a search engine.

http://www.matweb.com

Properties data sheets for over 41,000 metals, plastics, ceramics, and composites.

http://metals.about.com

Material properties and data.

 

 

2.12 BIBLIOGRAPHY

For general information on materials, consult the following: Metals & Alloys in the Unified Numbering System. 6th ed. ASTM/SAE: Philadelphia, Pa., 1994.

Brady, ed. Materials Handbook. 13th ed. McGraw-Hill: New York. 1992.

H. E. Boyer, ed. Atlas of Stress-Strain Curves. Amer. Soc. for Metals: Metals Park, Ohio, 1987.

K. Budinski, Engineering Materials: Properties and Selection. 4th ed. Reston-Prentice-Hall: Reston, Va., 1992.

M. M. Farag, Selection of Materials and Manufacturing Processes for Engineering Design. Prentice-Hall International: Hertfordshire, U.K., 1989.

I. Granet, Modern Materials Science. Reston-Prentice-Hall: Reston, Va., 1980.

H. W. Pollack, Materials Science and Metallurgy. 2nd ed. Reston-Prentice-Hall: Reston, Va., 1977.

S. P. Timoshenko, History of Strength of Materials. McGraw-Hill: New York, 1983.

L. H. V. Vlack, Elements of Material Science and Engineering. 6th ed. Addison-Wesley: Reading, Mass., 1989.

M. M. Schwartz, ed. Handbook of Structural Ceramics. McGraw-Hill: New York. 1984.

 

Image 177