69
For specific information on material properties, consult the following: H. E. Boyer and T. L. Gall, ed. Metals Handbook. Vol. 1. American Society for Metals: Metals Park, Ohio, 1985.
2
U. S. Department of Defense. Metallic Materials and Elements for Aerospace Vehicles and Structures MIL-HDBK-5H, 1998.
R. Juran, ed. Modern Plastics Encyclopedia. McGraw-Hill: New York, 1988.
J. D. Lubahn and R. P. Felgar, Plasticity and Creep of Metals. Wiley: New York, 1961.
For information on failure of materials, consult the following: J. A. Collins, Failure of Materials in Mechanical Design. Wiley: New York, 1981.
N. E. Dowling, Mechanical Behavior of Materials. Prentice-Hall: Englewood Cliffs, N.J., 1992.
R. C. Juvinall, Stress, Strain and Strength. McGraw-Hill: New York, 1967.
For information on plastics and composites, consult the following: ASM, Engineered Materials Handbook: Composites. Vol. 1. American Society for Metals: Metals Park, Ohio, 1987.
ASM, Engineered Materials Handbook: Engineering Plastics. Vol. 2. American Society for Metals: Metals Park, Ohio, 1988.
Harper, ed. Handbook of Plastics, Elastomers and Composites. 2nd ed. McGraw-Hill: New York, 1990.
J. E. Hauck, “Long-Term Performance of Plastics.” Materials in Design Engineering, pp. 113-128, November, 1965.
M. M. Schwartz, Composite Materials Handbook. McGraw-Hill: New York, 1984.
For information on manufacturing processes, see:
R. W. Bolz, Production Processes: The Productivity Handbook. Industrial Press: New York, 1974.
J. A. Schey, Introduction to Manufacturing Processes. McGraw-Hill: New York, 1977.
2.13 PROBLEMS
Table P2-0
Topic/Problem Matrix
2-1 Figure P2-1 shows stress-strain curves for three failed tensile-test specimens. All are plotted on the same scale.
2.1 Material Properties
(a)
Characterize each material as brittle or ductile.
(b)
Which is the stiffest?
2-1, 2-2, 2-3, 2-4, 2-5, 2-6, 2-7,
2-8, 2-9, 2-10, 2-11, 2-12, 2-18,
(c)
Which has the highest ultimate strength?
2-19, 2-20, 2-21, 2-22, 2-23
(d)
Which has the largest modulus of resilience?
(e)
Which has the largest modulus of toughness?
2.4 Hardness
2-2 Determine an approximate ratio between the yield strength and ultimate strength for each 2-13, 2-14
material shown in Figure P2-1.
2.6 General Properties
2-3 Which of the steel alloys shown in Figure 2-19 would you choose to obtain 2-15, 2-16, 2-17, 2-24, 2-25,
2-26
(a)
Maximum strength
(b)
Maximum modulus of resilience
2.8 Selecting Materials
(c)
Maximum modulus of toughness
2-37, 2-38, 2-39, 2-40
(d)
Maximum stiffness
70
MACHINE DESIGN -
An Integrated Approach
2-4 Which of the aluminum alloys shown in Figure 2-21 would you choose to obtain Stress
(a)
Maximum strength
2
(b)
Maximum modulus of resilience
(c)
Maximum modulus of toughness
(d)
Maximum stiffness
2-5 Which of the thermoplastic polymers shown in Figure 2-22 would you choose in order to obtain
(a)
Maximum strength
(b)
Maximum modulus of resilience
(c)
Maximum modulus of toughness
(d)
Maximum stiffness
Strain
*2-6 A metal has a strength of 414 MPa at its elastic limit and the strain at that point is 0.002.
(a)
Assume the test specimen is 12.8-mm dia and has a 50-mm gage length. What is its
modulus of elasticity? What is the strain energy at the elastic limit? Can you define the
Stress
type of metal based on the given data?
2-7 A metal has a strength of 41.2 kpsi (284 MPa) at its elastic limit and the strain at that
point is 0.004. Assume the test specimen is 0.505-in dia and has a 2-in gage length.
What is the strain energy at the elastic limit? Can you define the type of metal based on
the given data?
*
2-8 A metal has a strength of 134 MPa at its elastic limit and the strain at that point is 0.003.
What is its modulus of elasticity? Assume the test specimen is 12.8-mm dia and has a
50-mm gage length. What is its modulus of elasticity? What is the strain energy at the
elastic limit? Can you define the type of metal based on the given data?
*2-9 A metal has a strength of 100 kpsi (689 MPa) at its elastic limit and the strain at that
Strain
point is 0.006. What is its modulus of elasticity? What is the strain energy at the elastic
(b)
limit? Assume the test specimen is 0.505-in dia and has a 2-in gage length. Can you
define the type of metal based on the given data?
Stress
2-10 A material has a yield strength of 689 MPa at an offset of 0.6% strain. What is its
modulus of resilience?
2-11 A material has a yield strength of 60 kpsi (414 MPa) at an offset of 0.2% strain. What is
its modulus of resilience?
*2-12 A steel has a yield strength of 414 MPa, an ultimate tensile strength of 689 MPa, and an
elongation at fracture of 15%. What is its approximate modulus of toughness? What is
its approximate modulus of resilience?
2-13 The Brinell hardness of a steel specimen was measured to be 250 HB. What is the
material’s approximate tensile strength? What is its hardness on the Vickers scale? The Strain
Rockwell scale?
(c)
*2-14 The Brinell hardness of a steel specimen was measured to be 340 HB. What is the material’s approximate tensile strength? What is its hardness on the Vickers scale? The F I G U R E P 2 - 1
Rockwell scale?
Stress-Strain Curves
2-15 What are the principal alloy elements of an AISI 4340 steel? How much carbon does it have? Is it hardenable? By what techniques?
*2-16 What are the principal alloy elements of an AISI 1095 steel? How much carbon does it have? Is it hardenable? By what techniques?
2-17 What are the principal alloy elements of an AISI 6180 steel? How much carbon does it
*
have? Is it hardenable? By what techniques?
Answers to these problems are
provided in Appendix D.
2-18 Which of the steels in Problems 2-15, 2-16, and 2-17 is the stiffest?