Page 307 - Analysis and Design of Machine Elements

Shafts
5 List the factors that affect the fatigue strength of a shaft. If a shaft does not have 285
sufficient fatigue strength, what measures can be taken to satisfy the strength
requirement?

Objective Questions

1 When a shaft carries combined bending and torsional stresses, a factor is intro-
duced in the stress calculation because ___________.
(a) a deviation exists between theoretical and experimental results
(b) the torsional shear stress maybe not a completely reversed stress
(c) the bending stress maybe not a completely reversed stress
(d) the shaft has stress concentration

2 The purpose of increase a fillet radius in shoulder design is ___________.
(a) to ensure a reliable circumferential location
(b) to ensure a reliable axial location
(c) to facilitate manufacture
(d) to reduce stress concentration and to improve fatigue strength of shaft

3 Which of the following could not effectively improve the rigidity of a shaft?
_________
(a) Use high-strength alloy steels.
(b) Change the structure of shaft.
(c) Change the diameter of shaft.
(d) Change the bearing position of shaft.

4 In Figure P10.1, the width of the element installed on the shaft is B. The length of the
mating shaft segment is L. In order to locate the element axially on the shaft securely,
therelationshipbetween B and L should be___________
(a) B < L
(b) B = L
(c) B > L
(d) there is no relationship between B and L

Figure P10.1 Illustration for Objective Question 4.