Download presentation

1
**Chapter 18 Shafts and Axles Dr. A. Aziz Bazoune**

King Fahd University of Petroleum & Minerals Mechanical Engineering Department

2
Chapter Outline 18-1 Introduction ……… Geometric Constraints ……… Strength Constraints ……… Strength Constraints – Additional Methods ……….940 18-5 Shaft Materials ……… Hollow Shafts ……… Critical Speeds (Omitted) ……… Shaft Design ……….950

3
LECTURE 29 18-1 Introduction ……… Geometric Constraints ……… Strength Constraints ……….933

4
18-1 Introduction In machinery, the general term “shaft” refers to a member, usually of circular cross-section, which supports gears, sprockets, wheels, rotors, etc., and which is subjected to torsion and to transverse or axial loads acting singly or in combination. An “axle” is a non-rotating member that supports wheels, pulleys,… and carries no torque. A “spindle” is a short shaft. Terms such as lineshaft, headshaft, stub shaft, transmission shaft, countershaft, and flexible shaft are names associated with special usage.

5
**Considerations for Shaft Design**

Deflection and Rigidity (a) Bending deflection (b) Torsional deflection (c) Slope at bearings and shaft supported elements (d) Shear deflection due to transverse loading of shorter shafts Stress and Strength (a) Static Strength (b) Fatigue Strength (c) Reliability

6
**Considerations for Shaft Design**

The geometry of a shaft is that of a stepped cylinder bending. Gears, bearings, and pulleys must always be accurately positioned Common Torque Transfer Elements Keys Splines Setscrews Pins Press or shrink fits Tapered fits

7
**Common Types of Shaft Keys.**

8
**Common Types of Shaft Keys.**

9
**Common Types of Shaft Pins.**

10
**Common Types of Shaft Pins.**

11
**Common Types of Retaining or Snap Rings.**

12
**Common Types of Splines.**

15
Rigid Shaft Coupling.

16
Figure 18-2 Choose a shaft configuration to support and locate the two gears and two bearings. (b) Solution uses an integral pinion, three shaft shoulders, key and keyway, and sleeve. The housing locates the bearings on their outer rings and receives the thrust loads. (c) Choose fanshaft configuration. (d) Solution uses sleeve bearings, a straight-through shaft, locating collars, and setscrews for collars, fan pulley, and fan itself. The fan housing supports the sleeve bearings.

17
**18-3 Strength Constraints**

The design of a shaft involves the study of Stress and strength analyses: Static and Fatigue Deflection and rigidity Critical Speed

18
**Static or Quasi-Static Loading on Shaft**

19
**Static or Quasi-Static Loading on Shaft**

The stress at an element located on the surface of a solid round shaft of diameter d subjected to bending, axial loading, and twisting is Normal stress Shear stress Non-zero principal stresses

20
**Static or Quasi-Static Loading on Shaft**

Von Mises stress Maximum Shear Stress Theory

21
**Static or Quasi-Static Loading on Shaft**

Under many conditions, the axial force F in Eqs. (6-37) and (6-38) is either zero or so small that its effect may be neglected. With F = 0, Eqs. (6-37) and (6-38) become Von Mises stress (6-41) Maximum Shear Stress Theory (6-42)

22
**Static or Quasi-Static Loading on Shaft**

Substitution of the allowable stresses from Eqs and 6-40 we find (6-43) Von Mises stress (6-44) (6-45) Maximum Shear Stress Theory (6-46)

23
Fatigue Strength Bending, torsion, and axial stresses may be present in both midrange and alternating components. For analysis, it is simple enough to combine the different types of stresses into alternating and midrange von Mises stresses, as shown in Sec. 7–14, p. 361. It is sometimes convenient to customize the equations specifically for shaft applications. Axial loads are usually comparatively very small at critical locations where bending and torsion dominate, so they will be left out of the following equations. The fluctuating stresses due to bending and torsion are given by

24
Fatigue Strength The fluctuating stresses due to bending and torsion are given by where Mm and Ma are the midrange and alternating bending moments, Tm and Ta are the midrange and alternating torques, and Kf and Kfs are the fatigue stress concentration factors for bending and torsion, respectively. Assuming a solid shaft with round cross section, appropriate geometry terms can be introduced for c, I, and J resulting in

25
Assuming a solid shaft with round cross section, appropriate geometry terms can be introduced for c, I, and J resulting in

26
Combining these stresses in accordance with the distortion energy failure theory, the von Mises stresses for rotating round, solid shafts, neglecting axial loads, are given by

Similar presentations

Presentation is loading. Please wait....

OK

Chapter Outline Shigley’s Mechanical Engineering Design.

Chapter Outline Shigley’s Mechanical Engineering Design.

© 2018 SlidePlayer.com Inc.

All rights reserved.

To ensure the functioning of the site, we use **cookies**. We share information about your activities on the site with our partners and Google partners: social networks and companies engaged in advertising and web analytics. For more information, see the Privacy Policy and Google Privacy & Terms.
Your consent to our cookies if you continue to use this website.

Ads by Google

Ppt on software project management by walker royce Ppt on market friendly statements Ppt on aerodynamics of planes Ppt on output devices Ppt on op amp circuits design Ppt on the art of war online Ppt on stars and planets Ppt on save environment drawings A ppt on presentation skills Ppt on agriculture in india