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UNIVERSITEIT VAN PRETORIA
UNIVERSITY OF PRETORIA
Departement Meganiese en Lugvaartkundige Ingenieurswese
Department of Mechanical and Aeronautical Engineering
MASJIENONTWERP MOW217
WELDING 1
MOW 227 2013
Shigley chapter 9
Department of Mechanical and Aeronautical Engineering
Welding
Department of Mechanical and Aeronautical Engineering
Types of Welded Joints
Department of Mechan
Mechanical Springs
Shigley Ch 10
Lecture 21
Mechanical Springs
Why do we need springs?
Flexibility of structure
Storing and releasing of energy
Standard spring types:
Wire springs
- Helical springs
Springs Lecture 3
Extension Springs
Extension springs
Carry tensile loading
Max. Normal stress at A due to
Bending and Axial loading
A
KA
16 D
F KA
d3
4C12 C1 1
4C1 (C1 1)
4
d2
C1
2r1
d
Max. torsiona
Springs Lecture 2
Spring Design
Spring Design for Static Service
Ch 10-7
Preferred range of spring index is
4 C 12
Recommended range of active turns is
3 N a 15
Working range of the spring is 75% o
Influence of Mean Stress
Discussion has been limited to completely
reversible stress thus far.
Meaning m = 0
However, there are many instances of
dynamic loading when mean stress is nonzero.
Mean S
Class example
A 40mm diameter machined bar has to
withstand a load that fluctuates from 0 to
70kN tensile force. At a critical section there
is a radius=1mm with a corresponding
stress concentration f
Palmgren-miner method limitations
Damage method is not history dependant,
so one must take caution when using it.
Eg:
vs
Failure occurs sooner with one on right
because damage is accumulated quicker
Fatigue of Materials
MOW227
Semester 22013
Introduction
Repeated or cyclic loads can result in cyclic
stresses that lead to failure.
Failure can occur at stresses well below the
yield or ultimate st
WELDING 2
MOW 227 2013
Department of Mechanical and Aeronautical Engineering
Bending
Primary Shear Stress
d
V
M
y
V
A
Nominal Throat shear Stress
x
Mc
I
d
M
2
0.707h I u
1.414M
bhd
Compare 1.414 wi
SCREWS, FASTENERS AND NON
PERMANENT JOINTS
3
MOW 227 2013
Department of Mechanical and Aeronautical Engineering
Department of Mechanical and Aeronautical Engineering
Bolted and Riveted joints in shear
Stress Concentration
Mow 227
Shigley Ch 3-13
Stress Concentration
Stresses and strains are uniformly distributed
for parts of constant cross-section with
uniformly distributed loads.
However,
applie
Kopiereg voorbehou
Copyright reserved
UNIVERSITEIT VAN PRETORIA
UNIVERSITY OF PRETORIA
Departement Meganiese en Lugvaartkundige Ingenieurswese
Department of Mechanical and Aeronautical Engineering
Mas
Bearings
SM Roux
February 5, 2016
Bearings
Bearings permit smooth, low friction movement between two surfaces moving relative to one another.
This movement may be translational or rotational.
Beari
MOW 217: Belt and Chain Problems
Specify a belt and chain design for the following problems:
Machine Type
Rotational Speed [rpm]
Shaft Diameter [mm]
Centre Distance (Belts Only)
Power [kW]
Operating t
Question 1
The gear forces in Figure 1 shown act in planes
parallel to the yz plane. The force on gear A is
1.2kN. Consider the bearings at O and B to be simple
supports.
a. Calculate the force FC
b.
MOW 217: Ball Bearing Problems
Using the NTN bearing catalogue, calculate the answer which is in braces:
(All loading is purely dynamic unless stated otherwise.)
D
[mm]
70
Fr
[kN]
3.2
Fa
[kN]
0
N
[rpm
SCREWS, FASTENERS AND NON
PERMANENT JOINTS
2
MOW 227 2013
Department of Mechanical and Aeronautical Engineering
Department of Mechanical and Aeronautical Engineering
Department of Mechanical and Aeron
SCREWS, FASTENERS AND NON
PERMANENT JOINTS 1
MOW 227 2013
Shigley Ch 8
Department of Mechanical and Aeronautical Engineering
STANDARDS AND DEFINITIONS-THREAD
/Pitch diameter
Department of Mechanical a
SCREWS, FASTENERS AND NON
PERMANENT JOINTS
2
MOW 227 2013
Department of Mechanical and Aeronautical Engineering
Department of Mechanical and Aeronautical Engineering
Department of Mechanical and Aeron
Lecture 7
MOW 227
1
Strain Transformation
Transformation equations between stress
transformation and strain transformation are
analogous.
x, y, z are analogous to x, y, z
xy, xz, yz are analogous t
Shaft Design
MOW227
Semester 2 2012
Shaft System
A shaft is a rotating (or stationary) member
usually having a circular cross-section with
a diameter much smaller than its length.
A shaft generally
SCREWS, FASTENERS AND NON
PERMANENT JOINTS 1
MOW 227 2013
Shigley Ch 8
Department of Mechanical and Aeronautical Engineering
STANDARDS AND DEFINITIONS-THREAD
/Pitch diameter
Department of Mechanical a
SCREWS, FASTENERS AND NON
PERMANENT JOINTS 1
MOW 227 2013
Shigley Ch 8
Department of Mechanical and Aeronautical Engineering
STANDARDS AND DEFINITIONS-THREAD
/Pitch diameter
Department of Mechanical a
Chapter 10
10-1
From Eqs. (10-4) and (10-5)
KW K B
4C 1 0.615 4C 2
4C 4
C
4C 3
Plot 100(K W K B )/ K W vs. C for 4 C 12 obtaining
We see the maximum and minimum occur at C = 4 and 12 respectively whe
Chapter 11
11-1
For the deep-groove 02-series ball bearing with R = 0.90, the design life x D , in multiples
of rating life, is
L
60D nD 60 25000 350
xD D
525 Ans.
LR
L10
106
The design radial load
Chapter 7
7-1
(a) DE-Gerber, Eq. (7-10):
A 4 K f M a 3 K fsTa 4 (2.2)(70) 3 (1.8)(45) 338.4 N m
2
2
2
2
B 4 K f M m 3 K fsTm 4 (2.2)(55) 3 (1.8)(35) 265.5 N m
2
2
2
6
8(2)(338.4) 2(265.5) 210 10
d
1
Chapter 4
For a torsion bar, k T = T/ = Fl/, and so = Fl/k T . For a cantilever, k l = F/ , = F/k l . For
the assembly, k = F/y, or, y = F/k = l +
Thus
F Fl 2 F
y
k
kT kl
Solving for k
kk
1
k 2
2l
Chapter 8
Note to the Instructor for Probs. 8-41 to 8-44. These problems, as well as many others in this
chapter are best implemented using a spreadsheet.
8-1
(a) Thread depth= 2.5 mm Ans.
Width = 2.5
Chapter 6
Eq. (2-21):
Eq. (6-8):
Table 6-2:
Eq. (6-19):
Sut 3.4 H B 3.4(300) 1020 MPa
Se 0.5Sut 0.5(1020) 510 MPa
a 1.58, b 0.085
b
ka aSut 1.58(1020) 0.085 0.877
Eq. (6-20):
6-1
kb 1.24d 0.107 1.24(1