Example I
EXAMPLE 91
Shaft Design for Steady Torsion and Fully Reversed
Bending
Problem
Design a shaf t to support the attachments shown in Figure 95 with a
minimum design saf ety factor of 2.5.
Units
ksi
Given
Transmitted power
P
2 hp
Shaft speed
1725
Tutorial 9
ZHUO,Mingzhao
15/11/2013
I need the response from you
to decide what to teach!
Outline
Review of centroids & principal centroidal axes
Unsymmetric bending
Shear center
Centroids of Plane Areas
Define centroids
x=
Qy
A
xdA
ydA
, y =Q =
=
A
dA
Tutorial 10
ZHUO, Mingzhao
21/11/13
Outline
Comments on Homework
Plasticity in bars under axial loading
Plastic action in bending
Collapse loads in beams
Problems in Homework
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and honesty http:/
tl.ust.hk/integrity/
Tutorial 11
ZHUO, Mingzhao
29/11/13
Outline
Strain energy expression
Castiglianos first theorem
Castiglianos second theorem
Unit load method
Indeterminate problems
Homework 6 P1
(a)
(b)
Stress AC > AB > AD, so AC firstly yields, then AB yields
and we thin
Tutorial 8
ZHUO,Mingzhao
8/11/2013
Outline
Midterm Problem
Torsion Problem
Midterm Problem 1
A semiinfinite beam on winkler foundation is simply supported b
y a hinge. A rigid angle bracket OAB is fixed to the end of the be
am, as shown in the figure. Lo
MECH 3520 Lecture 1
Book: Machine Design: An Integrated Approach 4Ed. By Robert L
Norton
1
Engineering design
Requirements of engineering design
Performance
Sustainability
Appearance
2
Engineering design
Questions to be answered for engineering design
EXAMPLE 71
Stresses in a Ball Thrust Bearing
Problem
A ball thrust bearing with 7 balls is loaded ax ially across its races
through the balls. What is the size of the contact patch on a race and
what are the stresses developed in balls and races? What is
MECH 3520 Lecture 2
Book: Machine Design: An Integrated Approach 4 Ed. By Robert L
Norton
Stresses in Cylinders
Cylinders can be subjected to internal and/or external pressure
Stress Distribution in Cylinders
Stresses are given in general by the Lame equ
: ; :em An overhead crane wheel runs slowly on a steel rail. What is the size of
the contact patch between wheel and rail and what are the stresses?
What is the depth of the maximum shear stress?
en The wheel is lZin dia by 0.875in thick and the rail is
MECH 3520 Lecture 6 Notes
MicroMachines
Drive gear chain and linkages, with a grain of pollen (top right) and coagulated red
blood cells (lower right, top left) to demonstrate scale.
Microgear and shaft
Shaft Design I
9.0 98
A shaft is a rotating member,
MECH 3520 Lecture 4 Notes
Book: Machine Design: An Integrated Approach 4 Ed. By Robert L
Norton
Fatigue physics I
Failure of machine elements are often found to have fractured after operation.
The cyclic loading is designed to be below the ultimate stress
MECH 3520 Lecture 3
Book: Machine Design: An Integrated Approach
Failure theories ductile materials
5.0 5.1
One of the principal objectives of design: prevent failure
Failure of the part occurs when the stresses in the part exceeds the strength of
the mat
MECH 3520 Lecture 5 Notes
Book: Machine Design: An Integrated Approach 4 Ed. By Robert L
Norton
1
Surface Fatigue
When two surfaces are in pure rolling contact
Or when two surfaces are in rolling with a small portion of sliding
They have an identical fai
CHAPTER SEVEN
PLASTIC COLLAPSE and LIMIT ANALYSIS
7.1 Introduction and bars with axial loading
7.2 Plastic action in bending and plastic hinges
7.3 Collapse loads in beams
Review and Summary
l Structural design under static load
(1) Elastic analysis  All
CHAPTER THREE
SYMMETRIC BENDING OF
CIRCLE PLATES
* Governing equations in beam and plate bending
* Solution by superposition
1.1 From Beam Bending to Plate Bending
1.2 Governing Equations For Symmetric Bending of Circular
Plates, Some Typical Solutions
1.
MECH 3020  Mechanics of Solid II (Fall 20122013)
Course Description: Biaxial stress state and failure criteria; thickwalled
cylinders and spinning disks; bending of plates; elastic foundations;
unsymmetric bending and torsion; curved beams; frame anal
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Introduction
Mechanics: deals with the responses of the bodies to the action
of forces.
Objectives:
To give students an introduction to engineering mechanics with an
emphasis on engineering problem solving
Question:
What are the mechanical issues involved
Moment of a Force
Objects
a particle
a 3D body
External Effects
translation
translation and rotation
The moment of a force about a point or an axis: a measure of
the tendency of the force to rotate a body about that point or
the axis.
Definition: Moment
Deformation of Axially Loaded
Members  Single Member
P
P
Assumptions:
uniform cross section (A is a constant)
homogeneous material (E is a constant)
loads are applied at ends only
L
L
E
E
L
E
P
A
PL
EA
Axially Loaded Members  Multiple
Members
C
A
General Equilibrium Problems
Equilibrium Conditions:
2D:
r
F =0
r
M =0
F
F
F
Fx =0
Fy =0
M z =0
x
3D:
=0
y
=0
z
=0
M
M
M
x
=0
y
=0
z
=0
Problem Solving Procedure  Static
Equilibrium
Draw Free Body Diagram
Set up equations
Solve equations
Free Body Dia
Columns
DEC 2012
Introduction
Columns are commonly used to support roofs of buildings.
12/21/2012
ME Department, HKUST
2
Introduction
A common failure mode: buckling
12/21/2012
ME Department, HKUST
3
A Simple Model
Rigid
bar
Rigid
bar
Buckling of an ideal
Analysis of Stress and Strain
Review:
 Torsional shaft
 Axially loaded Bar
p
a
q
P
h
q
F P cos 2 q
sq = =
Aq
A
tq =
V
P cos q sin q
=
Aq
A
P
tnt
txy
sn
tyx
s n =t xy sin 2a
t nt =t xy cos 2a
Questions:
(1) Is there any general method to determine stress