ME 325
Mechanical Component Design "Machine Design"
Fasteners
Rafael Radkowski
[email protected]
Definitions and Standards
pitch: the distance between a
screw thread.
major diameter d: the maximal
diameter.
minor or root diameter dr: the
minimal diameter
-Solving Section 2
Problem
1. Problem Description: A bar of steel has the minimum properties
S e =40 kpsi, S y =60 kpsi , Sut =80 kpsi . The bar is subjected to a steady torsional stress
of 15 kpsi , and an alternating torsional stress of 10 kpsi , and an
s 1 and 2: For each of the plane stress states listed below, draw a Mohr's
Problem
circle diagram properly labeled, find the principal normal and shear stresses, and
determine the angle from the x axis to 1.
(1) Given condition: x=20 kpsi, y= -10 kpsi , x
F = 1500( /4)22 = 4712 lbf. From Table A-20, Sy = 37.5 kpsi
Pcr = nd F = 2.5(4712) = 11 780 lbf
1.
(a) Assume Euler with C = 1
1/4
1/4
64 11790 502
64 Pcr l 2
d 3
3
6
1 30 10
CE
Use d = 1.25 in. The radius of gyration, k = ( I / A)1/2 = d /4 = 0.
HW3 Solution
1
Sut 230 kpsi, N 150 000 cycles
Fig. 6-18, point is off the graph, so estimate:
Eq. (6-8):
Eq. (6-14):
Eq. (6-15):
Eq. (6-13):
Sut > 200 kpsi, so
f = 0.77
Se Se 100 kpsi
( f Sut ) 2 0.77(230)
a
313.6 kpsi
Se
100
2
f Sut
1
b log
3
Se
1
A solid round bar, 25 mm in diameter, has a groove 2.5 mm deep with a 2.5 mm radius
machined into it. The bar is made of AISI 1018 CD steel and is subjected to a purely reversing
torque of 207 N m. For the 61FXUYH of this material, let f = 0.9.
(a ) Estim
7KHILJXUHLVDVFKHPDWLFGUDZLQJRIDFRXQWHUVKDIWWKDWVXSSRUWVWZR9EHOWSXOOH\V7KH
countershaft runs at 2,000 rev/min and the bearings are to have a life of 40 kh at a combined
reliability of 0.96. The belt tension of the loose side of pulley 3 is 15 percent of th
$QVHULHVVLQJOHURZGHHSJURRYHEDOOEHDULQJZLWKD PP bore (see the following
tables for specifications) is loaded with a N1 axial load and a N1 radial load. The outer
ring rotates at 513 rev/min. Determine the equivalent radial load that will be experienced by
7KHILJXUHVKRZVDSDLURIVKDIWPRXQWHGVSXUJHDUVKDYLQJDGLDPHWUDOSLWFKRI
5 teeth/in
with DWRRWK pinion driving a WRRWKJHDU 7KHLQSXWLVKSPD[LPXPDW
1,800 rev/min. Find the magnitude of the forces acting on bearings A , B , C , and D .
Step 1:
Given: P = 5 teeth/in,
M a = 66.5 Nm, T a = 49.7 Nm,
M m = 60.0 Nm, T m = 31.6 Nm. For the shaft, S u = 650 MPa and S y = 595 MPa, and a
fully corrected endurance limit of S e = 160 MPa is assumed. Let K f = 2.20 and K f s = 1.68.
A shaft is loaded in bending and torsion such t
$SDUDOOHOKHOLFDOJHDUVHWXVHVDWRRWKSLQLRQGULYLQJDWRRWKJHDU7KHSLQLRQKDVD
ULJKWKDQGKHOL[DQJOHRI , a normal pressure angle of 20 , and a normal diametral pitch of
5 teeth/in. Find:
(a ) The normal, transverse, and axial circular pitches
(b ) The normal base ci
$VWHHOVSXUSLQLRQKDVDSLWFKRIWHHWKLQIXOOGHSWKWHHWKDQGD
pressure angle. The
SLQLRQUXQVDWDVSHHGRIUHYPLQDQGWUDQVPLWVKSWRDWRRWKJHDU7KHJHDULV
milled. If the face width is 2 in, estimate the bending stress.
Step 1:
Given:
Pitch, p = 6 teeth/in
Number of teeth, N
A spur gearset has a module of 3 mm and a velocity ratio of 2.93. The pinion has 20 teeth. Find
the number of teeth on the driven gear, the pitch diameters, and the theoretical
FHQWHUWRFHQWHUGLVWDQFH
Number of teeth on the driven gear, N G =
Pitch diamete
A steel spur pinion has a module of 1 mm and 16 teeth cut on the 20
IXOOGHSWKV\VWHPDQGLV
to carry 0.15 kW at 379 rev/min. Determine a suitable face width based on an allowable
bending stress of 142 MPa.
Step 1:
Given:
Module, m = 1 mm
No of teeth, N = 16
Shaft a in the figure rotates at 626 rev/min in the direction shown. Find the speed and
direction of rotation of shaft d .
Given:
N 2 = 20
N 3 = 40
N4 =8
N 5 = 17
N 6 = 20
N 7 = 60
n = 626 rev/min
Step 1:
e =
=
N2
N4
N6
N3
N5
N7
20
8
20
40 17
60
=
4
51
St
For the bearing application specifications given in the table, determine the Basic Load Rating
for a ball bearing with which to enter a bearing catalog. Assume the rating life to be 10
revolutions, a f = 1, x 0 = 0.02, = 4.459, and b = 1.483.
Radial Load
A part is loaded with a combination of bending, axial, and torsion such that the following
stresses are created at a particular location:
Bending:
Axial:
Torsion:
Completely reversed with a maximum stress of 60 MPa
Constant stress of 20 MPa
Repeated load,
ME325
Mechanical Component Design
Exam 1
(Notes on two double-sided, letter sheets allowed.)
March 3, 2017
STUDENT NAME: _Instructor_
STUDENT ID: _
I have neither given nor received any help during the exam.
Signature: _
1/7
Exam 1
ME325 Spring 2017
Probl
Week 9 - Gears
We can't solve problems by
using the same kind of
thinking we used when we
created them.
ALBERT EINSTEIN
Molian/Iowa State University
1
Summary of Week 8 Lectures
Example: Design a simple gear system for a
kitchen sink food waste grinder w
ME 325
Mechanical Component Design "Machine Design"
Journal Bearings
Rafael Radkowski
[email protected]
Table of Content
Journal bearings
Viscosity
Sommerfeld number
Design
Friction
Minimum Film Thickness
Temperature
Go home messages:
Understand the prin
ME 325
Mechanical Component Design "Machine Design"
Gears - Safety Analysis
Rafael Radkowski
[email protected]
AGMA
The American Gear Manufacturer Association (AGMA) sanctioned a method to
determine the safety of gear wheels. These methods cover:
bending
ME 325
Mechanical Component Design "Machine Design"
Shaft Components
Rafael Radkowski
[email protected]
Content
Shaft components
Keys
Retaining rings
ME 325 Course Notes
Spring 2016
Keys
Keys are used to secure rotating elements.
The transmit a torque fr
ME 325
Mechanical Component Design "Machine Design"
Rolling-Contact Bearings
Rafael Radkowski
[email protected]
Table of Content
Bearing nomenclature
Bearing Load-Life
Weibull Distribution
Reliability of Bearings
Go home messages:
ME 325 Course Notes, Io
ME 325
Mechanical Component Design "Machine Design"
Working with Fluctuating Stress
Rafael Radkowski
[email protected]
Content
Fluctuating Stress
Stess
Gerber and Goodman relations
Failure diagram
ME 325 Course Notes
Fall 2014
Overview
SN-Diagram: estima
ME 325
Mechanical Component Design "Machine Design"
Material Properties & Stress Analysis
Rafael Radkowski
[email protected]
Today
Ductile and Brittle stress Strain curves
Mohr's circles for brittle materials and ductile materials
Example problem
ME 325
ME 325
Mechanical Component Design "Machine Design"
Shaft Design Introduction
Rafael Radkowski
[email protected]
Content
Introduction
Shaft design.
Design for Stress
Go home messages:
ME 325 Course Notes
What is important when we design a
shaft.
Spring 2
ME 325
Mechanical Component Design "Machine Design"
Brittle Failure Theory
Rafael Radkowski
[email protected]
Today
Overview - Failure Theories
Maximum Normal Stress Theory
Modified Mohr Failure Theory
Coulomb Mohr Failure Theory
Sample Problem
Go home m
Midterm exam:
Monday, February 29, 2016
You need:
Something to write
Calculator
Your notes
ME 325 Course Notes, Iowa State University
1
Spring 2016
ME 325
Mechanical Component Design "Machine Design"
Shaft Design
Rafael Radkowski
[email protected]
Conten
In-Class Problem
Determine the approximate weight fractions of L and solid for an
overall composition C0 of 25 wt% B at T1.
C= 40 wt% B
CL= 15 wt% B
C C L
=
40 25
40 15
= 0.60 = 60% L
L
Temperature
WL =
C C0
L
W =
C0 C L
C C L
=
25 15
40 15
T1
= 0.40 = 40
Homework 4 Solution
1
d P 17 / 8 2.125 in
N
1120
dG 2 d P
2.125 4.375 in
N3
544
N G Pd G 8 4.375 35 teeth
C 2.125 4.375 / 2 3.25 in
Ans.
Ans.
_
2
nG 1600 15 / 60 400 rev/min
p m 3 mm Ans.
C 3 15 60 2 112.5 mm
Ans.
Ans.
_
3
20 8 20 4
e
40 17 60 51
4
nd
Homework 6 Solution
8-63 For an M 30 3.5 ISO 8.8 bolt with P = 65 kN/bolt and C = 0.28
Table 8-1,
Table 8-11,
Table 8-17,
At = 561 mm2
Sp = 600 MPa, Sut = 830 MPa
Se = 129 MPa
Eq. (8-31),
Fi = 0.75Fp = 0.75 At Sp
= 0.75(5610600(103) = 252.45 kN
i = 0.75 S
Homework 5 Solution
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 1
6
6
210
10
338.4 700 10
3
d = 25.85 (
Week 8 - Gears
Just stare at the machine. Just live
with it for a while. Watch it the way
you watch a line when fishing and
before long, as sure as you live,
youll get a little nibble, a little fact
asking in a timid, humble way if
youre interested in it.
Week 10
Design of Spur Gears
We've probably designed 4,000
products at IDEO over my
career, and for every one of
them I'd like to send a little note
with it that says, "I'm sorry that
it's in this present state. Given
what I know now, if I could start
ove