Warm-up Question (1):
Stress, shear, strain. whats with all the ss?
A. I know, right? No imagination.
B. Its a conspiracy against those with speech
impediments.
C. Its worse! First we had and , now its and
. Only one of those starts with s. No
consistenc
Objectives
Identify the moment of force and calculate it in 2- and 3-D.
Review the properties and applications of cross-products
Introduce method for finding moments about a specific axis.
1
MSE206: Mechanics for MatSE
2
Websites:
Class schedule, ann
Equations and relations
x0 =
x + y x y
+
cos 2 + xy sin 2
2
2
x0 =
x + y x y
cos 2 xy sin 2
2
2
x y
sin 2 + xy cos 2
x0 y0 =
2
x + y x y
1
cos 2 xy sin 2
2
2
2
x y
1
1
x0 y0 =
sin 2 + xy cos 2
2
2
2
y0 =
x =
y + z
x
E
E
y =
xy =
G=
xy
G
L
Z
=
0
y0 =
Warm-up Question (1):
Its soooo cold! I wish I were
A. Olaf the snowman
B. A hibernating grizzly bear
C. The BUMBLE!
D. On the ski slopes
E. Retired, so I didnt have to go outside!
1
Announcements
Exam #1 next Thursday (2/26) during class, but in ESB 19
Warm-up Question (1):
John Stewart leaving the Daily Show
A. Is the worst thing thats happened to me all
week!
B. Doesnt mean that I will actually start reading
newspapers
C. But how will I know which politicians to make
fun of now?
D. John Stewart isnt
MSE206: Mechanics for MatSE
1
Three things you need to do:
1.
2.
3.
4.
Register i>clicker on compass2g (by Feb. 2!)
Register with Piazza (questions to instructors, discussion about HW)
Read your syllabus (pay attention to details about written reports)
B
Exit Ticket
Thursday was a long time ago, what did we do or
what did we learn?
- Free body diagrams i.e. breakin it down!
- FBDs are hard!
- Its very helpful to choose a reference axis that
eliminates a lot of unknowns to simplify the
problem.
- Dry frict
Warm-up Question (1):
1
Whats your favorite low friction winter activity?
A. Sleddingdont you need hills or something
like that?
B. Skiingbut where are the mountains?
C. Ice skating
D. Ice skating, you mean falling like an idiot and
breaking my wrist!? (
23. Description of a Shock Tube
A shock tube is a device consisting, in its simplest form, of a long tube of constant area divided into two
sections by a diaphragm. One of the sections contains a high pressure gas (aka driver gas) while the other
contains
We know the following about the flow:
1. The gas properties are assumed identical on either side of the diaphragm, i.e. 1 = 2 = 3 = 4 and R1 =
R2 = R3 = R4.
2. The velocities in regions 1 and 4 are zero, i.e. u1 = u4 = 0.
3. The pressures and temperatures
Analysis of the Flow in a Shock Tube
The velocity and pressure behind the shock wave must be equal to the velocity and pressure behind the
expansion wave as shown in the figure below. The temperatures (and densities and entropies) are not
necessarily equa
Example:
A diaphragm at the end of a 4 m long pipe containing air at a pressure of 200 kPa and a temperature of 30
C suddenly ruptures causing an expansion wave to propagate down the pipe. Find the velocity at which
the air is discharged from the pipe if
2.
Now lets consider what happens if we accelerate the piston to the left from rest (u0 = 0) to a very large
speed. From Eqn. (12.389) (were crossing right-running characteristics) we have:
umax
2
2
2
c 1 u
u u0
1
c c0
1
2 c0
1 1
c0
c0
0
Since the
For high speed subsonic outflow or inflow, the unsteady effects at the open end must be included
making the analysis much more difficult.
Supersonic Outflow/Inflow
Since for supersonic flow the flow velocity is larger than the propagation velocity of the
Interactions with Boundaries
Stationary Boundaries
Near a stationary wall the fluid velocity must equal zero. This implies that a wave must reflect in a similar
sense as shown in the diagram below. For example, consider a right-running compression wave (d
Warm-up Question (1):
After the reading, Im feeling.
A. excited to be using calculus! Yay math!
B. scared to be using calculus! Oof math!
C. centered, and with inner peace. Om.
D. off-center, and in need of inner peace. Moo?
E. reading?
1
Announcements
Warm-up Question (1):
1
After the reading, Im feeling.
A. ready to tackle mechanics of materials, for I
am a materials science and engineering major.
B. excited to see method of sections again: its
not just for bridges any more!
C. like all of the things
Review Question:
A uniform rod of length and weight W is supported on one end by a
smooth wall, and on the other end by a lightweight cord of length s
attached to the wall. In this configuration.
A. both the rod and cord are 2-force members.
B. both the r
Review Question:
Replace the loading shown by an equivalent single resultant force and
specify the (x,y) coordinates of its line of action.
A. 800k N, x=2.125 m, y=4.50 m
B. 800k N, x=2.875 m, y=4.50 m
C. 1000k N, x=1.70 m, y=3.60 m
D. 1000k N, x=2.30 m,
MSE206: Mechanics for MatSE
Schedule:
Lecture: MW 2:00-3:50pm in 1320 DCL, Prof. Dallas Trinkle
Discussions in 4101 MSEB
AD1: F 1:00-1:50pm, Nicole Jackson and Dr. Laura Nagel
AD2: F 2:00-2:50pm, Dr. Laura Nagel and Emily Schiavone
AD3: F 3:00-3:50p
Warm-up Question (1):
What
A.
B.
C.
D.
E.
are you going to bid on at the MA auction tonight?
Keane/Kriven dinner
Faculty-student volleyball
Faculty-student basketball
Athenas hand-crafted keychains
Prof. Krogstads caramel brownies
1
Announcements
2
Remind
Warm-up Question (1):
An acceptable pun title for this chapter is
A. Bending Like Beckham
B. Beaming With Moment(ary) Pride
C. Flexure Muscles
D. Bending Bankruptcy (chapter 11? get it?)
E. There is no acceptable pun title.
1
Review Question (2):
2
Consid
Warm-up Question:
Whats your favorite part of EOH?
A. The cotton candy
B. No discussion section!
C. Hanging out with your friends while youre
supposed to be working on your EOH project
D. Showing kids (and adults) how awesome
MatSE is!
E. Too many people
Warm-up Question (1):
After the spring break, Im feeling.
A. refreshed, renewed, ready for mechanics of
materials!
B. Woooo! Spring break!
C. optimistic about spring weather.
D. I watched soooo much basketball.
1
Exit Ticket
Why do we need the superpositi
Review
Demonstrated a standard tension/compression test and begin
interpreting the stress-strain curve that results
Differentiated between ductile and brittle materials
Defined the yield strength, ultimate tensile strength and Youngs
modulus and extract t
Warm-up Question (1):
1
If any of the wonderful magical things/
characters in Harry Potter could be real, I would
definitely pick.
A. Flying broomsticks (time for some real
Quidditch!)
B. Chocolate Frogs
C. Invisibility Cloak
D. Portkeys
E. Talking paint
Review Question:
When a bar is placed under uniaxial tension, it extends in the direction of
the load by 0.1%, while it shrinks in the direction perpendicular to load
by 0.05%. What is the maximum amount of shear strain in the bar?
A. 0.20%
B. 0.15%
C. 0