## PSN-L Email List Message

Subject: RE: Shake table
From: felipe luevanos luevanos felicaribe5@...........
Date: Mon, 7 Apr 2008 20:17:40 +0000

```
Hi,
=20
=20
What you are building is nice; have you tried having inverted pendulums sup=
ported by a 2x4 piece of wood all of the pendulums in different lengths wit=
h lets say foam balls of equal or different masses, then you shake the tabl=
e with your hands at diffrent frequencies and observe the totally different=
responses of each (ball/mass/pendulum)?
=20
Good luck
=20
=20
Felipe Luevanos

From: kwyatt@................ psn-l@...................... Shake tableDate:=
Fri, 4 Apr 2008 09:57:58 -0700

Folks,
=20
Thanks for the feedback on the leveling screws for my seismometer.
=20
Now here is a question regarding a shake table.  =20
=20
I currently have a small shake table that has a 10" base plate which I use =
in the public schools to help kids understand the relationship of building =
structure and materials to earthquake damage.  I divide the kids up into te=
ams to construct their "buildings" and then individually set them on the sh=
ake table.  Because only one building can be tested at a time it is more ti=
me consuming and less "fun" for the kids because they can't easily see how =
their building measures up to another team's building.
=20
So, I am constructing a larger shake table with a 30" base that can hold fo=
ur buildings.  This lets a class divide up into four teams and then the ent=
ire class can watch their buildings shake at once.
=20
Say an actual building has a footprint of 100 feet square.  Relative to a m=
odel building which has a footprint of 12 inches square, the width is a fac=
tor of 100.  I have a variable frequency motor to which I am attaching off =
center cams to create the vibration movement.  Springs pull back the base t=
owards the drive shaft with the cams.
=20
So, here is my question.  Has anybody experimented with a shake table of th=
is size?  What displacements should I design the cams to create?  I could u=
se different size cams to create different "magnitude" earthquakes.  Also, =
what frequencies should I set the motor to run.
=20
Thanks for any help that you might offer.
=20
Kay
=20
_________________________________________________________________
Connect to the next generation of MSN Messenger=A0
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Hi,

What you are building is nice; have you tried having inverted pendulums sup=
ported by a 2x4 piece of wood all of the pendulums in different lengths wit=
h lets say foam balls of equal or different masses, then you shake the tabl=
e with your hands at diffrent frequencies and observe the totally different=
responses of each (ball/mass/pendulum)?

Good luck

Felipe Luevanos

From: kwyatt@.............To: psn-l@..............Subject: Shake ta=
bleDate: Fri, 4 Apr 2008 09:57:58 -0700

Folks,

Thanks for the feedback on the leveling screws for =
my seismometer.

Now here is a question regarding a shake table.&nbs=
p;

I currently have a small shake table that has a 10"=
base plate which I use in the public schools to help kids understand the r=
elationship of building structure and materials to earthquake damage. =
I divide the kids up into teams to construct their "buildings" and then in=
dividually set them on the shake table.  Because only one building can=
be tested at a time it is more time consuming and less "fun" for the kids =
because they can't easily see how their building measures up to another tea=
m's building.

So, I am constructing a larger shake table with a 3=
0" base that can hold four buildings.  This lets a class divide up int=
o four teams and then the entire class can watch their buildings shake at o=
nce.

Say an actual building has a footprint of 100 feet =
square.  Relative to a model building which has a footprint of 12 inch=
es square, the width is a factor of 100.  I have a variable frequency =
motor to which I am attaching off center cams to create the vibration movem=
ent.  Springs pull back the base towards the drive shaft with the cams=
..

So, here is my question.  Has anybody experime=
nted with a shake table of this size?  What displacements should I des=
ign the cams to create?  I could use different size cams to create dif=
ferent "magnitude" earthquakes.  Also, what frequencies should I set t=
he motor to run.

Thanks for any help that you might offer.

Kay
Connect to the next generation of=
MSN Messenger=A0  Get it now=
!
=
```