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 http://imagine-msn.com/messenger/launch80/default.aspx?locale=3Den-us&sourc= e=3Dwlmailtagline= 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= ble
Date: 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
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