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Suwat Sidthilaw
02-14-1995, 05:17 AM
Dear Netters,
According to my request about methodology and device to measure
impact force three weeks ago, I've got some response. I very appriciate
for your time and your suggestion. I'm now posting the results of that
request to the list.

Thanks to Juan Carlos Garbalosa, Center for Locomotion Studies ,
Pennsylvania State University, also thanks to Erik Eustache. Special
thanks to Professor Jim Sawhill, Professor Dennis K. Lieu at M.E., UC
Berkeley, Madeleine Moffitt at U.C. Berkeley, and special thanks to
Andrew Dainis.
Thanks again, Suwat.
Here are the results for my request.

Date: Tue, 31 Jan 1995 14:43:55 -0500 (EST)
From: SAWHILLJ@queen.lsc.vsc.edu
To: sidthils@UCS.ORST.EDU
Subject: Re: Need Help:Methodology and device to measure impact force

Read a thesis by Bruce Abbott from Washington State University done
approximately 1986. I was his major advisor.
We built a device incorporating a Kistler 3 axis force transducer into
an adjustable height stand and with a stiking pad that moved, once struck,
until it reached the end of its excursion on bearing shafts. A/D records
of the strikes also included the collision of the pad at the end of its
excursion giving us a dynamic view of the picture.
Last I knew Bruce was living in Spokane, WA area (actually Cheney) and
was looking to work at Eastern Washington University. You might find
him in that area and he would be more than willing to help out. He
personally owns the instrumentation, but you could easily replicate, or
improve it, in Corvallis.
Does Riley Chan still work in Chemical Engineering?

Good luck, Jim
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Date: Wed, 1 Feb 95 09:45:35 -0500
From: dainis%bmlvax.dnet@dxi.nih.gov
To: dxi: : , "sidthils@ucs.orst.edu"@ucs.orst.edu ; ;
Subject: Corrected message from Andy Dainis

Hello Suwat,

I have successfuly used a ballistic pendulum to measure punching and kicking
forces on more than one occassion. It is a device that is very simple and
inexpensive to build, and provides accurate results, as well as being
easy to
calibrate. In its simplest form, suspend a padded weight from the ceiling
with
a rigid bar, so that it pivots at the upper suspension point. If you
strike it,
the pendulum will swing and you can measure its maximum amplitude, with a
goniometer if you want to get a little fancy. Then, mg(dh) = (1/2)*m*v*v
which
gives you the velocity. Impulse = m*(change in velocity) = m*v = force
integrated over the impact time. If you measure the time of force application
with a simple contact switch, then you can easily calculate the average force
applied. Good luck.
################################################## ##################
Andrew Dainis Ph.D. |
ADTECH |
2002 Ruatan St. | Phone: 301/435-0785
Adelphi, MD 20783 | Fax/Ans: 301/434-5569
U.S.A. | Email: dainis%bmlvax.dnet@dxi.nih.gov
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Date: Wed, 1 Feb 1995 13:33:41 -0800
From: Dennis Lieu
To: sidthils@ucs.orst.edu
Subject: roundhouse kicks


If you send me your address, I will send you a paper on some work we have
done. There will also be a general interest article in the next issue of
the U.S. Taekwondo Journal, if you can get a copy of that. Maybe you can
visit us some time...

Dennis K. Lieu
Associate Professor
Mechanical Engineering
UC Berkeley

++++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++
Date: Thu, 2 Feb 1995 08:39:58 -0800
From: Dennis Lieu
To: sidthils@ucs.orst.edu
Subject: Re: roundhouse kicks

I put some of my papers in the mail for you. If you do not receive them
in a week, please let me know. Feep in mind that measuring impact *force*
can be very misleading. You need to know the force duration, and impact
velocity as well. Overall *energy* content must be considered.

A Prof. Willy Peiter, in the PE Department of Oregon State or University of
Oregon, as done a lot of work is the study of taekwondo injury. Have you
contacted him?

D.K. Lieu

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!++++++++++++++++++++++++++++++++++++++\
Date: Thu, 2 Feb 95 22:03 EST
From: Juan Carlos Garbalosa
To: sidthils@UCS.ORST.EDU
Subject: Re: Need Help:Methodology and device to measure impact force

Suwat
If you are only interested in the normal forces of the kick (foot-object)
you m
ay want to look at the Pedar unit manufactured by Novell. If you need
further
information let me know. Good luck!
Juan Carlos Garbalosa
Room 10 IM Building
Center for Locomotion Studies
Pennsylvania State University
e-mail: jcg2@psuvm.psu.edu
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