Subject: TAKENAKA
Date: Mon, 7 Feb 2000 07:55:59 -0600
From: "Imafuku, Nobuhiro" <Nobuhiro.Imafuku@mts.com>
To: "Larson, Rod" <Rod.Larson@mts.com>
CC: "Rood, Omar" <Omar.Rood@mts.com>, "Shigemasa, Yukio"
     <Yukio.Shigemasa@mts.com>, "Katabami, Yoshihiro"
     <Yoshihiro.Katabami@mts.com>, "Nakashima, Toshiaki"
     <Toshiaki.Nakashima@mts.com>

Hello, ROD san.

Both actuator works fine under TestStar Ils software, but I can NOT tell
you system works 100 % fine. We still have small problem regarding 100
ton actuator. When we supply $B!H(JLOW$B!I(J pressure, actuator sometimes moves
but this level is very small (within +/- 1 mm). I think this is caused
by HSM pressure supply time, so if we get another two slow turn on
accumulators, we can adjust all HSM. The difference between 469DU
software and TestStar IIs software is LVDT excitation frequencyy and AC
phase adjustment. I check oscillation problem by 469DU software with 2
kHz excitation and 0 AC phase, both actuators still goes unstable
(oscillation). But, if we use 10 kHz excitation and about 80 degree AC
phase (50 ton actuator : 78 degree, 100 ton actuator : 83 degree), both
actuators works fine. I think 50 ton actuator works perfect but 100 ton
actuator works perfect if we adjust HSM supply pressure. Anyway, both
system works fine under TestStar Ils software, so we will start training
tomorrow and TAKENAKA will start structure test next Monday. After this
test, TAKENAKA will start seismic test at the end of February. I think
we had better to re-calibrate LVDT with 10 kHz excitation in 469DU
software. What do you think ? Also, I can NOT understand why but do you
understand why excitation frequency effect actuator oscillation ? I need
your comment to explain TAKENAKA.

REGARDS     FUKU
