Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Mechanical measurement system
Reexamination Certificate
2002-09-17
2004-04-06
Barlow, John (Department: 2853)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Mechanical measurement system
C702S042000, C702S033000, C702S035000, C702S058000, C073S011040, C073S024010, C073S587000, C073S662000, C073S663000, C700S030000, C706S023000, C310S090500, C310S051000, C356S072000, C324S076210, C324S076330
Reexamination Certificate
active
06718270
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an actuator system and a vibration testing method used for evaluating characteristics of a structure which influences an earthquake response or for proving the strength and reliability of the structure by applying a deformation and a load to the structure. More particularly, it relates to a vibration testing device and a method for evaluating a vibration response suitable for a huge structure.
2. Description of the Related Art
A structure is required to be designed so as to have sufficient strength to a load which may be applied to the structure during its use. For example, for building and civil engineering structures, it is important to design them so as to have the sufficient strength to the severest earthquake that may take place during their use. Therefore, a vibration test is carried out to examine a vibration response of the structure itself to the earthquake or to test characteristics of members which influence the earthquake response. For the vibration test, various methods have been proposed. In one method thereof, a deformation or a load which is supposed to be generated at the earthquake is applied to the structure or its members by an actuator to examine a response, a damage state, etc. generated at this time.
In a particular case of the actuator suitable for a large-sized structure, the so-called hybrid experiment techniques have been proposed in which a numerical simulation and a vibration test are combined to reproduce the same vibration state as in the case that a test piece is actually used. One of the above techniques is disclosed in, for example, JP-A-60-13240. Besides, U.S. Pat. No. 5,388,056 discloses an apparatus and a method for carrying out the hybrid experiment technique in real time.
Furthermore, JP-A-9-79939 and JP-A-10-206304 disclose techniques for cooperatively using a plurality of actuators in remote places. These publications disclose constitutions in which a computer as a host sends command signals through a network to drive the actuators at the remote places.
In the case of a huge structure, a part to be subjected as a test piece to the vibration test is also large. Moreover, a plurality of parts of the large structure are often tested. It is difficult from the economical viewpoint that one experimental facility holds an experimental device suitable for the vibration test for such a huge structure. Therefore, it is desirable that one experiment can be performed by cooperatively using the experimental devices in separate experimental facilities that are not always near to one another. Besides, in the case that the numerical simulation is burdened with a heavy load, it is desirable to use a high-performance computer such as a supercomputer. However, such a computer is often put in a different place from the vibration experimental facility. Therefore, even in the case of not using the plurality of actuators, a hybrid experiment using the test device and the computer in remote places is necessary. However, in the technique disclosed in JP-A-60-13240 and U.S. Pat. No. 5,388,056 mentioned above, the computer for performing the numerical simulation is constituted so as to simultaneously control the actuators for the vibration test. This constitution is suitable for performing the test in one experimental facility. Thus, these conventional techniques do not consider the above theme.
Furthermore, the techniques disclosed in JP-A-9-79939 and JP-A-10-206304 mentioned above do not take into consideration a conception of actively varying command signals from the computer in accordance with responses such as the deformation and load of the test piece generated with vibration given by the actuator.
A hybrid experiment technique will be described below, taking as an example an evaluation of an earthquake resistance of a bridge shown in FIG.
2
.
A bridge used for a highway or the like is equipped with a plurality of supporting structures each constituting a footing
102
on a ground
101
and a pier
103
, and these supporting structures support an upper structure
105
via supporting members
104
. A vibration response in the case that the piers are excited horizontally in the IIB—IIB section by earthquake acceleration will be evaluated in a hybrid experiment. Assuming that the whole of the bridges makes the same motion, a partial structure
201
corresponding to one span is drawn and then considered. This drawn structure
201
is divided into a part
202
to be used for numerical modeling and a part
203
to be used as an actual model.
A testing device has a construction as illustrated in FIG.
3
. The actual model
203
(hereinafter referred to as a test piece) is fixed onto a base
301
. A movable part of an actuator
303
fixed to a reaction wall
302
is connected with the test piece
203
. In the connection between the actuator
303
and the test piece
203
, a load cell
305
is so disposed that the reaction forces to the deformations applied by the actuator can be measured. The vibration generator
303
is so controlled as to reduce the difference between a feedback signal from a displacement measuring device (not illustrated), which is incorporated in the actuator, and a command value input to an actuator controller
304
. A computer
306
has a numerical simulation block
23
, a waveform generating block
32
, and a measurement processing block
33
. The computer
306
generates the input of the actuator controller
304
and outputs it to the actuator controller
304
. To calculate this command value, the output of the load cell
305
is used.
The calculation of the command value is carried out by the computer
306
, as follows. By the numerical simulation block
23
, the computer
306
calculates a vibration response of the part
202
converted to a numerical modeling, using the following equation 1 of motion.
[
M
]
{
d
2
x
d
t
2
}
+
[
C
]
{
ⅆ
x
ⅆ
t
}
+
[
K
]
{
x
}
=
{
q
}
+
{
f
}
(
1
)
where [M], [C], and [K] represent the respective matrices of mass, damping, and stiffness, {x} does a displacement vector, {q} does an external force vector caused by an earthquake, {f} does a reaction vector generated at a boundary point between the numerical and actual models.
In the displacement vector, the displacement of the portion corresponding to the boundary point between the numerical and actual models is used as a command value to apply a deformation to the test piece
203
. If {q} and {f}, which correspond to external forces, are known, vibration response displacement vector {x} can be obtained by numerical integration at intervals of a minute time. For example, according to a centeral difference method, displacement vector {x}
i+1
at time t
i+1
can be obtained by the following equation 2, where suffix i indicates that the value is at time t
i
.
{
x
}
i
+
1
=
{
[
M
]
+
Δ
t
2
[
C
]
}
-
1
(
[
M
]
(
2
{
x
}
i
-
{
x
}
i
-
1
)
+
Δ
t
2
[
C
]
{
x
}
i
-
1
+
Δ
t
2
(
{
q
}
i
+
{
f
}
i
-
[
K
]
{
x
}
i
)
)
(
2
)
{q}
i
necessary for this calculation is a test condition, so it has been stored in the computer or it is externally given in accordance with the progress of the test. For reaction force {f}
i
, the reaction force of the test piece
203
actually generated in the test is measured with the load cell
305
. The output of the load cell
305
is properly processed by the measurement processing block
33
to be used as the reaction force {f}
i
. Besides, based on the processing result by the numerical simulation block
23
, a time function of displacement to be applied to the test piece is calculated by the waveform generating block
32
. The obtained function is output as command values.
That is, a vibration test process and a vibration response calculating process are simultaneously
Horiuchi Toshihiko
Konno Takao
Barlow John
Bhat Aditya
Crowell & Moring LLP
Hitachi , Ltd.
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