10
•
After measuring the period T the natural frequency
of the system
ω
0
can be obtained from
ω
0
= 2
π
/T = 3.3069 Hz
•
The most extreme deflection arises at a motor volt-
age of 7.6 V, i.e. the resonance case occurs.
•
Then the same experiment is performed with an
eddy current brake connected at currents of
Ι
= 0.2 A, 0.4 A and 0.6 A.
ΙΙΙΙΙ
= 0.2 A
Motor voltage V
ϕ
3.0
0.9
4.0
1.1
5.0
1.2
6.0
1.7
7.0
2.9
7.6
15.2
8.0
4.3
9.0
1.8
10.0
1.1
ΙΙΙΙΙ
= 0.4 A
Motor voltage V
ϕ
3.0
0.9
4.0
1.1
5.0
1.3
6.0
1.8
7.0
3.6
7.6
7.4
8.0
3.6
9.0
1.6
10.0
1.0
ΙΙΙΙΙ
= 0.6 A
Motor voltage V
ϕ
3.0
0.9
4.0
1.1
5.0
1.2
6.0
1.6
7.0
2.8
7.6.0
3.6
8.0
2.6
9.0
1.3
10.0
1.0
•
From these measurements the resonance curves can
be plotted in a graph depicting the amplitudes
against the motor voltage.
•
The resonant frequency can be determined by find-
ing the half-width value from the graph.
Resonance curves
1
5
10
15
20
A
[skt]
0
1
2
3
4
5
6
7
8
9
10
I=0,0A
I=0,2A
I=0,4A
I=0,6A
u[v]
3B Scientific GmbH • Rudorffweg 8 • 21031 Hamburg • Germany • www.3bscientific.com • Technical amendments may occur
