Civil Engineering Reference
In-Depth Information
Table 2.1
Impedance and mobility of the simple elements mass, spring and viscous damper.
F
- force,
v
-
velocity,
a
- acceleration,
k
- spring stiffness,
c
- damping coefficient.
Element
Symbol
Calculation
Impedance
Mobility
jω
m
1
/
jω
m
d
v
F
F
=⋅ =
ma m
=
j
ω
mv
Mass
m
d
t
j
k
ω
j
k
ω
k
F
∫
F
=⋅=
kx k vt
d
=−
ω
−
j
k
Spring
c
1/
c
Damper
(viscous)
F
= ⋅
F
c
cv
100
80
10
7
N/m
10 kg
60
10
6
N/m
1 kg
40
10
5
N/m
0
.1 kg
20
Mass
Stiffness
0
10
100
1000
20
50
200
500
2000
5000
Frequency (Hz)
Figure 2.5
Modulus of impedance for the components mass and spring, given as a function of frequency. Mass
weight and spring stiffness are indicated on the curves.
