The free-vibration responses of an electric motor of weight 500 N mounted on different types of foundations are shown in Figure Q2(a) and (b). Identify the following in each case:
(a)
Explain the different nature of damping provided by the foundation.5 marks)
(b)
Evaluate the spring constant and damping coefficient of the foundation. (15marks)
(c)
Determine the undamped and damped natural frequencies of the electric motor (5 marks)
x(t),mm
8
4
2
1
0
0.1
0.2 0.3 0.4
t.s
0.5
0.6
(a)
x(t),mm
8
6
4
0
1
t,s
0.1
0.2
0.3 0.4 0.5
(b)