Download Cubic Stiffness Estimation Exercise 3 Beam TIRA Shaker Axial force

Cubic Stiffness Estimation
Exercise 3
Figure 1 shows the experimental test rig on which measurements were made. Four
channels of data were captured:
1. The source signal supplied to the amplifier that drove the shaker
2. The force between the shaker and the beam
3. The acceleration of the beam at the point where the force was applied
4. The acceleration at the centre of the beam
Axial force
DYTRAN
Force gauge
Beam
B
TIRA Shaker
A
Fig. 1. Photograph showing the experimental setup for the stepped-sine measurement
of the beam-shaker system. A, Accelerometer 1; B, Accelerometer 2.
In the data file provided the measured acceleration of the middle point of the beam is
given when the shaker was excited with a stepped-sine signal with various voltage
levels supplied to the amplifier, 0.10 Volts, 0.12 Volts, 0.14 Volts, 0.16 Volts, 0.18
Volts, and 0.20 Volt.
The mass of the equivalent single-degree-of-freedom (s.d.o.f.) system is 0.345 kg.
Suppose that the equivalent s.d.o.f. system is a Duffing-like system.
Estimate the cubic stiffness of the equivalent Duffing system using a linear
least-squares fit to the data as discussed in the lecture.