ABSTRACT
Though not realizable in a real probe, the -ideally-clamped beam is wellunderstood theoretically and serves as an excellent vehicle to test the modal response of piezo-driven cantilevered beams. In the first experiment, an ideally-clamped beam, with a surface-bonded piezoelectric transducer mounted near its clamped end, was plucked and the damped vibrations recorded versus time. The beams, made of 0.38 mm brass sheet, were 31 mm long and 2.5 mm wide. The piezo-transducer output waveform was recorded with a digital oscilloscope. Fig. 2 shows (a) one cycle of the sinusoidal waveform, (b) several cycles of the damped sinusoid, and (c) an RLC equivalent circuit. The fundamental natural frequency .fn1 and exponential decay rate, quantified in terms of the logarithmic decrement On', were determined directly from the response . ... ,. .. ...,. .. .,., ... l!kllln: ibis Average a
(a) (b)
p-force :X:- velocity
(c) Fig.2: (a) one cycle of resonance, (b) the damped sinusoid, (c) series RLC equivalent circuit.
