Medición de frecuencias de resonancia, factor de pérdida y módulo de Young dinámico de varillas empotradas

Abstract

En este trabajo se estudian teórica y experimentalmente las vibraciones forzadas de varillas rígidas y flexibles empotradas en un extremo. Las experiencias que se analizan, además de ilustrar el fenómeno de resonancia en una estructura diferente del clásico oscilador masa-resorte, permiten medir el módulo de Young del material. En el caso de la varilla flexible es fácil visualizar también el segundo y el tercer modo normal de vibración, lo cual nos permite comparar la forma que adopta la varilla, cuando vibra en sus diferentes modos, con las predicciones teóricas. En particular se pueden observar los "cuasi-nodos" (o nodos con pequeña amplitud) que se deben al flujo de energía a través de los mismos para compensar las pérdidas.

Oscillations of end loaded cantilever beams

“…First, we measured the freeend displacement (A 1 ) of the strip for several frequencies in the vicinity of the first mode. Then, the square of this quantity is plotted against frequency [21].…”

“…Bending vibrations in beams with lumped masses at boundaries have been studied based on the advanced Timoshenko theory [15][16][17] and the natural frequencies and modal shapes of the Timoshenko beam have been determined. Some recent works [18][19][20][21] focus their attention on educational applications for experimental study of the cantilever beam. Digilov studies the flexural vibration test of a cantilever beam with a force sensor and describes an undergraduate laboratory experiment for fast determination of Young's modulus at moderate temperatures, which is calculated from the Euler-Bernoulli beam model.…”

Application of a computer sound card for measurement of mechanical vibrations

“…In the work presented in Ref. [2], the forced vibrations of rigid and flexible cantilever beams clamped in one end, are studied. An experiment useful to the study and analysis of the damages caused by an unbalanced machine in a given system when the machine presents a vibration frequency near the char-1 E-mail: everaldoeb@iae.cta.br.…”