Dynamics: Human Body Models in Structural Vibration

Indirect measurement of the fundamental natural frequency of a chicken

Fig. 19-13: Indirect measurement of the natural frequency of a chicken (Courtesy of Dr J Randall)

Six hundred million chickens are consumed each year in the UK. It has been observed sometimes during transportation that healthy chickens become ill and are unable to stand. Possible causes for this have been found to arise from the effect of resonance associated with the transportation.

In order to prevent the resonance in which a natural frequency of the truck matches the body natural frequency of chickens, the natural frequency of a typical chicken needs to be identified. When studying body biomechanics to determine the characteristics of a human body, a subject is asked to sit or to stand on a shaking table for a short period of vibration. However, this technique cannot be applied to studying the natural frequency of a chicken, as the chicken will fly off when the shaking table moves.

The method developed for indirectly measuring human body natural frequencies could be used to obtain the natural frequency of a chicken. Fig. 19-13 shows a chicken perched on a wooden beam. A slight impact on the beam can generate vibration of the beam and the chicken, which will not cause anxiety in the chicken. When the frequencies of the bare beam and the beam with the chicken are measured, the natural frequency of the chicken can be estimated from the two measurements and a simple equation.