Elasticity modulus and damping ratio of macaw palm rachillas

Módulo de elasticidade e razão de amortecimento das ráquilas da macaúba

ABSTRACT:

The macaw palm has been identified as a prime feed stock for biodiesel industries in the near future coming decades. However, there are no machines for harvesting and detaching fruits in the biofuel industry; hence, the study of the dynamic behavior of the fruit-rachilla system would aid in the development of such machines. Thus, this study seeks to determine the modulus of elasticity and the damping ratio of four different plant accessions obtained from the Active Germplasm Bank of the Universidade Federal de Viçosa (UFV). Tensile testing was conducted to determine the modulus of elasticity. From the graphical results of tension versus specific strain, it was possible to determine the modulus of elasticity by using the tangent method. To determine the damping ratio, the logarithmic decrement method was performed using vibration testing. Vibration test consisted of a generated impulse of 100% of the amplitude of acceleration that was used to excite the system. The acquisition of the generated information was performed by a piezoelectric accelerometer. The average modulus of elasticity ranged from 2.22 to 3.17MPa, and the average damping ratios ranged from 0.04 to 0.08. Thus, the macaw fruit-rachilla was an under-damped system.

Key words:
Acrocomia aculeata; dynamic behavior; mechanical properties