Effect of moisture content on some mechanical properties of mucuna bean

Abstract

Some mechanical properties of mucuna bean seed were studied at different moisture levels to provide relevant data for development of cracking machine for the seed. The frictional coefficient of the seed on five structural surfaces (plywood, aluminum, glass, steel, and wood) was determined using the incline plane method. The mechanical properties were determined using a Universal Testing Machine. The coefficients of friction of the seed on the respective structural surfaces were observed to have increased with increasing moisture levels. The force to crack the seed on its major axis decreased from 1595.1 to 244.9N as moisture level increased from 4.79 to 18.53% (dry basis), with a similar trend also observed on the minor axis. The deformation on both axes decreased as moisture level increased. The stress on the major and minor axes respectively increased from 2.79 to 21.61 N/mm2 and 5.12 to 21.01 N/mm2, as moisture level decreased. The force required to crack the seed and energy to break on both axes decreased as moisture level increased. The stress on the major and minor axes increased with moisture level. Regression equations were used to establish relationships between the properties measured and the moisture level of the seed.