Effect of moisture content and loading orientation on strength properties of corn cobs

This study investigated the effect of moisture content and loading orientation on strength properties of corn cobs using the Testometric Universal Testing Machine at crosshead speed of 10 mm/min. The strength properties investigated were bio yield point, yield point, rupture point, bio yield strength, compressive strength, rupture strength, modulus of stiffness, modulus of toughness, modulus of resilience and modulus of elasticity. Results show that all the properties decreased with increase in moisture content with values being higher at lateral loading than longitudinal loading, except for the Modulus of resilience that gave higher values on longitudinal loading orientation. In the moisture range of 5.87 to 28.4%, bio yield point decreased from 685 to 220 N and 570 to 150 N at the lateral and longitudinal loading orientation, respectively. Yield point decreased from 2223.6 to 800 N and from 1200 to 600 N, while rupture point decreased from 2130 to 1120 N and from 1280.7 to 576 N on lateral and longitudinal loading, respectively. Biofield strength decreased from 9.5 to 2.9 N/mm2 and 5.5 to 2.6 N/mm2, compressive strength from 3010 to 800 N/mm2 and 2550 to 650 N/mm2, and rupture strength from 2500 to 600 N/mm2 and 2000 to 300 N/mm2 in the above moisture range and loading orientations. Modulus of elasticity decreased from 2500 to 320 N/mm2 and 2200 to 150 N/mm2, Modulus of stiffness from 2600 to 420 N/mm and 2300 to 120 N/mm, Modulus of toughness from 240 J to 100 J and 210 J to 80 J, while Modulus of resilience decreased from 440 to 100 J and 500 to 150 J, for lateral and longitudinal loading respectively, in the above moisture range. Regression equations that could be used to express the relationship existing between the strength properties and cob moisture content were established and these yielded very high coefficients of determination.