Mechanical Properties of Rice Ear and Grain

Abstract

Mechanical properties of rice ear and grain were studied, which were of major concern in their proper handling; harvesting, drying and processing. The results were as follow.
1) Before dead ripe stage, there was a high positive correlation between stripping force (the tensile strength of abciss layer) and the moisture content of primary branch. Stripping force decreased in magnitude with a decrease in moisture content.
2) On the other hand, as moisture content decreased, the tensile strength of primary branch increased.
3) At dead ripe stage, there was not a correlation between moisture content and stripping force, as moisture content depends greatly on weather. But the distribution of stripping force is normal distribution, then knowing its universal average quantitative expression about the hardness of stripping is possible.
4) The angle between subsidiary empty glume and secondary branch was not a right angle. When this angle clossed to 90 degree, it required large stripping force. Stripping force was variable with the direction of tensile force.
5) The tensile strength of rice grain was much higher than compressive strength; at low moisture content the former was 1/10 of the latter and at high, 1/15. The fracture under compression, in, substance, is tensile fracture.
6) As moisture content increased, tensile strength decreased. At 20% moisture content the mechanical property of rice grain changes; at the lower moisture content rice grain is rich in elasticity and at the higher moisture content, in plasticity.
7) The rice grain of which moisture content is lower than 15% is elastic body and Young's modulus of elasticity values about 500kg/em².