ศูนย์นวัตกรรมเทคโนโลยีหลังการเก็บเกี่ยว

Mesomechanical characterization of in situ rice grain hulls.

Ouyang, Y. S.

Transactions of the ASAE. Volume 44, Number 2, 2001. Pages 357-367.

2001

บทคัดย่อ

Mesomechanical properties (those on a scale between micro and macro) of in situ rice grain hulls are of fundamental interest in engineering design of cereal postharvest processing equipment. However, their measurement often requires new experimental methods. A scheme was developed combining simple tension and three-point bending tests for characterizing mesomechanical properties of in situ rice grain hulls. Sample groups were examined at 27 deg C, 15% wet basis moisture content, and at 1 mm/minute crossbar speed. The load-displacement curves indicated that the hull fracture was brittle, and it appeared to be more so in the longitudinal tension mode than in the transverse (cross) tension mode. The general material orthotropy in the hull due to longitudinal or transverse cellular texture had a minor effect on these properties. Structural orthotropy was manifested primarily through the overall shape, surface profile, and silicon strengthening characteristics of the rice grain hull. The weakest link  is at the seam where the lemma and palea interlock into an S-shaped 'lap-joint,' where the stress concentration factor based on finite element analysis was from 5 to 9. The nominal structural orthotropy index (SOI) of rice grain hulls was estimated to be 5 to 7.