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Harvesting main crop rice with a wide header at a required height can increase its ratoon crop yield by decreasing the stubble rolling rate. However, an increased harvest width brings in more input material in a specific time, causing the size enlargement or working speed slowdown of harvesters. To solve this issue, a double-cutterbar structure was proposed. To provide a design baseline for the structure, the cutterbar configuration methods based on rice plant deformation were developed and verified, stalk shearing tests were conducted, and a double-cutterbar prototype was fabricated and tested. The results indicated that the methods developed for the configuration of the upper and lower cutterbars could considerably implement their functions of lowering the straw-grain ratio and keeping stubble height as required. The shearing tests indicated that the bevel angle significantly influenced the total shearing energy on each cutting point in Internode 2 and 3 (p &lt, 0.05) due to the increased stalk cross sectional area. The stubble rolling rate, panicle straw length and stubble height of the developed harvester were 26.9 %, 125 &plusmn, 80 mm and 332 &plusmn, 22 mm, respectively, which could meet the requirements of main crop rice harvesting. The outcomes indicated the functionality and practicability of the double-cutterbar structure developed based on rice plant deformation and shearing properties.

This paper deals with the numerical calculation method of deflection deformation of rice stalks. Due to large deflection of rice stalks caused by reel operation, it is improper to adopt the conventional formula that is usually used in small deflection calculation to fit rice stalk deformation curves. Therefore, a large deflection calculation formula in combination with Simpson&rsquo, s formula was utilized to compute flexural rigidity (EI) and to fit curves. The experiments were conducted under different loads (0.03, 0.04, 0.05, 0.06, and 0.07 N) on a self-established deflection testing rig to verify this method. As a result, the measured results corresponded considerably to ones predicted by this method, furthermore, the flexural rigidity was maintained at a stable level under different loads. This study can provide the basis for establishing a complete deformation model of rice plant and can also be applied in deflection calculation of other stalk crops.