Dynamic Cutting Properties of Miscanthus (giganteus) Stems Using an Impact Tester

Abstract

Miscanthus (giganteus) is a relatively new energy crop. Its mechanical properties are important for the design and modification of harvesting and processing machines or equipment. The cutting strength is critical to improve the field performance of mowing and other cutting mechanisms. The effects of the cutting blade type, sample supporting method, and sample locations (upper or lower) where it was taken from a single plant stem on the cutting force and energy were studied. A serrated cutting blade and a flat blade were selected to cut Miscanthus samples at the node and internode using a high-speed impact tester. The cutting force, sample diameter, and cutting speed were recorded. The specific cutting force and energy were then calculated based on the cross-sectional area of the stem sample. The average diameter of the Miscanthus samples used for this study was 9.5 mm. The blade cutting speeds for all treatments were ranged from 8.2 ms−1 to 11.3 ms−1. Overall, the maximum specific cutting force and energy of the flat blade were found at the upper portion of a plant stem, which was 441 N cm−2 and 8.3 J cm−2 at the node when one side of the stem sample was fixed, and 469 N cm−2 and 12.1 J cm−2 at the internode if both sides of the sample were fixed. The cutting strengths at the node and internode were significantly different no matter at the upper portion or lower portion of the plant. When using the serrated blade, the maximum specific cutting force was also found at the upper node section with a value of 511 N cm−2 and 437 N cm−2 for one-side fixed and two-side fixed, respectively. Meanwhile, the corresponding maximum specific cutting energies for these two cases were 10.5 J cm−2 and 10.3 J cm−2, respectively. Statistical analysis showed that the blade types and stem sample locations significantly affected the specific cutting force and energy with a 95% confidence level. The sample support methods did not make significant differences when comparing the specific cutting force and energy; but the actual cutting force and energy were significantly different.