Effect of Angle of Cut on Corn Stalks Mechanical Cutting Strength and Energy

Abstract

Orientation of fibers or direction of grains in the biomass stalks with respect to the direction of cutting element will influence the force and energy requirement of size reduction. An optimal orientation will lead to useful energy saving. This paper deals with the determination of the effect of angle of cuts with respect to cutting element, utilizing dry corn stalks as the test material (15% - 20% w.b.), and quantify the resulting input energy reduction advantages of optimal orientation. To evaluate the cutting characteristics of tougher corn stalks, a Warner-Bratzler device was modified by replacing the blunt edged cutting element using a 30° single bevel sharp knife edge. Cutting force-displacement characteristics obtained with a universal testing machine were analyzed to evaluate the orientation effects at perpendicular (90°), inclined (45°), and parallel (0°) orientations on internodes and nodes for cutting force, energy, ultimate stress, and specific energy of corn stalks. The corn stalks cutting force-displacement characteristics found to differ with orientation, and internode and node material difference. Overall, the peak failure force, and the total cutting energy of internodes and nodes varied significantly (P < 0.05) with stalk cross-sectional size. The specific energy values (total energy per unit cut area) of dry corn stalk internodes ranged from 11.3 to 23.5 N/mm, and nodes from 8.6 to 14.0 N/mm. The parallel orientation (along grain - 0°) produced a significant reduction on the cutting stress and energy values by one-tenth or better for internodes and about one-fifth for nodes compared to perpendicular orientation (across grain - 90°). The reduced energy requirements of the plant stalks in parallel orientation can be advantageously utilized in developing feeding mechanisms that take material orientation into consideration, when material were presented to the cutting elements during biomass size reduction.