Impact of nodal characteristics,moisture content,and position section on the quasistatic and dynamic mechanical strength of sorghum stalks ( Sorghum bicolor (L.) Moench )

Abstract

Sorghum stalks are thin and light, yet they are able to withstand the considerable weight of the spike at the top, as well as the winds of the natural environment. The mechanical properties of sorghum straw are a perfect harmony of plant structure and function. This research investigates the quasistatic and dynamic mechanical behaviors of sorghum straws, concentrating on their tensile, compressive, and bending strengths. The study examines three primary factors affecting the straws: impact of the presence of nodes, the specific section location (positions 1, 2, 3, 4, and 5), and moisture content levels (ranging from 5%–10%, 20%–30%, to 40%–50%). The mechanical properties of sorghum straws were extensively studied in relation to nodes, moisture content, and section location. Under quasistatic conditions, straws without nodes exhibited superior tensile and bending strengths but had lower compressive strength compared to those with nodes. Straws with nodes showed better impact toughness and specific energy absorption under dynamic impact conditions. Both the quasistatic and dynamic mechanical properties of the straws were greatly affected by moisture content. The quasistatic tensile strength of straws with nodes was at its minimum when the moisture content ranged from 5% to 10%, with values of 10.74, 11.22, and 11.46 MPa for sections 1, 3, and 5, respectively. Within the same moisture range, the axial compression strength of node-free straws reached its minimum, with values of 2.92, 4.50, and 6.41 MPa for sections 1, 3, and 5, and the radial compression strength of node-free straws also decreased. For straws with nodes, the impact toughness varied between 0.019 and 0.039 J/cm², while the specific energy absorption ranged from 1.65 to 2.83 J/kg. Given these notable mechanical characteristics, sorghum straws offer valuable performance data for engineering applications. They might inspire the creation of new materials or structures aimed at enhancing strength while minimizing weight.